Radiator cold. Feed and return pipes cold. TRV replaced, please help.

[abar121]

Need some help here, tried many things but still have one radiator at home that is cold. It was working ok last winter, perhaps not quite as hot as the others.

Tried:
1. Bleeding radiator, no air present. Plenty of water pressure.
2. Thermostatic valve. Moving freely and fully open. Now replaced with bidirectional valve.
3. Lock shield valve. Open.
4. Balancing radiators, tried closing the lockshield on all other radiators, but again, no flow through this radiator. Both pipes are cold.
5. Flushing with Sentinel X400. I left it in for a week, then flushed the system through. Also repeated this with another product. Water now flushes clearish.
6. Removing rad, flushing through with hose. Done, water ran through fine.
7. When re-filling the system, water passes through the return pipe fine. Nothing coming out of the feed / hot pipe.

Given number 7 above, I'm thinking that the feed pipe is blocked. It's 15mm plastic pipe unfortunately laid under a concrete floor.

Need some advice on what to try next. I was thinking of trying to back flush the feed pipe, with mains pressure.

Also, would the boiler trip out if all other rads where turned off at the lockshields? It doesn't seem too.

It's a conventional Vailliant bolier, with a megaflow style heat exchanger. High pressure mains.

Thanks,

Alan.

 

[dave1]

You could try a wet vac on the flow see if you pull the blockage out.

 

[JAH HEATING]

Where is your nearest rad to it ? Is it in 15mm ?

I'd be looking at repiping it myself

 

[abar121]

Where is your nearest rad to it ? Is it in 15mm ?

I'd be looking at repiping it myself

Yes 15mm. The nearest rad is about 1.5 metres away. Trouble is there is a brick wall in the way and concrete floor.

Cheers

 

[jonnyswamp]

You say you have nothing coming out the feed pipe (flow) and that its plastic under the screed
Is it just feeding this rad? can you access the pipe before it goes into screed?
If so drain back down, cut pipe before it enters screed, mains pressure hose on pipe and try and push blockage through and out the flow valve, if this or none of the other ideas work, then you'll need to repipe the rad

 

[abar121]

You could try a wet vac on the flow see if you pull the blockage out.

Thanks. I will try and get hold of one. Got to be worth a shot.

Thanks. I'll give it a try. Are there any attachments for the vac that could help connect it up?

 

[abar121]

You say you have nothing coming out the feed pipe (flow) and that its plastic under the screed
Is it just feeding this rad? can you access the pipe before it goes into screed?
If so drain back down, cut pipe before it enters screed, mains pressure hose on pipe and try and push blockage through and out the flow valve, if this or none of the other ideas work, then you'll need to repipe the rad

Yes this pipe just feeds the cold rad. The only other access is at the manifold which is mostly set in concrete. Also it is hard to identify which pipe feeds thus rad, at the manifold.

Thanks Alan

 

[abar121]

Thanks. I'll give it a try. Are there any attachments for the vac that could help connect it up?

 

[thompsonbrown]

7. When re-filling the system, water passes through the return pipe fine. Nothing coming out of the feed / hot pipe.
Have you removed the valve when testing for flow?

 

[dave1]

Yes this pipe just feeds the cold rad. The only other access is at the manifold which is mostly set in concrete. Also it is hard to identify which pipe feeds thus rad, at the manifold.

Thanks Alan

I've found a few blocked at the manifold before only way to clear was cut it out.

 

[abar121]

7. When re-filling the system, water passes through the return pipe fine. Nothing coming out of the feed / hot pipe.
Have you removed the valve when testing for flow?

Yes. I'm going to get some plastic pipe and bypass the radiator and see if the pipe heats up. I want to be sure the rad isn't still partially obstructed.

 

[abar121]

I've found a few blocked at the manifold before only way to clear was cut it out.

Thanks. Hmm, hopefully it won't come to that.

 

[abar121]

Ok I just bypassed the radiator with some fastfit.

The after running the CH the pipe is still cold. Damm. With the system still pressurized, if I disconnect the temporary pipe and open the hot/in rad valve, about half a cup full comes out, then a trickle.

What would be worth trying next? Vac or any chemicals that might work? Or would a powerflush help?

Many thanks, Alan

 

[1sammyj]

if its the last rad on the system could poss be a fault with the pump , might not be big enough or speed turned down