Danfoss 103 mechanical timer to FP75 programmer

[bjl]

im changing over the old danfoss 103 mechanical timer over to the danfoss FP75 programmer. It is a combi boiler so hot water side wont be used just wanted to check on wiring. The connections are

103 timer common terminal 3 linked to live
'on' terminal 1

FP75 programmer CH on terminal 4
CH off terminal 2

just to check where does cable on timer 103 terminal 1 'on' marked go on the programmer ?? CH on or off??

 

[tazz]

This programmer may not be suitable, as it has no dry relay contacts. The fp75 has only switch live outputs for CH and HW

 

[Johnmdc]

Connect it to terminal 4 CH on

 

[Leesparkykent]

Why use a twin channel programmer if you only need 1 channel?

 

[bjl]

i had this lying about. so on terminal1 is CH on ?

 

[Leesparkykent]

......

 

[tazz]

Connect it to terminal 4 CH on

Good tip on damaging his boiler......A combi requires dry contacts as already stated. Lee sparks has posted 2 diagrams, one for volt free timer (which is required) and one for the Danfross fp75 which has switch live. (which will not work)

 

[davesparks]

Good tip on damaging his boiler......A combi requires dry contacts as already stated. Lee sparks has posted 2 diagrams, one for volt free timer (which is required) and one for the Danfross fp75 which has switch live. (which will not work)

But the OP states that the live is linked to the common of the volt free switch on the existing programmer

 

[Johnmdc]

Good tip on damaging his boiler......A combi requires dry contacts as already stated. Lee sparks has posted 2 diagrams, one for volt free timer (which is required) and one for the Danfross fp75 which has switch live. (which will not work)

I don't know what you mean by "dry contacts" if you mean volt free then the OP already said that live was linked to common on the 103 which means the boiler is mains switched.
So not likely to damage the boiler at all!

 

[tazz]

I don`t know any combi which works on switch live, all I seen are volt free switching to timer then stat.
The op states this is a timer he has not what was fitted, so link was on backplate

 

[davesparks]

I don`t know any combi which works on switch live, all I seen are volt free switching to timer then stat.
The op states this is a timer he has not what was fitted, so link was on backplate

Worcester Bosch combi's all have a 240V switched live for external controls.

The OP states he has an old danfoss 103 in which the L has been linked to common which he is replacing with the new programmer.

 

[Johnmdc]

Most do Vailant, Worcester, Baxi, Potterton and Glow Worm are the most common ones I wire for BG and all these have switched lives.

 

[Leesparkykent]

The 1st pic I posted is for the danfoss 103 the second is for the danfoss FP75 which the OP says he's replacing the 103 with.
so if the boiler has a 240v switched live which it must if Live and 3 are linked then on the new programmer number 1 from old time clock will go to number 4 on new programmer.

 

[tazz]

Suggest the op checks this out first against the combi`s manual, to be on the safe side. I don`t want to give out bad info.

 

[Johnmdc]

If the OP could tell us which boiler he has we can confirm this.
But as me, Lee and Dave have all said if live and common are linked on the clock then the boiler is live switched.

 

[tazz]

Best idea, then its clear

 

[Leesparkykent]

Best idea, then its clear

I think so, boiler could have volt free contacts and the old time-clock could be switching a relay for all we know.

 

[bjl]

thanks for that it is a potterton 80 combi

 

[Leesparkykent]

Yes this boiler requires a 230v SL, so number 4 on new programmer connects to terminal 7 in boiler.