Feeds on a radiator

Im in the process of fitting a chrome radiator to the other side of the bathroom, now when the plumbers were in fitting my combi they removed the old radiator at my request and capped of the feeds under the floorboards, now when ive come to fit the new radiator ive just got two identical looking pipes.
How do i figure out which is the in and out for the new radiator
Cheers
Chris
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With difficulty!
You can tell on a working radiator because the feed is hotter than the return - but with no flow, these blanked-off pipes probably won't ever get hot.
Does it really matter? What sort of valves are you fitting. If manual, each valve can be either user-controllable or a lockshield depending on which type of top you put on. If using a thermostatic valve, it would be a good idea to get one which doesn't mind whether it is in the flow or the return.
If you *really* want to know which is which before fitting the new rad, you'll have to trace the pipework and see where each of blanked-off pipes ultimately connects.
Roger
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Possible simple way - but laborious:
fit a simple bridge between the two pipes - compression joints and a 'U' bend of pipe - refill the heating and turn it on and feel the pipes - one will get hot first. Then remove, and fit your radiator. This does invlove draining the system again.
This is only if you don't have radiator valves which work both ways.
Even if your valves are nominally one way flow you can fit the radiator and feel which leg warms up first, then swap the valves round if they are wrong.
In all this it helps if your 'in' and 'out' valves are the same size - otherwise swapping them round may be a problem.
Worth considering fitting a couple of isolating taps onto your capped ends to make taking the radiator on and off an easy task without draining the whole system.
However, as suggested elswhere the best option is just to buy a pair of valves which can flow both ways. It may hurt to buy more valves if you already have some, but the extra cost will probably be small compared to the hassle of trying to fit and remove valves until you get it right.
HTH Dave R
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Did the old rad have a TRV fitted ?
The rad in our bathroom doesnt (its the only one in the house that doesnt). I understand that this is normal practise. It is used as a 'by pass', so that of all the rads get up to temp then the water still has a route back to the boiler. If your system is the same i.e. doesnt have a by pass fitted, then just fit 2 lock shield valves.
Alan
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