Hi All. I replaced the presure relief valve on my combi last night. Bled the boiler but thesystem pressure goes right up. Is this purely down to air in the system (rads etc) expanding ?
Should I bleed upstairs first or downstairs and work up?
Misunderstanding how system works (1 bar cold, but up to 2 bar when system heats up, depending on size of system, temperature rise and size of expansion vessel).
wouldnt be the first time and not only by DIYers either,even alleged CORGI men do it..but then a lot of them dont even test for soundness these days,or tightness come to that!
I bled the valve at the top of the spirally tube that goes round the hot bit and the 2 walves eiter side (inlet + Outlet)
Tried the radiators, but no air was anywhere to be seen.
Seems OK today, I guess I had the cold pressure too high, which on start up was getting up to nearly 2.5 bar where the valve got sticky.
Lowering the pressure to about 0.9 bar, it goes up to about 2, then as the rad's shut down on 'stats, it seems to settle at about 1.5
I did notice however, when it was going right up in pressure and leaking, there were drips running from the bottom of one of the 2 flat(ish) cylinder tank type things (up the back next to the wall)
Your expansion vessel is either broken, underinflated or undersized. You could benefit from ensuring that it is topped up. If this doesn't reduce the high pressure spike, consider fitting an additional unit.
I will hazard a guess that the flatish cylinder tank type thing is an expansion vessel. (I may be wrong). Releasing water in the way you suggest would be indicative that it may be blown, which would explain the excessive pressure rise.
Thanks for your advice Christian, How/where would I look at topping it up,
Ah. Sounds like a big job, as I presume the boiler will have to come off the wall.
As long as I run it at the current pressure, and it doesn't peak to "leaking" pressure, I presume I can get away without replacing it untill spring, or is it likeley to deteriorate rapidly?
You'll need to post the make and model of your boiler, so that the flat cylinders can hopefully be properly identified by someone with some specific product knowledge (which won't be me!). Better still would be if you could also take a photograph and put it on the web with a link. (Don't attempt to post a photo direct to the group).
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