Autofill Valve possibly leaking by

Beefboi99

Just had a tech come service my hydronic oil fired boiler. He also flushed the system.

About 2 hours after he left the PRV was trickling out water. The pressure in the boiler was 35 psi. I called him back and he said the auto fill fast flow was left slightly open and he wired it shut. He also flushed the system again.

I asked if I should look into replacing the auto fill valve just incase it was leaking by and it wasn’t the fast fill valve. He said it should be fine now.

Can I close the ball valve upstream of the auto fill just encase it does leak by? Or is it best to leave it open for possible air. 

Jamie Hall

You can close it -- but only if your boiler has some safety device on it to stop it if the water level gets low or even the pressure gets too low.

Beefboi99

Jamie Hall said:

You can close it -- but only if your boiler has some safety device on it to stop it if the water level gets low or even the pressure gets too low.

I don’t believe it has a low water cut off. It also looks like the pressure keeps creeping up. 

EBEBRATT-Ed

leave it on for now and check the pressure occasionally. Cold pressure is 12-15psi approx. When the water is heated you might see 24ish. The pressure will change with the temperature.

Beefboi99

Ok so after the tech left for the 2nd time he told me it should be running at 15 psi and that even 20 psi is considered high. The boiler runs for my domestic hot water. 

After a few hours last night I checked it again and pressure was at 25 psi. I bleed some water out of the PRV to get it just below 20 psi. I do not have a vent on any off the highest baseboards. It was about 1/2 Gallon of water. I ran the heating zone circulator (single zone) and there didn’t sound like any air was in the system.

The boiler is currently at rest 17.5 psi and 20 psi when it’s finished running for domestic water. 

I really don’t want to call them back again to get a bad name, does this seem to be fine? 

neilc

your domestic is leaking back into the boiler (?)

isolate the domestic overnight, or when you can for hours,
set the boiler at 12,
hours later, or next morning, what's that pressure ?

the tech shold have mentioned this,
do you want him back ?
its their bad name.

neilc

post a picture of boiler and domestic,
floor to ceiling,
showing any connected piping, circs,

Beefboi99

Beefboi99

I do believe the Fill valve is what was leaking by Originally. 2 hours after the service it was over pressuring the PRV. He wired the fast fill shut and It has now been 18 hours and pressure hasn’t  gone up too much since I bled some out about 16 hours ago. It’s been sitting 17.5 psi cold - 20 psi running. 

I just don’t know if that is correct. I guess I will monitor over the weekend and if it keeps increasing I will call the company back or try the domestic coil isolation. 

He also did mention the Domestic Coil did had a leak at some point (he was referring to the visible calcium buildup in the picture) and he would look for parts if I wanted to preventively change it out but he believed there is not a current leak. 

neilc

ok, so,
domestic may not be pressurizing the boiler,
and boiler isn't leaking on the floor and holds or builds pressure,
go back to shutting off the boiler feed and check the pressure an hour, then 2 hours, then 4 hours later, staying at or above 12 without climbing?
check pressure next morning, staying at or above 12 without climbing?
maybe you need a new fill valve, a piece of dirt/gunk is on the valve seat and it is leaking thru,
or,
you could try opening fast fill wide open and letting it slam shut, or force it to slam shut, a few times and see if it clears ant obstructing crud,
have the valve changed.

this is ignoring the wise safety advise, LWCO, above, so if you're not able to keep an eye on that pressure, open the feed back up.

Beefboi99

neilc said:

ok, so, domestic may not be pressurizing the boiler, and boiler isn't leaking on the floor and holds or builds pressure, go back to shutting off the boiler feed and check the pressure an hour, then 2 hours, then 4 hours later, staying at or above 12 without climbing? check pressure next morning, staying at or above 12 without climbing? maybe you need a new fill valve, a piece of dirt/gunk is on the valve seat and it is leaking thru, or, you could try opening fast fill wide open and letting it slam shut, or force it to slam shut, a few times and see if it clears ant obstructing crud, have the valve changed. this is ignoring the wise safety advise, LWCO, above, so if you're not able to keep an eye on that pressure, open the feed back up.

Cool thanks for the unsafe advice hahaha. 

So you think I should get the pressure down to 12psi? Is the PRV the best way to keep lowering the pressure? Should I be Concerned I’m letting too much air into the system? 

neilc

if you've been using the PRV, and it keeps sealing tight, sure.
they can catch crud also, and that's where the snap shut trick should really shine, if it's going to.
if you use a different boiler drain, and it won't seal, there are hose end caps at the hardware store to stop those last drips.
and as long as the water pressure is up, and not at 0, and you're not hearing glug, glug, then air shouldn't be, isn't, getting in.

Beefboi99

neilc said:

if you've been using the PRV, and it keeps sealing tight, sure. they can catch crud also, and that's where the snap shut trick should really shine, if it's going to. if you use a different boiler drain, and it won't seal, there are hose end caps at the hardware store to stop those last drips. and as long as the water pressure is up, and not at 0, and you're not hearing glug, glug, then air shouldn't be, isn't, getting in.

Ok cool thank you. And 20 psi is definitely too high for the boiler? 

neilc

12 psi for 2 floors, 18 for 3 floors,
no need for 20,
did the tech check the expansion tank and its pressure?
you want that tank to match your cold fill pressure,
and the tank needs to have 0 water pressure on it to check its air,