boiler won't light

[GSUK]

Hi there,

I drianed the system today to change a rad. I've topped it back up but the boiler won't start. The pump kicks in and the gas ignites and then 10 seconds later the gas cuts out. According to the instructions this is due to over heating. There's quite a lot of gurgling going on and I'm assuming there is an air lock in there but I don't know how to clear it.

It's an open vented system. I've noticed a drain valve next to to the pump in the boiler. Can I attach a hose to that and the other end to mains water and push water through up to the expansion tank? Is that safe to do? I know you can do that to clear a HWT air lock but not sure if it's safe to do on a boiler?

All advice extremely welcome as I currently have no hot water and the misses ain't too pleased!

Cheers,
Glenn

 

[JPC]

yes, i would probably try to see opening the drain valve would draw some water down and shift the airlock that way, otherwise a hose ok, but make sure overflow in working order

 

[sbgasman]

what make/model of boiler,have you bled pump

 

[Registered Gas Man]

Make and model would help. But OV systems are a dog to bleed...... sometimes!

(Some may disagree so in advance i must post an apology if i am incorrect)

 

[GSUK]

It's a Servowarm Elite 50. The valve is on the inlet side of the pump. I can't see any other valves anywhere so wouldn't know how to bleed the pump itself

 

[GSUK]

yes, i would probably try to see opening the drain valve would draw some water down and shift the airlock that way, otherwise a hose ok, but make sure overflow in working order

I did try draining it via the valve but not much came out TBH. I would have expected quite a flow from it but it was more of a fast trickle...

 

[gas4you]

Probably a blocked cold feed.

Have you checked the water level in the F&E tank?

Servowarm had a habit of fitting F&E tanks without ballvalves, so they had to be filled manually with a hose and checked for water level annually.

 

[sbgasman]

turn power to boiler off,put old towel under pump,open large silver screw or black nut in center of pump until water appears ,turn power back on again, you will most likley have to repeat this several times hth Damian

 

[GSUK]

F&E tank is definitely full. I watched it drain when I emtpied the system and fill up again when I turned it back on. Oh, and yes, it has a ball valve. Think I will try forcing water back up to the tank using mains pressure if that's safe to do...

 

[sbgasman]

have you manualy opened any MVs?

 

[GSUK]

turn power to boiler off,put old towel under pump,open large silver screw or black nut in center of pump until water appears ,turn power back on again, you will most likley have to repeat this several times hth Damian

The pump is housed behind the time switch and I can't shift the screws on the plate holding the switch

I think I can see a large silver screw on top of the pump but the pump is sitting about 1" below the bottom of the boiler so I can't get to it without removing the pump.

Going to have to leave it for now as I'm supposed to be going out tonight. Will look at it first thing in the morning and let you know how i get on.

Cheers.

 

[GSUK]

have you manualy opened any MVs?

Sorry, what's an MV

 

[sbgasman]

moterised valves/zone valves would be normaly closed with power off

 

[GSUK]

I've still got the old manual valve installed here. I moved it over to "heating and HW" and it gurgled for a bit and settled down. I then moved it back to "water only".

 

[sbgasman]

set valve to water and ch then try bleeding then running pump a few times Damian