Potterton Profile won't light?

[Dean Heighington]

Typical Sunday night saga!

I have a Potterton Profile boiler situated in my garage which provides heat for my CH and HW (Gravity fed).

I have tinkered many times with my CH/HW system adding and replacing parts etc and have always managed to get her fired up with no hassles.

This time she just hums (fan presumably) but no pilot light nor fire-up occurs!

Gas, power, demand and water is there (at least I'm sure that water is there because the pump in the airing cupboard sounds like it's pumping water) and, in fact I never shut the system down... I just turned the programmer to "off" the other day as it was hot and I didn't want it kicking in come the morning!

The model is either a 30e, 40e, 50e, 60e or 80e the manual covers all and I can't be arsed to go down while writing this :) I'm starting to be convinced that something has gone in the boiler itself such as the Overheat thermostat and was wondering if anyone here can offer up some suggestions before I call in am engineer?

I've tried the manual reset button but that hasn't had any effect although it doesn't seem to have a satisfying click to the button when pushed... should it?

Appreciate any pointers.

cheers deano.

[Ed Sirett]

The reset button, I beleive will only go in with a click when it has previously popped out. I'm not sure but I think the fan would also be dead in that case aswell.

When the fan has run for a few seconds the APS should flick over to start the rest of the ignition switch.

The chances are that this switch has failed, or its supply tube inlets are blocked.

The manual is downloadable (I would expect) and that should help you to track down the fault.

[Dean Heighington]

Hi Ed.

When I turn the Thermostat knob to off and then back on again, the humming (fan) starts immediately and then there is an audible click... this is the point where previously, the next sound was the pilot light click and then the roar of the burners. Now, I only seem to get the initial click after the fan hum!

Could this be blocked jets? The heating has been off for a while because of the Summer heat!

With regards the downloadable manual, is there somewhere you know that I can get this? I have tried the Potterton website and they only seem to have the "User's Guide" which I already have!

Thanks for your help.

Dean.

[Sparks]

Does the fan stay on permanently, or does it cycle on/off?

I had a problem with my Potterton Profile, the fan would kick in, it would click, then just after the point it would normally light, the fan would go off, it would wait a couple of seconds, then repeat until it was turned off. It turned out to be the control board (well, something on it anyway!)

I replaced the board, and we had heat!

Before I replaced the board, I found sharply banging the bottom of the plate the board was mounted on *** just when it should be lighting "fixed" it - but this needed to be done every time it wanted to light!

***This board does carry mains voltage, so be careful if tinkering with it all switched on!***

Sparks...

[Ed Sirett]

This is because the relay does not swich over in response to the APS. Hitting it might just give it the help it needs. The OP would have mentioned the on-off-on-off cycling as its so distictive.

[Ed Sirett]

The manual is on their web site (it is for the 40eL and 80eL models but these are essentially identical to any of the profile range).

It includes a fault fininding flow chart (p32) but it is better to know how the sequence works and identify the problem yourself.

Profiles have a two stage ignition. First a small pilot jet is opened (after the fan is proved OK by the APS) This is ignited with a series of sparks. Upon satisfcatory flame detection the main gas valve is opened.

Sounds like the fan and APS are doing the stuff. So are there any sparks? NO - ivestigate spark problems. YES investigate gas/ignition problems.

[raden]

It's normally due to a capacitor drying out, or a zener diode failing

It can only get worse once it starts happening

"If in doubt, give it a clout" technology isn't really applicable here

Of course, it could also be an APS failure

(Back after a hard drive crash)

[raden]

In message , Dean Heighington writes

When you say fan hum, is it actually turning?

Fans usually "hum" when the part which holds the bearing in place breaks.

However ....

The click sounds like the APS is actually changing over

which would indicate that the fan is working

Ring me tomorrow on 01923 229224, I'll see if I can home in on the problem

Can you hear the spark trying to ignite the pilot ?

a repeated click at about 1 / second

[Dean Heighington]

Thanks Ed I'll get the manual next free period and have a study. Will probably be back here at some stage to confirm fault identification or with more questions.

[Dean Heighington]

Have only just seen your reply [sorry - hectic schedule of work/life balance :) ] When I next get some free time, this will be my subject of study, I'll get hold of the profile manual and if I can't fathom this myself, would it be OK to still call you for some assistance?

Many thanks,

Dean.

[raden]

In message , Dean Heighington writes

[Dean Heighington]

Automatic Protection System (Switch) ??

d.

[Dean Heighington]

Automatic Protection System (Switch) ??

d.

[Dean Heighington]

You got it right first time! The fan was humming, but not spinning. I removed the front panel which made this obvious and so I took the fan out and connected it to a flex with a 3amp plug and switched this on... the fan spun for about 5 seconds and then seized up and made the humming I'd heard earlier.

A quick trip to my local Plumb Center (and £102+VAT later - which I did think was extortionate - but worth it due to convenience) and the problem is solved!

Thanks for all the help from all who posted here.

Dean.

[Ed Sirett]

No: Air Pressure Switch.

It is a simple differential pressure switch (usually and in this case a changeover microswitch). The differential pressure is caused by the correct operation of the fan. It is operated by pressures in the order of a few millibars.

[raden]

In message , Dean Heighington writes

Next time look at my website

[raden]

In message , Dean Heighington writes

Air Pressure Switch

[Visitor]

Hi. I have the identical problem. When I took off the front cover off, the fan show no life at all. I did what you did, took fan off and connected to some flex with 3amp fuse. Nothing happened. Have I the same problem that its the fan? Grateful for your response.

[tony sayer]

If all else fails then give Geoff a call...