Potterton Prima 80F Boiler.........its that time of year and ive had enough

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Hi Everyone
Its been quite some time since ive been on the site so take care with me...Ta

We have a Potterton Prima 80F boiler, gravity fed system etc. This has been tripping out after 20 odd minutes, pump seems fine, 3 way valve fine. I thought it could be air as ive been doing a bathroom for months, alternative sludge in the system....I ran X400 for 24hrs , drained down, refilled....which took forever and ended up filling from lowest rad using a hose (its a bungalow, CWST and expanion in loft) never had much pressure so put in a pump some years back....sorry getting off track.
Refilled and still trips out...i tried boiler on low with no joy. The pump gets extremely hot and i reckon goes into shut downas the water from the boiler is not getting dispersed....after it trips the boiler starts banging....im thinking heat exzchange furred. I had a guy in today who said this and suggested new boiler etc...! Only problem...flat broke as im looking after my mums estate and all my savings have gone into that...what im looking for is a safe solution to get me by for 12 months hopefully until im out of the do do so to speak....Anyone ideas. I live in sussex.....a friend suggested fernox to try and free up perhaps enough of that scale but unsure. Its £20 notes and haven used X400 thought that may have helped......im after ideas....Ta
 
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If it took a long time to refill there's a good chance the boiler feed pipe is largely blocked, and if you drained it down without cleaning out the expansion tank first this may have made it worse.

If you can, try a magnet run along the outside of the feed pipe. If there is an attraction to the pipe, it is likely to be blocked with magnetite.

The best test, if possible, is to disconnect the boiler feed pipe from the system and see if the water runs freely. Before doing it tie up the F&E float valve, and bung the F&E outlet (which goes into the boiler feed pipe), disconnect, then remove the bung with the pipe over a bucket, with another bucket on standby. If only a trickle comes through the feed is partially blocked. The boiler feed should join the system within 150mm of the inlet side of the circulation pump. Its likely to be 15mm pipe.

You may have a combined feed and expansion system. The principle's the same but the pipe should be 22mm diameter.
 
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OK Many thanks for that ....I shall now try and find a magnet......ill let you know....
 
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The best test, if possible, is to disconnect the boiler feed pipe from the system and see if the water runs freely. Before doing it tie up the F&E float valve, and bung the F&E outlet (which goes into the boiler feed pipe), disconnect, then remove the bung with the pipe over a bucket, with another bucket on standby. If only a trickle comes through the feed is partially blocked
ye and don't fall off the ladder when rushing down to see the water flowing :ROFLMAO:
 
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Thanks for that....normally its a race on all fours through the loft , down the stairs, out to the garden to check any overflow...
 
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well the cylinder is at about 65 and i've been testing the boiler set at basically No. 1.......
 
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If the heat exchanger and flow and return pipes are scaled then the thermostat phial doesn't recognise the correct temperature of the water. Try getting some sort of surface temperature probe on the flow pipe and see what temperature it gets to when the stat shuts off.
 
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