Baxi 105e combi and rads gradually failing

Had my system power flushed about 2 months ago and everything was working well. Recently the downstairs rads stopped getting as warm as before, then after another week they are now stone cold. All upstairs rads were working as normal. Now only 2 out of 4 upstairs rads are still warm.

All rads have been bled (no air found), and I have checked the pump by removing the centre screw which seems to be running (also a little water ran out so no trapped air).

Watching the 6 red led lights on the boiler (30 deg to 80 deg) I can see that it heats up from 30 to 80 in about 30 seconds at which point the flames go out. It then takes about 5 minutes to cool to 30 deg before firing up again. So I basically get about 30 seconds of heat every 5 to 6 mins.

Not sure where to look now, but :-

1.) Should the boiler wait until it cools to 30 deg before firing up again. I am sure it didn't do this before.

2.) Is it possible for the pump to be failing and not pumping water round the system fast enough. Boiler is 12 years old and its never had a new pump.

Thanks in advance

steve17 said:

2.) Is it possible for the pump to be failing and not pumping water round the system fast enough. Boiler is 12 years old and its never had a new pump.

Click to expand...

Yes, but could be just a blocked return filter. Your boiler is definately not 12 years old

Could be a faulty pump, blockage or air lock.

Have you tried turning the working rads off then bleeding the others with the pump running?

If so try replacing the pump.

If it's not that, you're going to have to find some blocked pipework (which shouldn't be neccessary if you've had a powerflush)

baxpoti said:

steve17 said:

2.) Is it possible for the pump to be failing and not pumping water round the system fast enough. Boiler is 12 years old and its never had a new pump.

Click to expand...

Yes, but could be just a blocked return filter. Your boiler is definately not 12 years old

Click to expand...

Do you have to drain the whole system to check the filter?

Yes, not sure how long we have had the boiler. It just seems about 12 years.

david17uk said:

Could be a faulty pump, blockage or air lock.

Have you tried turning the working rads off then bleeding the others with the pump running?

If so try replacing the pump.

If it's not that, you're going to have to find some blocked pipework (which shouldn't be neccessary if you've had a powerflush)

Click to expand...

I will try turning the working rads off tomorrow. It just seems strange that the rads furthest from the bolier began to cool first even upstairs. The two that are left working are the nearest to the boiler.

Sounds more and more like the pump to me.

He'd have a problem with hot water if it was pump

turn off the htg isolation valves under the boiler and remove the filter from the return valve take the cap of the end of the valve and clean it out