new boiler, rads are cold at bottom and 1 doesnt work

[angela1982]

I had a new boiler system fitted 2 years ago. It has since been drained twice as i had an extension done and had 6 new radiators fitted so i'm pretty sure i can rule out sludge.
The rmajority of my radiators heat up at the top (red hot) but remain cool at the bottom. One radiator doesnt heat up at all, the pipe which leads from/into the left side of the rads usually remains cold as well.

My gas engineer who fitted the rads in the extension says he think its due to pipework that has been laid badly (lots of additional pipework with l-bends and uneccesary lenghts of pipe, but he wont know if this is the problem of course until he refits the pipework.

any ideas?

I've already been through and switched off radiators in the order of how close they are to the boiler, switched them on one by one to try and flush out any trapper air and also try and establish which rad could be the issue. Each rad heated up fully one by one, but then as more and more rads were switched on (in order) the problem then came back.

 

[DP]

Plumber should be able to check and 'see' what the issue is before the flooring is lifted. If six radiators have been 'tee'd' to the existing pipes, then I would looking there for the malfunction.

Turn off old radiators and check if new rads now heat up

 

[angela1982]

Ok thanks for that.

 

[angela1982]

I tried switching the old ones off but the new ones didnt heat up properly, i switched the new ones off and the old ones didnt heat up properly! my existing back room radiator doesnt heat up at all, the pipes are stone cold. all the radiators on the system that are before this radiator heat up fine, so it must be something to do with that rad correct?? any suggestions? my new heating engineer thought it was because there are loads of bends on the pipes leading to and from rad - could this cause the issue or is it something else??

Any suggestions please.

p.s. i tried to balance them but they were already turned quite far anticlockwise on the lockshield, didnt want to turn them too much more as then they'll be fully open which would cause the same issue wouldnt it?

 

[Hugh Jaleak]

To achieve a correct balance on your system it may be necessary to close some lockshields down, whilst opening others. Water is lazy, it'll take the easiest route, so radiators nearest boiler/pump/etc will rob lions share of heated water if allowed, whilst furthest rads will starve. Balancing restricts flow into 'nearest' rads, which then forces the water to travel to the far flung points of the system.

Guide to balancing: http://www.diydata.com/projects/centralheating/balancing/radiator_balancing.php I wouldnt worry too much about a thermometer, you'll soon tell if the rads are getting hot with your hand!

 

[angela1982]

Hi hugh,

thanks for the link. Im worried that if i start messing with the rads that are working that i'll make matters worse. the first 5 rads on the system work fine, its when it gets to the rad in the back bedroom that it goes pear shaped. No matter how far open or closed the locksheild is it doesnt heat up at all. the pipes leading to and from the rad are stone cold. and then the next 5 rads on the system after then all heat up either to luke warm or red hot at the top and cool at the bottom!

 

[Bodd]

Is the system Microbore at all?

 

[Hugh Jaleak]

Angela, is the other valve on the rad open?

Try turning all the other rads off, (use the wheelhead valve, not the lockshield for this). This should then force the entire output from the pump into the affected rad, and shift any airlocks. If you can get this one working then adjust the others.

You've had all the rads working at some point? It does sound like a balancing issue, but if you had 6 extra rads fitted to the system then it could be that the boiler and/or pump is struggling with the extra load.

 

[angela1982]

Hi thanks for that.
The boiler is brand new and was fitted knowing that we needed to add the extra radiators. we've got 11 radiators in total on a Gloworm Betacom 30c and its all brand new pipework, well 2 years old.

I'll try doing what you said to see if that works

Thanks once again

 

[angela1982]

Is the system Microbore at all?

Hi Bodd,
No its a Gloworm Betacom 30C

 

[angela1982]

Angela, is the other valve on the rad open?

Try turning all the other rads off, (use the wheelhead valve, not the lockshield for this). This should then force the entire output from the pump into the affected rad, and shift any airlocks. If you can get this one working then adjust the others.

You've had all the rads working at some point? It does sound like a balancing issue, but if you had 6 extra rads fitted to the system then it could be that the boiler and/or pump is struggling with the extra load.

Oh also, yes the other valve with the thermostat are all on the highest, 5.

 

[cantaloup63]

Is the system Microbore at all?

Hi Bodd,
No its a Gloworm Betacom 30C

Microbore refers to the size of the pipework and not the boiler. Microbore is roughly the same width as your little finger and 15mm is that of your thumb.

 

[Bodd]

Is the system Microbore at all?

Hi Bodd,
No its a Gloworm Betacom 30C

Hello Angela

How old is the house?

As siad above Microbore is the size of pipework.

Bod

 

[Hugh Jaleak]

That just means they are fully open, balancing is done with the lockshield valves. Worth checking with thermostatic valves though that the pin hasnt stuck in thus holding valve closed. Remove head and gently press pin, it should go down then spring back up when released. If its stuck down the valve is closed.

 

[cantaloup63]

Hi angela. Just going back to your opening post - has the extention been finished entirely now and what's happening with the plumber? Is he due to come back and finish it all off and try to balance it all?