Radiators furthest from boilers not heating up

[jpope1965]

I have a 10 year old Potterton Puma boiler. The heating is coming on as usual but it cuts out after about 30 seconds and then starts again after another minute. It repeats this pattern all day. Consequently it takes at least an hour for any heating to get through to the radiators. When they finally get hot, the first four radiators on the circuit work well. But the next five radiators won't work at all so I have no heating at the front of the house, upstairs or downstairs. I have a British Gas Homecare agreement and they have changed the pump and diverter valve and now say that the heat exchanger is clogged up and the system needs powerflushing. Apparently I am not covered for either of these two jobs under the Homecare agreement. I have had a plumber manually flush the radiators which are not working and there is no blockage there and the general consensus is that the problem is with the boiler which is not pumping enough to get the heat around to all the radiators. All British Gas want to do is to sell me a new boiler. I just want the boiler to work without cutting out and for all the radiators to work.

 

[crashndie]

am afraid from what ur describing B.G are correct in this case if there isnt enuff water passing tho the boiler it will cycle, its in the small print in the gas contract that b.g dont cover power flushing. personally i think b.g prices are a bit of a rip so id get a quote else were 1st

 

[jpope1965]

am afraid from what ur describing B.G are correct in this case if there isnt enuff water passing tho the boiler it will cycle, its in the small print in the gas contract that b.g dont cover power flushing. personally i think b.g prices are a bit of a rip so id get a quote else were 1st

Thanks for your prompt reply.
So are you saying that it isn't a problem with the heat exchanger? Could this not be the cause of the heating switching off after 30 seconds? Also, is powerflushing likely to make the difference as I have already had the offending radiators taken outside and manually flushed with a hose. Also the system has been flushed through with the heating on and hot water was passing through the last radiator which hasn't worked at all this year. So there can't be an actual physical block in the pipework because hot water did flow through. It's just that powerflushing is so expensive and I hear that it might not be the problem and it could do more harm than good to the system.

 

[crashndie]

if the boiler is cycling like yours is, the heat exchanger is moving the water fast enuff. theres ither a block in the boiler or pipe work could b caused by sludge.

thing with takeing rads off an running fresh water tho the system actually can cause more problems, specialy if you live in a hi scale area. id look in to a flush.

dose the boiler sing ? like water starting to boil before it locks out?