Overheating

[endoftether]

Apollo Fanfare boiler, open system.

Lots of problems over the years but I've now had the floorboards up this week to trace the problem. The flow pipes get hot quite quick and just keep getting hot. The radiator return pipes seem to take an age to warm up on every one of the radiator feeds? Unfortunately the overheating switches the boiler off so it only fires for a couple of minutes. this overheating also now occurs when I run the system on hot water only.

What is causing this? It's been descaled and anti-sludged, drained and refilled etc. The pump is also brand new. No apparent air in the system.

 

[peter anderson]

what happens if you open up the radiator valves on the return side more?
Did you balance the radiators?

Are you saying that the radiators get hot even when you set the system for hot water only?

 

[endoftether]

Thanks for your response.

No I have never balanced the radiators as I'm not sure what it means. I did request a plumber to do it some time ago when he was charging for every part of an hour and he went just over the hour so i made him stay.

if you see my earlier desperate attempts for assistant I have just posted a note to say that I have discovered my instructions for the pump and noted that the propellor shaft is mounted vertically. The instructions state that this can lead to an air loock in the pump.

I bled the pump screw and hey presto - the heating worked without overheating.

Presumably the propellor is spinning in the air and not pumping the water around although it sounds as if the pump is working of course. Is that likely and will it keep occurring?

Thanks

 

[peter anderson]

is the pump vertically up or vertically down? One of those two positoins would require an air separator. I think its the pump going down. Pump going vertically up is fine I think.

 

[endoftether]

Peter,

The flow pipe runs across the bottom of the pump and the bleed screw is at the top.

 

[peter anderson]

I think that means that the pump is set horizontally. I think its vertical when the flow pipe is on the side going up or down

 

[ChrisR]

You said your pump shaft was vertical - I think that's not allowed for any pump! The bearings willna take it, Jim. If the pipe layout is standard you won't need an air separator, but they can help in marginal situations. I wouldn't do anything until the pump shaft was horizontal. Get it put right.

 

[peter anderson]

Ignore anything i say. I can't work out what the shaft being below the horizontal plane or in the vertical plane on horizontal pipework looks like.