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QUESTION:Yesterday I noticed the overflow pipe (it comes off what I think is a blue
pressure relief value)
on my gas/hotwater boiler/furnace was dripping.
Does anyone have any ideas what that might be? Could the pressure relief
value
be going? How might I test to see if that is the problem? If it is the
value,
is it something I can replace myself?
ANSWER: It can be a sign of a few things, one the relief valve can be crapping
out, OR it can be the pressure in the boiler being too high. The
pressure being too high can be caused by a couple things. The pressure
reducing valve on the fresh water inlet could be failing and allowing
too much pressure into the system (if you installer leaves the fresh
water on, which most do as its best), or it can be a failure of the
expansion tank.
Typical boiler pressure, when cold, is 12PSI. When the boiler is hot it
can be as high as 20-25 PSI. The relief valve will blow at 30 PSI. To
narrow it down, if the pressure gauge on the boiler is reading normal
pressure (less than 30PSI when hot) its the relief valve. If the
pressure is up around 30 PSI its one of the other two but its best to
change the relief as well because they often weep when the system is
drained if they are old.
The only issue with you changing these components yourself, of course
after being able to diagnose them, is that the system will have to be
bled of all air otherwise you will hear what sounds like waterfalls
running through your heating pipes. This can be a tough one to explain
if you dont know how to do it. If you dont, you would be best to call
the service company for your boiler.
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