Keston 25 - Yellow Wire to Condensing Trap

[Ragworm The Abominable]

Hi All,

Quick question, whilst looking at something unrelated inside my Keston

25, I noticed that the yellow wire that went to the top of the Condensing Trap from the loom on the left hand side, was cut in half, and flapping around inside the casing.

What does this wire do?

Could it be the reason that Fan Control board fuses have been blowing?

Many Thanks!

[fred]

In article , Ragworm The Abominable writes

Looks like a sensor wire to cut the boiler if the condensate trap blocks, to stop it overflowing. My wiring diagram shows a yellow/green earth wire going to the trap too so I reckon the condensate making a circuit between that wire & earth will stop the boiler or perhaps just ignition. A cut wire suggests desperation in fault finding.

Leaving this wire open or having it flap against earth shouldn't cause your fuse blowing problem but it's not really a clever thing to do, remake the connection after you have the boiler back in working condition.

BTW, the wire goes to the DBI unit (the one with the spark generator), not the fan control unit and the signal is named 'flame probe', weird huh.

FYI, it's difficult for me to diagnose faults on this boiler as mine has been fine from day one (currently 4yrs old) but I know you can get problems with spark flashover on the DBI (spark) unit if the mixture is weak or the gap too great on the ignition electrode, look for tracking (shiny deposits) on the DBI board near the igniter connection. Do _not_ attempt to correct the gap on a used ignition electrode, it work hardens in the heat and *will* break.

[fred]

In article , fred writes

Probably not a clever thing to say, insulate and leave safe until you finish fault finding.

[Ragworm The Abominable]

Thanks Fred :-)

I've fixed the break in the wire. I can't understand how the wire was broken as the break was a clean cut. An engineer did fix a problem with a blocked trap a couple of years ago, maybe he cut the wire inadvertently then :shrug:

Have taken your idea regarding the spark gap - I'll take a look at this next time I've got the casing off.

Many thanks for your help.

[fred]

In article , Ragworm The Abominable writes

You're welcome.

Just remembered, watch out for the screws on the ignition electrode if you have it out, they're a bit weedy and can get seized as they poke through into the combustion chamber. A head popped off one of mine leading to much fun extracting the stump, they're now replaced by cap screws (ie. Allen heads). . . . Did I really say mine had been no bother . . . .

[Andrew Gabriel]

...and if your keston is mounted close to a wall on the right hand side, it's a real bu88er to get the electrode out. If you intend opening the combustion chamber, make sure you have a replacement gasket first (available from HRPC).

[Tony Bryer]

They use them for the case screws, which is a bind, but here they would be a great improvement as you haven't got a lot of room to hold the screw whilst starting it. Studs and wing nuts would be even better.