Tankless Water Heater Troubles

The intake is separate. There is a slightly smaller pipe that runs inside, this is the exhaust and has two functions. It preheats the air coming in (the outside of the smaller pipe) and also eliminates the need to an additional hole in the wall. As far as I know these are widely used.
 
My boiler is hooked up the same way Duane. The 70% RH will be an issue until that is reduced. Not sure if that is causing your noise though (via ice on the fan).
Considering what you are getting in that screen it might very well be a cavitation issue. Certainly solvable though. Just going to take some head scratching.
 
went out a bit ago and was running loud. I had the pump on low speed and the temp output set to 110°. Good flow of 1.5gpm so that tells me the filter is clean enough, turned up to 120 and she really started to moan, haha. I think I might monkey around with manifold pressure. Will probably wait on the flush now.
 
Is your water hard? May I suggest that you get your water tested. Once you know that, you may have a better idea of what to do, perhaps adding a filter before the unit. I used to work on spas and swimming pools. We use to check the water so that we could determine what chemicals and filters to use. You'd be amazed what's in your water.
 
silence dogood said:
Is your water hard? May I suggest that you get your water tested. Once you know that, you may have a better idea of what to do, perhaps adding a filter before the unit. I used to work on spas and swimming pools. We use to check the water so that we could determine what chemicals and filters to use. You'd be amazed what's in your water.
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This is a new install so water should not be an issue. Plus, I believe he used distilled water.

My thoughts...
1.) Pump cavitating.
2.) Air in the lines.
3.) Combustion fan wonky.
4.) Ice on the combustion fan.
5.) 62% glycol might be too high for a nice flow. 50% is usually the high limit. I wonder if the higher viscosity is creating an issue in the heat exchanger.

Those are not in order of likelihood. Just some some thoughts.
 
Well, if he is using distilled water, then that eliminates the idea of the hard water. Thanks for the update.
 
I can not hear the pump cavitating even with my ear right up to the pump. Been running the pump on slow speed and so far good flow still.
I went out and changed the DIP switch settings for altitude no change at all from what I could tell, the fan really throttles fast though on the higher altitude settings fan sounds fine.
My glycol mix right now is pretty low. I started out at ~ 35% then took out two gallons of mix and added two gallons of distilled. So I'm guessing 30% and probably a little lower than that. Maybe it's a little to high?
 
Oh, I don't think the mix is too high. I thought you had used 8 gallons of distilled with 5 gallons of glycol, which would be 62%. That might be a little high.
If this stupid Covid wasn't going on I would drive over there, but not now.
Well, what the heck, I just don't know what else to say Duane. If you don't have figured out later on I could maybe ask my HVAC guy. He is a good friend of mine but getting in touch with him is always a challenge.
 
Although there seems to be a change in the noise when I change flow it seems the real cause of it getting louder is when you increase the output temperature.
So what is happening in the unit when you do that?
To increase temp you need more BTU's so increased gas flow.
You're also going to need more air hence the fan speeding up.
The inlet temp now doesn't change for a very long time so you have a much larger ▲T.
Also I changed the regulator pressure up and down while the unit was running, no change at all in the sound.
One other thing to consider is maybe I didn't size my gas line correctly?
I'm sure there is air in the system because each time I clean the filter I end up pumping back into the system to fill lines. IDK.
 
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