Pressure relief valve leaking again

[PLOWJEEP]

Three years ago, I had to replace the expansion tank on my heating system. While he had it shut down, I also had him replace the pressure relief valve and air separator just for good measure. Now my pressure relief valve is leaking again. Could it be that my expansion tank has failed after only three years? My system is an older install, it is a primary, secondary loop system with a four gallon expansion tank installed beneath an inch and a quarter air separator. The primary loop has two zones (180 degree). The secondary loop has two floor heat zones controlled by an injection pump.

Any help would be appreciated.

Thanks,
Brian

 

[Jim Sperry]

The expansion tank you check at the Schrader valve. It is probably factory-charged at 38#. If water comes out, the relief valve would be kicking out lots of water.

You could open the relief valve all the way up and let it run for a few seconds. Let it snap shut. Then help it seat itself shut with a few taps on the central pin that the lever pivots against.

 

[Bondo]

Three years ago, I had to replace the expansion tank on my heating system. While he had it shut down, I also had him replace the pressure relief valve and air separator just for good measure. Now my pressure relief valve is leaking again. Could it be that my expansion tank has failed after only three years? My system is an older install, it is a primary, secondary loop system with a four gallon expansion tank installed beneath an inch and a quarter air separator. The primary loop has two zones (180 degree). The secondary loop has two floor heat zones controlled by an injection pump.

Any help would be appreciated.

Thanks,
Brian

Ayuh,.... What does the pressure gauge say the pressure is,..??

Does the system have an auto-fill valve in it,..??

 

[Ron Lombardo]

First check the gauge ...if its a std hot water heating system it should run under 20 psi depending on how many floors above. Then check the precharged expansion tank ..first poke it and see that air comes out them check the pressure shouldnt be more then 12 psi factory set. Next if check the automatic feeder ... to be preset at 12-15 lbs ... i usually change all 3 at the same time to eliminate the relief valve problems.

 

[PLOWJEEP]

There is 15psi on the system. The expansion tank says 12psi pre charged and yes there is an auto fill valve. I guess that I should drain the primary loop and check the pressure on the bladder of the expansion tank. Thanks, Brian

 

[PLOWJEEP]

Highest point in the system is about 7' above the boiler. It is a standard cast iron boiler 84% efficient. How do you test the the auto fill valve? The gauge said 15psi without the boiler running. It doesn't leak all the time and when it does it's not that much. I had air at the schrader valve. Thanks, Brian

 

[Jim Sperry]

Sorry, I wrote the wrong factory pressure on the expansion tank. It is 12#, as Ron says.

The think the pressure I typed is for whole house water booster systems.

 

[PLOWJEEP]

I opened the relief valve and let run into a bucket. I wasn't sure I was going to get it to close again. It shut off when I tapped the center pin. When I dumped the bucket I noticed some rust/scale in the water. Is there some type of flush I should be doing? This system has been in use since 2002. Thanks, Brian

 

[PLOWJEEP]

Where are you from Jim? I went to high school in Boyertown, PA

 

[LS6 Tommy]

If it wont seat after being "snapped" shut, it's time to get a new one. Sometimes spinning the release lever with the valve closed helps clear the seat, but a relief valve that drips below the pop off rating is usually a sign that the end is near.

Tommy

 

[anthony666]

what kind of boiler are you using brian ?? all the new stuff coming out have ports in their hook up kits so you can use a chemical flush once a year or so .. they all sell a descaling solution/fluid, i just use CLR .. whats the water like where you are ?? you on a well ??

use a tire gauge on the schraeder valve under the expansion tank .. adjust the pressure according to system specs .. if water comes out of the schraeder it's toast, the bladder is gone

sometimes a tiny piece of something will get under the seat in the t&p and grow like a pearl in an oyster eventually causing a drip .. guys will often use the t&p to vent air during fill (myself included) it's bad practice and should be avoided

for what a t&p is worth i'd swap it out & probably swap the exp tank too, give the whole system a flush to descale it and install a new pressure gauge

 

[anthony666]

If it wont seat after being "snapped" shut, it's time to get a new one. Sometimes spinning the release lever with the valve closed helps clear the seat, but a relief valve that drips below the pop off rating is usually a sign that the end is near.

Tommy

good advice

 

[PLOWJEEP]

The boiler is a WEIL-McLAIN gold CGS-5 133,000 btu input. I just noticed that the pressure is 20psi while running. The tag on the pressure relief valve says 30psi. I'm really interested in flushing the boiler before I install any new parts. I do have a water well.The ph is on the soft side. Thanks, Brian

 

[Jim Sperry]

All residential boiler relief valves are factory set at 30#.

Note: A water heater uses a Temperature & Pressure valve, set for both 210˚F and 150#. I've never known one to confuse boiler and water heater relief valves. The T&P has a temperature probe.

To flush the whole system, after allowing the boiler to cool for several hours, one would connect a hose to the boiler drain, crank it open, and let the auto-filler make up the difference. If the auto-fill has a bypass lever, open it up.

I've never heard of it being done any other way, but after flushing the whole system, one may be able to let most of the system drain, and then continue the flush, adding just as much water as the boiler drain will discharge, thereby concentrating the flush on the boiler itself. There may be valves to isolate the boiler from the distribution piping that will facillitate a more intensive boiler-only flush. It's been my experience that most of the sludge will come out in the first few seconds. - jim s.

 

[PLOWJEEP]

Thanks Jim, I am going to flush the boiler like you said. Replace expansion tank and pressure relief valve. Then I need to replace the antifreeze in the system. If I remember correctly 5 gallons brought the protection down to -10f. Should I add the antifreeze to the empty boiler and then fill with the auto fill valve. I am concerned about getting the air out when I refill the boiler. There is a boiler drain on the return side of the hot water storage tank zone. This drain is located at the highest point of that zone. Thanks, Brian

 

[Jim Sperry]

The expansion tank sounds like it is fine. They typically outlast the boiler.

I know nothing about adding anti-freeze; never had the need; sorry.

To purge air, there is usually a shut-off on the return and a boiler drain connection above it. After the boiler seems to be full, you run a short hose from the aforementioned boiler drain into a large bucket of water. Shut off the return look, open the drain, and allow the boiler to fill with more water. You'll see air bubbles in the water bucket as they are forced through the loop. When the bobbles stop, the air is out.

Some loops have air vents built into them.

 

[PLOWJEEP]

Thanks for all the advice. Brian

 

[anthony666]

I've never heard of it being done any other way

you never wondered why the isolation/hook up kits that come with wall hangers these days have hose thread connections ??

you're supposed to pump a descaling solution through yearly

 

[mygarageone]

All residential boiler relief valves are factory set at 30#.

Note: A water heater uses a Temperature & Pressure valve, set for both 210˚F and 150#. I've never known one to confuse boiler and water heater relief valves. The T&P has a temperature probe.

just a bit of info , there were water heater relief valves made with out a probe , several yrs ago but I have actually taken old water heater out with these non probe relief valves.
I have also seen them on the shelf in some hardware stores up here.
Remember the old side arm heaters used with wood stoves ? Well they used these type of relief valve.

 

[Jim Sperry]

you never wondered why the isolation/hook up kits that come with wall hangers these days have hose thread connections ??

you're supposed to pump a descaling solution through yearly

In 25+ years of plumbing the Philadelphia area, I cannot recall a single residential boiler descale procedure. The region uses mostly surface-collected water. There remain in operation former coal-fired residential boilers, converted to oil and then gas, that have probably never had a descale treatment.

There was one boiler with well-supplied water where I tried to descale a domestic hot water coil; it turned out to be easier to replace the coil, the original being in such blocked condition.

Outside the metropolitan region, where well-water dominates, I do not venture. After only once changing a foot switch on a well pump, I decided to leave these customers to plumbers who did this kind of work all the time.

 

[anthony666]

In 25+ years of plumbing the Philadelphia area, I cannot recall a single residential boiler descale procedure. The region uses mostly surface-collected water. There remain in operation former coal-fired residential boilers, converted to oil and then gas, that have probably never had a descale treatment.

There was one boiler with well-supplied water where I tried to descale a domestic hot water coil; it turned out to be easier to replace the coil, the original being in such blocked condition.

Outside the metropolitan region, where well-water dominates, I do not venture. After only once changing a foot switch on a well pump, I decided to leave these customers to plumbers who did this kind of work all the time.

all these modern high performance boilers, the efficiency drops like a stone once the heat exchanger see's the slightest bit of scale, once a year you hook up a utility pump and drop it in a 5 gallon pail of descaling solution and pump it through for 20 minutes or so .. the hookup kits are designed so you can isolate the boiler and clean it out relatively painlessly .. that's the propaganda anyway

 

[Jim Sperry]

the hookup kits are designed so you can isolate the boiler and clean it out relatively painlessly .. that's the propaganda anyway

I believe it! All that rocket science 95% boiler stuff goes right through my head when someone tries to explain it to me.

I'm more suited to heating systems like these:

 

[PLOWJEEP]

When I was young there where coal bins at the railroad siding. All the old row houses had a coal cellar under the front porch. They had to be filled with a scissor lift truck. A lot of those old coal fired heaters where converted to oil or gas and where used for many more years. I'd be willing to bet some are still in use today. Brian

 

[anthony666]

when i was a kid my grandmother had a wood stove with a built in boiler and cook top .. you wanted a wash in the morning you had to light the fire and wait for the boiler or it was cold water in a wash basin out of a jug