2 out of 8 rads. not heating

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leukoshoopr

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I live in a 3story house - 3 radiators on ground floor
3 on 1st floor
2 on 3rd floor
Our Baxi boiler,which is less than 1 year old is on the 1st floor

Our sitting room and hall rads. wont heat up to same temperatures as the rest.All the the others including the hot water are piping hot.

I've bled and bled them but still nothing- I've even drained them both and flushed them out with a hose and bled them again.

I've turned all the rads off barr the sitting room one and it just got slightly warm but not as warm as others.

These two problem rads. are 2foot longer than the rest- they used to heat up before fine, not sure what's going wrong
 
I've heard of a process called balancing when this happens rads - I think it involves turning the rads on and off at different stages but I'm not too sure after that - any plumbers to give advice on this one ?
 
spfeno said:
I've heard of a process called balancing when this happens rads - I think it involves turning the rads on and off at different stages but I'm not too sure after that - any plumbers to give advice on this one ?
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If the OP has already closed the valves on all but one rad (the suspect one) and it's still only lukewarm then balancing is unlikely to be the problem.

My brother reckons there can be a bubble of air trapped at the lockshield valve and bleeding the rad won't shift it but he said you'd usually do what the OP has already done-close all rads off bar the affected one to 'blow' the bubble out of the valve out into the rad.

Is there any chance the rads are actually blocked with crud? Maybe drain system down and take them outside and run a hose through them. I have had to do this but only on a much older system.
 
Hi leukoshoopr

Are the rads heating up at all, ie just the top, or are they compleatly cold, If you have just replaced the boiler did you replace the rads, if not I assume they are at least 10 yrs old, without any water treatment they may be full of sludge or blocked with corrosion.

My advice would be to isolate each one in turn and look at your flow rates.

Hope this helps
 
I would assume these rads a drop fed and there a partially airlocked in the fed or return pipework (bleeding the will not cure this) get ur plumber in the sort this one

One other thought, pump in ur system boiler will be a 5m head pump. 3 stories ideally should have a 6m head pump
 
sounds like they need balancing as one person has said
I followed this procedure a few years ago and each rad heats up to the same heat now
http://www.diydata.com/projects/centralheating/balancing/radiator_balancing.php

If you don't have a differential thermometer, you can do it roughly as follows

Close off all lock shield valves.

Count how many rads and how many revolutions on your lockshield valve takes from fully open to fully closed.
Say for example you have 12 rads and it takes 3 revolutions

First rad on system open lshield valve 1/4 turn
2nd rad open it half turn and so on until last rad is fully open

Its not 100% accurate but it will make it better
 
Thanks to everyone for the replies - apart from getting a plumber in I think I've tried them all- what if I drain the whole system and start over-is this a big job?
There's a draining valve on the kitchen rad.

One other thing- some of the rads turn on from the left and some from the right- does this matter in terms of balancing them/return etc
 
balancing doesn't seem to be the issue have you looked at the size of the circulting pump on your heating system as for a 3 story house the pump should at least be able for a 6 meter head if you have any doubhts send me a private message and ill give you a contact detail and ill walk you through it
 
the lockshield valve is on the inlet and the adjustment valve is on the outlet. It may vary from rad to rad but best check as they are easily swapped around
 
I would agree with be plumbing that your boiler ( assume a system boiler) will have come with 5m head pump that may need changing out

I would not suggest you drain and refill your system as if it is an airlock issue you may end up worse than when you started
 
thinking about it some more it could be something as simple as the balancing valve on your hot water cylinder you have a flow and return pipe usually going into the side of the cylinder and on the return pipe usually the bottom pipe on the side you should see a red handled gate valve if this is open fully it is taking the heat from the rads this valve should only be opened slightly enough for a flow of water to flow through approx 1.5 to 2 turns this happens because usually the pipes from the boiler go to the cylinder first and then to the rads hence the water will finds it easier to flow through the cylinder and back to the boiler then go through all the rads closing this valve till its only barely open will force the water into all the rads i hope this helps you out and i have left you my number in pm if you need other help
 
BD - you're a legend! I closed the bottom valve gate and then opened it slightly now all rads working superb- balanced the rest- I'm now wondering the gaff in me jocks-and the polar bears are leaving- cheers buddy
 
be sure and keep an eye on hot water temperture as you may need to open valve another bit to ensure correct temp.

congrats though, you balanced your system, A thing not many plumbers do.
 
cheers DavyJ- one last thing -the pressure's rose to 2.5 how do I bring it down, I only know how to increase it
 
vent key and bucket. may take a bit of time (venting rad) to decrease pressure but is safest. you can only get an accurate reading cold, hot water expands. should be 1 - 1.5 bar cold.
 
im delighted its sorted for you i just dont understand why the plumber who installed the heating system didnt check this as it is common practice to balance this valve as well as the rads on completion but anyway your sorted now any other probs just give me a ring happy to have been able to help
 
The problem rads were on the ground floor Davy,I increased the pressure after emptying them and bleeding them as it dropped

BD- I did some DIY in bathroom during summer- and not knowing which gate valve was which I closed them all,when I finished I opened them all back up fully including the "return" feed at the bottom-so it was only when I turned on all the rads a few weeks ago the problem came about

Thanks again
 
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