Pipes to radiator bent?

7 Oct 2014
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United Kingdom
We have recently had a new boiler fitted, new rad valves, system drained & a chemical power flush. There are a few radiators that do not warm up correctly or at all. The plumber also drained the radiators in question again and checked all valves, balanced system etc. He said the plastic pipes were possibly bent and it would be a big job to do, lifting all floor boards and replacing pipes etc.

Is there anything I can do myself to easily locate where these are bent and anything I can do to fix this?

Living room (opposite corner of house to boiler) - only the bottom right of radiator gets slightly warm, an area about an inch square.

* Bedroom (directly above the living room radiator) - along the top is warm and the bottom left is hottish, the rest is slightly warm
* En suite in the same bedroom - cold
* Landing radiator (outside bedroom door) - very cold
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Doesn't sound like a very thorough powerflush has been carried out.

The only way to find 'bent' pipes under your floorboards is to lift all your floorboards and look for them.
Thanks. He drained the radiators and the water was coming out clear after the flush. I think he tried a few other things in addition to those mentioned above, but I'm not particularly qualified. Would I start with the boards nearer the radiator, or any one radiator in particular? I wasn't sure with them being at one side of the house if it was a pipe that was feeding them all or somesuch.
To be honest, I don't think looking for bent pipes is the way forward. It seems that heat is getting to the rads but the fact that the heat is patchy over the surface area makes me think the flush was nowhere near as thorough as perhaps it should have been.
Was it a full chemical Powerflush you paid for ?
How long did the flush take?
And also, we're these rads hot before the boiler change?
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The radiators were the same before the boiler change (we'd chalked it up to the boiler to the honest, boiler works fine now though). I can't remember exactly what flush, I do recall Magnaclean chem pack and a machine? Not 100% on duration as I was working at home so wasn't watching each step. When I say some heat, it is very slightly warm to touch.
It sounds like the rads need replacing, although you can't do a full thorough power flush in one day. The chemicals need to be added at least a week before the flush.

However, some rads can be too knacked to clean through on a flush. You might have been better paying for some new radiators rather than a full flush.

What is interesting though is that the plumber has just left it like that ! And that you're having to ask advice on here to try sort it yourself ? Get the **** back to finish the job !!
I would suspect a blockage in the plastic pipe. The first place i'd look would be the pipiework on the landing as it sounds as though the 4 rads may be fed from there.
I agree with Shray. A thorough Powerflush will exceed the cost of 4 new rads and it does sound as if they are beyond repair.
You can't expect your plumber to pay for the new rads as it's not his fault that they are in this state, however he should be advising you of potential remedies and offering you a price for the works. Sounds like he's got his money for the boiler change and has no interest in any remedial works.
Ask him to come back, if he's not interested, get someone else to give you a price.
Thanks for the help, guys.

I do remember the chemicals being left in the system overnight and having to leave the heating on for a time then. The issue with the four radiators was mentioned when getting a quote, it seems like he thought it was the boiler and quoted as such (the boiler did need replacing, the cost of repair would have exceeded a replacement), we got quotes from a few plumbers who all seemed concerned about the boiler in particular, but obviously we are now left with the radiator issue.

Just to clarify, after the flushing, he did drain the non heating radiators and the water was coming out clean (which I saw), could this still be a radiator issue?

I don't want to unnecessarily replace radiators if it's a pipe issue (incurring cost of new rads and labour), but similarly I don't want to start pulling up floor boards and laminate if it's a radiator issue. Eek. Not sure what the most logical thing is to try, or if I can try cleaning out one of the radiators myself.
Not sure if this makes things any clearer, but the positioning of the radiators.
I haven't drawn all the downstairs rooms as all the radiators work apart from that single Living Room one.
Red is working, Blue is not working.

What happens to the rads that aren't working if you turn off some or all of the working ones?
You could try removing one of the nonworking rads and rigging a draining system to the valves and run water through it, do both valves individually and leave it running for a while. If you just open the valve, water discharges, turn it off, it might give you a false impression of being ok.
I've decided to test if it's the pipework, starting with the en suite radiator.

I have a small same sized radiator in the over stairs cupboard that I know works fine, so I'm going to try replacing the en suite radiator with that one. If it heats up, I'll know it's the radiator that was the issue (I can flush the radiator that's come off either way, and see how I get on!)

When I take the radiator off the cupboard wall, should I put the en suite radiator in it's place, should I just cap the pipes somehow before turning the heating back on to test? If so, what's best for capping the pipes?

We don't actually use the cupboard radiator (it was used for airing, but we only use it for storage now), would it be an issue to remove it anyway? It is the control, so no thermostats on it, not sure if I'd need to take a thermostat off another in that case.
You could try removing one of the nonworking rads and rigging a draining system to the valves and run water through it, do both valves individually and leave it running for a while. If you just open the valve, water discharges, turn it off, it might give you a false impression of being ok.

I'm with TW on this.
Assuming an open vented (loft mounted header tank) system...
You can check whether a pipe is kinked by removing a non-functioning rad, then checking the discharge rate from each valve in turn, catching the discharged water in a bucket (then putting the water back into the header tank to preserve the expensive chemicals). A kinked pipe will exhibit high initial flow, immediately dropping to almost zero flow. Check each pipe in turn BUT MAKE SURE ALL OF THE OTHER RADS ARE TURNED FULLY OFF AND THE HEATING SYSTEM IS OFF TOO.

A single kinked pipe will show a low flow to ONE END of each rad it feeds.

Oh, and often the location of partial blockages in plastic piped systems is the pipe stiffener at a joint.
How do I know if it's an open vented system? I don't have a water tank or anything in the loft. It's a Vaillant 831 Combi Boiler installed.

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