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Post by headcoats on Dec 2, 2019 20:37:53 GMT 1
Got 2 radiators that refuse to get hot and done the usual by bleeding them (been no air at all several last attempts) plus turning the other radiators down to about half to a quarter turn to force the flow to the cold ones Doesn't work, only luke warm)
Only thing that works is to turn the flow right off to the red hot ones , then the 2 cold ones get hot at last
But after the heating has gone off and comes on again in the morning etc, I am back to square one FFS !
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Post by headcoats on Dec 2, 2019 21:03:30 GMT 1
The only place the cold rads feel hot is in the inlet pipe and the other ends virtually cold
It's just not pulling through one end to the other ?
The one rad in the hall is an older one but the other one is pretty new
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Post by headcoats on Dec 2, 2019 21:32:11 GMT 1
I think the cold ones are last on the circuit but have no idea to check
Do the upstairs ones have to have different flow settings to the downstairs ones (just a semi house)
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Post by stusco on Dec 2, 2019 21:42:50 GMT 1
What size are the pipes? Are all the cold rads on the same floor?
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Post by headcoats on Dec 2, 2019 22:34:35 GMT 1
Cheers for the replies :-)
The pipes are about 10mm O.D. and the plastic type
The cool rads are on the same floor and next to each other (Hall and front room)
It's weird as you can feel the heat on the inlets trying to get into the rad, then something is happening ?
I will try tomorrow then , first to shut them all off, bar one cold one and let it run , then do the same with the other cold one , then whack them up to bleed , then go to the hottest one to only open enough to get hot
If I have got it right LOL
I will let you know
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Post by LC_BOTT on Dec 2, 2019 22:50:54 GMT 1
Sounds unlikely, but are the rad valves actually open and not seized or broken in the closed position, I know gate valves are easliy sheared at either end of travel. Have you tried a fully open/closed a few times?
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Post by stusco on Dec 2, 2019 22:58:05 GMT 1
Sounds like a blockage on the return probably at the manifold ,plastic pipe is crap the plastic attracts the sludge if the system water isn’t clean ,you will need a system clean maybe add x400 but you have to get it all out or it will eat your boiler and possibly pinhole the rads.
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Post by headcoats on Dec 2, 2019 23:18:53 GMT 1
But if they work and flow when the others are all shut down , would that mean the valves are working ?
It's like those 2 rads are independent of the rest of the system !
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Post by hoist1 on Dec 3, 2019 1:43:21 GMT 1
Should be easy to remove the adjusting valve with it wide open ( or in any position ) , it’s not going to gush out water. In any case put a rag underneath, apply wd 40 or equivalent to the exposed rod and give it a gentle tap with something like a small rubber or plastic hammer. Failing that anything non metal . I had probs with our system involving 4 out of 9 rads , they didn’t respond to bleeding and one by one they sorted themselves when they felt like it, the last one took a month.
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Post by hoist1 on Dec 3, 2019 2:05:52 GMT 1
Should be easy to remove the adjusting valve with it wide open ( or in any position ) , it’s not going to gush out water. In any case put a rag underneath, apply wd 40 or equivalent to the exposed rod and give it a gentle tap with something like a small rubber or plastic hammer. Failing that anything non metal . I had probs with our system involving 4 out of 9 rads , they didn’t respond to bleeding and one by one they sorted themselves when they felt like it, the last one took a month. Failing that, it could be the boiler itself , has it had any work done , or anywhere in the system? Or any changes in the water supply or pressure?
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Post by LC_BOTT on Dec 3, 2019 9:10:30 GMT 1
I'm no plumber, but have you checked the pump, how old is it, have you bled that too, they are only a centrifugal pump, so will turn and cavitate (ie no flow )if it has air in that too, the magnets and inlet/outlets also get rusted up/shafts break etc.
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Post by headcoats on Dec 3, 2019 11:13:56 GMT 1
I have got the 2 cool rads running hot with all the other rads turned down then slowly opened all the others up and they were ALL working I have switched it off to cool then get it back on but what has been happening is once switched back on the 2 cool rads fail to warm up again Let you know in 30 minutes !
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Post by midlifecrisisrd on Dec 3, 2019 12:46:16 GMT 1
I'll tell you what the problem is
Stop turning the heating off for months you tight git 🤣
My misses co.plained to me yesterday that I left the heating on the low overnight thermostat setting before going to work so she was cold when she got in at 1pm
It's set at 23 feckin degrees
The high setting for during the day is 25 😅
Even during the summer mine is switched on and kicks in during the night 😴😓
Steve
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Post by headcoats on Dec 3, 2019 13:08:55 GMT 1
Wow 25 is a killer
We have a log burner and when that shows 23 to 23.5 on the thermostat, we are melting !
22 is more comfortable
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dezcbr
Thrash Merchant
Posts: 414
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Post by dezcbr on Dec 3, 2019 15:13:22 GMT 1
I had a similar problem when I had a couple of radiators changed. They were the last 2 on the system. I googled it and it balanced the radiators using the check valves and it has been OK since. Hope this helps
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Post by stusco on Dec 3, 2019 15:15:28 GMT 1
I have got the 2 cool rads running hot with all the other rads turned down then slowly opened all the others up and they were ALL working I have switched it off to cool then get it back on but what has been happening is once switched back on the 2 cool rads fail to warm up again Let you know in 30 minutes ! When they are all hot half close the lockshield valves (non thermostatic)on the always hot rads and try that you may still have poor circulation ie:blockages/faulty pump, what kind of boiler is it :combi,system,back boiler if it’s a combi and your hot water is good then it’s not your pump normally (depends on boiler)
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Post by headcoats on Dec 3, 2019 15:20:30 GMT 1
Yes it's a combi system
Did switch it on again and seemed ok (cold rads much hotter but still not scorching like the others) but may not have left it long enough, so the big test will be coming back on from stone cold and rested for a few hours
Does seem a circulation problem but stumped to know the causes
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Post by midlifecrisisrd on Dec 3, 2019 17:00:09 GMT 1
I am by no means a heating engineer but water and electricity are the same in that it will always take the easiest path
It must be easier to flow throw the hotter reads than the further away ones
Also depends if who fitted it did it right
I have a radiator in my conservatory (ok I'll be posh and call it a run room as it has a solid roof) and instead of connecting the pipes at the manifold they just tee'd them into the nearest radiator pipes so needs a bit of messing with the valves to get it right and both hot
I read somewhere once (don't know how true) was that the flow valves at each rad should be adjusted to give a particular temp difference across the flow and return pipes
Steve
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Post by stusco on Dec 3, 2019 17:15:23 GMT 1
I am by no means a heating engineer but water and electricity are the same in that it will always take the easiest path It must be easier to flow throw the hotter reads than the further away ones Also depends if who fitted it did it right I have a radiator in my conservatory (ok I'll be posh and call it a run room as it has a solid roof) and instead of connecting the pipes at the manifold they just tee'd them into the nearest radiator pipes so needs a bit of messing with the valves to get it right and both hot I read somewhere once (don't know how true) was that the flow valves at each rad should be adjusted to give a particular temp difference across the flow and return pipes Steve Your right Steve yours will never heat properly teed into another rads pipework there should be about 11 degree drop acrosss the flow and return pipes
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Post by midlifecrisisrd on Dec 3, 2019 17:20:36 GMT 1
I am by no means a heating engineer but water and electricity are the same in that it will always take the easiest path It must be easier to flow throw the hotter reads than the further away ones Also depends if who fitted it did it right I have a radiator in my conservatory (ok I'll be posh and call it a run room as it has a solid roof) and instead of connecting the pipes at the manifold they just tee'd them into the nearest radiator pipes so needs a bit of messing with the valves to get it right and both hot I read somewhere once (don't know how true) was that the flow valves at each rad should be adjusted to give a particular temp difference across the flow and return pipes Steve Your right Steve yours will never heat properly teed into another rads pipework there should be about 11 degree drop acrosss the flow and return pipes I got it working in the end but probably not optimal A bit of messing with both valves got them both hot. Helps they are only 6 feet from the manifold Steve
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Post by headcoats on Dec 3, 2019 19:07:50 GMT 1
Back to square one FFS ARGHH !
Come on tonight and the 2 suspect rads are playing up again :-(
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Post by stusco on Dec 3, 2019 19:28:08 GMT 1
Is there a bypass valve fitted under the boiler between the flow and return pipes?
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Post by headcoats on Dec 3, 2019 20:01:57 GMT 1
Don't think but not sure what I'm looking at !
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Post by stusco on Dec 3, 2019 20:14:59 GMT 1
It’s a pipe that joins the two hot (flow and return)pipes with a valve in the middle it should have one but you don’t normally see them on combi’s if you have one screw the valve shut to increase the circulation,but if you have blockages it could overheat the boiler
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Post by headcoats on Dec 3, 2019 20:41:02 GMT 1
I don't think it has the valve
Bottom line is I can get the cold rads working by closing the others then slowly re opening them all to get every one working hot but soon as it shuts down and cools , then when it starts up again the 2 cold rads won't heat up
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Post by stusco on Dec 3, 2019 20:57:50 GMT 1
Have you half closed the lock shield valves on the hot rads?
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Post by headcoats on Dec 3, 2019 22:20:05 GMT 1
Have you half closed the lock shield valves on the hot rads? Yes , maybe a lot more than half closed too I had shut them fully and opened a bit at a time so rad got hot on the smallest of turns out
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Post by stusco on Dec 3, 2019 22:21:56 GMT 1
That usually work my guess is a blockage
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Post by ianboom on Dec 5, 2019 10:35:25 GMT 1
There should always be one radiator that has no valves closed or thermostatic valve fitted in case of a blockage somewhere. This is usually the bathroom rad.
The whole heating system should be balanced, if you google it, you should find an explanation, but basically, rads with good flow, need the lockshield valve closing down half a turn at a time so all rads have the same resistance to flow. As like was pointed out earlier in the thread, the water will flow the easiest path it can find, so may bypass some rads with resistance to flow.
Guy at work had this problem. He never 100% sorted it, but balancing the system on the valves helped loads.
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Post by headcoats on Dec 5, 2019 11:13:18 GMT 1
I think you have it there as in bypassing the ones with the resistance to flow
I do think it's a flow thing and not a blockage I'm almost back at square one but got the hall one a little hotter
Front room is pants and the others so hot you can't touch em !
Done all the lock shields, all the hot one screwed in at least halfway
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