Potterton Performa 28 flue fan

[Solstistel]

Hi,

My boiler recently stopped working, on inspection the pcb tracks to the fan were burnt out. I have a new pcb but do not want to connect it until I have checked the fan. The DC resistance of the fan is reading about 29 ohms, which seems low and I expect the coil is shorting. Does anyone know what it should be or have one they can measure before I buy a new one?

Any help appreciated.

Many thanks,

Terry

 

[SafeGasInstall]

welcome to the forum

are you electrician ???

 

[Solstistel]

Not exactly, I'm an electronics engineer.

 

[SafeGasInstall]

you aint going to like it but this is the link for you Gas Safe Register | Ensure your gas engineer is registered.

 

[Boilerbud]

Make fly lead and connect fan directly to 240V (put 3A fuse in plug this will blow if fan really is nackered but very unlikely), run fan for 5min if runs without problems it is safe to assume fan ok.

 

[Leo21]

Changing a fan on these require removing the combustion cover. Therefore you need to be gas safe registered or you're endangering people. And breaking the law I believe.

 

[mountainman]

Not exactly, I'm an electronics engineer.

An electronics engineer that doesn't know ohms law eh!

 

[Ian400]

Resistance = Volts squared / Watts. As an example a 50 Watt Fan would have a resistance of about a 1000 ohms.
( 230 x 230 ) / 50 = 1058 ohms.

To work on gas appliances you need to be competent. Being Gas Safe registered does help to prove this, but is not a legal requirement.

 

[mountainman]

So a fan with a resistance of 29 ohms will draw about 8 amps.
(I work it out as V over I,R btw)
Not surprised that the PCB was cremated.
Bit puzzled why the 3amp fuse in the plug or spur didn't blow though.
Even more puzzled that an electronics engineer couldn't work this out.

 

[Mickyplumb]

To work on gas appliances you need to be competent. Being Gas Safe registered does help to prove this, but is not a legal requirement.[/QUOTE]

Err, I think you should check this statement (raised eyebrows).

 

[Solstistel]

Thanks for all your replies.

Ohms law does not apply. Any motor/solenoid or similar will measure lower than calculated with ohms law due to the back emf produced by the magnetic flux when running.

 

[Leo21]

Ok so what experience/qualifications have you got to make you you competent. Or do you just think you are?

To work on gas appliances you need to be competent. Being Gas Safe registered does help to prove this, but is not a legal requirement.[/QUOTE]

 

[Mickyplumb]

Ok so what experience/qualifications have you got to make you you competent. Or do you just think you are?

To work on gas appliances you need to be competent. Being Gas Safe registered does help to prove this, but is not a legal requirement.

[/QUOTE]

I think you'll find that if you look up the word competent in the GSR bible, it will state that in order to be deemed competent to work on gas appliances etc, you MUST be Gas Safe Registered.

 

[Solstistel]

I thought I was talking about the electrical properties of the motor.

I have BSc electronics, MSc microwaves and optoelectronics, PHd optoelectronics.
Served as an apprentice and technician for BT.

I'm not saying I'm going to play with anything to do with gas, I just want to know if the part is defective.

 

[Leo21]

Sorry buddy but by removing the combustion cover to get to the fan you have to be gas safe or competent. That seal you've broke is all that's between you and possible carbon monoxide poisoning. I don't doubt you credentials please don't doubt ours. I doubt you've done t on purpose but you have.