Tankless Water Heater Problem

Thalweg

Hi,

I installed a Bosch Aquastar 1600H water heater yesterday to replace a Bosch Aquastar 125B water heater that the heat exchanger had cracked on. The 1600 does not heat nearly as well as the 125 did. Visually, it is very apparent that the 1600 does not have nearly as strong of flames as the 125 did.

The 1600 has a knob to adjust the “power” of the heater. Rotating this knob while the heater is in operation produces no visible change in the flames or temperature of the water. Is this normal, or could this valve be not functioning correctly?

I thought this could be a gas pressure problem, so I swapped the pressure regulator from the 125 onto the 1600, which produced no change. The instructions say that at elevations over 2000 feet, the gas pressure needs to be reduced (they gives specs). I live at about 4600 feet. However, I don’t have the tools to measure the pressure, and I don’t want to start adjusting willy-nilly. Besides, I don’t understand how reducing pressure would produce more heat.

Any advice?

sdsester

If it is Bosch, it sounds like you might have a warranty issue worth discussing? Did you install these yourselves or have them installed? I would call the installer back.

I put Bosch units in my former California house ages ago and as far as I know they are still working. I have heard quality has fallen off though.

Thalweg

I do plan on trying to get a replacement heat excanger for the 125 heater. I'm not overly optomistic that Bosch will honor the warranty. The unit is only about four years old, and the heat exchanger is supposed to be under warranty for 12 years. However, the place I bought it is out of buisness. I had a plumber install it, but he tried very hard to talk me out of it, as he wanted to sell me a conventional water heater. So I don't think he'd be any help. We'll see what happens.

I installed the new water heater myself. Since all the plumbing was already in place, it was a 15 minute process.

My real problem with the 1600 is that I don't know if I have a problem. Maybe this is as good as it gets, and I dougbt that my disappointment in the performance is a warrantyable issue. I was just hoping to find out if anyone on here has had similar issues so I can determine if I've got a legitimate arguement.

Michael Thomas

Did you change any portion of the gas supply plumbing? Are you sure that the shutoff valve is completely open. Is it possible that any part of the gas supply is obstructed, for example by excess Teflon tape across a pipe end?

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Thalweg

No, gas supply lines are all the same. I tried the new regulator that came with the new heater, and the old regulator off of the old heater...no difference. I'm certain that the gas cutoff valve is completely open, and I used pipe dope, so no teflon tape.