DIY Doctor UK DIY Forums

hi Folks

I just changed one radiator in my kids bedroom today, the problem is(which i'm sure you heard a million times) is there is NO DAMN HEAT going into it.

I'm no expert in plumbing so i'll tell you what i know

I have a combi boiler system, no tank in the loft.
Pipe is micro bore 8mm
Fitted thermostatic valve 15mm to the new radiator, i followed the instructions but hey no ones perfect!!
All other rads in house would scald your hand to touch except this one and one right outside kids room which is only mildy warm at the bottom.

The thing i find strange is the micro bore pipe coming out the floor in kids room aint even slightly warm!

Tried bleeding it and water comes out straight away so i'm guessing this means there is no air in it.

The rad outside his room i cant bleed because i only got a plastic key and it wont budge it, the last one i tried was metal and it broke too.

So please folks help me out on this one, without the obvious call a plumber or heating guy!!

Thanks mucho!!

The one thats only warm at the bottome will just require venting, you will need a decent vent key though.

The one you have changed, check both valves are open and turn off a few of the other radiators and see if it will push through. It should as long as the old radiator used to work ?

Silly question probably, but are you sure both valves are turned on?

If you drained the system down, it could be an airlock. Try turning off all the other rads that are getting hot. The increased pressure should hopefully free the flow.

ok i turned off all the other rads in the house while i went and got a new key. when i came back the pipe was a bit warmer but still not nearly as hot as the ohers. approx 20 mins

I bled all rads in the house and every one is fine now except this new one.

OK so how do i check if these new valves are on? The TRV & the lockshield?

Also it wouldnt matter if they are on or not would it? The pipe should warm before reaching the valve.

I'm starting to think that i've kinked the pipe at some point during the replacement. If so how can i check? without lifting floorboards please!!!!

Thanks Mucho!!

well after all that messing about it turns out the lockshield valve was closed, i opened it up and got heat.

All sorted i think!!

Does this mean i've put the valves the wrong way round?

When i turn on my heating the heat starts coming from the left side pipe first(on all rads in house), then sarts warming the rad so i assumed this was the inlet pipe and where the TRV should be fitted.

Have I assumed wrongly?

Probably not. It was always custom to fit the TRV on the flow and the lockshield on the return. Old valves were directional so TRV's needed setting according to the intended direction of the water flow. New valves are often bi-directional so check the instructions, but if everything seems ok - I should leave it.