Firebird combi 90 - no heating

[Bunker]

HW light on permanently:

Shut mains off, no change.
Changed out the flow sensor - no change.
Swapped out the store thermister with 4 different ones I had including Grant ones - no change.
Put a new PCB on, no change - aaaarrrggghhh!!

Even though HWOS sell the thermisters as being for tank or boiler - I found the manual shows them as different - black sleeving for boiler, white for tank (same as Grant).

So Ill check with them tomorrow but the only one I didnt appear to have was a white Firebird thermister so must be that despite HWOS description.

In the short term I took the HW link out from the 4 pin plug and installed a switch so they could select HW or CH but not both.....

 

[lame plumber]

good bit of lateral thinking there

 

[TFGplumbing]

did you fix it bunker?

I got a beast of a fault on one of these today! begging for mercy

no dhw or ch, no power to either pumps, power to both flow switch terminals.. probs stuck open.

no power to terminal 2 on the heat store relay, so its not getting satisfied & its over heating.

Does the heat store relay control power to the pumps? I suspect it does although iam not familiar with the firebirds to be honest!

I only went to change a mixer head on ufh manifold, and the ******* thing decides to to be a ****.

 

[lance]

looking at wiring diag, the only other thing that gives power to dhw pump is overheat stat? I have not worked on one for a couple of years, but good idea turning off mains, to eliminate flow, and also the tank stat route is good idea.

 

[Bunker]

Sorry, I thought I had replied to this. I got a new tank thermistor from FB which fixed it straight away - we assumed they were all the same but clearly not.

 

[TFGplumbing]

Sorry, I thought I had replied to this. I got a new tank thermistor from FB which fixed it straight away - we assumed they were all the same but clearly not.

exactly the same fix

 

[FirebirdVictim]

Hello Bunker and TGFPlumbing,
sorry to resurrect this thread but I seem to have the same issue with my own Firebird Combi.
The power is live to both terminals on the flow switch connection block - with the flow switch completely disconnected! I've tested the flow switch seperately and it works fine.
Even with the flow switch disconnected the CH pump will not energise unless I feed it power directly. Then I can get HW to the rads.
The HW pump is constantly working but with NO hot water getting through to the heat exchanger. I suspect the thermostatic mixing valve is also knackered. I'm about to order one.
The 3-pole 11-pin relay is energised as soon as the boiler is powered up and never switches thereafter.
What I really need to know is how to identify that "tank thermistor". I cannot find one called specifically by that name. Could you please show me a link so I can get the correct part?
Cheers,
Steve

 

[lame plumber]

you might be better off getting an expert in to repair and service your boiler, fixing by switching parts never saves money and can cause more issues, especially if you cant identify parts of the boiler.

 

[FirebirdVictim]

you might be better off getting an expert in to repair and service your boiler, fixing by switching parts never saves money and can cause more issues, especially if you cant identify parts of the boiler.

I take your point even if it is making assumptions about my abilities and intentions. Also I'm not quite sure what you mean by 'fixing by switching parts'. So far I'm just testing things to see what's good and what's not.
Certainly there are things on the boiler I wouldn't try to fix. But if it's a part that for instance connects by wires into connector blocks - well I can do that. To be honest I've paid so many hundreds of pounds out to keep this POS boiler on the road I'm trying to save a few bob on the simple to repair parts. Also I like to fix things.
All i'm trying to do at the moment is identify a part that doesn't seem to be mentioned in my manual. Once I know what the part is, I can judge whether or not it's safe for me to fix.
If i'm in any doubt, I'd ask for some advice from people like you in places like this. If you don't want to help then so be it.
I thought that sort of thing is what this forum is for. Or should only bona fide OFTEC guys visit here?

 

[tamz]

If you have a multimeter and know how to work it i'm sure you can figure it out

 

[FirebirdVictim]

If you have a multimeter and know how to work it i'm sure you can figure it out

Thanks tamz. That was just the boost of confidence I needed.

 

[SimonG]

Why play with something you know nothing about and then take the hump when given good advice. If you were able all you need is a set of testers and a logical mind. Find the problem and fix it.

If you are concerned about the amount of money the boiler is costing you then you either need to get it changed or find a decent engineer.

Its just a shame that the a$$ of a law we have in this country only applies to gas appliances and not all combustion appliances. Maybe it will if more morons fiddle and kill themselves. Heres hoping eh!

 

[Dotty]

Think we'll leave it there.