No heating or hot water but boiler very hot

[Djnikon]

Hi all,
I have an oil fired system (ACV boiler - old, no model number visible on it). Heating was working ok earlier today but went to put it on a while ago and nothing. I went out to the boiler house and the boiler pipes are all hot (to the pump is scolding). I turned the boiler up to Max and it fired up for about 5 minutes before tripping out but during this time none of the rads got warm. It seems like water is not being pumped and the boiler thinks it's at temp. The pump sounds like it's running but I can't be sure (it's a whirring noise it makes). It's a Bosch pump, big silver thing with a black box on top with a 3 position switch (currently set at III, set to II or I it goes quiet but still sounds like it's running).
Any ideas what could be the issue here?

Many thanks
G

 

[oilhead]

Your pump is not pumping. Take the screw out of the top and see if there is any rotation. Beware of hot water when loosening the screw.

 

[Aquilani]

Check pump is definitely working, check water pressure in system otherwise could be a blockage.

 

[Djnikon]

Thanks Oilhead, does the heating system need to be running to check this? Just to know so that I put it on before going outside.

How would I check water pressure? the gauge outside says 2.25bar and there is air in the radiators being pushed out.

 

[Djnikon]

Oh and by screw do you mean the big silver screw (this is on the front as it's facing out the way), or is there another screw I need to remove?

 

[Djnikon]

Update: Checked pump and there is movement, I got the boiler to fire-up very briefly but there was no hot water coming through the pump.
The impeller appears to be turning freely and there was little/no water came out when unscrewed.

 

[Agile]

The impeller appears to be turning freely and there was little/no water came out when unscrewed.

How can you say that? All you say you have done is to check that the shaft is turning!

The impeller may have fallen off or the eye may be blocked!

Tony

 

[Djnikon]

Fair point, ok the shaft is turning. Can I check the impeller by eye?
Getting hot water coming through ok, but don't know how as the boiler isn't firing up for any length of time to heat it.
When the boiler periodically does fire up it's still tripping out after a few minutes.
The pipes on either side of the pump are scolding hot.
From the pump the pipe travels down and there is a metal box with electrical cable coming from it.
It's very weird.

 

[oilhead]

The metal box is a valve, how many pipes come out of it? This could be the problem.
If it has manual lever on it, which it should have, then push it open.

 

[Djnikon]

There is one pipe in and one out of it by the looks of it. Just a black electrical cable going in to the top of it. The boiler house is an absolute mess of pipes going everywhere even the engineer that came to service it in August was perplexed by it.

There appears to be no lever in it at all. I can really only see about 25% of one side of it though due to it's location and position.

 

[Djnikon]

Here is a picture of the box thing on the pipe. It's really awkward to get in to so the image is 90 degrees out, black cable is going in to the top. View media item 42380

 

[Djnikon]

Update: There is a lever but it doesn't appear to be doing anything. I have moved it back and forth, it seems to move very freely and I assume that this maybe should not be the case.

 

[Hugh Jaleak]

Lever should open valve manually, i'd expect slight resistance as it's probably the type to motor open, spring return. (Should hear it 'whirr' as you move lever to open it.)

By its condition it looks to have been there some time, fair chance its broken.... If you are able remove the head, you may then be able to turn the spindle with a pair of pliers to open valve and hopefully get you going.

 

[Djnikon]

Thanks Hugh, no whirring noise at all. Also been out looking at it and due to it's location I can't see how to remove anything (no screws or bolts are visible).
Are these expensive to replace?

 

[Hugh Jaleak]

Can swap the actuator (head) on newer versions, leaving brass valve body in situ, (avoids draining down). Doubt you'll be that lucky, even if valve was serviceable, head unlikely to be removeable.

New valve about £50ish (for Honeywell), plus fitting. I'd check the lever for resistance with all power to boiler etc off, just to ensure the valve hasn't powered open and is actually working as it should be!