Oh what a day!!!

[oharaf]

Today I went to change the 7 day programmer and thermostat combined at the local methodist church.

Eventually narrowed it down to a Danfoss TP7000, lovely piece of kit.

So off I trot happy as a spring lamb, isolate the heating circuits, mount the old 'new' 7 dayer, program it up. go to cupboard to turn circuit on (great big MEM switch).

All good, anyway reducing temperature down a tad,

FLASH BANG FIZZ SPIT SPARKS SMELL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

Cannot believe my eyes the feckin thing is burn't out!!!!!!!!


First, check the fuses, all okay power back on and notice that the 3 neon switches that operate the 3 heaters are not lit, mmmmmmmmmm!!!!!

So follow the circuit to a huge MEM box, open it up and there is the contactor!!! So attempt to recontact, neons on finger off neons off, contactor will not set.

Get the tester out check everything between termo and MEM isolator then to Contactor, IR good, Continuity Good.

So next logical step is chase the entire system.

And this is where it all goes tits up, the rest off the system is in the loft area, so what you say.

This area is riddled with ASBESTOS, so no way on earth I can enter and was informed this by church warden last week.

So now there is no heating, I could change the contactor (1972 date stamp) but this may or may not be the problem.

Gutted for them and miffed that i cannot chase the fault.

Any suggestions for alternative heating, I thought curtain heaters, they only expect to be in the church another 6 to 12 months so it is a case of weighing things up, but they do need heat most are well into their 60's.



Suggestions???

 

[Spark123]

What's the resistance of the contactor coil?
What went fizz pop bang?

 

[RF Lighting]

I take it this is an all electric heated building, and there is a programmer & room stat controlling a contactor which supplies a CU for the heaters?

Is it the contactor which will not hold in?

Have you metered the contactor supply?

 

[ColJack]

so form the sound of it...

you replaced a timer / stat controller and it worked fine untill you turned the stat down a bit?
at which point the controller got fried?

manually operating the contactor results in the heating comming on?

have you tried "bodging" the contactor temporarily ( put a wire from the L1 feed to the A1 coil contact, essentially removing the timer / stat from the equation and confirming that the contactor opperates correctly )

if you fried the stat when you turned it down, it sounds like you either miss wired it and shorted something out when the contacts changed, or the new stat is not man enough to run the contactor ( unlikely if it's a like for like swap )

what was the reason for having to change it in the first place?
did you clear any existing fault that may have caused the old one to fail?

 

[oharaf]

Not tried bodging the contactor!!

I thought perhaps I had made a cock up with the wiring at the timer, but, I had not!!!

The pop bang fizz came from the programmer as it died!!!

cont and IR'd as far as I could, all clear!!!

Would love to cover whole system but coz of the Asbes. no way of doing it.

By the way the supply area looks like some one threw a bag of assorted cables into it about 30 years ago!!!!

I'm completely baffled, all I can think is the contactor is buggered or there is something more sinister.

They wanted the timer changing because people kept leaving the overide on!!

 

[Spark123]

You havent ended up with 415 across it have you?

 

[oharaf]

NAFAICT!!!!

 

[Spark123]

Does the time switch have a neutral or does it rely on the power through sw live?
Is the contactor coil 415v? (sorry about the old school voltages).
Another thing could be someone has connected a heater directly to the controller.

 

[securespark]

415?

Next you'll be talking about the white phase.....

 

[Spark123]

Good old patriotic colours - don't know why they changed them