Pressure Relief Value Leaking?


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Old 08-27-07, 07:34 AM
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Pressure Relief Value Leaking?

I have read another thread to try and fix but I am unsure. My pressure relief value is leaking and do not have a drain and woke up to a flood. I shut the water going to the boiler and now I looked online for answers. It is a oil/water system with an expansion tank. I also use the unit for domestic hot water with a reserve tank.

It seems when I went back to the system today and tried to put the water back on to get a better look. It seems to be leaking from the top bicycle type valve on top of the expansion tank and the pressure relief valve. The pressure read about 15 psi. Is my expansion tank bad where do I purchase another one? Home Depot?
 
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Old 08-27-07, 08:04 AM
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Would the pressure relief value still leak with no PSI?
 
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Old 08-27-07, 10:57 AM
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It sounds like its leaking from the air vent, if its the bicycle thing on top of your expansion tank. It lets air out when water is added to the boiler. You can screw that cap down tight and it should stop the water but if you furnace is already drained(or close to it), you mind as well go to the hardware store and buy a new air vent.

If its ALSO leaking from the relief valve then you will need a new relief vale and probably a new expansion tank. It can continue to leak if there is 0 PSI. Air can be leaking in from somewhere(your bad air vent for example) and drain the furnace down. Normally a old relief valve won't reseat itself properly. You can do that work yourself or make it easier and just hire someone. They will also make sure there isn't any air in the system when they are done. Don't use the furnace until the water is back on.
 
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Old 08-27-07, 11:02 AM
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Beware!!!

If the tank has a Shraeder (sp?) valve, and water is coming out of the air valve, then the bladder is leaking and the tank is most likely saturated with water!! Be aware that these tanks hold at least 4.4 gallons of water when full! They will weigh almost 40 pounds when full of water, and they are very top heavy! Be careful when removing.
 
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Old 08-27-07, 12:13 PM
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Thanks for the comments. I changed the Pressure Relief Valve and now it is not coming out. When I add the water back to the system and turn on the boiler. Air comes out of the air valve first then it starts and is continuing to drip water. The Expansion tank does not seem to be filled with water by tapping on it.

After a trip to Home Depot they had a few expansion tanks and didn't know which one to get. The one I have is rated at 75 PSI as is the Air vent (Armstrong 502 75 PSI). They had one rated at 60PSI and was not sure if I should get this one? or do i try and just change the air vent? Thanks for any help.
 
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Old 08-27-07, 12:45 PM
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I have an Extrol (expansion tank) rated at 75 PSI same with the valve. Can I use the Home Depot one Watts ET-60 rated at 60 PSI with the related valve? Is there any certain way to install? I am sorry to beg.
 
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Old 08-27-07, 02:29 PM
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[QUOTE=rnappi;1222435]I have read another thread to try and fix but I am unsure. My pressure relief value is leaking and do not have a drain and woke up to a flood. I shut the water going to the boiler and now I looked online for answers. It is a oil/water system with an expansion tank. I also use the unit for domestic hot water with a reserve tank.

QUOTE]

This advice is offered as is and is a non professional opinion.

One more time... If the Shraeder bicycle type valve on the expansion tank is leaking water when you measure the pressure, the tank bladder has ruptured and the tank is probably full of water. Especially if the tank is mounted upside down as you indicate in your first post (valve is up.) Note: if full of water, it will be EXTREMELY HEAVY AND TOP HEAVY!!!!

The system pressure and the tank pressure are two different things. To measure the tank pressure, you must release the system pressure so the tridicator on the boiler shows 0 pounds pressure. You then measure the tank bladder pressure using a tire gage. The tank should be precharged between 12 and 15 pounds (for a single story house.) ONCE YOU PRESSURIZE THE BOILER, THE TANK AND BOILER WILL READ THE SAME. YOU NEED TO READ THE PRECHARGE ON THE TANK WITH NO BOILER PRESSURE.

You would replace the tank with one of the same size: i.e. 4.4 gallons, or whatever the tank is rated for. The pressures you are mentioning are the test pressures for those tanks. Any large box home improvement store will have the tanks. The tank you need is for a closed loop hydronic heating system, and will have a 1/2" male thread. It should be precharged for 12# from the factory. They are normally gray in color... There are similar tanks for potable water--they are are non-ferrous and generally have 3/4 male threads and a much higher precharge..

The pressure relief is releasing most likely because the boiler pressure is going beyond the safety limits because the bladder tank is saturated, and there is no room for the water to expand when heated.
 
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Old 08-27-07, 03:33 PM
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Tank is mounted with bicycle valve down. It does not leak from here but measures 5#'s. What is leaking is the air vent which is on top. When I put on the water it starts dripping from the Air vent. Thanks for your help and I am sorry for the confusion. What should the pressure measure? If I install a new expansion tank. It comes with 12 PSI installed already. What PSI do i put this at and do i do this before mounting?
 
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Old 08-27-07, 03:52 PM
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Oh, okay. You must have an airscoop with a brass air bleeder on top of it? That could have a bad seal if it doesn't stop leaking once the air self purges from the pipes. If you have a one story house with the boiler in the cellar, the expansion tank should be pressured to about 12 PSI before adding water to the system. The boiler pressure gage should be at 12 to 15 PSI once water is added to the system. Why don't you post a link to some photos of the problem areas so everyone can see what is going on?
 
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Old 08-27-07, 08:02 PM
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RC's Right

A picture, as they say, is worth a thousand words.

If it is configured as RC suspects:
Drop the boiler pressure to zero.
Add air to the downpointing schrader to 12#.
Replace the leaking air vent.
Re-pressurize the boiler with water to 12# & fire it up.
The operating pressure should be around 15# when hot.
 
 

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