Oil Burner - Cutting out - No air - Plenty of water, new stat and pump?

Quid

Hi there,

I have a very old oil boiler. Its burner units is probably about 7/8 years old though.

Started it up for the first time since the beginning of the summer last week and it fired up grand but kicked off after about 20 mins.

Shut down all rads bar two upstairs - cranked the stat up to 80 and ten mins later the two rads upstairs were litterally rattling off the wall.

Bled a shed load of air, but 10 mins later the boiler knocked off again.

Let the pump run with the stat set at 0 for about an hour and again bled shed more air. however the run for a few mins/stop behaviour persisted.


Replaced stat

On the ground that some of the rads upstair were bleeding neither air nor water topped up the system ( but that was somewhat of a guess job as there is no pressure guage on system!) - Just opened it up for about 30-40 secs until some water bled from previously lifeless rad.

Replaced Pump today which I though might be the problem as the old pump is the thick end of 20 yrs old.

Behaviour remains unchanged with the principal difference that after the intial cold start run - after 15 mins when it cuts out - there is litterally no head from any of the rads.

I can feel the pump vibrating away on both the IN and OUT pipework.

The Output is very hot.

The Return is barely luke warm

Ran the pump again for an hour with stat at 0 this evening

No air to be bled at any of the rads and the water egressing is stone cold.

I have made two arrangement for a plumber to call in the last week and neither showed up!

Any Suggestions for a next step?


would like to get this sorted before it gets proper cold!

Many thanks?

Billy Bunting

Really sounds like an air lock somewhere but without being there and seeing the layout first hand i think its a hard one to really diagnose, engineer required i think.

Quid

Yip Billy - me thinks you are right - I am not a plumber - haven't a bogs really! and feeling rather stuped at €120 down, save renewing some very old parts, I am no better off.

Thanks for the feedback though!

Any other suggestions welcome!

Quid

Quid

Okay Billy - having given up for the evening - I mande a sambo - had some tea - posted the above thread - went up stairs to go to be and noticed a tiny amount of heat in the bathroom rad (remember the stat on the boilder was set to 30). Tried to bleed it. Got 5/6 seconds of moderate air pressure release. Threw caution to the wind and open the filler gate valve for another 30 seconds. Turned up stat to 50 left it run for 20 mins - and it ran. A few more small splutters of air. Sill running 30 mins later - up-ed state to 70 - it continue to run for about another 20 mins and hey presto - every rad is evenly hot all over. The burner kick off about 10 mins later and has been off since - but thats okay cause all the rads are hot and the house is toastie all over (notwithstanding the fact that the boilder is 42yrs old - the house was very well insulated internally in a refurb a few years ago).

Obviously as you say it was an airlock - but amazed what must surely have been a small amount of air (compared to what I had already bled) was causing such problems.

Guess it was no harm to renew pump - Old one was about 20 years old (or possible more!) and it feels/sounds like the new one is doing more - perhaps that is B/S

Final admission - I think I know where all water left the system and air got in.

One of the penny valve on one side of the pump appears to be loosing water at a rate of about 2-3 drop/min.


I will take that on another day. That and getting a pressure gauge fitted somewhere in the circuit!


night!

Quid

cikearney

Take the screw out of the pump and insert a screw driver slowly, sometime thine pump cand vibrate in you hand and still not be pumpin, if the screwdriver spins your pump is fine, if not replace.

sometime the pump valve will leak when turned but the can also stop leaking when the heating is back in operation, so you may be losing water somewhere else

Quid

Hello there cikearney - thanks for your insight. Replaced the pump, did some final gymnastics to bleed some of the last bits of air/top-up system and the heating has been fine since - and that 10 days ago. Thanks for the tip on the pump valve - will take a look at this evening to see what its like...

All the best

Quid