isolating valve in pipe runs

[byron]

I want to add a rad to my c/heating system which is a worcester 28i combi.Would it be okay to put isolating valves in the new pipe run to save me draining off ,because due to ongoing work i am having done the new rad will have to moved again shortly.
regards

 

[anjme]

use "full bore" isolating valves some "ballofix" type valves reduce the internal diameter of the pipe and can restrict the flow to the rads.

 

[chrishutt]

Don't worry about reduced bore in isolating valves, but do worry about the quality of the valves. Some of the cheapest ones are liable to develop leaks which you might not even notice if valves are under floor.

 

[byron]

Thanks for that chrishutt,can you recommend ones to get.

 

[ricarbo]

Chrishutt is right. A restriction by something like a 'ballofix' valve won't cause a problem. Because the hydraulic resistance depends upon the whole route, not just one bit of it. The pipe size is related to the heat output required, as it affects the flow rate. You won't have to worry about this for one rad, unless it is enormous.