DIY Doctor

Boiler woes

Postby andy_harrogate » Fri Dec 05, 2008 11:32 pm


My Glowworm Compact 100 is starting to make some hissing noises with the central heating on. Pressure is about 1 bar when cold rising to no more than 1.5 when going max chat.

The boiler doesnt seem to hiss when hot water is demanded. I originally thought that the radiators needed bleeding as we have had a few off whilst doing some renovation work. I have done this several times in the last few weeks and the problem is still there. When bled all the radiators let water out rather than air so I think the problem rests within the boiler.

Just to add a bit more, the noises aren't constant. More prominent after initial light up and then dying away after a few mins. I am worried that there might be a load of gunk in the central heating system, this is backed up by the odd cold spot on some radiators.

Is flushing the way ahead, anything to wary of? I am guessing this is going to need a few attempts ( fill it, run it, drain it) until I get the worst of it out.

Is the Fernox stuff any good? or will a good flushing with fresh water be as effective.

Lots of questions, Sorry!! If any one could offer any advice that would be great, can't really stomach a big bill this close to xmas!


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Simply Build It

Postby htg engineer » Sat Dec 06, 2008 11:55 am

It may be a build up of limescale and debri in the heat-ex, but you normally fine the noise will get worse the longer the heating has been on as the heat struggles to get away from the boiler.

However cold spots on radiators can be a sign of sludge - flushing, adding cleanser, draining, flushing and adding inhibitor wont hurt and should do some good.

Chedck the auto airvent, as this will make a hissing noise as trapped air is released from the system, also check auto airvent for any signs of a leak.

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