Central Heating problem!!

raddo

Before the winter sets in I decided to clean out the radiators in my house. Last year they were hot on top and cold near the bottom so I suspected that they had sludge in them. Bought some sludge remover and put it in the expansion tank in the attic, drained down the system from one of the rads downstairs to get the sludge remover working. Turned on the pump to get the flow to each rad, pump making quite a strange noise. Took out the pump, seems to be moving quite freely. Put it back in but still noise persists. Drained and refilled the whole system again about 3 times to make sure the liquid was clear. Bled all of the rads, turned on the pump, still noisy but heating up the hot water cylinder and all of the rads upstairs, none of the downstairs rads working. Pump / System is still making noise, I presume I have a blockage somewhere but not sure because when I drained the system from downstairs, I had no problem. Any hints or tips would be greatly appreciated!!

ART6

raddo wrote: »

Before the winter sets in I decided to clean out the radiators in my house. Last year they were hot on top and cold near the bottom so I suspected that they had sludge in them. Bought some sludge remover and put it in the expansion tank in the attic, drained down the system from one of the rads downstairs to get the sludge remover working. Turned on the pump to get the flow to each rad, pump making quite a strange noise. Took out the pump, seems to be moving quite freely. Put it back in but still noise persists. Drained and refilled the whole system again about 3 times to make sure the liquid was clear. Bled all of the rads, turned on the pump, still noisy but heating up the hot water cylinder and all of the rads upstairs, none of the downstairs rads working. Pump / System is still making noise, I presume I have a blockage somewhere but not sure because when I drained the system from downstairs, I had no problem. Any hints or tips would be greatly appreciated!!

Still sounds like a faulty pump to me. It's possible for thermal lift to create a degree of circulation, particularly to the higher levels, and many hot water cylinders operate that way so that they circulate when the central heating and it's pump are not on but the boiler is running simply to provide hot water.

Incidentally, repeated draining and refilling of the system is not a good idea, since each time you do it you are introducing oxygenated water which will cause corrosion inside the rads. Normally the first fill causes some corrosion but the rusting takes the oxygen out of the water and then stabilises. Keep on draining and refilling and the rusting never stops and sonner or later you have leaking radiators.

Micky Dolenz

Don't worry too much, what you hear is air trapped in the pump head. See the pump head and you will notice a flat head screw, unscrew to bleed air out. you may have to do this a few times. You have to leave the sludge remover in the system for a few weeks for it to work or double the dose if you what a 24 hour turn around. For best results remove offending rads and put a hose through them out in back yard, becarefull it can get messy.

What you have now is a system that has a lot of airlocks,.