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dodders · Joined: 25 Aug 2003 Posts: 13 Location: grimsby

hi, the basic question is should my red gate valve be open or shut?

it is situated on what i believe to be the last radiator in the system off a combi boiler which i cannot get to work. it is closest to the boiler in the kitchen and also has a drain valve attached. However I get no flow to it, although the radiator fills up ok. i have changed both valves and the radiator but still no joy. the entire system has been balanced and the radiators get very hot other than this one.

the only thing i don't know is what this gate valve is for, how it works, so whether it needs to be on or off so that i can continue to try and solve the problem.

any advice would be much appreciated. thanks in advance, Paul

AlanE · Posted: Mon Aug 25, 2003 2:29 pm Post subject:

It could be there as a manual bypass valve or it could be there to isolate final rad.

What is the effect of opening it? or fully closing it? That is provided it actually works. These valves are notorious for siezing up or the innards breaking unfortunatly.

The radiator will fill up regardless provided ONE pipe can supply water but it will not heat up unless there is a complete path for the water to flow around.

The small drain valves have a habit of leaving the washer in place when opened so giving the impression there is no water even when there is.

To give a more definitive answer email a drawing of this part of the layout.

Alan

AlanE · Posted: Thu Aug 28, 2003 8:17 pm Post subject:

Paul received your email with pictures and the gate valve has been fitted in order to provide a system bypass in event that all the rads are closed off - either manually or because the thermostatic valves have closed.

I would suggest you replace it with an automatic bypass valve. In meantime leave it almost closed.

Is the non heating rad connected to the two rad valves shown in your pics? If so place receptical under each in turn, slightly open each valve to ensure water can flow from each. If it doesn't you need to investigate. Fit rad then open ONE valve and start to bleed rad. Close that valve and open other anf finish bleeding. This will ensure any trapped air in pipes is released.

If that rad still fails to get hot then you need to balance the system by closing down a bit, on each of the OTHER rads the lockshield valve. This is the one with the cover on it to prevent random adjustment. Close each a bit at a time until this final rad gets hot.

Alan

AlanE · Posted: Thu Aug 28, 2003 8:29 pm Post subject:

Deleted repeated posting.

Alan

dodders · Joined: 25 Aug 2003 Posts: 13 Location: grimsby

hi, despite another day of tinkering, still no flow. the results of opening the taps without the radiator in situ are: the right hand tap produces flow whatever the position of the red gate valve. the left hand tap produces flow ONLY when the valve is open. From that i concluded firstly that the valve still works, as it effected change when operated and secondly that the water was flowing to it only from the top pipe and not the bottom pipe. from that i guess that the bottom pipe is for return. i decided not to buy an auto sensing valve at this stage, mainly cos the Plumb Centre did not have an in-line one and i guess it still works anyway.

however these findings have not solved the problem. i conneced the radiator again, then having left it for a while with no heat, reduced the flow to the others by turning the lockshields right down so they were just open.

my next test was to shut the taps to the radiator and open the drain valve with the heating on; this produced a flow of very hot water. i figured that there could be a blockage on the return pipe. i changed the radiator, put a thermostatic valve on the left with the flow arrow pointing down to force it through the bottom pipe. at this stage i am really guessing, but of course still no joy. then turned all the radiators right off with the lockshield, still nothing.

that concludes the experiment so far!!!! i've not quite given up, so any further suggestions would be most welcome.

Paul

thescruff · Moderator Joined: 03 May 2003 Posts: 4619 Location: Bath

The mind boggels Crying or Very sad

Send us a copy of the pics paul.

scruff2@blueyonder.co.uk

scruff Idea

AlanE · Posted: Sun Aug 31, 2003 10:50 am Post subject:

They should be with you by now.

Alan

thescruff · Moderator Joined: 03 May 2003 Posts: 4619 Location: Bath

Thanks Alan.

Red valve should be open because it looks like a onepipe system.

more photo's of the other side of the wall might help, and one of the pipes from the boiler.

scruff Cool

dodders · Joined: 25 Aug 2003 Posts: 13 Location: grimsby

hi, glad to hear that its not a simple problem then!! sent some more photos, let me know if you need anything else or further explanation.
thanks
paul

AlanE · Posted: Sun Aug 31, 2003 12:09 pm Post subject:

Haven't received other pictures. Still recon its a 2 pipe system with the gate valve used as a manual bypass.

Alan

AlanE · Posted: Sun Aug 31, 2003 12:16 pm Post subject:

Forget last comment!! at least bit about pics. Have them.

The braided hose for repressurising system should not be left connected. To comply with water regulations it should only be connected as and when the need to top the system up arises.

Comment regarding valve being used as manual by pass still applies though.

Alan

dodders · Joined: 25 Aug 2003 Posts: 13 Location: grimsby

The silver flexi pipe has a black tap which i leave in the closed position, unless as you say, I need to refill the system; which incidentally has been necessary more and more often recently.

Is that ok, or do i need to do more here?

thescruff · Moderator Joined: 03 May 2003 Posts: 4619 Location: Bath

Its a two pipe system so valve should be shut for now.

Connect and open the radiator valve, fill with water, gradually turn all the other rads off ( the wheelhead end ) till it flows throught he rad.

Alternative is to connect the two ends together and see if you have a flow.

The position of the rad it should get red hot, have you taken the rad outside and blasted it through with mains water.

scruff

dodders · Joined: 25 Aug 2003 Posts: 13 Location: grimsby

yeah, i have blasted the radiator through several times, in fact i have tried two radiators! the latest radiator i tried i know to work.

if the red valve is closed then i will only get flow to the right hand end; is that ok.

more experimenting needed i feel!

dodders · Joined: 25 Aug 2003 Posts: 13 Location: grimsby

for my own knowledge please, what is the difference between the 2 pipe n 1 pipe system you guys talk about, and what is the significance?