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Baseboard Heating

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Baseboard Heating Pressure Relief Valve

The Home Wizard app calculates your ideal home care program to avoid problems with your Baseboard Heating, but sometimes trouble can still occur. Here are answers to questions about baseboard heating pressure relief valve.


I have baseboard heating, my pressure relief valve keeps dripping, at the proper pressure point
I have not drained and refill the expansion tank, would this be the reason I keep building up pressure. I did bleed the radiators at the beginning of the season, but I did not do the exp. tank.


Dear Bill:

Yes, if your pressure relief valve is leaking, this could be caused by your system's expansion tank being filled with water. As you may know, the expansion tank must be properly charged with air to prevent water in the system from boiling and exceeding the proper pressure level.

On the other hand, another reason that a pressure relief valve may leak is that the valve may have sediment in it that is preventing it from closing. To check this you will need to turn your boiler off and let it cool. Then lift the manual pressure relief lever letting it discharge water for about 3 seconds, and then let the lever snap back into its closed position. When the water discharges it should come out strong and be relatively clean. If the valve still leaks afterward, you can try the procedure a second time. And if after this the valve still leaks, the problem may be sediment trapped in the valve's seat, or the valve itself could be bad. Keep in mind that there is a possibility that when doing this test, especially on an older valve, that it could get stuck in the open position. So you will want to know where your water shutoff valve is, and you should probably do the test early in the day on a weekday, when you will still have time to call a professional plumber to come out during their normal working hours.

And before you replace your pressure relief valve, another possibility is that the pressure regulator on your main water supply is allowing the pressure to be too high in your system. Over time the rubber and metal parts in these regulators can fail and allow excessive pressure in your system, which could be causing your pressure relief valve seat to lift and therefore leak. Testing this involves putting a pressure gauge on your system to see if it is at the proper level.

Please note that from a safety standpoint you need to be sure to be VERY careful working around your pressure relief valve, as the water coming out of it will be scalding hot. Also, be absolutely sure that you NEVER block your pressure relief valve, as this could allow the pressure in your system to build up to dangerous levels.

Hope this is helpful.


Is there a video available for a step by step instructional on how to drain & refill an expansion tank for a baseboard heating system.

Thank You



We don't have a video on the site for how to drain & refill an expansion tank for a baseboard heating system. However, here is a video about how expansion tanks work from another website, along with several links to websites that describe the steps for draining an expansion tank:

Hope these are helpful.

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Baseboard Heating