2 radiators not working

piperm87

Thanks. Hopefully it's something simple. I'll get the floor up over the weekend and see if nothing to obvious. I'm glad were heading towards spring now as im sick of messing with the heating system. 

ThisIsWeird

piperm87 said:

Thanks all i really appreciate it. Ive just tried it and turned off every rad apart from the one on the landing and there was no change. I did the same with the bathroom one and the same result. I know its  pex pipe under floor so im wondering if its kinked maybe when ive been moving rads around. Its only happened this winter though and has been fine over previous years which is weird

Very unlikely you have kinked a PEX pipe - that would take some doing. It's possible, but unlikely.

Ok, at one end you have a TRV, and on t'other a 'lockshield'. TRVs are easy - unscrew and remove the head, and expose the pin underneath. That pin should be clean, and be easy and smooth to move. BUT, it'll need a firm press. Use summat over yer thumb - a spoon will do - and check you can press it down around 8mm-ish, whereupon it'll bottom out with a gentle thunk. When you release it, it'll pop up instantly and cleanly. Do that a few times. If it moves smoothly, it's fine.

With the TRV head off, does it now heat up? Look at the bottom of the head, the central part that presses on the pin - when you turn the head from '*' to '5', does that part move in and out?

If all that looks ok, then replace the head, but leave it at '5'.

Now the other end - the lockshield. Pull off the cap (or remove the screw) to expose the spindle. Before you turn this fellow, tape a paper flag to it to act as a pointer, 'cos you should measure and note down exactly how many turns and part-turns it takes to close it off. Now turn it clockwise until it bottom out - that might be only a couple of turns. Note that down. Now open it a good half-dozen turns.

Does the rad heat up?

piperm87

I removed the TRV'S from the landing and bathroom rads and replaced with lockshields because the TRV'S were knackered and not working properly plus im hoping to refurb the two rooms in the next couple of years so it's just a temporary measure.

Since ive removed the TRV'S the inlet side of the rads do get hot but the outlet is still cold / cool so its not making a circuit and thus not workingn correctly. ive had the outlet lockshield at various settings but it doesnt make a difference. Its so frustrating. . . 

ThisIsWeird

Ok, next try Plumb's suggestion. Turn off both valves fully. Open the bleed screw, and wait for the water to stop coming out - not much should do so.

Now open each valve in turn, and see how forcefully the water fires out t'bleed screw. Repeat for t'tother end. Are both ends clearly supplying a decent flow?

Is your system pressurised - does the boiler have a pressure gauge?

piperm87

ThisIsWeird said:

Ok, next try Plumb's suggestion. Turn off both valves fully. Open the bleed screw, and wait for the water to stop coming out - not much should do so.

Now open each valve in turn, and see how forcefully the water fires out t'bleed screw. Repeat for t'tother end. Are both ends clearly supplying a decent flow?

Is your system pressurised - does the boiler have a pressure gauge?

i'll give it ago when i get back from work.

The system is pressurrised and is sitting about 1.1 bar on idle. It goes up to around 2 when the heatings on. The 2 trouble radiators are getting luke warm only - the flow pipes are red hot but the return pipes only get as warm as the radiator so to me its like there's a restriction somewhere preventing the flow of water back to the boiler. All the other rads are working fine these days. I balanced the rads about 2 months ago and the one in the bathroom worked really well for about a week - i placed a temperature monitor on top of the rad was hitting 40 degree but it just suddenly stopped working one day now i'm back to square one with it.

I know were heading to the end of winter now but without the bathroom one working the temperture over night in that room drops down to around 11 degree one the frosty mornings. 

ThisIsWeird

piperm87 said:

ThisIsWeird said:

Ok, next try Plumb's suggestion. Turn off both valves fully. Open the bleed screw, and wait for the water to stop coming out - not much should do so.

Now open each valve in turn, and see how forcefully the water fires out t'bleed screw. Repeat for t'tother end. Are both ends clearly supplying a decent flow?

Is your system pressurised - does the boiler have a pressure gauge?

i'll give it ago when i get back from work.

The system is pressurrised and is sitting about 1.1 bar on idle. It goes up to around 2 when the heatings on. The 2 trouble radiators are getting luke warm only - the flow pipes are red hot but the return pipes only get as warm as the radiator so to me its like there's a restriction somewhere preventing the flow of water back to the boiler. All the other rads are working fine these days. I balanced the rads about 2 months ago and the one in the bathroom worked really well for about a week - i placed a temperature monitor on top of the rad was hitting 40 degree but it just suddenly stopped working one day now i'm back to square one with it.

I know were heading to the end of winter now but without the bathroom one working the temperture over night in that room drops down to around 11 degree one the frosty mornings. 

The flow will likely feel hot as the flow supply pipe that it's tee'd off will be just under the floor, and hot. And the tiny trickle of hot water that does get through the rad is enough to get that flow tail pipe and valve hot too. But as soon as that hot trickle gets in to the rad, its heat is lost.

The restriction could be anywhere, even at the TRV end. I guess more likely it'll be at the l/s end, tho'.

So, fully shut off both ends. For the TRV, that means hard down to 'frost'. Even then, TRVs can let by a little, so if you have a shut-off cap that replaces the TRV head, then use that instead.

NB - note how many full and part turns it takes to close off the l/s, and let us know, please.

With your pressurised system, the pressure at each end of the rad f&r should be the same. So you are trying to compare how each end is allowing water into the rad. Bleed screw open, aim it into a cup, open one valve and gauge how fast/how much water is squirting out. Close, open t'other, and repeat. 

Obvs if the system pressure drops too far, that will affect results to some degree. 

Anyhoo, report back.

ThisIsWeird

The pressure rising from 1.1 to 2 when hot is usually 'ok' - Ie 'acceptable' - but not ideal. As long as it doesn't go higher, then I wouldn't worry about it. Perhaps at the next service, ask the fellow to check your EV charge.