Relief Valve on Navien

Garageboy

Installed Navien CH-210 last summer(2013), has worked fine until late December when heating relief valve (Watts 3/4", 30psi) began to intermittingly "pop". At first it was when we opened a domestic hot water faucet?????. I replaced the relief valve suspecting that early January 2014, no issues for about 2 weeks. Now it is "popping" again, this time with no specific action to tie it with. It will happen in the middle of the night, during the day. Many times without even a call for heat or domestic water. Called tech support, they told me to check incoming gas pressure which is within range of manufacturers specs(6.8"WC@maximum burn). Also checked cleaned combustion air intake. Any suggestions?

Ironman

Gas Pressure??

Why would you check gas pressure for a relief valve that pops when the boiler is not firing?



What is the static fill pressure when the boiler is cold?

Are you using an external PRV for the fill or the internal electric one?

Is the expansion tank's bladder intact and is it properly sized for your system?



If you would post the answers to these questions and maybe a pic or two of the boiler and it's near piping, someone here should be able to help.



You are referring to the hydronic side relief and not the potable side aren't you?

Garageboy

Relief Valve on Navien

I checked the gas pressure per tech support @ Navien. Static pressure(inlet water) is 72 PSI. No external PRV, using internal electric. Bladder seems to be ok, checked pressure 12.5 PSI, system pressure was 10.5 PSI. Not sure how Navien regulates the pressure on internal valve.

Yes the space heating relief valve. Hope the pictures appear.

Ironman

No pics

Static fill pressure refers to the pressure on the boiler side when cold and not running. 72 psi is your street pressure.



I know that Navien Tech Support told you to check the gas pressure. SMH. It just befuddles me how someone in Tech Support could think the pressure in gas line could effect boiler water pressure when it's not even firing.

HomeOwner1

Similar thing happened to me

The 30 PSI pressure relief valve is on the main heating loop. Mine turned out to be a expansion tank misbehaving.



Also, if you have a fast fill line and valve attached to your heating loop (i.e. city water line to bleed out the lines) on the main loop, ensure it is full closed, or the valve is not faulty. This is commonly installed as a faster way to get the air out of the lines when filling up the system loops.

Garageboy

Navien Relief Valve

Thanks guys for your help. To be fair to Navien tech support when I spoke to them the relief valve was "relieving" as far as we new when we used the domestic hot water and unit was firing.. Once again that seemed strange but it seemed to happen when we opened a hot water faucet. After replacing the valve we began to notice it happening intermittently without any common occurrence. I shut the ball valve off yesterday that feeds the auto feeder and no "relieving" for 6 hours. As soon as I turned it back on it popped 2-3 times in a row. Called Navien tonight and they are sending me a new auto feeder valve under warranty. Another thing I noticed when the auto feeder was in play my system pressure was 24-28 psi, with valve closed it was 18-21 psi. Hopefully this will solve the issue.

On a side note, I have been reading threads on here for about a year or so as I have been contemplating this new install. I had a fuel oil fired Utica boiler with a Beckett burner for 27 years. Only a few minor issues, replaced aqua stat and circulating pump. Did annual pm(filter, nozzle, electrodes) but the fuel bill was breaking me, so far this winter and it has been colder 75% savings. I am in a rural location and the local supply house is a Navien distributor, of course they said they have had good luck with them. Time will tell .I appreciate all of the expert information on this site. Thanks again.