Central Heating Pressure

Peerzy · 13 Mar 2014 at 18:47

Evening all,

I've been in my current house for about 2 months now and it looks like the pressure on the 4 year old Combi boiler has dropped. The red and black needle have never been identical before but tonight the shower is certainly giving out a lot less power.

When we purchased the house we had someone come and look at the boiler and they said if the pressure drops I'd need to do something in here;

https://dl.dropboxusercontent.com/u/70236751/2014-03-13 18.40.05.jpg
https://dl.dropboxusercontent.com/u/70236751/2014-03-13 18.40.12.jpg

But I can't remember or work out what. The big red leaver appears to completely kill the water / pressure to the shower, the small black leaver that is closest to me won't turn and is screwed in really tight and the middle leaver (also small and black) turns 90 degrees upwards but doesn't seem to do anything either way.

The large black leaver that is the nearest thing to me is screwed in really tight as well and I don't remember the boiler man saying anything about that.

I've fiddled around and cannot work out what to do - any help? Forgive me for being useless, first house and first boiler issue!

RJC · 13 Mar 2014 at 18:55

I think the two black levers need to be turned on to allow the mains pressure to top up the system.
The fitting above the lever on the right (2nd black lever) may be a non return valve - as the system has not needed to be topped up in a while the left lever could have seized up. You may need to remove the handle and use a spanner.

neodude · 13 Mar 2014 at 18:57

Defo the two black taps.

Dunks · 13 Mar 2014 at 19:01

The two black taps with the flexi hose between them.

LiamC · 13 Mar 2014 at 19:01

Turn the black handle on the filling loop and the pressure will go up

Peerzy · 13 Mar 2014 at 19:04

Okay, unscrewed the tight black tap and turned them both up and it started moving the black needle up. I've not got anything on at the moment (heating or hot water), how high should I go (until it touched the red needle)?

mattyfez · 13 Mar 2014 at 19:07

Just do it slowly until you get a feel for how fast the pressure builds.
If you over pressurise you'll need to bleed a radiator to bring it back down.
Its probably a good idea to bleed all the radiators before hand to get rid of any air.

There's YouTube tutorials if you're unsure, boilers will bee different but the principles the same.

Peerzy · 13 Mar 2014 at 19:09

Yeah I've increased it slightly (very slowly) so I know that's how to do it now - just unsure of how high to go?

mattyfez · 13 Mar 2014 at 19:15

I think mine should be about 2 to 2.5 bar iirc but worth checking properly as i can't remember if that's for when the waters hot or cold.

Is there numbers on your pressure gauge?

Peerzy · 13 Mar 2014 at 19:15

I thought black needle should match the red needle (which is set for each boiler when setup)?

Deleted member 651465 · 13 Mar 2014 at 19:16

Between 1 and 1.5 bar is what my combi is set to.

I certainly wouldn't crank the pressure as the pressure will fluctuate when the boiler is under load.

Speaking to a plumber is probably your best bet.

mattyfez · 13 Mar 2014 at 19:18

Pass!. Maybe get this thread moved to the house and home forum, more chance of a better qualified answer.

mattyfez · 13 Mar 2014 at 19:22

Just spoke to a mate who's a plumber, hes sure it should be 1.5 cold.
Max of 2.5 when hot!

Peerzy · 13 Mar 2014 at 19:24

mattyfez said:
Just spoke to a mate who's a plumber, hes sure it should be 1.5 cold.
Max of 2.5 when hot!

Thanks, I know the previous owner had to do this every so often as well.

The red needle isn't quite 1.5 so I'll match black to red and see what happens.

Devrij · 13 Mar 2014 at 19:27

I have to do this all the time as the PRT valve is knackered and keeps dumping every time the heating comes on. Just top it up so it isn't above the red needle, and if needed google the model of the boiler.

Darey · 13 Mar 2014 at 20:18

I need to do this too, it's not a problem. I was told to keep it around the 1.5 area too, as stated above.

Peerzy · 13 Mar 2014 at 20:43

It won't go any higher than 1.1 when cold, but when we start using the system it goes up to just below the red needle. That's how it's worked since we moved in so I guess that's fine.

jh30uk · 13 Mar 2014 at 20:59

1.0-1.5 while cold and off (not pumping), 0.1 for each 1 meter a radiator is above boiler level that Max 1.5.

So ground floor flat ideally 1.0, a house with upstairs radiators approx. 3 meters above top of boiler then 1.3.

This is for a combi.

mattyfez · 13 Mar 2014 at 21:05

Peerzy said:
It won't go any higher than 1.1 when cold, but when we start using the system it goes up to just below the red needle. That's how it's worked since we moved in so I guess that's fine.

Have you blead all the radiators to remove any air pockets?

Peerzy · 13 Mar 2014 at 21:27

mattyfez said:
Have you blead all the radiators to remove any air pockets?

No, I haven't got a key nor the time tonight. I just wanted to get it working to have a shower and heating tonight.

It's the first time it's happened in 2 months of us living here so surely not a big issue.

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Central Heating Pressure

Deleted member 651465

Deleted member 651465