Cold Radiator Help Needed. Any Heating Experts In?
After moving house a few months ago I have finally got round to trying to sort out a cold radiator problem.
It’s a traditional central heating system with a boiler, hot water cylinder, 2 feed tanks in the loft and a motorised valve. Most of the radiators including the cold one are being fed by 10mm copper pipe.
Things I have tried so far are
•Bled system including every radiator and the air vents by the cylinder
•Turned every other radiator off except the cold one. This made no difference.
•Remove radiator and flush
•Drained down entire system and filled back up x2
•Drained down and filled back up adding sentinel cleaner. Left this in the system for 4 weeks.
•Replace TRV on right hand side with a new non TRV (I couldn’t get a TRV to fit the old size thread)
•Checked left hand valve (opened and hot water came out under pressure)
•Whilst the radiator was off I flushed it again. Whilst flushing I blocked the other end to make sure water was coming from the bleed screw hole.
Whilst the radiator was off I tested the valves again and the left one when opened shot hot water out under pressure but the right valve just trickled hot water out (which I assumed may be correct as I wouldn’t expect pressure on both sides of the radiator).
When the radiator is connected and the system is running the valve on the left (the one that shoots out hot water under pressure) is cold but the right (the one that dribbles out) is hot.
Any help would be great as I’m out of ideas. I would rather try and fix this myself if possible but I guess I’ll get the answer of needing a power flush. I would rather avoid this at the moment as I want to get a new boiler before next winter and would update all the TRV’S and get it flushed out at the same time.
AndyPosted 4 years agofootflapsSubscriber
How would I clear a blockage without specialist equipment?
You can try filling with something quite viscous like Fernox DS-40, although check your boiler heat exchanger is compatible.
Failing that, I’d try feeding some wire down the pipe to see if you can locate the blockage, it can’t be that far away unless your radiators are massively spaced apart (stately home)?Posted 4 years ago
I wasn’t sure the existing TRV was opening/working properly and the pin looked slightly bent so I planned on removing it and taking it to a plumbers merchant to get a replacement. It was corroded and had been painted so I had to cut it off the pipework only to find that a replacement wasn’t available due to it being an old size. I ended up replacing it (temporarily) with a normal valve.Posted 4 years ago
I have no chance of getting to the pipework as it appears to come out of the wall with no indication of what direction it is going in.
Wire sounds like a good idea. We have rolls of 4mm at work I can probably borrow a bit of. Is it as simple as feed/twist it in and hope?
Knowing my luck ill probably just hit a t-junction!
Annoyingly I was sure it was going to be the valve I put in some new inhibitor which will now just end up down the drain. Or is it feasible to capture it and re use it? it only went in on Saturday.Posted 4 years agoglobaltiMember
I would expect water to gush from both the flow and return with equal force; the pressure is the same after all.
The wire down the pipe seems the best solution to me though I’d be a little wary of dislodging something like a lump of solder and sending it into the pump impeller. Can you send the wire down with the pipe full of water in the hope that the pressure might flush out the obstruction? Failing that, cut out the section between the rad and the main pipework and replace.
Yes, I would try to save the inhibitor and reuse it, as long as the water is generally clean.Posted 4 years ago
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