GCH: join between radiator and tap water

[bengee]

I recently moved into my house, and the central heating bioler has a join between the radiator and tap water pipes (it's a silver flexi pipe with a tap/switch similar to that of the red/blue switches on a washing machine pipe). When i open this switch the pressure of the system increases from about 1.5bar to 4.5bar.

Anyone know what this is used for? I can't work out why someone would want to mix the radiator and tap water together!

 

[AnonymousImport]

Hi,

Urm............

The pipe you are talking about is a filling loop for the central heating system. I'm guessing you have a combi boiler?

The pipe is used to fill the heating circuit directly from the mains water supply. When refilling the system it should be filled to about 1 bar. Most combi boilers run at between 0.5 and 2.5 bar normally, so the 4.5 bar you have is too high.
Assuming yours is still at 4.5 bar you need to drain partially dsrain the system until the pressure drops to about 1 bar (or whatever your boiler qoutes as a normal running pressure). You can do this via a drain off point either near your boiler or on one of your radiators on the round floor.

Hope this has helped.

 

[bengee]

Yes that's right it's a combi boiler (central heating and hot water for taps, with NO seperate tank to store hot water, right?)

Also, i made a mistake with pressure readings... it should have read: "When i open this switch the pressure of the system increases from about 1.1 bar (normal/when join pipe is closed) to 3.0 bar".

At the mo, it's on 1.1 bar with the join closed. If i were to go downstairs now and open the switch, it would goto 3.0 bar. When i close the switch, it gradually makes it's way back down to 1.1 bar (over a period of a about a week).

So, do i need to keep this switch open all the time, or just every-so-often? Sorry if i sound a total plum asking these questions, but this is all a bit new to me

 

[AnonymousImport]

Should be closed,just check the pressure setting say each month.Use to fill system when bleeding radiators.See your boiler manual,but most systems are at about 1 bar when you fill the system.

 

[AnonymousImport]

Hi again,

Yeah keep the tap closed i.e. so no waterv flows into system.

You also say that he pressure within the system drops down gradually. Combi boilers are sealed systems, so the pressure shoud remain pretty constant, unless you have a small leak somewhere. I'm not suggesting that this is the case but it is a possibility.

Hope this has helped.

 

[bengee]

Thanks for all your help.

 

[AnonymousImport]

sorry it is late but this is what you have

http://www.gasman.fsbusiness.co.uk/picture gallery.htm