Boiler pressure about 30 psi

saniolin

Hello,

Last year, I moved into my new house, and everything seemed to be running smoothly with the boiler. I decided to take a proactive approach to boiler maintenance and hired a plumber to purge the system and clean the fire tubes.

However, when I fired up the boiler for the first time this winter, I noticed a significant issue: the pressure gauge shot up to a whopping 40 PSI, and to make matters worse, a considerable amount of water began pouring out from the pressure relief valve. Concerned about this sudden problem, I sought the expertise of a professional plumber. To my surprise, the plumber recommended replacing the expansion tank, which had apparently failed, for a hefty cost of $XXX. Additionally, the plumber suggested a system purge for an extra $XXXX, an expense that didn't seem particularly reasonable to me.

Unwilling to break the bank for a task I believed I could handle, I decided to take matters into my own hands and attempt the system purge on my own. During this process, I observed that the pressure initially measured around 12 PSI when I introduced water for purging but increased to 20 PSI as soon as I stopped the water supply.

Furthermore, when the boiler was in operation, the pressure rose to approximately 30 PSI, with only a minimal amount of water escaping from the relief valve. This situation left me both perplexed and determined to find a solution to the issue at hand.

I have a couple of pressing questions. Firstly, I'm curious about why the pressure shoots up to 20 PSI even when the boiler is not in operation. Secondly, I'd greatly appreciate any insights or advice on how to rectify this situation and ensure that the pressure remains within a safe and acceptable range.

Your assistance and advice on this matter would be immensely appreciated. Thank you in advance!

GGross

Remove pricing please, not supposed to share quoted prices for work performed here.

That being said, the pressure increase you see DURING burner operation could very well be from a failed expansion tank.

The pressure increase you see after filling, but before burner operation. This could be a bad gauge, or possibly your fill valve is leaking by, if you have a ball valve to close off the fill valve you can test this. Fill your boiler to the correct PSI close off ball valve to the fill valve, don't let boiler fire, see what happens to the pressure


Several brands recommend NOT mounting the expansion tank in that vertical position for various reasons. Additionally I believe the piping of the expansion tank and the fill valve could be affecting the fill valves performance as it needs to be in a point of no pressure change, it looks to be just piped in the supply header. Turn system off, adjust to correct cold fill pressure, close off ball valve to the autofill, see what happens.

Ideally you would repipe the expansion tank and fill valve, replace if exp tank is bad it might not be. I also as a general good practice will replace a pressure relief valve when it has been operated due to high pressure.

Also there does not appear to be good air elimination here, which can cause other problems. I would recommend repiping the expansion tank and fill valve with a good air eliminator.

EBEBRATT-Ed

@saniolin

Without the boiler running the fill valve pressure reducing valve shown in your second picture should be set to maintain 12-15psi in the boiler when it is cold. As the water is heated and it expands the expansion tank (picture1) absorbs the expanded water. But the water pressure will rise somewhat when heated to as much as 16, 18, 20 or24 psi or so. This is normal. If the water pressure rises to 30 the relief valve opens as you well know.

It could be the PRV valve leaking by or it could be a bad expansion tank.

To find out. Drain some water out until you get 12-15 psi the shut the water off to your PRV valve (the red handle ball valve downstream of the prv where it enters the boiler supply pipe) and run the boiler. If the pressure shoot up the expansion tank is bad.

Big box or plumbing supply store sells those tanks. Before installing it check the air pressure in the tank to be sure it's correct the tank will (should have) 12-15 psi in it. You have a size 30 tank which is very common.

You will have to drain the system to do this.

To purge close all 3 the ball valves located under your zone valve on the left side of the boiler above your circulator. Hook a hose to one of the drain valves above your zone valve. Open the drain and open the make up water and use the fast fill on your PRV to keep 15 psi or so while purging. Purge each zone 1 at a time until the drain hose runs with no bubbles.

saniolin

GGross said:

Remove pricing please, not supposed to share quoted prices for work performed here.

That being said, the pressure increase you see DURING burner operation could very well be from a failed expansion tank.

The pressure increase you see after filling, but before burner operation. This could be a bad gauge, or possibly your fill valve is leaking by, if you have a ball valve to close off the fill valve you can test this. Fill your boiler to the correct PSI close off ball valve to the fill valve, don't let boiler fire, see what happens to the pressure


Several brands recommend NOT mounting the expansion tank in that vertical position for various reasons. Additionally I believe the piping of the expansion tank and the fill valve could be affecting the fill valves performance as it needs to be in a point of no pressure change, it looks to be just piped in the supply header. Turn system off, adjust to correct cold fill pressure, close off ball valve to the autofill, see what happens.

Ideally you would repipe the expansion tank and fill valve, replace if exp tank is bad it might not be. I also as a general good practice will replace a pressure relief valve when it has been operated due to high pressure.

Also there does not appear to be good air elimination here, which can cause other problems. I would recommend repiping the expansion tank and fill valve with a good air eliminator.

GGross said:

Remove pricing please, not supposed to share quoted prices for work performed here.

That being said, the pressure increase you see DURING burner operation could very well be from a failed expansion tank.

The pressure increase you see after filling, but before burner operation. This could be a bad gauge, or possibly your fill valve is leaking by, if you have a ball valve to close off the fill valve you can test this. Fill your boiler to the correct PSI close off ball valve to the fill valve, don't let boiler fire, see what happens to the pressure


Several brands recommend NOT mounting the expansion tank in that vertical position for various reasons. Additionally I believe the piping of the expansion tank and the fill valve could be affecting the fill valves performance as it needs to be in a point of no pressure change, it looks to be just piped in the supply header. Turn system off, adjust to correct cold fill pressure, close off ball valve to the autofill, see what happens.

Ideally you would repipe the expansion tank and fill valve, replace if exp tank is bad it might not be. I also as a general good practice will replace a pressure relief valve when it has been operated due to high pressure.

Also there does not appear to be good air elimination here, which can cause other problems. I would recommend repiping the expansion tank and fill valve with a good air eliminator.

Hi Ggross,

I wanted to update you regarding my previous post. I have removed the pricing information from it, and I apologize for any inconvenience caused.

Regarding the expansion tank, it's a new installation done by a plumber. After the installation, the psi reading is at 30 when the boiler is running. The plumber advised me to purge the system, which I did by myself.

I've also attached some pictures. Could you confirm if the attached valve is the ball valve you mentioned? Furthermore, the fill valve looks to be in good condition. To test the fill valve, do you mean I should close off the ball valve while purging the system (During the filling process, the psi reading is around 12, which seems to be a good sign.)

Your advice and input are greatly appreciated. Thank you!

saniolin

EBEBRATT-Ed said:

@saniolin

Without the boiler running the fill valve pressure reducing valve shown in your second picture should be set to maintain 12-15psi in the boiler when it is cold. As the water is heated and it expands the expansion tank (picture1) absorbs the expanded water. But the water pressure will rise somewhat when heated to as much as 16, 18, 20 or24 psi or so. This is normal. If the water pressure rises to 30 the relief valve opens as you well know.

It could be the PRV valve leaking by or it could be a bad expansion tank.

To find out. Drain some water out until you get 12-15 psi the shut the water off to your PRV valve (the red handle ball valve downstream of the prv where it enters the boiler supply pipe) and run the boiler. If the pressure shoot up the expansion tank is bad.

Big box or plumbing supply store sells those tanks. Before installing it check the air pressure in the tank to be sure it's correct the tank will (should have) 12-15 psi in it. You have a size 30 tank which is very common.

You will have to drain the system to do this.

To purge close all 3 the ball valves located under your zone valve on the left side of the boiler above your circulator. Hook a hose to one of the drain valves above your zone valve. Open the drain and open the make up water and use the fast fill on your PRV to keep 15 psi or so while purging. Purge each zone 1 at a time until the drain hose runs with no bubbles.

Hi EBEBRATT-Ed,

I wanted to express my gratitude for your valuable suggestion. The expansion tank is a recent installation by a plumber, and I think it should be in good condition.

In reference to your mention of the PRV, could you please confirm if the provided image corresponds to the PRV you are referring to? Here's the image for your convenience:



Regarding your instructions to "Drain some water out until you get 12-15 psi the shut the water off to your PRV valve (the red handle ball valve downstream of the prv where it enters the boiler supply pipe) and run the boiler" I would appreciate further clarification. Do you mean that I should close the ball valve during the purging process to maintain a pressure of 12-15 psi? Or should I use a different valve to drain the water?

Thanks!

Jamie Hall

"PRV valve" is one of those abbreviations. It has two meanings, and you have both valves on your system. The one in the last picture is a Pressure Relief Valve, and it's function is to open if, for some reason, the system pressure gets to high, to protect the system. The one in the first picture is a Pressure Reducing Valve, and its function is to provide, at its output side, a fixed, set pressure.

The relief valve is not adjustable -- when the pressure reaches its labelled pressure -- in you case 30 psi -- it opens. The reducing valve is adjustable -- that is what the screw on the top is for -- but it's best not to play with it unless you have an accurate pressure gauge. It can also be opened manually to allow water to fill faster, if needed (but it won't regulate pressure that way), but it usually won't allow water to flow fast enough for purging air.

As sort of an aside, it is sometimes assumed that a reducing valve will act as a check valve or backflow preventer. It won't.

saniolin

Jamie Hall said:

"PRV valve" is one of those abbreviations. It has two meanings, and you have both valves on your system. The one in the last picture is a Pressure Relief Valve, and it's function is to open if, for some reason, the system pressure gets to high, to protect the system. The one in the first picture is a Pressure Reducing Valve, and its function is to provide, at its output side, a fixed, set pressure.

The relief valve is not adjustable -- when the pressure reaches its labelled pressure -- in you case 30 psi -- it opens. The reducing valve is adjustable -- that is what the screw on the top is for -- but it's best not to play with it unless you have an accurate pressure gauge. It can also be opened manually to allow water to fill faster, if needed (but it won't regulate pressure that way), but it usually won't allow water to flow fast enough for purging air.

As sort of an aside, it is sometimes assumed that a reducing valve will act as a check valve or backflow preventer. It won't.

Thank you, Jamie!

I've been troubleshooting, and it appears that the Pressure Reducing Valve might be causing the issue. When I purge the system, the pressure starts at 15 psi and then increases to 20 psi once I stop filling it with water. Does this seem reasonable?

I also have one more question: When I purge the boiler, I've been leaving the Pressure Reducing Valve as usual, without setting it to fast fill. Is this the correct approach? I've been running the water for 10 minutes in each zone, and I haven't noticed any air bubbles coming out. I've done this process twice.

I appreciate your advice!

saniolin

Hello, everyone,

I have another question: Assuming the pressure gauge is working correctly, as previously mentioned, 'the pressure starts at 15 psi when I purge the system and then increases to 20 psi once I stop filling it with water.' Is it advisable for me to manually adjust the pressure reducing valve to lower the PSI to 15 (when the boiler is filled with cold water and not yet running)? Is this workable?

Thanks for your insights!

neilc

sure, try backing out the screw on top a turn and see where that settles, or 2 turns, , ,
tap on the gage face while adding water, or now, static,
does the needle jump at all? is it catchy?

or, as suggested above, just shut off the ball valve feeding into the system when you hit 12~15,

was the tank pressure checked prior to putting in on the system ?

saniolin

neilc said:

sure, try backing out the screw on top a turn and see where that settles, or 2 turns, , ,
tap on the gage face while adding water, or now, static,
does the needle jump at all? is it catchy?

or, as suggested above, just shut off the ball valve feeding into the system when you hit 12~15,

was the tank pressure checked prior to putting in on the system ?

Hello Neilc,

I dedicated two hours tonight to adjusting the pressure reducing valve by turning the screw while purging. After numerous attempts, the gauge reached approximately 14 PSI, as indicated in the image below (the temperature was around 55°F; should I wait until it completely cools down?). I initially believed this was a positive outcome.



I also observed that when filling water during purging, the PSI is around 7 while the pressure reducing valve is in normal mode (not in fast mode). Does this observation make sense?

However, upon attempting to run the boiler again, the PSI remains at approximately 30, and there is some bubbling sound coming from the baseboard, even though I am sure that no bubbles emerged during the purging process (I leave one side of the pipe in water to observe the bubble).

I would greatly appreciate your insights and advice. Thank you!

neilc

your cold water fill pressure should be 12~15, closer to 12,
but first, and while water pressure is 0~7, the air pressure in the tank needs to be 12~15, your to match your cold fill pressure.

55 is plenty cool, under 100 is good enough to call cool,

if you're purging without the fast fill, yeah, pressure will drop, to 7, or lower,
this may be why you're not getting a good purge,
if anything, use the fast fill to keep the pressure higher, 20~25,
you need the higher pressure and water speed to push bubbles down to your purge points,

the bubbling you're hearing in the baseboard is just a bad purge job,

the cap on the boiler vent is loose to release air, correct?

you're purging 1 zone at a time, right?
boiler off,
all zone valves manually open and latched open by the lever,
all the ball valves closed under the zone valves,
hose on one purge bib, maintain pressure at 20~25, open purge bib until water runs bubble free,
open and close that zone's ball valve a time or 2 to burp any air that might be under there,
bubble free on that zone?
release the fast fill and close the purge bib,
move to the next zone, rinse and repeat,
all 3 zones bubble free,

release the zone valve manual levers,
open all the ball valves,
lower or set the cold fill pressure to 12, **
turn boiler back on,

** either drain down to 12,
or fill/fast fill back up to 12,
and close the ball valve on the fill line to or from the pressure reducing fill valve,

you're pumping toward the expansion tank, which is wrong, and can continue to give you air noise,
matters of fact, you may be trapping air right up there under that tank, there's no vent there, and usually the tanks are hung under a water line or air separator,
yours is at the top of that stack,

read or search "Pumping Away",
consider moving / Move the tank and fill line to the inlet of the circulator,
(above the circulator and below that last zone return tee),
the system will go dead quiet,
you have room there to do this,

hot_rod

fill valves have a tendency to not shut off at the psi setting , especially if they have not been used periodically 
After you fill and purge, shut off the water to the boiler fill valve.