Replacing a Honeywell ST699C with Danfoss FP715Si - Help !

[Kevvy]

Hi
Just moved into a new house and wanted to replace the old Honeywell programmer.

The issue i have is that for some reason when the heating is on the hot water appears to be on as well... should it be ?

If i press the Hot Water Button +1hr it comes on ok
If i press the central heating button +1hr the hot water comes on as well as heating and i cant switch off hot water option

So i thought i would replace the unit with an FP715Si
I used the wiring diagram in the booklet with the new programmer but i now find again if i press the Heating button the Hot water light comes on as well.

In addition it looked like on the old honeywell the HTG ON was connected to the N terminal
If i remove this from the N terminal which obviously also has the N cable it doesnt work at all

Now i don't know if its because this unit cant do hotwater without heating or if its just wired up wrong by previous owners ?
Can the Glo Worm boiler do this ?

Also should there not be a cable on number 2 of the new unit ? - HTG OFF ?
And would this be a pumped system or gravity system as there is a dip switch to change on the new programmer.. not sure what difference it will make.
Picture of wiring.. Note Yellow was on connection 7 on old unit but not shown in pic

View attachment 35234

View attachment 35235

 

[Last plumber]

Hi
Just moved into a new house and wanted to replace the old Honeywell programmer.

The issue i have is that for some reason when the heating is on the hot water appears to be on as well... should it be ?

If i press the Hot Water Button +1hr it comes on ok
If i press the central heating button +1hr the hot water comes on as well as heating and i cant switch off hot water option

So i thought i would replace the unit with an FP715Si
I used the wiring diagram in the booklet with the new programmer but i now find again if i press the Heating button the Hot water light comes on as well.

In addition it looked like on the old honeywell the HTG ON was connected to the N terminal
If i remove this from the N terminal which obviously also has the N cable it doesnt work at all

Now i don't know if its because this unit cant do hotwater without heating or if its just wired up wrong by previous owners ?
Can the Glo Worm boiler do this ?

Also should there not be a cable on number 2 of the new unit ? - HTG OFF ?
And would this be a pumped system or gravity system as there is a dip switch to change on the new programmer.. not sure what difference it will make.
Picture of wiring.. Note Yellow was on connection 7 on old unit but not shown in pic

View attachment 35234

View attachment 35235

Your Boiler is old. It's possible that you have Gravity Hot water. In that case your programmer would be on 10 programs ( hot water or hot water and heating are your only choices)
Do you know if you have a Gravity hot water and pumped heating ?

 

[Kevvy]

i can see a pump on the side of the hot water tank i think, would it be on there for heating ?

I just set the programmer to pump instead of gravity and its now allowing me to control seperately and firing the boiler depending on which button i press.

however no idea if its actually working as it should

 

[Leesparkykent]

i can see a pump on the side of the hot water tank i think, would it be on there for heating ?

I just set the programmer to pump instead of gravity and its now allowing me to control seperately and firing the boiler depending on which button i press.

however no idea if its actually working as it should

Do you have a 3 port valve by the pump and cylinder?

 

[Kevvy]

This is what i see

View attachment 35245

 

[Leesparkykent]

Yeah its a Y-plan, If its been wired correctly then you should be able to select hot water or heating independently. Change the programmer to fully pumped and check both programmes function correctly.

 

[Last plumber]

That red thing is your pump and the silver thing is a 3 port motorised valve. From what I can see you have a Y plan ( which is fully pumped) and from looking at the picture it also looks like you have a wire on the hot water off terminal so in theory and going off the little I have seen, it should operate ok now it's on 16 Progs ( pumped)

 

[Leesparkykent]

If it doesn't function correctly it could be wired as hot water priority in which case the wiring needs altering in the wiring centre but I doubt this will be the case

 

[Kevvy]

thanks, appears to be working ok on pumped. no wire on the HTG OFF terminal on the programmer though.
Also there is a blue cable going to the N pin as well as the main N on the programmer. I tried it without it but wouldnt work, so put it back to it as it was on the old programmer. No idea what that is for

 

[Leesparkykent]

thanks, appears to be working ok on pumped. no wire on the HTG OFF terminal on the programmer though.
Also there is a blue cable going to the N pin as well as the main N on the programmer. I tried it without it but wouldnt work, so put it back to it as it was on the old programmer. No idea what that is for

You wont need heating off. Standard Y-plan uses hot water off, hot water on and heating on connections from the programmer.