New vertical alu rad keeps going off - problem with rad, plumbing or TRV?

[achillea]

Hi

I had a new vertical aluminium rad installed in the living room last week (repositioned from old location). It gets reasonably hot (although never as hot as the steel horizontal ones - you can still keep your hand on it) then keeps switching itself off. Today it cooled down when the room got to 19' when all the other rads are blasting out. I've spoken to the plumber, Danfoss (TRV manufacturer) and the rad supplier and I get lots of different answers. Its a new WB combi boiler and the TRV is located at the bottom of the vertical rad at the side. I've tried bleeding the rad but there was no air. The thermostat is located in the hallway and is set to 21' but it never seems to get that warm out there so that isn't switching it off.

I've never had a vertical or alu rad before so not sure if its a problem with these rads or the TRV.

I've been ripped off and messed about by two plumbers installing this rad and trying to see if there is a home fix before I have to call someone out again.

Danfoss said to try just replacing the TRV head but the retailer says that this is unlikely and that if it is the TRV at fault then the whole thing should be replaced.

Any thoughts or ideas would be gratefully appreciated,

Cheers

 

[Millsy 82]

Remove the TRV head for a couple of days and test it that way.

 

[PlumbBobBob]

i agree take the head off as millsy said.

 

[gastec]

have you tried balancing the heating system out???

 

[achillea]

Thanks - will have a go this weekend to see what happens. This morning when it was really cold I got the living room down to 14.5'c, turned the TRV down to II then switched on the boiler. The rad did come on although slower than the other living room rad (I thought that these alu rads were supposed to heat up quickly but doesn't seem to be the case here!).

 

[achillea]

No - haven't tried this and have never done it before but will have a go and will ask the plumber who fitted it if he did this. Thanks.

 

[acecharly]

Yeah have you tried turning of all other rads and see if it gets warmer? There could even be ptfe blocking one of the valves a bit. Also how many rads have you got on the system?

 

[achillea]

Thanks - no haven't tried that although yesterday I managed to shut off all but 2 rads to see if I could find an air lock by bleeding the ones that were on. I've got one old rad in the kitchen that has no TRV so I can't turn it off. Will try this tonight though! Tomorrow after my guests have gone I'll take the TRV head off and see what happens.

I've got 11 rads on the system - 3 bed semi (WB CDI combi). All upstairs rads are new and never had a problem with them. All downstairs (old) rads get red hot apart from this new one. Someone else I know has a vertical and says it never gets as hot as the old steel ones. Not sure if this is a general problem.

Will report back.

 

[Dotty]

Sounds like a balancing issue to me. And did you have trv's on your system before the new rad?

 

[achillea]

Thanks - might save that lovely job for next weekend! We removed the large old steel rad from the living room (which had a trv) and moved the new vertical to the other side of the room. No increase in the number of rads and the new one is slightly lower wattage.

 

[achillea]

Quick update. Took the TRV head off today and ran the heating for 6 hours. It did not turn off and seemed to get a lot hotter than normal (not as hot as the steel rads but definitely an improvement). The room got to 21.5' before I couldn't take it any longer and had to switch the heating off. Hopefully replacing the head will be sufficient?

Many thanks for all the suggestions.

 

[ggman]

hi
I only talk for personal experience: I have several tall radiators in my house they're not aluminiun but I think the installation method should be the same.
(1) When the length of it is above 1500 mm, to get the quickest response the flow should be connected to the top, the return at the bottom opposite (TBOE).
(2) You have connected them at the bottom (BOE) some manufactures supply a diverting kit to be installed inside the rad, some other radiator have already the diverter or restrictor fitted on the flow side so particular care should be taken when connecting the pipe.
you never specified the rad size
Regard
GGman

 

[achillea]

Hi

Rad is 340 x 1800 with flow and return connected at the bottom.

 

[ggman]

Sounds like that this maybe the problem, you need to investigate if there is any fitted restrictor(buffle), fitted the wrong way around, do u have any fitting instruction? you may have to contact the manufacturer or the supplier.
[DLMURL]http://www.heatline.co.uk/assets/products/radId4/Tubular%20Steel%20Instructions.pdf[/DLMURL] thses instructions may help.
Regards

 

[JCplumb]

With the TRV head off it worked great so the problem is the TRV, not a baffle and not the pipe layout. Tell the manufacturers what you have told us, they may send you a replacement head for your TRV.

 

[ggman]

Sorry, I wrongly understood, he only mentioned an improvement, but it seems not very happy, the rule are that radiators higher than 1500 MM in order to achieve the max output have to be connect TBOE if you want to connect both pipe at the bottom BOE you have use a divertor

 

[JCplumb]

All rads are more efficient plumbed in top to bottom, infact when you see manufacturers outputs for rads the outputs shown are for that pipe arrangement.
In practice though rads are generally plumbed in at the bottom only so that only a small amount of pipework as visible, although that wouldn't be the case in the OP's scenario.