central heating boiler fireing up

saver_1_2

Hi all, We have a glow worm economy plus around 15 years old. We plan to get a new boiler mid 2011. At the moment when we have the central heating on our boiler fires up for around 1 minute then goes off for another minute before coming back on again. It has been like this for around a month now it is annoying as if the house is quite we can here this whooshing like running water noise in the airing cupboard where the immersion heater is and down stairs where the boiler is we can here it turning on and off at these intervals. Could it be somthing to do with the pump speed it is currently on setting 2. The rads have all been bled but even though they are hot they could be hotter.
I thought once your central heating was on the boiler was supposed to stay on until the rooms had got to the desired temp set by your thermostat in the hall. If we just have the water on we don't get this problem.I have been in the loft and the header tank has water in.

Pincher

Sounds like sludge.
Returning water is still hot.
Boiler shuts down due to overheating.

saver_1_2

Thanks for that. I just hope it sees us through the winter.

gas4you

Check there is water in the little tank in the loft.

If there is, it could be a cold feed blockage and the system isn't full of water properly.

penrhyn

Have you a motorised valve that switches between radiators and water. These can fail.
If its just or mostly just heating the hot water tank then the boiler will cycle more quickly.

If the boiler is making a sound like a rusty gate, like an electric kettle coming to the boil then it could be calcium deposits in the heat exchanger causing hot spots which make the boiler shut down, its called kettling. You can get bolier noise reducer from places like Wickes to sort this out, but I'd advise getting a heating engineer along if you can.

saver_1_2

gas4you. Thanks yes there is water in the little tank.

penrhyn.Hi there is a mortorised valve in the airing cupboard near the pump. pump is a year old btw. It's a white thing that vibrates slightly when water and heating are on.[ Sorry not my cup of tea plumbing.]Boiler not realy loud but louder than normal. It's just annoying hearing it come on and off every minute or so.
Thanks both for your help

penrhyn

Hi, can you see the actuating lever for the motorised valve, try turning the water off with the heating on, then water on with the heating off, and see if the lever moves.
If it doesn't you have found your problem.

Just a thought, what temperature have you set the boiler itself too? There should be a thermosat knob, if its set to minimum then the boiler wont fire up for long.

saver_1_2

Hi sorry for the delay but i have just tried the above as you suggested and the levers did move from right to left as the water/heating was pressed on and off. I don't know where the boiler thermostat is. The only thermostat i know of is on immersion heater.
Thanks for your help. much appreciated.

penrhyn

The boiler thermostat is under the control tray on the boiler, on the left hand side.

To remove the control tray pull forward.

saver_1_2

Thanks for that it was on 2 so i moved it to 4 it goes up to 5. See how that goes .Cheers