Hi.
I have a Potterton Netaheat 10-16 MkII boiler at home that seems to be as old as the hills but has given stirling service.
Since the clocks changed last weekend we've noticed a bit of a problem with it - but only cos I got up one morning and discovered the rads were cold and wondered if I'd put the clock the wrong way!
When the controller ticks over to "HW / CH" (or even "HW" on it's own) the boiler does not appear to be lighting normally.
The pump can be heard coming on, the fan in the boiler starts and that's about it. No other noises.
Usually within a few seconds the igniter kicks in and the boiler fires up and runs properly but what's happening more and more lately is that the boiler remains in this "pre start" state - the pump runs and the fan can be heard whirring away.
In the past we had an issue with one of the rubber tubes to the pressure switch getting kinked and causing a similar problem - I've checked for this again and not found anything.
I have discovered that if I blow down the tube to the pressure switch (not a hard blow, but enough to blow bubbles slowly out of a straw in a glass of water, if you follow me) the boiler will light and run normally. This suggests to me that either the fan isn't developing sufficient pressure to activate the pressure switch or the switch itself is out of tolerance.
If left for about an hour in this pre-start state it will eventually light and run but then when the thermostat kicks in and it turns off gracefully it may or may not relight afterwards.
I mainly suspect the fan because when the boiler is in one of it's "strops" and won't light, the noise the fan makes does seem to go up and down in pitch as if the motor is speeding up and slowing down - to the best of my limited understanding gleaned from the circuit dia. on the back of the front plate covering the pressure switch etc.., it's a fixed speed fan and there is no speed control circuitry other than the "on / off" master relay so it shouldn't do this...?
Any thoughts?
As you can see, I have my own ideas but with there being such a wealth of knowledge here (and me not having any!) I would appreciate some pointers or suggestions before I call out the engineer so I have a good idea of what I'm looking at with the fault, the parts needed to cure it and so I know I'm not beeing fleeced.
Thanks in advance!
Jim
I have a Potterton Netaheat 10-16 MkII boiler at home that seems to be as old as the hills but has given stirling service.
Since the clocks changed last weekend we've noticed a bit of a problem with it - but only cos I got up one morning and discovered the rads were cold and wondered if I'd put the clock the wrong way!
When the controller ticks over to "HW / CH" (or even "HW" on it's own) the boiler does not appear to be lighting normally.
The pump can be heard coming on, the fan in the boiler starts and that's about it. No other noises.
Usually within a few seconds the igniter kicks in and the boiler fires up and runs properly but what's happening more and more lately is that the boiler remains in this "pre start" state - the pump runs and the fan can be heard whirring away.
In the past we had an issue with one of the rubber tubes to the pressure switch getting kinked and causing a similar problem - I've checked for this again and not found anything.
I have discovered that if I blow down the tube to the pressure switch (not a hard blow, but enough to blow bubbles slowly out of a straw in a glass of water, if you follow me) the boiler will light and run normally. This suggests to me that either the fan isn't developing sufficient pressure to activate the pressure switch or the switch itself is out of tolerance.
If left for about an hour in this pre-start state it will eventually light and run but then when the thermostat kicks in and it turns off gracefully it may or may not relight afterwards.
I mainly suspect the fan because when the boiler is in one of it's "strops" and won't light, the noise the fan makes does seem to go up and down in pitch as if the motor is speeding up and slowing down - to the best of my limited understanding gleaned from the circuit dia. on the back of the front plate covering the pressure switch etc.., it's a fixed speed fan and there is no speed control circuitry other than the "on / off" master relay so it shouldn't do this...?
Any thoughts?
As you can see, I have my own ideas but with there being such a wealth of knowledge here (and me not having any!) I would appreciate some pointers or suggestions before I call out the engineer so I have a good idea of what I'm looking at with the fault, the parts needed to cure it and so I know I'm not beeing fleeced.
Thanks in advance!
Jim
