Rheem not hot, no errors

[Bruce_Juice]

Hi,
I have a Rheem ECO180DVN3C tankless water heater.
Water has gradually been getting cooler, it doesn't give any error codes. I called tech support and ran through a series of tests, buddy told me I need a new "Water Control Assembly". I can't find this part anywhere or any diagrams with that part listed! I called Rheem Canada they told me they can't deal with the end users.
I've noticed when looking through the site glass with one faucet running hot that only a partial flame is available, turn another faucet on and more flame is applied...so according to demand, as it should be.

Question: Can I reprogram the device to increase the amount of flame applied when one faucet is used?

As it stands, when I take a shower I have to turn the hot water tap on the bathroom sink up to full hot in order to get hot water in the shower.

 

[Jadnashua]

Have you been regularly deliming the heat exchanger in the tankless system? It could be that there's a mineral deposit which acts like an insulator...limiting the heat that can be added to the water. Most of them call for doing this at least annually.

 

[Sponsor]

 

[Bruce_Juice]

Yes, I've been doing it annually, using vinegar, also used CLR and water the last time I did it which was recently, no change in performance.

 

[Phil Armstrong]

Likewise I thought it might have been a deliming issue as well.

Have you had any progress with this at all Bruce? Sounds like you activation temperature has been adjusted. What kind of interface does your unit have? I am not too familiar with this model.

 

[Bruce_Juice]

Thanks Jim and Phil,
The unit uses a wired remote, the only functions on it are Power, Increase Temp and Decrease Temp. On the board there are no USB, Serial or Parallel ports.
I called Rheem Canada (useless), they never heard of a "Water Control Assembly" the tech told me needs replacing, but they did give me two Part#'s and told me Home Depot could order them, RTG20164L and RTG20164M, Home Depot couldn't find anything with those part #'s.
I'm going to try another Home Depot location and see if I can track down a more qualified plumbing associate.

Ideally if I could simply adjust the amount of flame (gas) applied when hot water is on demand, I think that would be the easiest solution. If that means adjusting dip switches or replacing a sensor or module, that would be ideal!
REF: (I've noticed when looking through the site glass with one faucet running hot that only a partial flame is available, turn another faucet on and more flame is applied...so according to demand, as it should be).


Cheers,
Bruce

 

[Phog]

Hello Bruce, I do not have any experience with these systems, but I am a controls engineer by trade. In this case I would suspect that a temperature sensor in the water flow path is giving a falsely high reading. The control electronics as a result thinks that water is warmer than it actually is, and therefore subsequently calculates a too-small amount of heat needed raise the temperature to hit the target. This would explain why the flame adjusts with flow, and yet is always too small to get the water warm enough. If I were a betting man, I would say that you will find a faulty temperature sensor on the incoming (cold) water side of the heat exchanger, perhaps integrated into some sensing unit. Disclaimer: this is just an educated guess, you can easily waste a lot of money following the advice of strangers on internet forums. A pro could probably diagnose your problem in 5 minutes.