This is a follow-up to my original post about our Bosch 635ES (250SX) water heater, which you can find here.
My first post was a recap of all the problems that we’ve had with this heater over the last two years. Tonight’s post is a very happy one. About 10 days after I sent my long email to Bosch detailing all the steps I’ve taken to remedy the startup noise issue, I finally received a reply. I had given up hope, since they promise responses within 24 hours and an earlier one I had sent months ago went unanswered. Imagine my shock when I read these words:
I am sorry to hear that you are having so much trouble with your water heater. I would like to offer a possible solution. Since you have tried to dial in the air/gas mixture to no avail, I think that we should swap your heater for a new one. Please call our toll free tech support line at (866)330-2730 and we can set this procedure up. I have updated your record to reflect this so any tech you talk to should get it going quickly.Thanks for buying Bosch.
I called the number right away, and the tech support person took only a few minutes to get me set up with an emailed warranty return number and return instructions. I called George Morlan, the local plumbing shop where I bought the heater in December of 2004, and explained the situation to the store manager. Even though he was unable to reach Bosch due to it being after 5 on the East Coast, he said they’d go ahead and swap it if I brought in the old unit. I went home a little early, pulled the old one down, brought it in, exchanged it, installed the new one, and….
Looks like all the agony and gas line upgrades may not have been necessary. My opinion has undergone a complete 180, and my new mantra is:
Bosch tankless heaters are great!
I appreciate all the suggestions that people gave to help troubleshoot the problem, but it looks like we just had the 1 in 1000 lemon. When I think back to how many times I had to fiddle with the gas/air mixture setting on the old one, it felt amazing to have this one just fire up with NO tweaking. I probably took the cover off the old one about 20x to try to adjust it. It is better than the first unit a couple ways:
- No startup noise. None. I’ve noticed that it is even quieter than the old one was even at its best. On our ground floor directly above the heater, I can’t hear it at all. With the old one, you could always at least hear the burner fire up, or more commonly, the GRUNTING noise.
- More stable. The old one had a really difficult time handling low-flow situations. I always thought it was typical performance for a tankless, but this one is noticeably better. While you still need the 3/4 gal/minute flow rate to get it to turn on, the burner will still stay on if you then turn it down. I’d estimate that it’ll go down to 1/3 gal/min before turning off. Big improvement!
While I wish that I had been more aggressive with pursuing this with Bosch before now, I hadn’t had any other experience with tankless heaters and therefore had no good frame of reference. If I now had to go back to our old heater, I’d know it was messed up. My gut feeling is that all of my gas line upgrades were unnecessary. While they will allow the heater to get as much gas as it can eat, I believe this one wouldn’t have made the noise even with the 3/4″ line. On the bright side, who doesn’t want enough gas line capacity in their basement to be able to run a kiln, a restaurant and a glass blowing workshop, all at the same time?
In case anyone missed the morals of this story, they are…
Tankless heaters are great, if yours doesn’t work well, it may just be a dud, and
We LOVE Bosch!!
9/7/2008 update: After living with the new heater for another year and a half, we we revise our statement to say that Bosch tankless heaters are merely OK. Every year at the peak of summer, the heater will have a tough time maintaining its temperature, and we will get blasts of cold in a shower. My impression is that this heater is great for “full throttle” use, but it struggles with low to moderate flows. Again, this makes we wonder if we would have ultimately been more satisfied with a smaller unit that would regularly run closer to its maximum output.