oil heating boiler T&P pressure relief valve discharging (new expansion tank)

anthonySD

Hello, the pressure relief valve on my oil boiler recently started discharging water, and I was hoping someone could help me troubleshoot the issue.

here are the known facts.

1. pressure relief valve discharges at roughly temp=190deg / pressure=30psi
2. pressure relief valve appears to be in working order (ie. does not drip or discharge until 30psi)
3. expansion tank was just replaced about a year ago. it still measures 30lbs of pressure, does not have moisture at the valve stem, and does not sound like it is waterlogged
4. boiler temp dial is set to 210deg

any thoughts on what could be the culprit, or any suggestions on what else I could check?


** sorry in advance if this ques has already been discussed, please link me to the existing thread - thanks **

BDR529

Call local service company and come up with a plan to troubleshoot with them.

JUGHNE

To check the pressure in the tank it must be removed from any system pressure.....tank must be removed or system pressure dropped down to 0 PSI. 12-15 PSI of air to match the system pressure determined by the PRV set when the boiler is cold.

Do you need 210 degree water? 180 is considered high.

Jellis

20psi seems high for a pre-charge in an expansion tank, did you drain the system when you checked the air pressure?
Also, 210°F is very high for a hi limit.
12psi is the pre charge for a typical 2 story home.

anthonySD

thanks @JUGHNE and @Jellis, I'll remove the system pressure before testing the expansion tank again, I'd think it should be OK as it's only 1yr old unless its defective.

as for the boiler thermostat, it's been that way since I moved in a few years ago, I can turn it down and see if that helps.

thanks for your input.

STEVEusaPA

Way too high. Even if the gauge is perfectly accurate (unlikely) you're too close to steaming.
If the expansion tank charge is fixed, properly sized and the tank isn't damaged, you'll need to investigate a few more things.
-Air in the system.
-Water feed letting water into the boiler when it shouldn't.
-If you use the boiler for domestic hot water, possible leak in the coil adding street pressure water to the boiler.

JUGHNE

And you should get no water out of the air fill valve, tank should be empty at 0 PSI.

HVACNUT

Pics?
Like @STEVEusaPA said, if you have a tankless coil, there could be an internal leak in the coil. Street pressure is obviously higher so it will make it's way into the heating system.
Remove and checked the charge on the extrol. 12-15 psi.
Is there proper air elimination on the boiler?
When the extrol is back on, fill and purge the system of air. Pressure on the boiler should be 12-15 psi. Close the manual fill valve behind the PRV. If pressure still rises, bad coil in the tankless or indirect water heater coil. If pressure stays in 12-15 psi range, the PRV is likely faulty.
I think you just didn't know but it should not be a T&P on the boiler. It should be a 30 psi boiler relief valve.

JUGHNE

I doubt if he has a T&P, he was just stating the values.

EdTheHeaterMan

@JUGHNE Your post is a bit confusing?!?
I believe you mean to say...

Test your air pressure in the pre-charged tank when the boiler pressure is 0.

The pre-charged tank should be empty (Because the boiler pressure is at 0 psi)
You should not get water from the air side of the pre-charged tank because the bladder separates the air pressure from the water side. So the water will never come out of air pressure valve.

HVACNUT

> @EdTheHeaterMan said:
> @JUGHNE Your post is a bit confusing?!?
> I believe you mean to say...
>
> Test your air pressure in the pre-charged tank when the boiler pressure is 0.
>
> The pre-charged tank should be empty (Because the boiler pressure is at 0 psi)
> You should not get water from the air side of the pre-charged tank because the bladder separates the air pressure from the water side. So the water will never come out of air pressure valve.

What's confusing is @JUGHNE posted just about the same thing you just did. ???
Or did I miss something? @JUGHNE has been here a long time and knows how to test an extrol. What did I miss?
Or am I reading your post wrong? Now I'm confused. But that's par for the course for me.

EdTheHeaterMan

We all know what @JUGHNE means... Does @anthonySD know what we already know from experience?

"And you should get no water out of the air fill valve, tank should be empty at 0 PSI."

0 PSI measured where? at the air valve? Does @anthonySD know the answers to my query? I thing not!

I believe that @HVACNUT may be able to help @anthonySD better after he takes all the air pressure out of the bladder tank to make it 0 if that is in fact what @JUGHNE means.

Or am I confused now?

Disclaimer:
@anthonySD should not use the information herein. This is a sarcastic post to make a point about assuming someone not in our trade understanding the meaning, when the info is so minimal and somewhat cryptic.

Just trying to add more information to the minimal post of @JUGHNE so the novice heating system owner understand what we all already understand.

HVACNUT

> @anthonySD said:
> thanks @JUGHNE and @Jellis, I'll remove the system pressure before testing the expansion tank again, I'd think it should be OK as it's only 1yr old unless its defective.
>
> thanks for your input.

Seems like the OP got the meaning.

EdTheHeaterMan

OK, makes sense.