Water coming out of Relief Valve for new Tankless Water Heater

[Bartonsprings]

A plumber installed a new Navien 240A2 tankless water heater system. But over past 3 months multiple times the pipe connected to relief valve to the drain keeps running hot water until I switch off the heater and shutoff the cold water. But as you can see in picture that relief valve is not open yet water is running. I think the plumber installed the relief valve wrong. Per manual all valves should be installed after relief valve.

What could be going on?

 

[GReynolds929]

What's your water pressure? What temp is the heater set to? Looks like you have a recirculation return line. What are the recirculation settings? Is there an expansion tank installed. Can we get some more pics of the installation?

 

[Bartonsprings]

What's your water pressure? What temp is the heater set to? Looks like you have a recirculation return line. What are the recirculation settings? Is there an expansion tank installed. Can we get some more pics of the installation?

It was set to 125F and I changed to 110F to see if it makes any difference but it did not. Yes, it has recirculate in return line. There is no expansion tank installed. Navien NPE 240A2 has built in recirculating feature.

 

[Bartonsprings]

What's your water pressure? What temp is the heater set to? Looks like you have a recirculation return line. What are the recirculation settings? Is there an expansion tank installed. Can we get some more pics of the installation?

I don’t know how to measure water pressure. Note that the water running by is on the hot side

 

[havasu]

Have you checked for any codes thrown? Below is a pic of my old Navien 240 NPE, with a recirc system tied into it, but it looks plumbed differently. These are the only pics I have but something is vastly different in the installation.

 

[GReynolds929]

You can get a pressure gauge to put on a hose bib that will tell you what your pressure is. With recirculation the navien needs a thermal expansion tank installed on the cold water side. As far as the T&P relief releasing water you either have excessively high water pressure or it is defective and needs replaced. I'm leaning towards it being defective cause it's not supposed to relieve pressure unless it's 150+ psi. There could be a piece of sediment or debris keeping the valve from sealing. Have you tried lifting the lever to open and let a lot of water flow a time or two to see if it stops leaking.

 

[Bartonsprings]

Thank you GReynolds and Avasu for your insights. I will buy a water pressure reader and try it tomorrow and let you know the readings. Thanks

 

[user 32496]

Have you tried lifting the lever to open and let a lot of water flow a time or two to see if it stops leaking.

I would do what @GReynolds929 said before anything else. 9 times out of 10, that will fix it.

 

[Bartonsprings]

Yes - You all were right. Checked the water pressure. It was 151psi. The main PRV of the house was busted. Replaced it and all is well (for now). Though I have complained to the city water utility about such a high pressure coming into the mains.

THANK YOU!!!