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Comap Sphere Radiator Valves - Help please

Postby Ossaman » Tue Jun 10, 2008 4:03 pm

I have just bought several pairs of Sphere rad valves from Screwfix, to replace the old ones on my indirect central heating system. Both valves in the pair appear identical i.e. Wheelhead as I understand it. No lockshield as such. This is despite Screwfix telling me, before buying them, that one was a lockshield & the other Thermostatic!!! I emailed another company selling these same valves, as a pair, & they replied saying they were both Lockshields!!! Gor Blimey.
I quite like the look of these valves & would like to use them, so can some kind soul tell me whether they will work ok as a pair on one radiator. I guess it would be like having two Wheel heads on one rad & I suppose someone could easilly upset the system balance by twiddling, but does it matter that much?
I would really appreciate some thoughts on this.
Thank you. :?
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Simply Build It

Postby htg engineer » Tue Jun 10, 2008 6:40 pm

Check whether the boiler has a bypass fitted, if it does then there's no problem.

The only problem with having all wheelhead valves, are that if all were closed and the boiler was turned on the water cannot circulate and may damage the boiler and componenets. It's very unlikely that all would be turned off together though. It's the same with TRV's you cannot fit TRV's to every radiator unless there's a bypass fitted.

If there's a bypass this will allow the water to circulate if all valves were closed. If there no bypass or you're unsure, all you need to do is make one radiator the bypass by fitting 2 x lockshield valves, this means they cannot be accidently turned off, as you have to remove the head and use a spanner.

I normally make the bathroom radiator the bypass, as people turn the rads off or down in bedrooms and living areas, but after bathing and showering you always want a nice warm room - so people tend not to close them anyway.

htg engineer
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Postby Ossaman » Wed Jun 11, 2008 8:20 am

Thanks Htg Engineer.

No, I don't have a boiler by-pass, but I will set the bathroom rad up as one, as you suggest. Thanks for your prompt reply.
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