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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Diagram of unvented water heater & boiler https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1307386877 Message started by Twobarrows on Jun 6^th, 2011, 8:01pm

Title: Diagram of unvented water heater & boiler
Post by Twobarrows on Jun 6^th, 2011, 8:01pm

I am now in a house with an unvented water heater & boiler, and have never come across these sytems before, so have no idea how it is plumbed in, or more importantly, what to do to turn off the water to change a washer in the bathroom on the first floor! (actually I'll go round and change them all while I'm at it). There only appears to be only one valve in the airing cupdoard on the second floor? Does anyone have a link to a good diagram of how this set-up works?
None of the sinks, baths, showers etc. appear to have isolating valves on them! I suspect this could turn into a right bundle of fun.
Oh dear..... [smiley=banghead.gif]

Title: Re: Diagram of unvented water heater & boiler
Post by thescruff on Jun 6^th, 2011, 10:26pm

As per usual, no makes or models are mentioned.

A pic showing the connection to the cylinder would be good.

If you have a stopcock on the incoming mains turn it off and see what stops running.

Title: Re: Diagram of unvented water heater & boiler
Post by Twobarrows on Jun 7^th, 2011, 11:40am

It's a Glow worm Ultimate 100FF on the ground floor, A/S OSO 250l unvented water heater on the second floor. I was looking for a sort of 'generic' diagram of how it is piped, is that not possible?

Title: Re: Diagram of unvented water heater & boiler
Post by thescruff on Jun 7^th, 2011, 1:06pm

If you only have one valve, it's possible a DIY job and doesn't meet the regs so could be unsafe.

Title: Re: Diagram of unvented water heater & boiler
Post by Twobarrows on Jun 9^th, 2011, 11:16am

Many thanks, I turned off the mains & the cock in the airing cupboard & changed a shedload of tap washers in various stages of wear & disintegration. I didn't even think about this with an unvented system, it's easy isn't it :-)
I don't think this was a DIY job, the previous owner definitely wouldn't have been capable. So how many / where should there be cocks? The one there is extremely stiff so if I have to drain it all down to add some I'll replace that as well (with 22mm ball / lever type).
Cheers.....

Title: Re: Diagram of unvented water heater & boiler
Post by Twobarrows on Jun 13^th, 2011, 6:28pm

Oh the devil farts in my face yet again!
After some knocking & banging from the boiler, it stopped. Turned out the water pressure switch wasn't activating. Closer inspection revealed that the switch is broken, so will need replacing. I guess I need to drain down to do this, but on the cylinder in the airing cupboard it states not to drain???

Title: Re: Diagram of unvented water heater & boiler
Post by thescruff on Jun 14^th, 2011, 12:41am

thescruff wrote on Jun 6^th, 2011, 10:26pm:

As per usual, no makes or models are mentioned.

A pic showing the connection to the cylinder would be good.

If you have a stopcock on the incoming mains turn it off and see what stops running.

Are you sure it's an unvented cylinder.

The reason it say don't drain maybe because of the inhibitor, or the type of cylinder.