Potterton Neataheat MK2 16/22 Ignition problem

[RayPeck]

30 year old Potterton Neatahet MK2. Having problems with ignition of the pilot light, the boiler fan etc will run but the pilot light will not light, have changed the Ignition monitor for a old one that I had in stock,, this worked for a couple of ignition cycles then stopped working. Checked original Plessey Unit (which has earth) and there seemed to be dry joint on the circuit board, resoldered and worked OK for a couple of hours and several start cycles now stopped working again. I notice that the spark generator neon is flickering. Has anyone a clue what might be the problem. If not able to resolve would like any information on a boiler that may be a direct replacement.
Thanks in advance for any info.
Spark Generator is
Electronic Ignition Generator Part No. 407/1/72048/002
Flame current 1.5 micro amps

 

[Agile]

This is not a boiler for DIY repairs.

Without seeing why its not working well I cannot make any guesses.

There are many boiler suitable as a replacement like the Worcester Ri series or the Viessmann OV.

Tony

 

[RayPeck]

one of the things I was trying to get my head around is the ignition sequence, Thermostat calls for heat, relay operates, fan runs and purges boiler, SPARK GENERATOR ignites pilot light, main gas valve opens. Does the boiler cycle if pilot does not light and retry?
Looking at he sequence,as it occours, the pilot light will light if the neon type item in the spark gen gives a sharp snap light , but as said before it is flickering.
I do not want to go into the gas side of the boiler other than understanding how the electrical side works.
I suspect that the spark generator unit is faulty as in the spare one I have the neon is black inside.

 

[Rob]

I could guess what the problem is but its not really a diy job. To test the spark gen just see if theres a 230vac feed to it (terminals 22 and 26)

 

[Agile]

Your "neon" device is a gas filled spark gap.

When new they are clear and become blackened over time.

They are open circuit until the voltage across them reaches about 100v and then they heavily conduct and the resulting current pulse is used to produce the HT voltage through the transformer.

THe ignition aspects of the pilot light are beyond the capabilities of a DIYer and this is a particularly dangerous type of boiler.

Tony

 

[RayPeck]

Thanks for the advice, have replaced spark ignition unit and boiler now working OK, also invested in a CO detector as boiler is now 30 years old and you never know.
Next thing is to investigate a new boiler, but am a bit put out that no one seems to make a Class A boiler with a cast iron heat exchanger, plus I am going to have to run a new feed to the pump from the boiler to the pump for pump overrun.

 

[misterdubya]

Thanks for the advice, have replaced spark ignition unit and boiler now working OK, also invested in a CO detector as boiler is now 30 years old and you never know.
Next thing is to investigate a new boiler, but am a bit put out that no one seems to make a Class A boiler with a cast iron heat exchanger, plus I am going to have to run a new feed to the pump from the boiler to the pump for pump overrun.

Why, not all boilers need an overrun.

Mr. W.

 

[heatingman]

the n/heat 16/22 should have had the pump wired direct of boiler, so blame the original installer.

 

[Agile]

Can you not see that a big block of cast iron has to be heated up at the begining of a heating cycle, wasting heat, and has to cool down at the end of the heating cycle, again wasting heat.

Modernb efficient boilers use low latent heat capacity heat exchangers.

Tony Glazier

 

[RayPeck]

Thanks one and all, sufficient for me to say the lump of cast Iron has lasted for 30 years with no problem, friends nice shinny Potterton 's heat exchanger went after 5 years and it was fully serviced and treated.
End of topic now.
Regards
Ray