Hi guys, I have purchased a house and i have been trying to find out why the pressure/temp relief valve on my buderus hot water storage tank keeps opening approximately 1 minute before the boiler shuts downs and continues approximately 1-2 minutes after the boiler shuts down. I have replaced the relief valve thinking that maybe it was old and the spring went bad but im still having the same problem. Can anyone help me ??

Thanx

p.s. The boiler low is set at 160 and high at 180. The aquastat is set at 110. The PSI of my boiler is at 10.
If you need any other info to be able 2 help just ask.

 

It sounds like you are in need of a thermal expansion tank. If you already have one, it may need replacing. The expansion tank for the boiler is not the same as a thermal expansion tank for domestic water.
It may look just like it, but it is designed for different pressures.

When your water heats up, it needs to expand. If there is some kind of check valve on you water main, combined with no expansion tank, you have noplace for the water to expand to other than your relief valve. Your domestic water pressure is probably at 150psi when the RV starts leaking, then once the boiler stops the pressure will drop along with the release at the RV.

 

I think you have a number of issues that need addressing.

Can you take pictures of your system? Create a (free) account at www.photobucket.com (or similar photo hosting site) and upload the pics there. Provide a link here for us to view the pictures.

The immediate problem first... the water storage tank, which I believe from your description is called an 'indirect water heater'.

The P/T relief valve that opens is probably on the domestic water side, NOT the one on the boiler itself, is that correct ?

Start by turning the LOW setting on the boiler control (also an aquastat by the way) down. Since you have in 'indirect' water heater, there really is no reason at all to keep that boiler hot all the time. I would go so far as to say that you could even change that control to one designed to 'cold start' the boiler and not have to burn fuel to keep it warm. It's not necessary with your type of water heater.

Turn it down to 120° and set the third dial labeled DIFF to 20°.

This isn't going to stop the valve from opening, but it will save fuel. More about this in later posts, after we see the pictures to be sure my assumption is correct.

There is an EXPANSION TANK on your boiler system. Looks like a gas grill propane can, right ? Is there ALSO one on the hot water tank ?

You said the boiler pressure is at 10PSI ... that's LOW... even if the boiler is COLD... more so if the boiler is HOT... when the boiler is cold, it should be a minimum of 12 PSI, and as much as perhaps 5-8 PSI higher when the boiler is hot.

The gauge could be defective.

Your feedwater regulator could be defective.

There might be a closed valve on the system that should be open.

You stated 'the aquastat is set to 110°'. Can I assume that aquastat is the one on the indirect water heater ?

Are you on city water ? or private well ?

Do you know what the domestic water pressure in your home is ?

Do you know if there is a pressure regulating valve on the incoming water service?
If you can locate where the water comes into the home, and there is a valve device there, take a pic or two of that also.

Let's see some detailed pictures though... make sure to include several wider shots that show the entire system so we can relate the closer ones...

 

ok i have signed up at photobucket. I will take pics 2morrow...Im redoing the basement and i have no lighting down there yet.

I Dont have a thermal expansion tank. Only the expansion tank on the boiler side.

The feed water regulator...i dont think i have 1. But 2 make sure you gus can tell me once i upload the pics.

As far as the aquastat thats set at 110 degrees its the one thats sensing the water temp at the storage tank.

Also i am on city water and i have NOOOO idea what the pressure is. can find out from the ater authority what it should be but i wont have any means to check what it actually is.

Just would like to thank every1 in advance for helping me on this mission thats driving me nuts GI2

 

I just signed back on and I see you figured out what was wrong with the reply problem.

As far as the pressure goes, you water works should have a rough ides, but what you should do is go to the big box stores and get a house water pressure gauge for about $10.00. Then hook it up to a outside faucet, washing machine, or water heater as a last resort, and get the pressure of the house. Run the water for just a few seconds before putting gauge on. Take reading. These gauges usually have a high pressure needle, so leave the gaige on overnight and the read the high pressure reading. If I am correct, it will go up to around 150psi.

Take some pictures around the water heater and around the water meter.

 

OK, we'll wait for the pics...

If they don't/can't/won't tell you what the pressure should be or is ... you can go to Home Depot or Lowes, and pick up a nifty little pressure gauge that has a garden hose fitting on it. Screw it onto a hose fitting and turn on the valve. It will show you the pressure.

Around $10 or so... lawn sprinkler folks use them ...

If you find that your pressure is high, let's say 60 PSI or above, this could possibly be the cause of the relief valve (mark called it an RV I believe, in case you didn't get his acronym which he didn't define... )

When you replaced the pressure valve on the tank, do you recall what pressure that was set to open at ? can you read the specs on the valve and let us know ?

 

OK, ok, I know....................................My bad

Sorry

 

Yea i found the problem of the reply...it was AOL being stupid so now im using internet explorer...ok i will find out the house pressures...i have a guage im sure i can rig it 2 work on a faucet.

The PT vlv i removed from the storage tank was set at 125 PSI...the 1 i bought was set at 150psi and 240 degrees.

I went down the basement to chck and i noticed that i dont not have no check vlvs or feed vlvs of any kind for the domestic water side...only the boiler side has a flow valve and check valve.

 

ok guys i went down there w/ a flash light...pics came out pretty good hopefully you can see them.

the URL is

http://s452.photobucket.com/albums/qq241/Milillo02/

dunno how it works exactly...let me no if u can get in

 

There is a basic rule that you should know.

NEVER replace a pressure relief valve with one that has a higher rating than the one you took out.

If Buderus put a 125PSI valve on there, it's because their engineers determined that was a safe pressure.

I believe that your tank is rated for a MAXIMUM pressure of 145 PSI, and now you have a 150 PSI relief valve on it.

This is NOT good ! That valve MUST be changed back to the manufacturers specified device.

If you replaced the valve and it is still opening, it is probably due to the domestic water pressure too high.

Check that and let us know ... in the meantime CHANGE THAT RELIEF VALVE TO THE PROPER PRESSURE ! IT's DANGEROUS NOT TO!

 

OK, let's start with, That fitting to the right of the water meter is most likely a check valve. It is hard to tell for sure, but I would look for more wording or numbers on it. I do not think it is just an angle/90* fitting.

Secondly, I agree with Trooper on the Relief Valve, (RV) issue.

And if the gauge you have does not have a high point dial, you may not get ALL the information we need. It may read 60psi under normal conditions, but when nobody is using the water and the water heater is coming up to temperature, you may find the pressure reaching 150psi causing the RV to start to leak. This will definitely tell us if the problem is a lack of a Thermal Expansion Tank, (TET) .

 

ok so i will start looking for a p/t relief valve that has the same specs. Also in the meantime i will buy /find a guage and install it at what?? My faucet?? and leave it until my boiler cycles and makes hot water and see the highest the pressure went?

Also yea u r right and i didnt notice it..that fitting to the right of the meter has some numbers on it...but it dosnt say its a check valve but it must be...the numbers are as follows minwp 175...maxwp 180

 

It is possible to damage the tank in the water heater with excessive pressure, so please, don't drag your heels on changing that out.

Connect the pressure gauge to any hose fitting on your domestic water system. NOT a drain on the boiler, you aren't concerned at this point with the pressure in the boiler (but remember I did say that it was too low, more below on that). If you have a laundry room and there is a hose fitting around there... or perhaps there is a domestic water drain on the water tank (I don't remember seeing one in the pictures), or on a garden hose fitting outdoors.

With a faucet open in the house, make note and report the pressure that you see.

Zero out the 'memory' needle, and leave the gauge in place for 24 hours or so. Report back with the MAXIMUM pressure that you see.

I believe that you will need to install an expansion tank on the domestic water system at the end of this investigation. If the pressure in the home water system is that high, I might even recommend having a plumber install a PRESSURE REGULATOR on the incoming water supply. I'm never comfortable with domestic water pressure above 80 PSI.

About your boiler pressure:

In some of your pictures 1477, 1478, 1479 there is a green bell shaped device on a pipe leading to your boiler. That is your FEED WATER PRESSURE REGULATOR. On the same pipe, above that regulator there is a valve with a black handle. Is that valve OPEN or CLOSED ?

 

This is a watts dual check valve, Without the union, it looks very similar to what you have, except yours is an angle style. I tried finding one angle style, but found none. Yours is older and they may not make them any longer, or, it could have been made specifically to go with that meter setup. I could be wrong, but it does look very similar, and if you look at the bottom of yours, it looks like it is accessible for repairs.




This is the type of pressure test gauge I am talking about. The black needle is the pressure needle, and the red one will stay at the highest water pressure reading. Available at most big box stores for about $10.00 I know HD sells this exact gauge.

 

To the question asked by NJTROOPER that black handled valve is closed.

The bottom of that check valve does seem like the bottom unscrews off for repairs.

I was out all day 2day, but will go most likly 2morrow to HD to get a guage and check for the 125 relief valve.

 

ok guys so i went to HD and bought the guage. Installed it on 1 of my outside water spigets for about 7-9 hrs so far and i just came home and checked the guage it is currently reading about 65PSI but the red needle is reading 160PSI. So my water pressure spiked to as high as 160PSI...

Now What?

 

Do you have a potable-rated expansion tank on the cold line feeding into your water heater?

 

"Who" is correct, you need to install or replace if you already have one, a thermal expansion tank for potable water, not for a boiler. The ratings are quite different.
You need to size the tank properly. I will do this given the water heater capacity.
Also the tank pressure will need to be set at 62psi before installation.

 

ok so wat would i need to b able to know what type of expansion tank i need and its specs?

Also what tank are we talking about when you say that it needs to be set at 62PSI? the hot water storage tank? How do i set its pressure?

 

How big is your water heater? What is the incoming temperature? What is you maximum water temperature that you ever use?

 

Side thread:

Can you open the black valve easily ? If so, open it a little while watching the boiler pressure gauge. Keep it open until it reaches 12 PSI ... then close it again ... optionally :

It would be good to know if your feed water regulator is working. To do this, leave the black valve open and see if the pressure starts to creep over 15 PSI (when the boiler is cold/cool). If it stays put between 12 and 15, it would be safe to leave the black valve open. It might be closed though because that regulator is defective, so keep an eye on the pressure if you do leave it open.

If the pressure goes to high, you can always drain a little off by using a boiler drain. It should be at least 12, but not more than 15 when cold.

End side thread.

I think you did say that you didn't have a tank already installed. Are you comfortable soldering copper pipes ? have the tools, etc ? In order to install that tank, you will need to cut a pipe, insert a tee, and a threaded fitting to accept the tank.

Talking about the tank that is yet to be installed, the expansion tank for your domestic potable water system.

PG, couldn't he temporarily install that tank using a hose ? (be sure to use a POTABLE DRINKING WATER hose, the kind they sell for RVs (Recreational Vehicles!) . They are usually white with a stripe ... Regular garden hoses may contain high levels of lead! Don't drink out of the garden hose !

I would imagine that washing machine hoses are lead-free also, non ? You can get them fancy braided ones if yer afeared about the hose bustin' when yer not home.

I'm pretty sure that you could put that tank anywhere on the system, as long as it's after the check valve, which is at the head of the line anyway ...

So maybe temporarily, just hook it up with a hose until you have time to 'do it right' ... Is that OK Mark ? (Mark is the plumbing code official here ...)

 

You said the normal operating house pressure is 65psi, subtracting 3psi from that makes the pressure setting at 62psi.
There is an air valve, possibly covered with a cap at the opposite end of the installation nipple on the tank.

To determine the expansion tank size the water heater capacity in gallons is needed.
This is Amtrol's sizing chart
http://www.amtrol.com/pdf/TXT%20Sizi...artsMC8520.pdf

 

Actually, if there is a vacuum breaker installed above the water heater on the cold inlet as there should be, it can be removed and with some BRASS nipples and fittings, the expansion tank can easily be installed there with no soldering. Do not forget to re-install the vacuum breaker.

 

Thanx alot guys. What i still dont understand is why im leaking water from the relief valve. If my house pressure surges to 150 PSI occassionally, why does it leak only when the boiler is about to shut off. I guess what im trying to say is are we sure the expansion tank is the solution? Another friend of mine was saying that i should have a pressure regulator of some sort?
What u guys think of that or of any thing else?

 

Because that is when the water heater is up to its highest temp, hence the higher pressure.

Your normal pressure is 65psi. When you heat the water in the hot water storage tank, you increase the pressure because of the temperature increase. Trust me, install a thermal expansion tank properly and you will have no more problem

 

Mark is correct.

Since it appears that there is a check valve at your incoming water supply, when you heat a tank of water, that expanding water has nowhere to go. If there was no check valve there, the expansion would be absorbed by the city water system. Since it can't go that way, it expands in your piping. The only relief that it has is the one on your water heater.

A regulator would not help you at all in this situation. If your pressure from the water main was ALWAYS that high, then you would absolutely need a regulator, but like Mark sez, your normal pressure is around 65 PSI.

I would do this SOONER than later if I were you. 150 PSI is a lot of pressure...

Mark, please comment on my idea of temporarily connecting a tank via a hose connection. Good idea or not ? I'd like to see him get that connected up ASAP ...

 

I did post the easiest way without soldering a few posts back. I would not recommend using sharkbite fittings here because of the weight of the tank. A soldered or compression tee would be the best. The problem with putting it on a hose connection is someone could accidentally shut it off. This must be connected at all times.

 

ok so i need an e3xpansion tank, and all that explaining made more sense and reassured me. Now i know that a few posts back i asked how do i find out what tank i need and its specs but u guys overwhelmed me w/ all the quations about pressures and temp's. So i guess simply if u guys can guide me to how or maybe a site that i would go to 2 get the proper spec'ed tank.

 

What size water heater(s) do you have?
I already know the pressure is 65psi

This is the link to Amtrol's thermal expansion tanks installation sheet with sizing chart. If you need help, just give the the water heater capacities and I will look it up.

http://www.amtrol.com/pdf/TXT%20Sizi...artsMC8520.pdf

 

Thanx for the patience. I have a 52.9 gal water tank...so i guess it will equal to a 50 gal tank. I went on that chart and i came up w/ the ST-5. What you think?

Also if my city water surges to 150 PSI will that effect anything?

I install this expansion tank on the inlet side of the water heater after the water meter, correct?

Should there b anything else installed before or after the expansion tank? (like another check valve, reducing valve or anything?)

 

The only reason you are seeing surges to 150psi. is from the thermal expansion. If the cities water is doing that, they have big problems, and you would need a pressure reducing valve.

Yes, an ST-5 sounds correct to me.

You can put the tank any place between the water meter and the water heater, but is recommended on the cold side close to the water heater. Nothing else will be needed. Horizontal installation of tank is not recommended unless some kind of support is used. The tank will get heavy at times.