Heating pressure

[PositronicRay]

I noticed the heat g pressure was high the other day, 2.5 bar. I checked this morning about 20mins after it came on and its up to 3 bar. Last yr I seem to remember it was steady, around 1.5-2bar.


It's not been touched, or serviced so why the increase? Faulty filling loop valve?


Looks like I've a place to bleed, (the pipe gets hot with the rads) but as I don't want to create a leak, am I better off using a rad?

Edited by PositronicRay on Tuesday 19th November 07:06

[PositronicRay]

I think I've answered my own question.

I took the top off the filling loop valve and using mole grips got another 1/4 turn.

Hope it's OK for now, I'll get it changed in the spring when the boilers serviced. Bleed excess pressure from rad or bleed pipe?

[Fore Left]

I am not an expert but I'm pretty sure that red knob is the pressure relief valve. It should vent to the outside via a tundish (an open connection where you can see the water flow). Open it and get the pressure back down to 1.5 bar.

The filling loop should have two valves. Check they're both fully closed. If they are I'd get an expert in.

ETA; just seen your post. Glad it's(hopefully) sorted. Again, not an expert but I thought filling loops always had two valves to avoid this very situation. Definitely get someone to look at it and maybe update the system if you only have one valve.

Edited by Fore Left on Tuesday 19th November 07:28

[PositronicRay]

There probably is another filling loop valve, behind all the boxing,

I've bled a rad, hot pressure down to 2.2bar. Off to work now so don't want to fk about too much.

Edited by PositronicRay on Tuesday 19th November 07:49

[Peanut Gallery]

Just to say check the pressure when its cold as well. Mine went down to zero when cold, and up to 3 bar when hot.

New expansion vessel, all sorted now.

[MJNewton]

Fore Left said:

I am not an expert but I'm pretty sure that red knob is the pressure relief valve. It should vent to the outside via a tundish (an open connection where you can see the water flow). Open it and get the pressure back down to 1.5 bar.

It's best not to do this.

You are right that the red knob is indeed the PRV but it's there to fulfil a safety function, not as a means of reducing pressure. If you do use it for this there's a good chance of the dirt getting caught in the valve seat and it failing to re-seal. If there's a drain valve it's far better to use that.

Edited by MJNewton on Wednesday 20th November 19:50

[caziques]

Peanut Gallery said:

Just to say check the pressure when its cold as well. Mine went down to zero when cold, and up to 3 bar when hot.

New expansion vessel, all sorted now.

Expansion vessels tend to lose air pressure over time. A few pumps with a bicycle pump generally sorts it out.

[PositronicRay]

Seems okay now.

1.5 bar cold 2.0 warm.

Incidentally the gurgling we experienced (and didn't resolve) prior to over pressurisation has disappeared.

I'll get the filling loop valve changed when we service the system in the spring.

Thanks all.