Blocked Flow Pipe

[bwerd1]

Can someone offer some advice please?


The last rad on the system (no TRV) has been cold for a fewweeks now. The flow valve is hot but theradiator does not heat up. The returnvalve is cold (obviously) as not hot water is going through the radiator. I have checked the lockshields and they seemok. I’ve taken off the radiator andflushed with a garden hose (small amount of black water before being a lightbrown colour).


While the rad was off, I opened each lockshield in case ofan air lock in the pipe. The returnvalve was strong immediately. However. Theflow valve was much slower with black water for a few seconds before beinglight brown. The strength of the flowfrom the flow valve is very poor (noticeably different from the return valve). Does this explain why the radiator is notheating up?


Does it mean a faulty flow valve, blocked pipe or somethingelse?





I’d appreciate any help.





Thanks


drewb

 

[townfanjon]

You have diagnosed your own problem my friend . Change the valve first , its quickest and cheapest . Hopfully that will cure it ! If not theres a few other things it maybe , report back .

 

[lame plumber]

could be trv is on return and not flow, trv is a one way valve and not bi flow, trv is knackered, lockshield needs opening more and system needs rebalancing to get it working, pump is failing etc etc. A few things to ponder over.

 

[bwerd1]

Thanks for replies. There is no trv on this radiator, just a lockshield at either end. Balancing isn't ruled out but the same problem exists if I turn off all other rads. Flow valve is hot but rad not heating up.

I presume I will need to drain system before flow valve to replace or the water will just gush? I've done it before so no big deal.

Again, thanks for the help.

 

[snowhead]

I presume I will need to drain system before flow valve to replace or the water will just gush? I've done it before so no big deal.

Again, thanks for the help.

Yes drain it.

If it does gush, you'll have cleared the problem..

 

[bwerd1]

I have changed valve with minimal effect. Can I flush the pipe with a garden hose and use stop ends on the f&e tank or is it better to drain down and try a strong cleaner first?

Thanks.

 

[SimonG]

What size pipework?

 

[bwerd1]

15mm

 

[bwerd1]

Thinking about it, the pipes to the rads look more like 10mm.

 

[townfanjon]

Thinking about it, the pipes to the rads look more like 10mm.

Does a 10 mm spanner 'just' fit ?

 

[bwerd1]

Will need to reply on sat, away from home at the mo. Thanks.

 

[Stu Davis]

Will be a blocked 10mm pipe, i rigged a tyre foot pump up to the rad valve on a blocked system a few times where poor flow and it cleared it, otherwise its a case or tracing pipe back to where it joins into either a manifold or system flow and cutting it off and checking.

 

[bwerd1]

Does a 10 mm spanner 'just' fit ?

Yes, 10mm spanner just fits over pipe.

 

[bwerd1]

Cleaner didn't work so flushed with garden hose, cleared within 10 secs. Will now fill and drain until water is clear and add inhibitor. Thanks for all advice and help.