Boiler cutting out after just a few mins after drain down.

[barriegreen]

Hi. Hoping someone could advise on this as I`m stuck.

We have an open vented system with FE tank, Grundfos pump and Honeywell V4044C valve in loft and we have a Baxi Bermuda back boiler in our lounge. We live in a bungalow so only one storey.

I had to drain down the system today to remove a radiator for DIY purposes. Have re-filled the system, and bled all of our radiatiors as well as any air vents in loft.

Problem I have is that the boiler doesn`t seem to stay on for very long ( few mins) then cuts out and doesn`t relight after a while. I have set the programmer to water and heating (the only other option is water only) and have set the room thermostat to highest possible but no joy.

I have drained a little more water from the main drain off point and also drained some from the drain off point by the boiler. But still have problem.

Could anyone help please ?

Thank you.

 

[Boilerman2]

There is air trapped at a high point somewhere, as there is only YOU on site then YOU will have to find it - could be anywhere!!

Why did you drain down just to remove the radiator, isn't hat wat adiator valves are for??

 

[JohnD]

sounds like the water is not circulating properly. Most likely air in system. When you bleed the highest rad in the house, does water squirt out forcefully? If not, a blockage may be preventing filling.

Undo the shiny centre screw on the pump, a few drops of water should trickle out. If air, wait until it stops hissing.

Sometimes turning the pump opn and off multiple times will help shift the air.

If the pump is surprisingly hot, it is jammed or dry.

You can set the programmer to HW only.

You can do all this with the boiler temp turned right down so it does not get hot.

If necessary you can attach a hose to the vent pipe over the F&E tank and gradually fill it through there, it should push the air or blockage back up into the F&E. If there is much mud and sediment in the F&E (very likely) bale and sponge it all out first and consider using a cleaning chemical once you have got the water circulating.

 

[barriegreen]

Thanks for the replies. I had to remove the radiator and its surrounding pipework that went straight into the main feed and return as we are removing the wall that its currently on.

Have turned the hot water only on and tried turning speed up and down on pump but still no joy. The pump isn`t over heating and when bleeding it the water does bubble out from the main screw. The main feed into the pump from the boiler isn`t warming up at all and the boiler is still remaining off. Boiler temp has been set to low.

Any thing further I could try ?

The pump is now making a bit more of a humming sound since doing the bleeding ?

Thanks

 

[JohnD]

leave it off for a bit, the air might move.

run the pump again in a few hours. You have to turn the pump right off for a while, not just to low speed.

Does the flow pipe from the boiler get hot when the boiler is firing and the pump is running? How far up the pipe does the heat go?

It will be easier to track it down if you set prog to HW only and not CH.

Find your hose and jubillee clip in case you need to refill through the vent pipe. You will probably need a push-fit 22mm to 15mm converter, unless you can find a tap connector for the hose that fits the vent pipe.

What can you tell us about the mud and sediment? What came out of the old rad when you tipped it up?

 

[barriegreen]

Hi johnd. Thanks for reply. I`ll leave it for a bit now and will then re-try a little later.

The water that drained out of the system was clear from all rads with no discolourtion. Same when I drained down a little bit from beside the boiler in attempt to remove air lock. The F&E tank is all clear too, no sediment present at all as the system was drained down just over a year ago for a new pump to go in.
When I re-try and boiler does fire I`ll check how far up heat goes along pipe but it certainly got nowhere near the pump.
Will let you know what happens.
Thanks again.

 

[barriegreen]

Just wanted to say all working fine now.

Had to leave system running and keep bleeding rads and other vents. Particularly the pump and then system came to life.

Thanks all for your advice.