Sludge Maybe?

[CXoL]

My central heating isn't working properly.

I have 4 radiators downstairs. 2 in lounge, 1 in hall and 1 in kitchen. I have 4 radiators upstairs. 1 in bathroom and 1 in each of the 3 bedrooms. About 3 weeks ago 5 of the radiators stopped getting hot. And the others apart from the new one in the kitchen and the one in the bathroom were only getting slightly warm. A plumber was called (I rent the house off a relative). He was round for an hour max, there was a lot of banging, he turned all rads off and then back on, one at a time. And the heating was working again. Some radiators were not as hot as I would have liked but, the house was warm enough.

The same thing has happened again. And the only way I could get it to work again was to turn all the radiators off and then one on at a time. However turning them all on seemed to make it stop working again??? So I have just left some on and he seems ok.

All of the radiators are hotter at the top than the bottom. The pump isn't over noisy. There is a return valve (if that is the correct wording) near the pump that allows excess hot water to return to the boiler??? I have had this set to nearly off otherwise the water just does a quick circuit straight back to the boiler. What would happen if I turned this off completely?

Also I think. but can't be sure. that having the hot water on seems to reduce the heat of the radiators???

Any help would be greatly appreciated. I'll try to answer any questions if you need to ask any.

Cheers.

 

[CXoL]

Update to the above....

All radiators have now failed. Can't get them to work. Hot water is leaving the boiler to the pump, then from the pump it splits into 3. 1st off to heat the radiators through a motorized valve? 2nd off to the hot water cylinder through another motorized valve? and the other back to the boiler through a stop cock? which is set to 3/4 off. All exiting pipes are hot to the touch. Have tried turning off all radiators and turning on one at a time, which worked in the past but no luck. When radiators did work they were cold at the bottom. Have tried turning off the return stop cock to see if the extra pressure dispersed a blockage but no luck. Header tank is full (now that was a mission crawling through the smallest of lofts!). I don't know what else to try apart from asking you guys. Left a message on our plumbers answerphone. Help I'm cold!