What is the problem with my oil central heating system?

[Butchy10]

Context for issue:

Last winter the temperature switch on my boiler shorted somehow, the boiler was then running WAY too hot and ended up blowing/melting a hole in one of the pipes. I repaired this by putting in a new stretch of pipe in and just connecting it to the existing pipes with two valves. Which has successfully patched the pipe and no leaks or anything like that.


I replaced the temperature switch on the boiler also - and that seems to be operating correctly now.


Issue:
The issue now is that the radiators aren't heating up. My guess is that the water isn't circulating due to some blockage or trapped air due to the previous gaping hole in the pipework lol

The boiler kicks on and heats up, and I can feel out pipe on the hot side of the boiler heat up, but only for the first 1ft or 2ft then the pipe feels cold further along. This is what makes me think something is stopping the circulation of the water.


The obvious go to for me was check for trapped air, I started by bleeding the radiators but nothing but water was coming out, the I realised the trapped air is more likely stuck at the highest point of the system so I went to the attic and checked for an air release valve, I found one and opened it up and some air came out rapidly and then stopped. Tried the heating again and no luck.


I can't see anywhere else to bleed air from so I came to the end of my air lock thought process there.

Then I thought to myself maybe it's a pressure issue, I checked the pressure on the red expansion vessel and it was 2bar, which is above what the internet told me, so I reduce it down to about 1.25bar. There is another pressure guage in the attic near the expansion vessel but I don't know what pressure it's measuring but it's sitting just below 2bar so I figured that sounds about right.


THEN I thought maybe it's the pump, I tried to bleed it and it was just water trickling out but I didn't hear any air hissing out so its not air locked, but when I turn on the heating I don't feel a vibration or even a murmur from it so it's not actually kicking on, but the lights are on.

Lastly I opened what I assume is the water/air release valve on the top left of the boiler to see if any air was going to come out of it, a lot of water came out but I don't know if any air came out aswell because the water was hitting the side of the boiler house and making too much noise to hear for hissing air.

Help:

Does anyone have any suggestions? Or am I doing something obviously wrong?
I dont mind spending time on it, I find it all very interesting and challenging (obviously).

ANY help would be great, the cold weather is here and I'd like to stop using electric heaters.

 

[exedon2]

Heating pump not running
Remove large brass screw and check with a smaller screwdriver pump shaft is free.
There will be water leak out !
So towel/ bowl under pump.

 

[Butchy10]

Heating pump not running
Remove large brass screw and check with a smaller screwdriver pump shaft is free.
There will be water leak out !
So towel/ bowl under pump.

I just did this, the internal motor shaft is free, twisting both ways with minimal effort but pump still appears not to be running

 

[Brambles]

Either the pump has failed or you have a wiring problem. Test the 240v feed to the pump - it is fed directly from a 13 amp socket.

 

[SimonG]

So control stat and high limit failed at same time? Wouldn't expect both to fail, potential wiring issue.
Hole blown in pipework? Plastic pipe within 1.8m of boiler? Failed pressure relief valve?
How did you test the pressure on the expansion vessel? If the system was still pressurised you won't get a correct reading.

Your pump is goosed, but boy that's a real diy disaster install.

Maybe worth getting to look at the whole system for safety's sake.

 

[Butchy10]

Either the pump has failed or you have a control / wiring problem. Test the 240v feed to the pump. If you have a feed replace the pump, if not you have a wiring or pump overrun control issue ( assuming the pump is controlled by the boiler)

So wiring to the pump hasn't changed since it was in operational state, only wiring that changed was the stat but it seems to be operating correctly. Maybe I'll replace the pump just to rule that out as the issue?

 

[Butchy10]

So control stat and high limit failed at same time? Wouldn't expect both to fail, potential wiring issue.
Hole blown in pipework? Plastic pipe within 1.8m of boiler? Failed pressure relief valve?
How did you test the pressure on the expansion vessel? If the system was still pressurised you won't get a correct reading.

Your pump is goosed, but boy that's a real diy disaster install.

Maybe worth getting to look at the whole system for safety's sake.

Yeah I think there was loose wiring in the stat before that caused a short and that's what blew the pipe, I've fixed that and that part seems to be operating correctly. Now the boiler shuts off before overheating as it should, no more blown up pipes.

Didn't realise there was regulation for pipe material within a certain distance from boiler, that's interesting...

To test the pressure on the expansion vessel I just attached an analogue pressure gauge to the inflation nozzle on the back of it.

I guess it's time for a new pump..