I have a Potterton Netaheat Profile 60e. It worked fine until last
week.
Now it has developed a delay between the fan starting and the boiler
firing up. This delay varies between 10 minutes to over an hour. The
funny thing is that it starts up ok first thing in the morning until it
reaches the heat and the roomstat turns it off. When the roomstat turns
it on again the delay sets in. I've checked the CH pump and the
roomstat and both work ok.
It was particularly windy last week, could this have damaged the air
pressure sensor, or is it a boiler thermostat problem?

"KenL" wrote in message
ups.com...
I have a Potterton Netaheat Profile 60e. It worked fine until last
week.
Now it has developed a delay between the fan starting and the boiler
firing up. This delay varies between 10 minutes to over an hour. The
funny thing is that it starts up ok first thing in the morning until it
reaches the heat and the roomstat turns it off. When the roomstat turns
it on again the delay sets in. I've checked the CH pump and the
roomstat and both work ok.
It was particularly windy last week, could this have damaged the air
pressure sensor, or is it a boiler thermostat problem?

If this beast works as I recall, there is a sealed cover that the fan
pressurises before the burner fires, the pressure being sensed by the
pressure sensor.

One possible problem is a small leak - so the fan takes longer to get the
pressure up. The difference in "first time" and when the system has been on
earlier could be a simple issue of the leak being sealed when cold and
opening when warm.

Brian

On Wed, 05 Apr 2006 06:43:42 +0000, Brian Reay wrote:


"KenL" wrote in message
ups.com...
I have a Potterton Netaheat Profile 60e. It worked fine until last
week.
Now it has developed a delay between the fan starting and the boiler
firing up. This delay varies between 10 minutes to over an hour. The
funny thing is that it starts up ok first thing in the morning until it
reaches the heat and the roomstat turns it off. When the roomstat turns
it on again the delay sets in. I've checked the CH pump and the
roomstat and both work ok.
It was particularly windy last week, could this have damaged the air
pressure sensor, or is it a boiler thermostat problem?

If this beast works as I recall, there is a sealed cover that the fan
pressurises before the burner fires, the pressure being sensed by the
pressure sensor.

One possible problem is a small leak - so the fan takes longer to get the
pressure up. The difference in "first time" and when the system has been on
earlier could be a simple issue of the leak being sealed when cold and
opening when warm.

If there is a leak in the combustion chamber cover then that is classed as
a serious safety fault.

More likely there is debris at or around the inlet to the pressure tubes
or the APS is marginal.

However the delay could be coming from the time between pilot ignition and
full gas. This could be due to a failing gas valve sensor bulb or more
likely a dirty pilot flame that's not heating the sensor aright.

The OP should make sure the boiler is serviced based on a thorough strip
down. Then see what symptoms still remain.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

In message . com, KenL
writes
I have a Potterton Netaheat Profile 60e. It worked fine until last
week.
Now it has developed a delay between the fan starting and the boiler
firing up. This delay varies between 10 minutes to over an hour. The
funny thing is that it starts up ok first thing in the morning until it
reaches the heat and the roomstat turns it off. When the roomstat turns
it on again the delay sets in. I've checked the CH pump and the
roomstat and both work ok.
It was particularly windy last week, could this have damaged the air
pressure sensor, or is it a boiler thermostat problem?


At what point do you hear the ignition spark clicking?

--
geoff

Thanks for your replies ...

Brian, Ed ... The leak theory, sounds expensive and potentially
dangerous. In view of that I have arranged for an engineer to call on
Saturday.

Geoff ... The fan runs and runs then eventually when the ignition spark
clicks it lights immediately. I've checked the flue outside and there
is no smell of gas.

In message . com, KenL
writes
Thanks for your replies ...

Brian, Ed ... The leak theory, sounds expensive and potentially
dangerous. In view of that I have arranged for an engineer to call on
Saturday.

Geoff ... The fan runs and runs then eventually when the ignition spark
clicks it lights immediately. I've checked the flue outside and there
is no smell of gas.

So, it looks like it must be a pressure switch associated problem then

could be the leak as others have said

or

the fan running slowly, bad contacts on the air pressure switch (APS)
microswitch, APS diaphragm ruptured or a capacitor gone on the pcb

You need to establish whether the APS is changing over or not

--
geoff

"KenL" wrote in message
ups.com...
Thanks for your replies ...

Brian, Ed ... The leak theory, sounds expensive and potentially
dangerous. In view of that I have arranged for an engineer to call on
Saturday.


Good idea- not something to tackle yourself but good to have an idea on what
is happening.

Brian

All ... thanks for your help. The engineer called and serviced the
boiler. He spent a bit of time on the air switch side and found that
one of the tubes (into the flue) was suspect. All appears to work now.

Ken