Fan Pressures

[EPH]

Got issues with a fan on a boiler and wondered if there was anyway of telling what the negative and positive pressures should be?

 

[villa_tom]

It just need to be enough to activate the pressure switch.

Check the data on the APS

 

[EPH]

Can only see a maximum pressure on it. Not sure if there's enough negative but the fan seems to be doing fine.

 

[bigads28]

The pressure on the APS is that point it activates no min or max. Just use a gauge on the venturis or tubes to see the pressure your fan is producing.

What issues are you having?

 

[Ermintrude]

Venturi

 

[EPH]

Boiler goes into fault about 5 seconds after lighting.
Works ok with case off or negative hose disconnected from APS.
Replaced hoses as they'd gone brittle with heat.
Removed fan, cleaned venturi but was fine.
Swapped APS and same problem.
Flue looks ok and fan spins well.

Think I might be having a "moment" with this and it's something glaringly obvious

 

[bigads28]

If the blades are dirty the fan spins but it wont shift any air, the pressure test will show this up though.

 

[EPH]

Cleaned the blades with a brush and air duster when I took it out to check the venturi that sadly wasn't blocked :-(

 

[bigads28]

HHmmmm, which boiler is it?

 

[EPH]

Worcester 28 Cdi standard efficiency

 

[Millsy 82]

What fault code does it bring up?

 

[EPH]

Rapid flashing DHW light.

 

[bigads28]

Rapid flashing DHW light.

Does the hot water work? Or is it just the heating it fails on?

 

[EPH]

Same fault no matter what

 

[bigads28]

Have you tried taking out the restrictor ring if it's fitted?

If it works with the case off then the fan can shift enough air, putting the cover on restricts it down. You'll probably find its the fan but I'd take the ring out first.