Looking for advice
My mums boiler is leaking from the auotmatic pressure valve on the top of t he boiler, its been dripping and went you run the hot water you can hear ai r coming out of it. I read on here about checking the pressure vessel and t here is air in it no water comes out of the valve.
The pressure has fallen to 0 bar which i think it would due to the valve on top leaking, but she has been told the boiler needs replacing.
Is this fixable ?
Chances are the air valve has leaked and there is no air in the pressure vessel. Try pumping it up a bit... I don't suppose it suddenly started doing this just after a service?
And it is fixable. At worst you just fit another pressure vessel somewhere else.
Someone who really knows will be along shortly.
Andy
I can't tell from this description if the OP is describing an auto bleed bottle valve, or the pressure relief valve.
The auto bleed valve will have a way of closing it - usually screwing closed the knurled cap on the outlet.
They have a limited life when left open, because a small amount of water ejected each time before they reseal will evaporate, and will eventually leave hard water scale which stops the seal working anymore.
Normally it would be left open for a few days after refilling to let trapped air out, and then closed. Maybe an occasional open and close thereafter if you are still getting gasses accumulating.
Agreed, also IME pressure relief valves often never seal again after they have been released a few times. Either because of scale or because of seat erosion. Most (water) pressure relief valves are operated by a knurled knob like a truncated cone, about 30 mm diameter, often green plastic.
OK this one is red
Air release valves are often cylindrical, with a plastic cap a bit like a tyre valve cap.
I'm a bit bothered about the description of air coming out when you run hot water. Is this consistent with an expansion vessel problem, either no air or leaking diaphragm? If that isn't working, perhaps you will eject water (not air) from the pressure relief valve after running the DHW because the system pressure "bounces" over the limit just after it's turned off?
Not really enough information here. Maybe it's been assessed by a competent plumber who has come to the conclusion that it is not *worth* fiddling with at this stage of its life. DIY-ers are (rightly) more inclined to fiddle than a professional because he might well do a good repair only to be unfairly blamed for a subsequent independent failure.
Or he might just be looking for business, as you seem to suspect.
WB will fix it within an hour for £250 ish. Sometimes that can be a good deal
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