Radiators hot at top and cold at bottom

[hquinn2batman]

New radiator fitted in conservatory has been cooler at bottom since it was fitted. Trv fitted to feed/ normal valve on return. Microbore pipe. Has been checked with head off Trv. Plumber says it needs balanced and has been fiddling with every radiator in the house for months and now I have other rads with the same problem and the original rad is no different. Plumber says it is normal for radiators to be hotter at the top and I now think that he's fobbing me off.

Any ideas?

 

[Softus]

You need to replace your plumber with a proper heating engineer.

 

[Agile]

It can be very difficult to add radiators to a microbore system, particularly large ones.

It rather sounds to me as if he may have just fitted it parallel to another rad so they share the same flow route.

The original concept with microbore is that each rad is fed directly from a central manifold. If there are no spare outlets then that makes adding an extra rad difficult.

Another hybrid method is to use more normal pipe sizes but just use 10 mm as the feed size for the last metre or two up to the rad.

All rads will be hotter at the top! The flow differential with a non condensing boiler was traditionally 11*C so there can be up to 11*C between the top at the flow end and the bottom at the return end. Thats normal and correct.

If the flow rate is too low then the temperature differential will increase. This has to be compared with the differential at the boiler.

Tony Glazier

 

[dal5band]

Your conservatory radiator is not getting enough flow. Check both valves are fully open. Then turn the other radiotors off starting with the radiator nearest to the conservatory one. With two or three others off, the flow should improve in the conservatory, then gradually turn the others back on, a little at a time, but only enough so they get hot.
This will balance things out and may also clear any little blockage in the new pipework.