Rads not getting warm enough

7 Apr 2010
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United Kingdom
I have an oil central heating system in a two storey house,
the system can be used to heat water only and heat water and the rads, but this past week whenever the heating is on only a few rads heat up, i have switched the room stat up to full and the temperature on top of the boiler to 90 but still not all rads heat up. i turned off all the rads but one in the hall and it got very warm, so i switched on another rad in the downstairs bathroom and it got warm so i tried a few other rads but they will not heat up, anyone offer any help please?
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Pressure if sealed system?

Sludged system?

Failed or obstructed pump?

There can be many causes!

What do you mean by sealed and sludged system? if the pump was obstructed surely no rads would heat.
If the pump impeller is obstructed it will still give a weak pumping action and a little circulation into the easiest flow path.

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What and where is the pump impeller, is this situated outside at the boiler?
The impeller is the part of the pump which spins inside the veloute and provides the pumping action.

They are technically a circulator rather than a pump!

Just had a mate who is an electrician check all the electrical bits on the system, room stat clock and he even checked to see if the pump was working, all were working fine but he thinks the motorized valve is shot, he could not look at it as its down the side of the fireplace which is inside a wooden partition and is wallpapered over, so before i go removing the partition and ripping wallpaper a plumber is due anytime to see what he thinks is the problem, i will report back.
Plumber called and he thought the motorized valve was stuck, so he used the little paddle to open it manually, he said that you rads will warm up now so we where talking for a while and he said i will check the rads now but they where only lukewarm so he checked the pump and he informed me that it was shot, so he fitted a new pump today and all seems fine now, nice and warm and the motorized valve seems to be working fine now also, so can i assume that the valve is now working ok and replace the wooden partition?
If it is working, then i don't see a problem. That would have been a nightmare job if the home owner didn't know that was behind undisturbed wall paper :LOL:

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