Firebird Combi 70

MarkOil · Mar 4, 2014

Got a Firebird combi 70 that I went to today, limit stat trips every other week.
Today I turn up and all is fine, reaching temp ok etc.
With system up to temp it was at 1 3/4 bar, so not sure what it is when cold.
So I said to them next time it trips, and goes cold, check pressure, top up to 1 bar if needs be, then restart.
Am I right in thinking that low system pressure can cause overheat?
I need to speak to Firebird about it tomorrow anyway, because for some reason (not sure if it's also causing problems) with the water off, heating on 24hr but with room stat down, the boiler fires, should it?!?
There's always power coming out the orange wire (11) on the relay, could that e faulty because that makes the boiler fire and no power goes to either pump!?
Confused.com

kimbo · Mar 4, 2014

Unfortunately difficult to say without being there when it happens.
problem s I have had with these over the years is
it could be a faulty stat, check temp of water in stat pocket it may show control stat is way out.
sticking pump
sticking check valve have renewed a few of these recently.
Does the customer have to keep topping up pressure. The possibilities are numerous.
air in pump, relay

lame plumber · Mar 4, 2014

first issue is its a firebird

kimbo · Mar 4, 2014

Nothing wrong with the older firebirds they have been around for a long time. They use the more reliable two pump system rather than diverter valves and diaphragms used on the other boilers. The problem is its a combi whatever make it is.

lame plumber · Mar 4, 2014

went to a grant ext combi today, not serviced for 3 years, 45 mins to service clean as could be 🙂 3 alpacas stood watching me as the boiler was in their field 🙂

MarkOil · Mar 5, 2014

I had a Grant like that the other month, been a few years since a service, I told the custard I thought he was having me on lol.
Thanks Kimbo, I have a suspicious feeling the pressure could be low, I'm going back for a service soon, so I'll leave the pumps running to get it as cool as, then see.
It was on 1.25 bar when I was there and it was up to temp, so think it could be low.
I tested the temp in the pockets, water tank at 81.2 main HE seemed to heat fine up to 90 I think, but sometimes I suppose it could stick and not turn off, but I think it's system pressure issue tbh.