firebird 90 overheating on CH mode.

[markadams]

It originally started leaking from the DHW heat exchanger seal, I replaced all the seals and since then the boiler overheats/boils when in CH mode. I have replaced the stat but no change.

I am sure the DHW seals are just a coincidence.

 

[kris]

The seals have probably perished dew to overheating but does in not over heat in HW

 

[kris]

Its probably a circulation problem,,, look at the HW pump inside the boiler , CH pump

 

[kris]

Sorry just noticed is this on open forum ,,, my appoligies cropp,

 

[markadams]

Hi Kris,

I am a GSR but not an Oftec engineer, I suspected the Pump so I retained one from a gas boiler, I guess they are interchangeable. they look like a standard circulating pump.

 

[TFGplumbing]

Hi Kris,

I am a GSR but not an Oftec engineer, I suspected the Pump so I retained one from a gas boiler, I guess they are interchangeable. they look like a standard circulating pump.

Check the heatbank sensor is fully pushed home into the pocket, have you got circulation on the heating at all op?

 

[markadams]

Just checked again as I have had it turned off, the rads are scalding to the touch and the boiler is boiling, literally.

 

[TFGplumbing]

could it be an issue with the external controls perhaps?

 

[markadams]

Surely the hi limit stat should cause it to lock out before it boils even if the external controls were faulty?

 

[lame plumber]

prehaps a new boiler stat needed and check the stats are all in the pocket so they can work as per TFGs comment

 

[markadams]

Just to say that their are two liquid expansion stat capsules in the pocket and one just hanging loose on its own.

I replaced the pump just because I had one laying around and the problem still exists.

 

[lame plumber]

spect the one hanging loose is a fire valve sensor capsule

 

[TFGplumbing]

I had one do a very similar thing but on dhw, and it was the heat bank sensor relay. Check it, it must have 240v on terminal 2 when satisfied.

You have changed the control stat?

I personally would check that the dhw flow switch is open circuit when the hot taps are off, just for good measure.

Give firebird tech a ring they are really helpful.

Also make sure all the vials are in their pockets, and they must be pushed fully in or they wont work correctly.