Radiators at the end of loop not working.

[greenwell9]

Hi all,

So, I've been having a few issues with two of my radiators located upstairs at the end of the loop. They were working a year ago but have steadily been getting colder and colder as months go by. Now they're cold. I've spent a couple of days trying troubleshooting methods but no joy. Btw my system has 10 rads, 6 upstairs and 4 down. My boiler is a Baxi 105e. TRV's fitted to all Rads.

I've tried

- Bleeding rads
- Balancing system
- Turning all other rads off and isolating the affected one, opening valves fully while heating is on full heat and increased the pressure to 2.5.
- Taking affected rads off and flushing with high pressure water.
- Checked TRV valves for pin movement - all ok.
- Had floor boards up to check heat is getting through the flow pipe - hot pipes up to valve.

The only thing that I've noticed was when the rads were off I thought I'd check the valves for flow of water by opening them. The return was fine and blasted water out but the flow just trickled when opened fully. I filled the pressure back to the boiler after each try. I also tried a working TRV from another rad but had the same results. This was true of both rads. My suspicion is a blocked/broken valve but I aint a plumber and haven't had this issue before.

Any help would be greatly appreciated.

 

[ShaunCorbs]

Have you tried taking the rad valve off (trv) any muck / restrictions and maybe best to change the trv valve

 

[greenwell9]

Thanks for the response Shaun.

I'll give that a go. Just wanted to check before draining the system.

I've also noticed that on one of the problem rads the TRV is on the return side and lock-shield on the flow. On this the lock-shield just trickles.

 

[Sparkgap]

Thanks for the response Shaun.

I'll give that a go. Just wanted to check before draining the system.

I've also noticed that on one of the problem rads the TRV is on the return side and lock-shield on the flow. On this the lock-shield just trickles.

So, if the lockshield on the flow and TRV on the flow both give trickles when opened it sounds like a blocked flow pipe, assuming the same pipe serves both rads. Could you hook up a hose off the mains to the flow somewhere and hopefully blast it clear?

 

[greenwell9]

Thanks for the reply Sparkgap,

You're spot on. I've changed the TRV that was connected to the return onto the flow, turned up the pressure and blasted it through. There was a lot of sludge came from it and now hot water passes through freely. 1 down, 1 to go.

 

[greenwell9]

Sorted!!!

Sparkgap you were correct about the blockage on both flow feeds to the rads. The second one required lifting the floorboards to gain access to the joints, removing and replacing them. As soon as the pipe was removed you could clearly see the blockage. A quick poke down the 15mm pipe with a straightened coat hanger and the blockage was freed.