probs with circuit for boiler

[andy1020]

Hi folks,
I've actually posted in plumbing already, so don't go saying I'd be better speaking to a heating engineer...! I reckon you might be able to help here... I have some elec experience but not sure how on earth a basic heating system is wired? (ie: the idea of a live feed to turn something off??)

Here goes- the programmer for our heating went yesterday and I replaced it today (new Danfoss FP715Si programmer)

You know how the backplate has L, N and 4 switches, on & off for each CH and HW. (non combi system, separate control of heating & HW, fully pumped)

Point is, the old terminal block had the L linked to the off for both CH and HW. As per instructions for new programmer (which seemed confusing on the matter) I removed this link but wasn't sure whether I should have? Now the programmer works for turning on HW and CH but if I try to switch both on at once then the programmer dies and the boiler goes off. an error code flashes and then it turns off. I need to turn off the power and restart it.

Do you reckon I should reconnect the live to the 'off' switch terminals again?

See I don't get how you need Live going to anything when it's switched off. I understand the turning it on bit... Can anyone enlighten me with the general idea even, which might help...

Thanks!

 

[Pensdown]

You dont need any links. Put the live feed in L and the neutral feed in N

Put the heating feed in 4 and the hot water feed in 3

 

[andy1020]

thanks.
yea, that's what I thought, which is why i removed it.

However, I've just reconnected it now, and the system is working as it should (the Ch and HW can operate at the same time) (I also realised i misread the instructions- it said keep any links basically...)

weird

 

[Pensdown]

Your new programmer has internal links so I'm not sure how you had it wired. Anyway, I'm glad to hear it's working OK now

 

[kevnurse]

Just so you know, the zone valves are driven by motors that have "valve open" and "valve shut" microswitches to cut off the live supply when the valve reaches the desired position. Otherwise, during a selected "24hr" setting, the zone valve motor coils would get hot. For this reason a phase wire needs to be connected to both the "on" and "off" switch.