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Hydronic Boiler relief valve problem?

Releif valve is lifting when temp is up, but not when cold ?
Where should I first look to solve problem?

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Re: Hydronic Boiler relief valve problem?

Check the pressure guage. Typically the pressure in a water boiler should not be more than 20 psi. If you are approaching 30, the relief valve is doing it's job. I would replace or adjust the automatic water feed if the pressure is high. Always replace the boiler relief valve. Tap on the expansion tank, it should sound hollow. Replace it if it is full of water. If you have one of the old expansion tank that has no bladder in it, drain it.

Posted on Dec 04, 2007

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I have no air pressure

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Jan 27, 2016 | Heaters


How to maintain a Water Heater

A water heater can last you many years if you take proper care of it. Every few months, you should check your water heater for leaks and flush it out to avoid buildup of sediment inside the tank.

Before draining and flushing your water heater, turn off the gas or electrical power and let the water cool down a little. Close the incoming water valve, and attach a hose to the drain valve to run the water into a large bucket, or to a drain or the outdoors.
Open the drain valve, and turn on one hot water faucet somewhere in the house to let in air. When all the water has drained from the water heater, turn the cold water valve on and off until the water from the drain runs clear. Then close the drain valve and the hot water faucet, open the cold water valve, and turn the water back on.
This is also a good time to test the temperature-pressure relief valve, which keeps pressure in the boiler from building up too much. Lift or lower its handle. Water should drain from the overflow pipe. If it does not, call in a repair professional as this could result in a potentially dangerous situation.

on Sep 03, 2010 | Heaters


Valve Pressure Reducing or Pressure Reducing Valve

dfef4ee.jpgThe pressure reducing valve on a boiler is the way that the water pressure in the boiler is controlled. The standard pressure for many hot water boilers is considered to be 12 PSI. To keep the boiler pressure at or near the 12 PSI mark a small valve is used for pressure reducing. Most domestic water systems run between 20 and 60 PSI, so the pressure must be reduced for the boiler.

This pressure reducing valve is installed in the pipe that goes from the domestic cold water to somewhere in the piping on the heating system, usually at or near the expansion tank. The valve is mostly maintenance free but will create some problems at times. Some of the things that can go wrong are:

  1. The valve seat can get dirt stuck under it causing water to leak by and increase the pressure in the boiler, causing the relief valve to release water periodically.
  2. The valve can become plugged with dirt causing the boiler to not have enough water pressure, which will cause circulation problems with the boiler pumps.
  3. The valve can leak causing a mess around the boiler area.

Replacement of the pressure reducing valve is not difficult if the installer strategically placed manual valves so that the reducing valve can be isolated from the rest of the system for replacement.
If the water pressure reducing valve fails in any way, it is usually best to just replace the whole valve rather than trying to repair or fix it. I have tried a number of times with only temporary results. These valves are not a high dollar item and the time it takes to fix them is not worth it.

on Dec 23, 2009 | Heaters

1 Answer

Loss of pressure in boiler, no obvious leaks, water pressure switch changed plus pressure release valve

Check that your make up water is on.

Make sure your fill valve is working but it sounds like it is not. Your min pressure should be 15 psig. on the boiler. Fill valve will maintain a15 psig on the boiler. Water and pressure does get out of the boiler when radiators are bleed. When fill valve is not working people will keep bleeding the radiators trying to get heat but only lowering the boiler pressure with no water make up.

Make sure your boiler is getting water and has pressure when running.

If it isn't...SHUT DOWN and have a professional look at it.

Pressure relief valve is factory set ta 30 psig and opens when pressure is above 30 psig. This is a safety valve.

Feb 17, 2011 | Heaters

1 Answer

The releif valve on my water heater was activated. Do I have to replace it or just wait until it cools off and then I can refill the tank. Kenmore Model # 153.333130

It should reseal itself; however, sometimes the seal will leak. As long as it doesn't leak when you refill the tank, you will not have to replace it.

More information on Safety Relief Valves

Hope this helps
Please leave a rating.

May 09, 2010 | Heaters

1 Answer

My Crown Boiler leaking water from escape valve when its on

The probelm if either a bad fill valve or a bad expansion tank. Either one of those things will make your boiler leak through the relief valve.
Tap on the expansion tank and see if it is totally full of water. If it is then that is your problem, if there is air in it and it sounds hollow then the fill valve is the problem.
This tip I wrote pertains to your problem although not exactly the same... it may help you.

I hope that this will help you to solve your problem!

Thanks for using Fixya!!


Dec 11, 2009 | Heaters

1 Answer

Hydronic heat water feed valve

You should be ok. Most of the time the boiler are charged to about 10psi and dont have feed valve. You would only feed if you have a slight leak in system. Rus

Dec 05, 2009 | Heaters

1 Answer

Water overflowing after i raised the temp, put

Your expansion tank needs to be drained or the mini expansion tank has a hole in the diaphram...pump the mini expansion tank back up with approx 15psi air ....ofetn once the overfolw is activated it doesn't stop...try opening the valve manually and snap it closed again...if it doesn't stop you will need a new relief valve

Oct 28, 2009 | Heaters

2 Answers


I have some confusion about what you are asking......

There is no such thing as "Hydronic Electric Baseboards"......

I am assuming you are referring to the oil filled baseboard heaters. If so....

The same amount of btu's required to heat a space remain the same whether the elements heat a liquid to warm the air or whether they heat the air directly, the same amount of wattage will be consumed. So, their is no more or less efficiency between the two.

If you are referring to "Hydronic Baseboard Heaters" (these baseboards are fed from a boiler with a pump) Then....I will assume that it is a gas boiler. In which case, the gas boiler would be more cost efficient to operate. If it is an electric the same rule applies as above......the cost is the same.

Oct 04, 2009 | Fahrenheat FBE15002 Baseboard Heater

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