Tip & How-To about Heating & Cooling

Boiler Leaking Water - The Boiler Leak may not be the boiler

Went on one call today and had another query by Facebook about this so I though why not write an article about it. Both persons were very concerned as they saw water dripping from theirs boilers. A closer inspection for both showed that it had nothing to do with the boiler its self.

There are many things that can make water leak from your boiler. If you know for sure that the water is coming from a hole in the sections then you may have a serious problem. Usually though there is an easy fix for that also, more on that in another article. Both boilers today were leaking water from the relief valve.

This valve is design to relieve the excess pressure from the boiler in case of a build up of extra pressure in the boiler. The extra pressure can come from a number of different things. A few of the causes may be a bad expansion tank, a bad fill valve or pressure reducing valve, or an open bypass valve. The bypass is easy, just close it and relieve the extra pressure. The others are not as easy.

Your expansion tank is simply a tank that allows water from the system to go in and out according to the pressure in the system. This tank contains about ½ air which acts as a cushion to absorb the extra volume of water that is created as the water is heated. Hotter water takes up more space or volume, so it needs a place to go to when it is heated. If the expansion tank is totally full of water then, it will push water out of the relief valve. Changing your expansion tank will fix the problem.

If the reducing valve or fill valve is leaking by then you can also get extra pressure in the system. A normal heating system will only run 10-20 psi pressure. Most well systems or city water is way higher than that. If the pressure in your boiler gets over 30 psi then it will begin to relieve the extra pressure by dripping water.

If you have a drip from your boiler this is what you check. First the expansion tank, the reducing valve, and the bypass valve that bypasses the fill valve. This valve is usually installed to quick fill the system, or purge the water lines of air.

Often there is just a small problem that looks like a big problem. Do not get excited and methodically check through the possibilities. You will usually find that the problem is not nearly as bad as you first thought that it was.

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