Pressure relief valve leaking... any advice?

edsut

Hi,
I moved to a different home, heat is natural gas, hot-water baseboard. This spring I noticed that my pressure relief pipe is dripping (a few cups a day even with system not in use). Everyone I talk to says I should replace the expansion tank along with the valve. Is that true?
Assuming yes... I assume I can shut the system off, cut off the water supply, open the drain valve to allow water to drain out, then I can start replacing parts. Referring to the attached picture, my plan is to replace the expansion tank and the pressure relief valve (if I've labeled something incorrectly please inform!!). What is that thing I reference in the picture and should I go ahead and replace it also?

Any advice would be appreciated. I've done plenty of sweating pipe for both plumbing and hot water heat in previous home, but I haven't really touched the system itself.
Thanks in advance! This forum has been really helpful.

Picture is attached.

RayWohlfarth

You could check your system pressure The PRV could be set too high

edsut

Hmmm... I assume you are talking about the pressure "reducing" valve, which in my picture is below and behind the expansion tank?

Larry Weingarten

Hi, I'll add that the "what is this" by the expansion tank is a float valve for releasing air. There are better ways of doing this function. You have an isolation valve under the expansion tank, but to test the tank, or recharge it, it must have no pressure on it from the system. A T with a hose bibb, or something similar above that isolation valve would let you figure out the condition of the tank and whether it needs to be replaced. I'd want to put a pressure gauge on the system, so you can see if it reaches higher pressures.

Yours, Larry

EdTheHeaterMan

You could replace the expansion tank and the pressure relief valve and end up with the same condition if the pressure reducing valve is the reason for the problem. You could replace all three reasons that your relief valve may be leaking, but if the new valve starts to leak again, What will you check next? You could also replace 4 items, the PReliefV and the PReducingV the expansion tank and the air vent. This way all your problems will be solved maybe

Personally, I like to be sure when I replace something that it is in fact the cause of the problem when ever possible. Granted, sometimes the process of elimination is often the only way to know, but replacing each part one at a time may be time consuming and replacing everything is easier and cheeper in the long run (when paying Retail for service calls). The air vent as installed is not the best way to solve air problems. There is a better way to design the piping that includes relocating the circulator pump to the supply side of the boiler after the expansion tank. Now the project is getting out of hand with lots of changes and parts

I might suggest that you

1. Check the pressure gauge on the boiler to see if it is correct. (There are pressure gauges available that can be connected to a hose connection to see if the pressure is close to the boiler pressure gauge)
2. Set the boiler pressure correctly at about 12 PSI, then observe the boiler pressure after a few days to see if the pressure reducing valve is passing. The boiler pressure will go up to 30 PSI over time.
3. Check to see if the Pressure relief valve is leaking at a boiler water pressure below 30 PSI
4. drain the boiler to zero PSI (you dont need to take all the water out for this test)
5. Check the air pressure in the expansion tank with a tire pressure gauge. (it should be about 12 PSI.)

With these tests you can determine which part(s) are bad.

Pressure relief valve still leaks at boiler pressure below 30 PSI. Replace PRV
Pressure relief valve does not leak at water pressure below 30 PSI. PRV is good

Boiler gauge does not read the same pressure as the test gauge. Replace pressure temperature gauge
boiler gauge and test gauge are close. Pressure temperature gauge is good

Pressure reducing valve allows water pressure in boiler to rise above desired setting. Replace PRV
Pressure reducing valve holds boiler pressure at desired pressure. PRV is good

Expansion tank is less than 12 PSI on the air valve. Add air to tank
Expansion tank will not hold 12 PSI or there is water on the air side. Replace the expansion tank
Expansion tank has 12 PSI and is holding pressure over 1 hour test. Tank is good.

There are different ways to go about making boiler repairs. Some just shoot the parts cannon at the problem and hope for the best. I like the test and verify method.

One of my comments I would say to my technicians " After you replace that (Expensive) part and you still find the same problem, what will you check next?" Sometimes the answer is as inexpensive as a fuse. I would suggest that they check the inexpensive option first. My customers liked that about me.

JUGHNE

You are very fortunate to have an isolation valve under the expansion tank.

IIWM, I would shut that valve off, remove the tank, you may get a little or a lot of water.

If the tank is full and water comes out you have lost the air charge.

If the tank is full and no water comes out you have water on the wrong side of the bladder and need a new tank.

If empty, check the air charge, it should be about 12-15 PSI (and hold that pressure) when the tank is not connected.

You could add a tee under the tank with a hose bib for future testing.
You would shut the isolation valve off, open the hose bib above it and then check the air charge as you know there is no residual water inside.

I would do this first then open the iso valve and watch the pressure.

Pressure should go up to only that 12-15 PSI.

If it goes beyond then your fill valve is either stuck or needs adjusting.
You can exercise the fill valve with the lever on the top, lift and drop several times, you should hear water flow. When you lift the lever it lets full pressure in and could open the relief valve.

You can exercise the relief valve by lifting, flowing a good stream and letting the lever snap shut. Often debris gets under the seat because it does not get a good flushing and will seep.

hot_rod

You have two yellow handle ball valves to isolate the boiler and relief valve, so no need to drain down the system. To the left of the pump and next to the air vent

 How old is the tank, should be a date code on it

Over .10 years?  Id replace the tank,  air vent, and relief.  Probably a hundred bucks or so worth of parts . 

edsut

Ok, thanks for all the feedback!
Trying to respond to all and ask more questions...
1. I ordered a pressure gauge. I assume I can just connect this to one of the hose bibs and test correct? Pressure on the gauge on the boiler looks like it is right on the money at 12PSI (see picture).
2. Regarding testing the pressure of the expansion tank... I see a connection at the top, so I can just connect a tire-pressure gauge to that?
3. I can't really tell how old the current tank is. It has a label with some numbers stamped into it (see picture), but the numbers don't make any sense to me. I'm guessing it's more than 10yrs old.
4. Is it true that the expansion tank should not be mounted upside down? Based on the label orientation of mine, it is upside down.

Someone said I could adjust the boiler pressure... Where is that done?
I see that I have a backpressure preventer followed by a PRV (see pic), neither of those appear to have adjustment.





Thanks for the continued responses!

JUGHNE

What do you have for a water heater for faucets etc.?

EdTheHeaterMan

edsut said:

Ok, thanks for all the feedback!
Trying to respond to all and ask more questions...
1. I ordered a pressure gauge. I assume I can just connect this to one of the hose bibs and test correct? Pressure on the gauge on the boiler looks like it is right on the money at 12PSI (see picture). Yes that is correct on both items.
2. Regarding testing the pressure of the expansion tank... I see a connection at the top, so I can just connect a tire-pressure gauge to that? Yes that is also correct
3. I can't really tell how old the current tank is. It has a label with some numbers stamped into it (see picture), but the numbers don't make any sense to me. I'm guessing it's more than 10yrs old. You are probably correct, it is over 10 years old
4. Is it true that the expansion tank should not be mounted upside down? Based on the label orientation of mine, it is upside down. The expansion tank manufacturer does not put labels on upside-down. If installed properly, the weight of any water in the tank during normal expansion will rest on the bladder or diaphragm differently based on the orientation of the tank. the "inerds" will last longer if properly configured according the the manufacturer. How true this is, I can't be sure. I have always placed the tank with the air side down and the water side up. I believe they last longer, but I never took a survey of how long upside down tanks last compared to properly installed tanks

Someone said I could adjust the boiler pressure... Where is that done?
I see that I have a backpressure preventer followed by a PRV (see pic), neither of those appear to have adjustment.The PRV can be adjusted see instruction sheet below
Thanks for the continued responses!

https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/11908-source/1910265-pdf
Paragraph 3 in the operation section has adjustment instructions

But I would not make any adjustments to the PRV auto-feeder.
Based on your photographs, your boiler gauge is most likely good and the pressure is below 30 PSI
If your relief valve is leaking at 12 PSI then you need a new relief valve.
The Extrol tank is most likely the reason for your relief valve failure. Do the air pressure test by lowering the boiler pressure to ZERO PSI. If the tank does not have 12 PSI pressure on the air side with ZERO PSI on the water side, Then just replace it at the same time as the relief valve.
Leave all the other stuff alone. Leave the tank upside-down.

This is your lowest cost repair.

HomerJSmith

That tank is really old based upon the faded label. I read the number as 1233964. The six was hard to read.
As I recall from the dim depths of my memory, the 64 is the year, the 39 is the week of the year or the 339 day of the year in 1964. If I'm correct that tank is long over due for a change out.
Of course, the year may be 96 and the 4 is the month, makes more sense.

Date Code 11219102 was manufactured on the 191day (July 10) of 2002?.

PC7060

Hmmmm, based on the many pictures posted on the forum, I’ve come to believe boilers operate better when covered with a thick layer of gunk, and surrounded by piles of household detritus.  

Your boiler and basement appears to be too clean and the well organize shop and tools are just asking for trouble! 

edsut

Thanks again to all...
Responses (and maybe more questions) below:

@JUGHNE
The water heater is a separate gas fed item (also due for update soon) just behind the boiler.
@EdTheHeaterMan
Thanks for all the detail. Assuming I get confirmation that the 12PSI on the gauge is correct (by verifying with the gauge I ordered), I'll order the tank and relief valve. Any reason to not go ahead and replace the air vent also (it just looks corroded and old, and since this sits right next to my garage work table it annoys me every time I look at it)?
@HomerJSmith
The house was built in the mid-80's so, the 1964 date isn't likely. I'm not sure where you got the 11219102 number from, but that date is certainly possible. Bottom line... it will be replaced.
@PC7060
LOL! Yea, the fact that I have my tools right next to something that could end up soaking them with hot water is my primary motivation behind making sure this is fixed!

Thanks again to all for the feedback. I will post a picture of all the shiny new parts installed when I complete this! :-)

edsut

I can see the specs on the other parts, but with regard to the expansion tank, I assume I want 30PSI, but I can't find anything that shows the capacity/volume specification for the water in my system. I've got a single zone of about 150' of total 3/4" pipe finned baseboard (this includes the baseboard as well as the piping in crawlspace between rooms. According to a pipe volume calculator that comes out to about 3.5 gallons, so does this look like a fit for my system?

edsut

@EdTheHeaterMan I measured the pressure at the expansion tank using a tire gauge: 21PSI.
UPDATE: I missed the step about draining to zero PSI, so I need to do this first...

hot_rod

That tank was manufactured on the 339 day of 1984
Its a # 30 by  the first two digits

Jamie Hall

edsut said:

I can see the specs on the other parts, but with regard to the expansion tank, I assume I want 30PSI, but I can't find anything that shows the capacity/volume specification for the water in my system. I've got a single zone of about 150' of total 3/4" pipe finned baseboard (this includes the baseboard as well as the piping in crawlspace between rooms. According to a pipe volume calculator that comes out to about 3.5 gallons, so does this look like a fit for my system?

Ah... hold on. You want the air pressure -- the Schrader valve opposite the water inlet -- to read 12 psi (your system pressure) when the tank is completely empty of water and isolated from the system.

mattmia2

If you don't have DHW provided by the system and the pressure is slowly rising without the boiler firing then it has to be that the pressure reducing valve is leaking. You may have isolation valves to replace it without draining the system. Replace the leaking automatic air vent too. It looks like you could isolate the boiler and replace the automatic air vent without draining the rest of the system.

edsut

@Jamie Hall
Ok, yea I see I missed one of the steps from @EdTheHeaterMan ... I need to close both valves to isolate the boiler from the rest of the piping, then open my drain valve and allow that to drain, and then I measure the pressure on the expansion tank... correct?

mattmia2

edsut said:

@Jamie Hall
Ok, yea I see I missed one of the steps from @EdTheHeaterMan ... I need to close both valves to isolate the boiler from the rest of the piping, then open my drain valve and allow that to drain, and then I measure the pressure on the expansion tank... correct?

Correct, you have to check the pre-charge with no pressure on the water side.

mattmia2

The boiler is cold start, right, it only fires if there is a heat call, it is allowed to get to room temp if there is no heat call?

edsut

@Jamie Hall Ok, I won't be able to do that till later tonight... cause I have to hook up a hose to the drain.

@mattmia2 Sorry, not sure what you mean... I "believe" it only fires if the thermostat is on "heat" and room temperature falls below the setpoint. Note that I am not 100% sure of that, so when I have the house on AC mode (i.e. now), I just turn off the switch to the circuit that the boiler is on.

mattmia2

I just wanted to confirm that the pressure is increasing while the boiler is not heating. If that is happening it has to be the PRV(pressure reducing valve) leaking and adding more water to the system. If it had DHW as part of the system a leak in the heat exchanger for the DHW could also cause it but you don't have that so unless there is some other source of water or air connected to the system, it has to be the PRV. You can turn off the manual valve ahead of the PRV and confirm that the pressure stops rising with that shut off.

edsut

Something just occurred to me... why would the pressure at the expansion tank be 21PSI, while the pressure shown on the gauge is 12PSI?
Tonight I will do two things:
1) Assuming I get the gauge I ordered from amazon, I'll have a "2nd opinion" on the system pressure.
2) I'll close the two valves, drain the boiler and measure at the expansion tank.

Meanwhile, I still don't get why there is a difference between the two measured values.

Larry Weingarten

Hi, Tanks can be shipped with air in them. DOT rules allow up to 40 psi in a tank. Maybe your tank was precharged and nobody adjusted it to match system pressure.

Yours, Larry

edsut

Ok, referring to new picture below, my goal was to get to zero pressure at the point where the expansion tank is in the circuit. I initially thought closing the upper and lower valves would do that but then I realized that these valves isolate the boiler from the rest of the radiator pipes, but they don't isolate the expansion tank from anything. So, I turned off the water supply valve (behind exhaust pipe in picture), opened up the other two valves and let the system drain just so I would be sure that there was no pressure at the expansion tank. If you look close, you can see the gauge I bought shows zero psi.
Anyway, that didn't change the pressure at the expansion tank. It still reads 20-21 PSI. What does that say about the expansion tank?

Jamie Hall

MikeAmann said:

edsut said:

It still reads 20-21 PSI. What does that say about the expansion tank?

Does the gauge on the boiler also read ZERO? If so, then the tank is charged to too high. Reduce it to 12 psi while there is no influence from the water side.

This. You should be able to reduce the pressure by holding the air valve open, just like letting the air out of a car tire.

That would explain -- at least partly -- the problem, as with the tank overcharged, it can't accept anywhere near as much water and the system pressure won't be properly contolled.

edsut

Ok, that's easy enough... does that mean I don't need a new expansion tank?
BTW... yes, the main gauge also reads zero.

EdTheHeaterMan

I believe that one key point in the Extrol Tank air pressure measurement is missing. To be absolutely sure that there is no water pressure on the water side of the tank you can remove the tank and place it on the floor next to the boiler. That is the only way you can be sure that there is no water pressure on the water side.

The procedure I outlined previously will work as long as you are sure there is no water pressure on the water side of the Extrol tank. If you follow the 5 steps in the photo, you can avoid removing the tank form the boiler system piping. If you still get 21 PSI in the air side of the Extrol tank, then you need to remove the tank from the boiler piping. By leaving some of the valves closed on the system piping, you may not allow the water pressure on the water side of the Extrol tank top be released out the boiler drain.

Have I mentioned how important it is to have no water pressure on the water side of the tank? Because if there is any water pressure on the water side of the tank, that water pressure will compress the air in the air side of the tank to equal the pressure on both sides of the tank. That may be your 21 PSI reading

Just so we are clear, you must have no pressure on the water side of the tank in order to get an accurate pressure reading on the air side of the tank

As long as you are sure the water side has zero pressure, then you check the air charge. If you still have 21 PSI, your tank is overcharged as mentioned by @MikeAmann and @Jamie Hall. Lower the pre-charge pressure to about 12 PSI along with the other repairs you are doing (New Pressure Relief Valve) and you may not need a new expansion tank. But at the age of your tank and the problem you are trying to solve, I would install a new tank if it were in my home.

EDIT: If you were going to make any other repairs while the boiler water was drained, I would add 2 valves to make future repairs easy

edsut

@EdTheHeaterMan your steps are exactly what I did. The picture I posted may actually show the valves closed, but they were opened at the time of the drain. Just to be absolutely certain of this I will walk through it again tonight...
Based on your (and other) comments regarding the old tank, I have to agree... For around $60 it makes sense to just replace it. I'm assuming a good replacement is this, so if it comes precharged I assume I need to adjust the pressure to 12psi, correct?

mattmia2

Have you addressed the issue with the prv yet?

EdTheHeaterMan

edsut said:

@EdTheHeaterMan your steps are exactly what I did. The picture I posted may actually show the valves closed, but they were opened at the time of the drain. Just to be absolutely certain of this I will walk through it again tonight...
Based on your (and other) comments regarding the old tank, I have to agree... For around $60 it makes sense to just replace it. I'm assuming a good replacement is this, so if it comes precharged I assume I need to adjust the pressure to 12psi, correct?

By the picture with the closed valves, I wanted to be crystal clear about the water side. Now that you have specifically said it, I believe you fully understand the process.

As far as the replacement, it comes factory pre charged with 12 PSI, so you can check it with a gauge but it should be fine.

Some folks have mentioned the auto feed PRV might be passing. I personally do not believe it is passing, but because I mentioned the test procedure for that part, you may as well get everything back together with a new relief valve and Extrol 30, then you can observe the boiler gauge over the following week to see if the pressure creeps up over time. If it does not, then you are good to go. If it does then I would order a Watts 911S. I don't think you need it. I just posted ALL the tests to determine the reason for the relief valve failure, not making any assumptions as to the condition of any part. It’s just a way to rule out parts that are not defective.

mattmia2

EdTheHeaterMan said:

Some folks have mentioned the auto feed PRV might be passing. I personally do not believe it is passing, but because I mentioned the test procedure for that part, you may as well get everything back together with a new relief valve and Extrol 30, then you can observe the boiler gauge over the following week to see if the pressure creeps up over time. If it does not, then you are good to go. If it does then I would order a Watts 911S. I don't think you need it. I just posted ALL the tests to determine the reason for the relief valve failure, not making any assumptions as to the condition of any part. It’s just a way to rule out parts that are not defective.

If the pressure is creeping up and the boiler isn't firing and DHW is a separate system then the prv is really the only option(unless the circulator is running over the summer and something weird is happening with it pumping pressure in to the expansion tank or something else very unusual).

HomerJSmith

I would definitely replace the Ex-tank, they're cheap. I have seen some working fine at 15 yrs and some that failed at 3 yrs. Yours is long in the tooth. I like my pressure set at 15 psi so I will have a little margin when the boilers cut out at 10 psi. Set the air pressure in the tank to the psi on the boiler fill valve. They should be the same.
Dump the Watts PRV, keep the double check with atmospheric vent. I would use a Caleffi auto fill valve with pressure gauge. I love that valve almost more than I love my wife. Just kidding, Honey. I would replace the boiler pressure relief valve, 30 psi rated because it was leaking and why not, eliminate problems down the line (later).
That's my 2 cents worth which is a lot less than what I charge for a service call. Please, send the 2 cents to the following address,,,
https://www.supplyhouse.com/Caleffi-553642A-1-2-NPT-AutoFill-Boiler-Feed-Valve-w-Pressure-Gauge
https://www.supplyhouse.com/Amtrol-102-1-30-Extrol-EX-30-Expansion-Tank-4-4-Gallon-Volume

edsut

@EdTheHeaterMan, I verified that I definitely am at zero PSI. All valves are open (except for the feed of course), and water drained. It was still at 21PSI, but as suggested, I'm gonna replace the tank anyway.

I received the relief valve today and replaced it. I ordered the expansion tank as per @HomerJSmith 's pointer. The www.supplyhouse.com claims I'll have it tomorrow even with just UPS ground shipping. I'll believe that when I see it...

The only thing I can think of now is the procedure of refilling the system and purging the air. I assume I just close the drain, open all the isolation valves, open the highest hose bib that is in the system (with hose connected) then open the feed valve to allow a few gallons to flow until there is no "spitting" (air gaps) in the water out of the hose. Is that close to correct?

Again, I can't thank you all enough for the detailed comments.

mattmia2

edsut said:

I received the relief valve today and replaced it. I ordered the expansion tank as per @HomerJSmith 's pointer. The www.supplyhouse.com claims I'll have it tomorrow even with just UPS ground shipping. I'll believe that when I see it...

They ship from different warehouses and are good about getting things to you next day. I don't know if they are part of one of the national chains or if they just have agreements with regional supplyhouses.

Purging the system the best way is to close off a valve at the boiler such that you have the prv and a boiler drain isolated so if you hook up a hose to the boiler drain and open it, pulling the fast fill lever on the prv will force water through the system and out of the boiler drain to purge the air out. You will have to look at your system to figure out how to do this or if it is possible with your system.

The Caleffi valve above does auto fast fill so you don't need to do anything but close a valve to isolate the boiler and open a boiler drain with the prv open.

edsut

@mattmia2 referring to picture, I'm guessing that is the "fast-fill" lever?

mattmia2

Yes. Watch the pressure as you do it, if you open it too much you can cause the relief valve to open.

EdTheHeaterMan

mattmia2 said:

"EdTheHeaterMan" said:
Some folks have mentioned the auto feed PRV might be passing. I personally do not believe it is passing, but because I mentioned the test procedure for that part, you may as well get everything back together with a new relief valve and Extrol 30, then you can observe the boiler gauge over the following week to see if the pressure creeps up over time. If it does not, then you are good to go. If it does then I would order a Watts 911S. I don't think you need it. I just posted ALL the tests to determine the reason for the relief valve failure, not making any assumptions as to the condition of any part. It’s just a way to rule out parts that are not defective.


If the pressure is creeping up and the boiler isn't firing and DHW is a separate system then the prv is really the only option(unless the circulator is running over the summer and something weird is happening with it pumping pressure in to the expansion tank or something else very unusual).

I do not see where the OP mentioned the pressure is creeping up. Maybe I missed it

I believe i was the first to mentioned that the PRV passing, could be a possibility. I was listing several reasons that a relief valve could leak. I did not make the assumption that it was passing. I was offering a way to see that it was not5 passing as a way to rule out the PRV auto feed as a cause of the relief valve leaking. No one said it was passing, and the photo of the boiler gauge indicates a cold pressure of 12 PSI. That if pretty conclusive to me that the PRV is not passing, because the cold boiler pressure is where it should be.

So lets not ask the OP to replace something the is working properly.

The test also shows that the Extrol tank is over-charged. The simple fix is to remove some air pressure to make the air side 12 PSI. But it was discussed that the tank is over 30 years old and may fail at any time so might as well replace it now since the cost was fairly low.

The forensics of this issue probably goes something like this:
1. The overcharged Extrol tank caused the boiler pressure to go above 30 PSI causing frequent relief valve discharges over several seasons.
2. Eventually the frequent relief valve discharges caused the valve to stop sealing properly allowing water to leak past the relief valve at pressures lower than 30 PSI
3. As the water left the boiler via the failed relief valve, the auto feed replaced the water keeping the boiler at 12 PSI cold pressure.
4. The homeowner found the relief valve leaking and asked about the expansion tank.

Does that sound about right?

hot_rod

The chances of a 40 year old, iron body fill valve sealing tightly after being put in fast fill for the first time? Slim to none.

I consider these 3 critical parts to be consumables, replace the whole group for peace of mind Fill, expansion tank and relief.

edsut

@EdTheHeaterMan, well assuming I'm the "OP" (not sure what that stands for), yep you're on the money. I appreciate all the comments, realizing that some may be too little, others may be too much. Every time I've interacted with this forum I've gotten good healthy responses.

@mattmia2, I did receive the tank in less than 24 hours after I ordered it! Major kudos to www.supplyhouse.com!

So I've installed the relief valve (that's the only part that required sweating/soldering). I've got the new tank and air vent in hand and will install them tonight.

The vent is at the high point in my system, so I get that this automatically gets rid of air, but what is the knob at the top for? I assume that just allows me to shut off the vent?

Hopefully this time tomorrow I will have everything back together.