Had it with the Bosch water heater!
Written by julio on January 23rd, 2007We have had a love/hate relationship with our water heater for 2 years now. It’s a Bosch 635ES (aka 250SX) tankless, which for the most part, we love. It’s energy efficient and is great when we have guests and need to do 4 or 5 showers in a row (or even run 2 showers at once). So what’s the problem?
Noise. Since day one, this heater has made one of two different noises:
- A loud, combustion-engine-sounding, house-shaking groan/grunt upon startup, and/or
- A loud whistle during operation that can be heard a block away
The noises are related to the gas valve in the unit. It is apparently very finicky and tough to get adjusted properly. If the gas delivery is too little, it’ll groan; too high, and it’ll whistle. We are often lucky enough to get both. Our next door neighbor has asked questions such as “did you know your house farts?” and “why did you have a 1kHz tone coming out of your house?” (He works for a radio station, so I guess he listens to sine waves in his spare time). While they’re laid back enough not to let it bother them too much, it bothers me that we keep projecting noise out into the neighborhood. Since we already have 2 dogs and a 4 year old, it’s best not to add to the list of noise makers! The part that drives me insane is that we paid a ton of money for this thing, so I don’t think it’s unreasonable to expect it to be quiet.
I have called Bosch tech support a couple of times, and they’ll walk me through the adjustment procedure. One time I even paid an “expert” listed on the Bosch website to make the adjustments. He turned out to be an ordinary plumber who also had to call Bosch to learn how to adjust the valve. Big waste of $$. Each time it’ll work great for as long as 24 hours, then it’ll start making one of the noises. I’ll then adjust it so it only grunts, since it only happens when firing up vs. a 10 minute whistle during a shower. I have probably tried adjusting it at least 20 times, but I can never find the sweet spot.
Earlier on, there was a possibility that the unit was not getting enough gas, since our heater is on the opposite side of the house as the gas meter. To rule out the possibility, I changed out the 3/4″ line with 1″. No change. A year later, I changed over half the 1″ line to 1 1/4″. Everywhere I tried to find it, I was asked “you want it for what??” Nobody had ever heard of someone putting 1 1/4″ in a residential application, but I pressed on until I found it at a local plumbing supply shop. There was a slight lingering doubt due to our being about 1′ over the Bosch-recommended length for 1″ line, once all the elbows were factored in. I was pretty sure it wouldn’t even make a difference, but I had to find out for sure. And besides, even though I was often mad enough to rip the heater off the wall, it was maybe $60 to change out the pipe again vs. the $1000 that the heater cost. Guess what…even the mammoth line didn’t fix the problem. Even with the furnace and gas dryer running full blast, the heater is still getting well above the minimum pressure it needs. I know, because I found a way to make a homemade manometer on the net and tested it out.
I’m not sure how we ended up 2 years down the road, not really any closer to solving our problem. The only thing that has changed is my willingness to do something drastic, if necessary. I just sent Bosch a long email today, basically as a plea to hopefully have them send someone out to replace (or somehow adjust) the gas valve. To really adjust it properly, a CO2 meter is required, but neither I nor the “expert” had one. In case worse came to worst, I found the valve online, and it’s a $350 part! For that money, we could almost buy a new (smaller) heater once the new Federal Tax credit is factored in. We’ll see if Bosch responds favorably to my email and how long my drive to replace the heater lasts. It usually dies out just as soon as I figure out how much we’d have to pay, at which point I start thinking “well, it’s just a little noise…”
Picture of the water heater right after being installed (with the original 3/4″ gas pipe) [note: the install was not quite finished, so you don't need to comment about the partially-finished temp-pressure release or the lack of pipe insulation]
Picture of the insane 1 1/4″ gas line (the black line running to the right) as it transitions to the 1″ line. It doesn’t look too big in the picture, but keep in mind that our joists are true-dimension 2×10′s!
Feb 2, 2007 update:
This story did end happily. See the new post here.
The short version of the story is that Bosch offered to replace our two year old unit with a brand new one in an effort to take care of the problem. The new one works perfectly.
Aug 19, 2008 update:
We’ve now gone through two summers since installing the new heater. Around August, we’ll find that the heater will turn off at least once during a shower. I’m assuming it has something to do with the incoming water temp being higher than the rest of the year, but it still doesn’t make sense as the flow rate for a shower is well above the heater’s minimum. Since it has happened two summers in a row, I am further convinced that there is a design flaw in this heater.
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Just from reading other houseblogger posts by people who have tankless water heaters it seems this is a standard for these. I was interested in replacing my old water heater with one of these but will not do it until improvements are made.
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Thank you for posting about this. We are considering a tankless system in our new home. I hope it all works out because I really like the idea of a tankless system. Have you heard of others with this issue? I have always heard that it is more difficult to install these in old homes because of the requirement of a larger than normal gas line (sounds like you have explored this). I am interested in hearing about how this works out.
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We have a Titan tankless that’s electric. The main reason I didnt go with gas is that I hate the gas company. The electric tankless was only $229, it works pretty well. The only two areas I have an issue with is filling the bathtub, the water comes out luke warm due to the high rate of flow. Once we have our master bathroom done upstairs the clawfoot in it will have a shower so I’m not too concerned with it. The other is the time it takes for the hot water to get over to the kitchen, we’re going to add a second tankless on that side of the house though so it should take care of it.
I think Bill over at Enon Hall is having a similar problem as yours.
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Man, I was *this* close to getting a tankless for my house. Between you and Enon Hall’s experiences I think I’m gonna put the kibosh on that plan.
It’s too bad because I live alone and mostly eat out so it made no economic sense to keep an 80-gallon tank of water hot 24/7. My girlfriend’s brother-in-law is a master plumber and although he’d never installed one he said there was a bad buzz about tankless heaters in his industry and they’re being maintenance queens. Richie from Sessa Plumbing here in Bay Ridge echoed those comments and also said that the burners in the gas-fired tankless heaters need a special stainless flue liner due to the high heat and moisture in the exhaust gases.
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My intention really wasn’t to sour anyone on tankless heaters, because I do think they’re great. BUT, given my experience, I’d hesitate to recommend the Bosch brand. I have a friend in CA with a Norwitz heater, and he says it’s great. Since this is one of the larger units, we have no problems with lukewarm water – I’d estimate this thing is running less than 50% of it’s capacity with a (low-flow) shower. Throwing a dishwasher or washing machine into the mix doesn’t faze it at all.
BrooklynRowHouse – you’re correct that it needs special stainless venting, which is about $200 for a basic kit (mounted on exterior wall with venting right out the side of the house just above the unit).
Because of all the “special” considerations, I haven’t recommended these to many of our friends. Once I get through the list of caveats, they drop the idea. For me, the energy conservation was the #1 factor, so I’m willing to put extra work and money into it. But had I known our path ahead of time, I might have considered a tank. In our case, we replaced a 20+ year old gas heater, so the energy savings were dramatic. Our old gas bill was about $29/mo in the summer, with me taking 8-10 showers a month while working on the house. The current summer bills are $14-15/mo, with 3 of us taking showers and running a gas dryer. It’s especially great when we go on vacation and automatically save energy without even bothering to turn anything off. However, I know that tank insulation and overall technology has improved greatly over the years, so a more realistic comparison between a brand new tank and a tankless might would likely not be so dramatic.
After I get this all sorted out, I’m planning to write a new post detailing all of our experiences from start to finish. We also are in the process of adding a 2nd “mini” tank to feed our bathrooms with instant hot water. As you’ve likely read before, tankless heaters are great for showers, laundry and the like, but they are not good for hand and dishwashing due to the minimum flow requirements.
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Try and go over to HeatingHelp.com . There is a lot of knowledge to tap into over at that sight.
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I’ll second Rob’s suggestion to check out heatinghelp.com Be sure to ask very specific questions and don’t even hint that you will be doing the work yourself.
When I replumbed my house I got a lot of odd looks when I said I wanted 1-inch back to the water heater. The idea was that one day I would be putting in one of these babies. I know two other people who have them and don’t have this problem. One is a Bosch and the other is a Japanese model that I can’t think of right now. My gut feeling tells me it’s the $350 valve.
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Julio, I don’t know how many people actually looked at your pictures.
I saw immediately a problem.
Your 1″ or 1 1/ 4″ lines do not go all the way back to your gas meter. I am almost sure you have a 1″ supply line coming to your house. That means your gas volume is finite.
Installing a 1 1/4″ pipe somewhere inline after the meter will not get you a larger gas volume. I can see in the pic of your original ¾†setup a gas valve installed which looks like the bore in the ball might not be of ¾†diameter.
In your transition pic a thinking mistake is obvious. Going from 1†to 1 ¼†will yield you nothing except a pressure drop in the larger line – not a greater volume.
The bottom line, Julio, to solve your problem, is a continuous homogeneous gas line of the same size from your Bosch all the way back to your incoming gas meter without any restrictions smaller than 1†if you are using a 1†pipe.
Total length of the gas line as well as the number of elbows will have a significant impact on your gas flow/pressue.
A 3/4†has always been sufficient for most applications.
Also your plumber should have used black parts and not galvanized ones.
Your methyl mercaptane in the gas will over time react with the zinc and form zinc mercaptide and zinc sulfide, which will eventually clog your fine screens in the gas valve on your appliance.
For the joints a sealing paste is used rather than Teflon tape.
Always remember that a plumber is a plumber and not a brain surgeon or a rocket scientist. He probably does not remember the fluid. mechanics or gas laws from his physics class,
A better choice would have been the 125FX model (smaller output but considerably less maintenance problems)
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BERND,
Thanks for the information. I’ve got a couple of comments…
The gas line is 100% black pipe…there is no galvanized in the system. Also, the line is just about 100% 1″ or greater after the meter (except for about 2′ at the heater). The pic I put up was very old, and it looks very different today. I did learn that paste was better for gas and replaced the few teflon joints with paste.
I added the 1 1/4″ line to replace about 50% of the 1″ per Bosch’s recommendation. It’s been WAY too long since my college classes that would have covered gas pressure/volume issues, but I do believe that Bosch’s position is at least a reasonable one on this issue. While the pressure would drop in a larger pipe, it would have the ability to move a much larger volume. A tankless heater needs a large supply of gas, which moves quite freely through the 1 1/4″ pipe. I think principle is illustrated well by thinking of an extreme example.
If you had a few feet of 1/2″ pipe after the meter connected to a 100′ run, would the heater get more gas if the 100′ section was 1/2″ or 1″? Just because it may be more restricted at one point doesn’t mean that there’s no benefit to increasing the size over a later section. Obviously, the longer the 1/2″ is, the less benefit there would be to increasing it down the run. A big benefit I believe I get out of the 1 1/4″ pipe is that the bends no longer cause me grief. Bosch says to add 5′ to the distance calculation for each elbow, so that adds up quickly. I don’t have the spec sheet in front of me, but I believe it allowed 70′ of 1″ pipe and over 200′ of 1 1/4″. By making some of my bends with 1 1/4″, the calcs come out much better. With the bends factored in, my equivalent length came out at maybe 72′ of 1″, so that’s why I opted to add the 1 1/4″ to give a margin of error.
I can attest to the fact that gas delivery is not a problem. When a bunch of faucets turned on, this thing can crank! It’s a simple issue of startup noise that won’t go away at any setting of the gas valve, unless I turn it enough to make it whistle very loudly.
I appreciate your input on a smaller model. That is the direction I will be heading if I have to replace this. Of course, I will be getting a different brand this time!
Bosch has not replied to my email after 3 days, so they are not living up to their 24 hour promise. I’ll call them next week and then make a decision on what to do…
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I work for the local gas utility as an engineer (and am fixing up my 1938 Californian Bungalow). The problems you are experiencing could be related to your local gas system, rather than the heater.
In older neighborhoods, the a low delivery gas pressure is maintained for the entire neighboorhood at one regulator station. In modern systems a high distribution pressure is stepped down from the house, typically droping from 60 psig to 0.25 psig. If your gas meter set is lacking a regulator, you are on a low pressure system.
Low pressure systems will not be as responsive to pressure drops in a single household as high pressure systems. If you are on one, the pressure in your houseline may be dropping too low on start up due to no fault of yours or Bosch. We’ve found tankless water heaters and low pressure gas systems don’t get along well.
If you are on a high pressure system you can ask your local utility for higher delivery pressure which could help your problem.
Hope I’ve been some help.
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Jen,
Thanks for your suggestions. We are on a high-pressure system, and (please don’t tell my gas company!) I did goose the regulator a bit to bump up the pressure (per some tips I found on the internet, of course). I have it well into what should be the “zone,” but it’s still not happy.
I can already feel my resolve to see this through slipping, especially if it involved a lot of money. We’ll see what Bosch says when I get them on the phone…
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i just installed one a 250sx in my house, and i am sorry to hear all of the problems you have had. so far the unit has been great, so much better than the last tankless unit i had (omega brand – you want to hear a horror story, let me know when you have a few days and i’ll tell you). i am wondering how to adjust the unit for altitude, because i live at 5500 feet. i don’t have a CO2 analyzer and haven’t found any info on how to do it without one. any suggestions would certainly be appreciated. julio, i hope you get your system running smoothly. good luck!
jon
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jon – glad to hear that yours is working well. It’s definitely a quality product, other than the issue I have with it.
I think the CO2 anaylyzer is the only “right” way to do it. The other way is the “turn-the screw 1/4 turn until the noise goes away” method. It’s not very reliable…
If there was a way to rent one, I’d jump on it. Anybody out there have any suggestions on how to find one without having to buy it?
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I updated the post with a link to the happy ending to this story. See above…
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I’d get fired if I was discovered upping the pressure on my house. I don’t recommend keeping it up – it is a felony in California (don’t know about Oregon).
Most gas utilities will adjust your furnace for free (we do at least) and they should have a CO2 analyzer/methane detector extraordinaire in their truck specifically for that purpose. Any serviceman worth his salt though would look at the size of that pipe and check your pressure.
Glad Bosch has stepped up and replaced your unit.
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I so wish I had read this prior to purchasing my bosch tankless water heater. I too have a whistler, and yes it can be heard a block away. What’s worse, it faces our retired neighbors bedroom window, so every morning while we are showering getting ready for work they are blasted out of bed by the horrendous whistle. I just googled in hopes to find a solution when I stumbled on your blog. Is it worth trying to make adjustmens with tech support or should I just return it now? I don’t have 2 years to get it right, our neighbors won’t make it 2 more weeks!
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Ronda,
If it’s new enough that you can just return/exchange it, I would. The adjustment procedure is slightly tedious, and I wouldn’t recommend it, especially since we were never able to get ours properly tuned anyway. To do it right, a CO2 meter is required.
I don’t know whether you did it yourself or used a plumber. Although I’d never pay a plumber to do it because of the expense, it would be a huge advantage when it comes to dealing with the problem. The burden would then be on the installer, instead of you.
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I appreciate the advice. My husband and a plumber friend installed it, and it was quite a task, so I know they will not be thrilled about taking it back down! It does help talk to someone who has been thru it. Thank you again, I’ll let you know how it turns out.
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We are getting close to having a tankless system installed. Anyone heard of a Norwitz? I cannot find any info on the web about Norwitz. As for tankless comments I have seen, they run about six to one negative. Even the posts that are positive include some serious negative thoughts.
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I have a good friend in California who had a Norwitz, and he’s been very happy with it. It is his first tankless experience, and it works so well that he was surprised when I asked him whether or not he had had problems with it. He gave it a big thumbs up when I was contemplating replacing mine.
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It took a lot of Google searches to hit your blog but I am sure happy I found it. I have been laughing out loud reading it and relating to your experience.
I installed a Bosch 250sx here in my old Van Nuys, CA house. I also installed the Webstone Isolator bypass valves, which have been a huge benefit in troubleshooting. If I use the bypass portion of the Webstone valve and fully open the ball valve to a garden hose, the unit senses the flow and turns on, heating the water nicely, though it does make a little noise (sounds like a mild groan or roar) until it stabilizes. If I turn on a valve like a sink or shower, the unit senses the water flow and tries to start combustion that promptly goes out (about 1 second). This process repeats 3 times and then the display shows a code EC. I must have enough gas (pressure and volume) if it runs “full-out”. I am suspecting the CO2 setting but I have no way of measuring it. I am tempted to try some “quarter turn” adjustments on this portion of things to see if it improves. What should I expect turning clockwise vs counterclockwise?
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According to the manual, the CO2 valve is not a culprit for the EC error code. You may want to check the other things it lists… Manual is here
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Im glad your story ended well. I’ve had the bosch 250 SX for 5 months. We are $3000 in to this heater 4 service calls and 5 weeks with no hot water. I live in a city of about 300,000 people. Bosch has no service rep in this area yet thay sell it at Lowes. The plumber that has the most experience I could find says they stopped installing them because of nothing but problems. When the plumber does come the Bosch service center has an average wait of 50 minutes, at $70/hour for the plumber it ads up. Boschs advice,”buy a new unit”
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Would love to hear the horror story on the Omega!! We have one now and it was fine for the first 6 months..the company we bought it from is HORRIBLE! He says he sending a part, etc..and never does. Terrible customer service. So much for buying USA products! Dont buy from the guy in CA. Would like great product (price less important than quality) Will pay more for better products.
rj41206@hotmail.com
Thank you
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I’m back for a follow-up to my post of 28-may-2007. The short version is that Bosch swapped my heater and now I have hot-hot-HOT water.
The longer version follows:
I sent email to Bosch describing my situation (hot water at 6gal/min but no hot water at 2gal/min). They requested a bunch of info to create a file on me, which I supplied. I had difficulty with a couple of lines since I received the heater as a gift and could not verify the vendor. Also, my neighbor was a plumber and helped me install it. He has subsequently relocated out of the area, but was not that significantly involved in the installation other than sweating some copper pipe. I was instructed to call them with my plumber, who didn’t exist, so they could troubleshoot. They seemed interested in dealing with a plumber. I guess I couldn’t blame them. I’m sure most homeowners try to cheat on some of the installation and blame Bosch. That wasn’t the case with me but how were they to know.
Frustrated, I went online for several weeks and finally was able to purchase a UEI c75 combustion gas analyzer on ebay. I also fashioned a manometer from some vinyl tubing and water with food coloring. Using a gallon container, I marked positions on the webstone bypass valve for 6gpm/4gpm/2gpm/1gpm. I went through the Bosch manual and service bulletins and took CO-2 measurements for the settings that I could. I also verified the gas pressure even though I knew it was not a consideration since the device worked at high flow. I even took photos of the installation and video of the behavior the device exhibited at water flow rates below 2 or 3 gpm. I packaged the entire thing into an email to Bosch and received a reply from one of their technicians named Bannon. He requested that I call him from the device. I did so and worked with him for a short time when he indicated that he thought the gas valve was malfunctioning. He was very good to work with. After giving him a credit card number for a deposit he arranged for a replacement to be shipped. The credit card was to guarantee I’d send the old one back.
The new unit arrived and I installed it. It is much, much quieter and delivers hot water once the flow rate is achieved. I’ve had a couple issues. Since I live in Los Angeles and we’ve had record high temperatures recently, the hot water temperature has been very hot at low-flow levels since the water entering the device has been over 70degrees Fahrenheit. Also, one of my showers has very low flow (not sure why but it’s always been that way) so I have to turn on the faucet in the sink to get the minimum flow to cause the unit to fire-up.
All things considered I’m pretty happy with the overall setup. I plan on installing an electric in series and some items to help with water-hammer.
The UEI c75 combustion gas analyzer was really easy to use and provided some really cool info on the C02 levels and temperature in the vent pipe. It was over 500degrees Fahrenheit at the point where I was getting the best CO2 readings. Now that everything is working, I’ll put it back on ebay and hopefully get most of my purchase price back.
Thanks again for your site. It has been a big help
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Charlie,
Wow…you really went above and beyond in your quest. Your story and our experience has made me think that if I were doing it again, it’s better to pay a plumber to do it. But once you add that expense into it, I might just go with a well-insulated tank?
Your update resonates with me a little bit, because we began having some issues at lower flow rates. Our shower is consistently going cold about 4 or 5 minutes into it. The hot water comes right back, but it’s pretty annoying. I haven’t yet measured our flow rate, but even the lowest-flow shower will easily exceed the 3/4 gal minimum. I am also thinking it has something to do with incoming water temp, since it never did it before June. Also, the temp has will spike a bit at that time, so it may even be hitting an overtemp limit. You are inspiring me to get out a bucket and start measuring the flow rate. Damn. I’ll bet I easily have 60 hours of work invested in this heater between install, gas line upgrades, reinstall and gas valve adjustments. Sure wish we picked a different brand!
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Not directly related to above but useful info. I’ve been futsing all day with a Bosch tankless that stopped working overnight. After countless searches I read something about cross-over flow which can reduce the flow through the heater and therefore prevent ignition. FINALLY dawned on me we had just done some work on a shower and to test the soldering had opened hot & cold valves but plugged shower outlet. Perfect source of cross-over. I shut the valves in the shower unit and voila all is back to normal. One problem does remain though. Have to leave the temp adjustment to max hot otherwise the heater does not kick in at all even with no cross over. Hope this helps somebody out there and I’m returning the favor of so many people posting on the net.
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Two years ago, we had a Bosch 635 professionally installed by a plumber referred to us via the Bosch web site. It has been a huge source of aggravation for us, with the installer needing to return 4 times in the last 8 weeks, not to mention the 3-6 times he came to service it before. The unit makes those horrible and rattling noises, then flashes the “EA” code, and gives us no hot water. Our plumber insistes that it is due to water getting into the system through the outside vent, and now recommends a special venting hood. He has repleaced parts many times. Has anyone else had this problem?
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Just when I think I’ve heard it all, someone comes up with something new. If the plumber’s referring to the exhaust hood, that shouldn’t be a problem, as it can exit through the drain hose. If it’s the intake, then I don’t know what’d happen. Unless your installation was really poor, though, it’s hard to imagine it was done in such a way that it’d allow a bunch of water to get in.
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Just wrote a detailed reply on tankless units and lost it when the security code was not accepted. Keep away from the Omega tankless units as they are junk,and Omega 2000 group is a one man show and merely a scam artist. I replaced mine with a Rinnia which I am very happy with. The only issue as stated previously is once you shut the water off you will get a “slug of cooler water when started again. like when shaving or washing dishes where one may be turning the water on and off.I just fill the sink when shaving. It has to do with safety issues as the units are required to see the exhaust fan running before the burner is allowed to start.The rinnia runs very quiet and have had no problems as described with the Bosch units. The rinnia was recommended to me by my Propane supplier who has been installing them for about two years with no complaints.
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Wow what an ordeal…Bosch is certainly at the low end of my preferred manufacturer list. Glad to see a happy resolution
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I just bought a condo with a Bosch Aquastar tankless water heater (brand new). My first shower started out fine, and then the water got hotter and hotter until it nearly burned me (i did not adjust the valve at all). I was able to turn it down (trying to get back to “warm”), and then it shut off all hot water and went straight to icy cold. Even though I lived in Guatemala for two years and am used to cold showers, this was not a pleasant experience. Luckily, I had not signed all the contracts before realizing this problem (I was a squatter), and the seller has agreed to fix the problem. One month, two bosch tankless water heaters later, two visits from ComEd, countless unreturned phone calls to Bosch, and I am still taking cold showers. CUSTOMER SERVICE IS A JOKE. Do not buy this product. And if you happen to know of a solution please post a reply!
Thank you!
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Hi Lindsay,
My friend is having the exact same issue with his Bosch tankless heater. It would be great if someone knew how to fix the issue.
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We have had a Bosch tankless for 2 years and had a problem recently after having a certified trained Bosch dealer come to remore scale from the heater. Then the noises referenced by you in the initial posting was a problem. They came back and adjusted and fine tuned and the noises went away. But we are now trying to find out the best solution for scale on the heat exchanger. If anyone has the best solution for this I would love to hear from you. We had to have the tech run a vinegar solution through the system for three hours to get rid of the scale at our cost of $800.00. We are not happy if this has to be done every year.
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This afternoon I spoke with Ernie at Bosch this is what I learned that there is a scaling problem that was not mentioned in our manual but NOW they address it in their NEW manual! So it is obvious to us there was a problem all along! What happens when there is finally too much scale on the heat exchanger the tank stops working.
In the current manual they suggest a water softener. Amazing as I asked our tech what we could do and he did not seem to know that this was in the new manual but it is on page 29 in very legible print. There are other companies that will have the same problem if your water has any degree of hardness. Our hardness is 7-8.
Then we have others telling us to use an item called a Scalewatcher or special osmosis system it goes on and on. We do say money on the cost of natural gas but everyone has to calculate the initial outlay against the maintenance and the requirement to prevent scaling.
Good Luck
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Dorothy & David,
Thanks for posting. That sounds like a major pain, and that it could get very expensive! You are making me very glad that our water here in Portland is very soft. I was curious after reading your post, so I looked up our water hardness, and it ranges from 1/3 to 1/2 grain of hardness per gallon.
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Hi all!
We have now installed a water softener as when I spoke with Bosch and was told to print their new manual on boschpro.com…this is a much longer manual. It warns in 6 places that the 15 year warranty will be voided if you have hard water which will cause the heat eschnge to fail. Note they do not tell you what they consider “hard” So we have now compared the original manual to the new one and found originally there was no mention of hardness of water or that you need to test the water for hardness before installing the a tankless water heater.
We have written them a certified letter about their discrepancy in the manual we received with the water heater and their newest revision. My advise is to check your water hardness. We found that the Kinetico softener system. It is the best and reliable as it does not depend on electricity and is based on water usage not a timer. Good luck all and we will let you know the results of our certified mailing to Bosch.
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Just put in an Aquastar….this is my fourth…also put in a couple other brands….this was installed in a suburb of chicago…gas simply refused to appear…suspect low gas pressure….have to go back out there…will try to increase gas piping size-wize….but it is a purple drag……..Bosch should sell a regulator with the unit….some way of regulating gas pressure…bring it up or down…..then there is the venting. Double wall piping fails…stainless will not but cost is frankly out of this world. Standard flue liners are OK….but one can never really be sure….my brother had a client replace a third of the brik in thier chimney after one year of “tankless” waterheating without a flue vent! The condensation is like a Chinese laundry. Hard to say if it is worth the bother….obvious the “kinks” arte not being worked out…any time soon. Obvious a PVC hightemp flue pipe system is needed but Bosch does not want the liabillity…those cracked up in the 80′s…lotsa lawsuits! That is what this is all abourt..everyone wants to make zillions…nobody gives a rat’s ass about the planet…..me? I just want to be able to advise my clients. Also…tired of wondering…”is it gonna work”? Jack in Chicago
2
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I too have a Whistler’s Mother.
More than two years with the problem on the 280sx ng. Calls to Bosch have not resolved the problem.
I wanted to prove my installion was ok so I did a test with the flue open and the air intake open and the unit still whistled its tune. I put everything back together. ( That was only for a test)
Looking at my 16 pound sledge I was tempted to adjust the unit forever.
Seeing that Bosch has a problem with these units and really no fixes, I tried some experiments on the air intake.
Disconneting the air intake and placing a modified air intake fashioned from a plastic aerosol can top I drilled holes changing the pattern from the Bosch units air intake. After a few tries,
No noise!!!!! Runs great at high and low flow. Its an air flow problem with this unit. Bosch has to admit that they are causing air turbulence with the various speeds of the fan. It would seem that the air flow of the system is a contributing cause of all this noise, a poor design. These units should be recalled, or fixed!
So far this expeirmental fix is working. I’m going to try and change the hole pattern and make the can top smaller to fit inside the cover so I don’t have any air flow problems.
2
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Looks like you’re on to something, John. Good luck with your research!
17
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Please post a pic of your air intake conversion, I am desparate. I live in Portland OR and have a bosh 635ES. I have had all of the problems listed above and more. I installed the first in 2006. Before Bosh would even care that I existed I spent untold hours proving to them that I installed it to their specs and even better. One and a half years later I installed my second water heater as Bosh finally after 100′s of calls and hours of troubleshooting and replacing parts sent me a new one. On the first one I changed temperature sensors 4 times, and the computer once. The new one has had problems too. One that I didn’t see above, but might relate to Chicago, is the condensation in my 3′ long exhaust pipe was more volume than the condensation drain could handle and the paint on the exhaust collar blistered, cackle off and clogged the drain. In fact if you run it with the vent off you’ll be shocked at how much steam comes out of it.(energy efficient?) It turns out that Bosh has a new requirement that a second condensation drain be put in the exhaust pipe. (This was printed in a Service Bulletin long after I bought my 1st unit) They nicely sent me one. My original design didn’t include this, so of course it was a real pain installing it. I guess the problem is solved, my symptom before was the overflowing water from between the exhaust vent and the exhaust collar. I don’t have water overflowing now but the paint on the outside is blistering. I wonder what’s happening on the inside. Bosh told me that the only thing that water dripping back into the unit my damage is to the gas valve, but that is “not likelyâ€. For now I am fighting the whistling piece of shit. Apparently my neighbors have been putting up with it for years, though maybe only in the warmer months. Now that I am actively investigating it, it seem that it doesn’t whistle until its been running for about 7min. I wonder if it relates to water dripping back into it?
Oh yeah one of the Bosh’s reasons my heater stopped working in August was that the water had to heat to at least 70 degrees higher than it came in at, however if the incoming water was warm the heater would shut itself off because it reached “dangerous hot tempâ€. My first unit would just burn you and melt the pipes so cold showers in August are safe. Aww…… August is coming again I wonder if that problem ever got worked out or if August ended last year and I could no longer troubleshoot it. In the mean time Rinnia has been recommended to me by plumbers, heating companies, and the local do it yourselfer heating specialty store.
12
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Great post. I will have to bookmark your site for later reading.
21
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Really liked this post. I will have to bookmark this site to tell my friends.
17
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I am buying a new tankless waterheater and came across your site. Great information. I’m looking at a Paloma 7.4 GPM unit for a natural gas installation. Has anyone had any experience with these units?
12
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I HATE my Bosch!!!! My husband just HAD to have the stupid thing and I gave it the fish eye from the moment I saw it at the store. I don’t know if we have a lemon or what, but it is coming out of the basement because I am done with it. Hot, cold, hot, cold, hot, cold. Had something in it replaced or adjusted, now it is at it all over again. Junk. Period.
23
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I think the main problem is lack of knowledge. What I mean by that is; you have to be familiar how tankless water heater works. It is different from tank type. First and major thing is to dimension the system properly… not enough gas, not enough power and hot water is not hot. Other thing is minimum water flow rate.
Every tankless water heaters has the minimum activation rate and it can be as low as 0.4 gph… so you have to open the hot water tap little bit more than what you did with the tank heater.
Tankless units are also more sophisticate and therefore, way too sensitive than tank type.
23
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Zee,
While I agree that tankless heaters are more complex and definitely are more exacting in their requirements, there is no question in my mind that these Bosch heaters have a problem. In our case, we did multiple upgrades of the gas line, to no avail. As soon as the unit was replaced, it worked better, proving the first was defective. Even today, ours will (not too often) cycle itself in the middle of a shower (which is definitely over the min. flow threshold), causing a blast of cold water.
I have not hear nearly as many complaints with the other brands.
13
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I also have a Bosch 635 ES and have a problem with it going cold (sometimes daily) after getting the EC error code. Then I have to go into the basement and reset it. I have never had the whistling but it does cycle repeatedly (flame goes out and tries to restart a few times)and make a noise when it is cycling. Sometimes after three tries or so to restart it will get an EC code. I have a long gas run so I ran 1-1/2 black all the way to just before the unit where it has to switch to 3/4. I also installed the second condensate drain as the service bulletin suggests but see no water coming from either one. I have removed the igniter a couple of times and found it had a slight reddish residue on it which cleand off with steel wool. I also found bugs on the top of the heat exchanger that flew into the vent so I cleaned out the bugs and put aluminum window screen over the vent cap. My problem seems to occur mostly in hot humid weather. I believe it is related to low flow rates since it mostly happens when you use the dishwasher or kitchen sink and occasionally the shower. I have it set to 120 degrees which is fine for showers but marginal for the dishwasher. We had a run of cool weather recently (first week of Sept) and it went for a whole week without requiring a single reset from the EC code. Then it went back to needing its daily reset. Maybe the incoming water temp is the issue, I’ll have to start measuring it and see if it correlates. My wife and I are sick of the problem which has been going on for six months and about ready to yank it off the wall. Any suggestions would be appreciated.
7
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We have a Bosch tankless heater and it quits producing hot water. The water flow is fine as I drilled a bigger hole into the shower head and have removed all the water restrictors from the taps. We have removed the cover to allow more airflow. I feel it ia a gas delivery problem. The gas lines in the area are 14 years old so small and low pressure is not an issue. Other people I have talked to have not had a problem wiht there heaters and love it. We hate it, cold showers are not fun. We have the spark operated by batteries. I have just contacted Bosch about changing it to ac. Make sure you don’t have batteries when getting one!! Any suggestions on the problem, we want to get rid of it and get a tank again. Our gas bill increased when this one was installed!!
19
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3 years into a 10 year warranty I’ve just had a catastrophic failure of the heat exchanger.
Bosch 250SX.
Dripping water all over the floor, I’m waiting 2 hours on “hold”, I finally got Bosch service to answer the phone. At that point, I got Scott on the line who spent the next 30 minutes on a mission to figure out how to cancel my warranty. He wanted to know if I had a “momometer” of something like that, what altitude I was at, if I had a water softener, how long my exhaust pipe was… (he wanted me to get up in the ceiling and measure it)… Finally he figured out a was to exclaim that the water heater warranty was VOID because the exchanger had compromised the gave jet by dripping into it and that possible moisture in the 21 foot exhaust pipe had caused the heat exhanger to fail prematurely and that it must be my fault. Now I have a boat anchor…
I installed an electric hot water heater yesterday.
If it fails.. Throw it away and save yourself a lot of aggravation!
Don’t call Bosch… They just want you to go away.
Beware!!!!!!!
Don’t buy Bosch anything!!
19
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Tom,
That’s one of the worst stories we’ve heard. It’s an effective way for them to push away customers!
Julio
16
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we have a Bosch and have all the same problems as others listed here hot, cold, hot, cold, have had it 3 years. checked with local plumbers and they are not hot on these either. could be scaling problem or water restriciton problem. just a pain. we have to let the water run forever just to get it hot and then don’t dare shut if off while doing dishes or else it is immediately cold. showering is a nightmare 5 minute shower usualy takes at least 20 with temp adjustments constantly. we are taking ours out this spring and going back to basic gas heater. this thing was really expenseive around 1500 total for all the special pipes etc.
27
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Just have to add my horror story to the bunch. Our Bosch tankless heater is a worthless appliance that frustrates us on a daily basis. Between the hot, cold, hot, scalding, cold and the shut-offs, we easily waste 20-30 minutes a day dealing with it, especially when trying to do something basic – like wash dishes or hands. Major pain. I would NEVER recommend this to anyone or purchase one again. Biggest nightmare ever. We are thinking of switching back to a tank.
5
AM
i have a bosch tankless and can appreciate all of the comments. i can deal with the loud bass noise at startup, which is my only problem. i will not invest any more money in this heater. i am disappointed with the bosch customer service when i asked to speak to a tech about this issue. i will not buy all the fancy equipment to test this or hire someone to do so. i live in an older neighborhood and now understand that it must be lower gas pressure. i do have a 1″ gas line from meter to heater and a water softener installed before the unit. this technology just isn’t there yet.
i guess i am pretty disappointed in Bosch customer service. seems like all big business leave me hanging like this anymore (e.g. GE, Clearwire, Milwaukee, etc.) they build crap and don’t want to help solve problems. My recommendation is to start a black list and don’t buy these products anymore.
9
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I have the electric version, an AE125. The first one lasted two years and Bosch replaced it no charge. The second one lasted four years after that and the controller went out. After a few back and forth’s Bosch is going to replace it too. Can’t say enough about how well they’ve treated me. I love my tankless water heater.
16
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Can you post a picture of where to adjust the gas valve and some more detail on how to do it? I’d love to give it a go and see if I can get rid of this whistling. A few months back, I tried resticting the air flow in myself same as above by creating holes in a plastic cup and placing it over the intake. Works for a short period of time, but is not fool proof.
20
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Jeremy,
You can see the procedure on pg. 32 of the manual. You have to guess without a CO2 meter, but it shows you how to make the adjustments.