Firebird 90 Oil combi boiler no central heating but have hot water

[clayo74]

Hi All

I have a Firebird 90 oil filled combi. A short while ago at random intervals the central heating would trip out the RCD, we had a slight leek that was dripping on the central heating pump that I believe may have been causing the issue. Now we have no heating what so ever the light illuminates but nothing works. The pump is free not sticking. We have had a plumber out who scratched his head for an hour and let costing us £74. Is there anything anyone can suggest please?
Does the pump start up first? Or should I be looking elsewhere

Many Thanks

 

[dontknowitall]

Arrgghh! I hate it when I read of stories of tradesmen coming out to fix something, fiddle around, fail to fix it then charge for their time. I'm one of those who doesn't charge unless I can fix it (or unless I know what the problem is and the customer doesn't want to me to fix it.)

Anyways ...

A few questions to ask you first:

Presumably the rcd is just for the central heating - ie boiler, zone valve, circulating pump, room stat, etc and not anything to do with sockets, etc?

Is the hot water working OR the central heating OR are both not working?


A leak in the pump is unlikely to be enough to cause the rcd to trip out. I suspect the zone valve has failed. This is the aluminium box in the boiler where the pipework forms a tee shape.

You say the pump is free and not sticking but are the pipes both sides of the pump the same temperature when the boiler is firing? If they are the same temperature then the pump is working fine but if they're different temperatures then the pump is not working normally.

Sorry for the questions but it's a little tricky for me to feel and see the pipework from here!!


PS - welcome to the forums!!!

 

[kimbo]

The firebird combi does not have a diverter valve it uses a 2 independent pump system, if water has dripped onto the electric box on the pump which does happen when the filling loop valve leaks (common problem) it will short out and will trip the rcd, you may find it has burnt out the pump, the only way to find out is to check for a live supply to the pump and if there is and the pump is not circulating, that is your problem. The light you describe is it the light on the control panel or the lockout light on the burner.
Also check the overheat switch has not tripped.

 

[SimonG]

I'd be straight to the central heating pump, as kimbo said, common problem.

 

[dontknowitall]

As a subscript (correct word?) to my post above, the pump, zone valve etc are found in the boiler and naturally it's the "boiler" (complete with it's gubbins) that's causing the tripping.

I could have been clearer and agree with both Kimbo and SimonG.

 

[clayo74]

Sorry have been away for a few days Thank you so much for all the replies. Dontknowitall I wish there was more tradesman like you

I have tried again with the central heating and still no heat. The hot water is working, the central heating is now firing up but no heat in the rads.The bottom pipe on the pump is slightly warm the pump is hot but nothing on the return, does this point to the pump again??

The pump is a Grundfos 25-60, can I use a 15-60 in the meantime

 

[dontknowitall]

Rather than repeating, Kimbo's post has the pointers that you need.

If you get a towel and two screwdrivers you can do a little test yourself but it doesn't always prove the pump has failed.

1. Turn off boiler and place towel under pump.
2. Use a large screwdriver and remove the large screw on the pump - this should release water, more than a trickle. If it doesn't the pump definitely has no water going through it and is probably a gonner.
3. With a 3mm screwdriver, turn the impeller inside the pump. It should move easily. If it's stuck, or difficult to turn, then the pump has definitely failed.
4. Replace large screw.
5. Replace pump/call in plumber.

 

[clayo74]

Thanks dontknowitall, the impeller doesn't go around when central heating turned on and there is power going to it. The impeller does turn freely with screwdriver

Appreciate your help

 

[dontknowitall]

If the impeller is not turning when central heating is on the it's best to change the pump. If it's repairable, any repair won't last long, to be honest and household items have a habit of failing at really inconvenient times (e.g. Christmas Eve afternoon).

I can't guarantee changing the pump will fix it but it does seem the most likely case.