Pressure Release Valve Temporary Fix For Navien Tankless Water Heater Heating Issue

[Kmarisetty]

Hi,

Currently I am seeing an issue with my Navien tankless water heater where I am needing to use the pressure release valve once a week to solve heating issues with my heater. The temperature stays hot after the fix and there are no drops in pressure. Any idea what could be the cause? Also there are no error codes. Thanks.

 

[havasu]

Does the PRV need replacing?

 

[GReynolds929]

Model? Any error codes? What are the symptoms?

 

[Kmarisetty]

Model? Any error codes? What are the symptoms?

No error codes. The model is NPE-240A2. The pressure release valve doesn’t seem like it is leaking. After I do a pressure release with the PRV, the tankless water heater ignites immediately and starts to heat the water. FYI, there is no pressure drop prior to and after using the PRV. This fixes the issue for approximately 1 week until I have to repeat this process. Also, I am using the Aquasure water softener (https://www.amazon.com/gp/aw/d/B07F18VG8L?psc=1&ref=ppx_pop_mob_b_asin_title)

 

[havasu]

Just guessing, but maybe the pressure switch is bad, and mother board is not recognizing it? Honestly, stuff like this is why I tossed my TWH and replaced it with a conventional gas water heater.

 

[Kmarisetty]

Just guessing, but maybe the pressure switch is bad, and mother board is not recognizing it? Honestly, stuff like this is why I tossed my TWH and replaced it with a conventional gas water heater.

Yeah, honestly.

 

[Kmarisetty]

Here is what Google AI is saying about the Pressure Release Valve method I'm using:



Can AI be trusted?

 

[havasu]

Having been a vet tech, the only AI I understand is artificial insemination!

 

[GReynolds929]

The flow sensor can get scale and buildup on it that will cause it to not spin freely. How old is it, when was it last descaled? Do you have recirculation, or is the unit set to internal recirculation? Without recirculation set you need at least .5 gpm to start heating water, with recirc there is no flow requirement. Can you post some pictures of the install?

 

[Kmarisetty]

The flow sensor can get scale and buildup on it that will cause it to not spin freely. How old is it, when was it last descaled? Do you have recirculation, or is the unit set to internal recirculation? Without recirculation set you need at least .5 gpm to start heating water, with recirc there is no flow requirement. Can you post some pictures of the install?

Hi,

Yeah it came with my new construction condo. So it is about a 1 year old system now. It never got descaled. I have a water softener, but for over 1 month it was running on no salt in the brine tank (accidentally forgot to keep track when to refill), but I put in a new bag 2 weeks ago. I”ll send pics of how my builder installed the system.

Also in my water softener, before putting in the salt, I had water that looked like this at the bottom of the brine tank (see attachment). Based on the pics, is it normal?

The flow sensor can get scale and buildup on it that will cause it to not spin freely. How old is it, when was it last descaled? Do you have recirculation, or is the unit set to internal recirculation? Without recirculation set you need at least .5 gpm to start heating water, with recirc there is no flow requirement. Can you post some pictures of the install?

 

[breplum]

Installation is normal. Looks like you have a recirculation pipe ready to go but not piped? Navien covers labor from NSS up to one year. Thereafter, parts only 5 yr

 

[Kmarisetty]

Installation is normal. Looks like you have a recirculation pipe ready to go but not piped? Navien covers labor from NSS up to one year. Thereafter, parts only 5 yr

Hi,

We contacted the builder about the pipe that is closed off. We are yet to hear from them if it is used for external recirculation.

 

[Kmarisetty]

Hi,

So when the water stays cold over 10 min requiring me to use the PRV earlier, instead of using the PRV, if I turn on two faucets (instead of one), the water gets hot again. I checked the RPM on the Navien system and it was running at 1500 RPM with GPM around 0.4 to 0.5 before turning on the second faucet. After turning on the second faucet, the GPM went up around 2 with the RPM still at 1500.

Any ideas? Also, I have a water softener. Thanks for all the help so far!

 

[havasu]

Doesn't a water softener restri t water flow a bit?
I myself don't know. Just wondering.

 

[Kmarisetty]

I put

Doesn't a water softener restri t water flow a bit?
I myself don't know. Just wondering.

I put the water softener in bypass mode for now. If this fixes the issue after monitoring for 1 week, then I think it isn’t a problem with the tankless water heater, but my water softener.

 

[GReynolds929]

Set the tankless to internal recirculation and see if that changes anything. If not my guess is the flow sensor.

 

[Kmarisetty]

Set the tankless to internal recirculation and see if that changes anything. If not my guess is the flow sensor.

Thanks, will try that.