mikky Posted January 18, 2012 Report Share Posted January 18, 2012 just had 9 rads and a new boiler fitted..managed without for the past 30 years..however...after the install the pressure reading on the boiler dropped from 1 bar to 0.4........found several leaks and fixed them...so my question is...when the heating is switched on and then goes off the bar pressure reading seems to drop from 1 bar to 0.8 and go up to 1.1...is it normal for the pressure to fluctuate....getting paranoid there is a leak somewhere in the system mikky Quote Link to comment Share on other sites More sharing options...
Cosd Posted January 18, 2012 Report Share Posted January 18, 2012 Water expands when hot therefor the pressure rises. I have a pressurised Vailant system which sits at 1.3 bars when off and rises to about 1.9bar when fully hot. So in answer to your question, yes it is normal for the pressure to drop when it switches off. I'm not an engineer. Quote Link to comment Share on other sites More sharing options...
super sharp shooter Posted January 18, 2012 Report Share Posted January 18, 2012 That's normal for it to do this. I have just had an external expansion vessel fitted as it kept dropping down to 0 bar , but now it sits at 1 1/4 bar when off and 1 3/4 bar when on. Quote Link to comment Share on other sites More sharing options...
Daany Posted January 18, 2012 Report Share Posted January 18, 2012 Yes it's normal for it to rise when boiler reaches it maxium temp but if it's droping below the 1 bar Mark the boiler wil cut out and if it's droping wile boiler is of then yer u will have a leak somewhere, is the boiler a combi or a system boiler, Quote Link to comment Share on other sites More sharing options...
mikky Posted January 18, 2012 Author Report Share Posted January 18, 2012 its glow warm betacom 28a....when not on it stays at 0.8b...however he has left a loop on it and i can up the pressure..just put it at 1bar..non of the rads seem to be leaking.. mikky Quote Link to comment Share on other sites More sharing options...
Daany Posted January 18, 2012 Report Share Posted January 18, 2012 Is any pipe work under concreate floors, if not open both valves on the filling loop ( the silver flex hose) and there should be a pressure gauge on the boiler wait till the pressure gets to 1.5 bar and shut the valves of that is the correct operating pressure when cold then when the heating is at max it should read 2 bar. Quote Link to comment Share on other sites More sharing options...
mark@mbb Posted January 18, 2012 Report Share Posted January 18, 2012 You can have a small leak on the gland nut on your valves and it may only leak a little bit when the heating is off and may well evaporate when the heating fires up this will cause your pressure to drop there used to be a product called ls 1 this was designed for this problem Mark Quote Link to comment Share on other sites More sharing options...
mikky Posted January 18, 2012 Author Report Share Posted January 18, 2012 cheers everyone mikky Quote Link to comment Share on other sites More sharing options...
-Mongrel- Posted January 18, 2012 Report Share Posted January 18, 2012 Check the pressure when the rads are cold, it's the only way you can get like for like readings, any heat will cause a pressure increase to some degree. Cold pressure should be between 1 and 1.5 bar and it should always come back to the same cold pressure. If it's regularly dropping then you have a leak somewhere. Don't worry too much if it loses a little bit of pressure over the first week or two, it's normal. The boiler has an automatic bleed valve and will clear any residual air in the system, however bleeding air out is bleeding pressure out too. If it's only a slight drop I'd wait and see how it settles down. Quote Link to comment Share on other sites More sharing options...
s.wray Posted January 18, 2012 Report Share Posted January 18, 2012 Is any pipe work under concreate floors, if not open both valves on the filling loop ( the silver flex hose) and there should be a pressure gauge on the boiler wait till the pressure gets to 1.5 bar and shut the valves of that is the correct operating pressure when cold then when the heating is at max it should read 2 bar. :good: Quote Link to comment Share on other sites More sharing options...
mikky Posted January 19, 2012 Author Report Share Posted January 19, 2012 put it at 1b this morning and it was still at 1b at tea time when i got home..hopefully no more leaks mikky Quote Link to comment Share on other sites More sharing options...
-Mongrel- Posted January 19, 2012 Report Share Posted January 19, 2012 Is any pipe work under concreate floors, if not open both valves on the filling loop ( the silver flex hose) and there should be a pressure gauge on the boiler wait till the pressure gets to 1.5 bar and shut the valves of that is the correct operating pressure when cold then when the heating is at max it should read 2 bar. 2 bar hot is not set in stone, 1.8 is fine, 2.2 is also fine, you don't want it going over 2.5 really, once again that would suggest a problem. Quote Link to comment Share on other sites More sharing options...
Daany Posted January 20, 2012 Report Share Posted January 20, 2012 I sed 2 bar as it saved I'm going abit over the top and it dishcharing if I'd sed 2.5 bar and he went over he would of been worried why water was running out side if u fit heating then ul no it's tricky to fill up on your own and get the pressure to where u want it If it's staying at the same pressure wile cold mate u dnt have owt to worrie about Quote Link to comment Share on other sites More sharing options...
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