Pressure drops on Combi boiler

amandathepanda

We have a Myson Midas combi boiler. Everything always seems to work fine during the summer months but as soon as winter comes the pressure drops really quickly, down to nil over about a couple of hours. There appear to be no leaks on the system, someone mentioned that it could be that our expansion chamber needs pumping up, any ideas ?

uncle_buck_3

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UB

cheenyweeny

From my experience it can only be+
a) faulty pressure indicator.
b) leaks

I do read you say there APPEAR to be no leaks. but if you have pipes, manifolds under the floor or buried in walls. its quite possible a leak. Normally when system is on pipes expand etc, more chance of leaking. Pressure is very low in combis. It only take about a pint or so water to leak in a day to drop pressure. also this can be absorbed by any nearby insulation like rockwool in loft with really showing and damage anywhere. Never heard os the expansion chamber needing pumped. Only leaks and 1 faulty pressure indicator keep cutting off central heating. Hope this helps

economiser

I had this problem and eventually found a leak but it still did not solve the problem entirely but it was more or less OK. Then the pressure loss started getting more rapid and I found when operating the pressure went up very high. This turned out to be loss of air pressure in the pressure vessel. Pumped it up again (used car foot pump) and back to the very slight loss again. Same problem as you, no pressure loss in the summer but starts going down as soon as the system operates. Must be a small leak somewhere but I have spent hours looking for it without success.

Jake54

Have you bled the rads

bestyman

Fav things to leak are rad valves. check them all and pull the plastic caps off them and look at the spindle too.

The pressure relief pipe could be passing, check the pipe (usually 15mm copper) that goes outside and make sure its not dripping ( if it is dripping please DONT fix it by putting a stopend on it as the boiler could explode - Ive seen it done)

The heat exchanger on the boiler could be leaking , the gases would be steamy.

If you are a bit of a bodger Fernox do something that you put in the system to stop leaks. Personally Ive never used it as Im supposed to be a proper plumber ;O)

Hope this helps

bruce2110

best advice from bestyman, if you have got water dripping from your discharge pipe, it could just be a sign that your pressure vessel in your boiler just needs pumping up! check manf' details for advice and trouble shooting if you fancy having ago yourself, if your not sure i would recommend you get a qualified plumber to give it the once over but make sure you checked around for leaks, bled the radiators etc