DIY Doctor UK DIY Forums

hi all,
i have a danfoss TP5000 SI thermostat controlling my underfloor heating(water) single zone,in my conservatory.i find this thermostat to be over complicated with no shut off button for summer,so i am going to replace it with a simple honeywell ST9100C timer wich i have now purchased.can i just swap over the fronts as i believe the back plates are a industry standard,can anyone confirm this,if not so,how do i wire the honeywell,i only have 2 wires in the danfoss.any help would be much appreciated.thanks.

the backs of the room thermostats are not an industry standard, but it is true most are the same.
A room stat can have any or all of the following:
permanent live (live all the time),
common live (becomes live when the programmer is timed to come on), calling (power from the room stat when room temperature is below the stat setting),
satisfied (power from the room stat when the room temperature is above the room stat setting),
neutral
and earth
the 2 wires will most likely be common live and calling, which mean your probably will not be able to fitted a room thermostat will timing controls, unless it uses batteries. somewhere on the room stat there should be a wiring diagram, usually on the back of the unit once to take it off the backing plate. Under the circumstances, i would fit a danfoss rs1! :wink:

hi eggers
thanks for your info,it states on the instuctions for the honeywell that it fits industry standard backplate,and that this timer is suitable for single zone heating systems thats why i bought it,the 2 wires in the danfoss are brown and blue,they go into a wiring centre,the brown goes to the mains live and the blue which has a brown sleeve on it connects to the brown on the 2 port valve and the brown for the floor heating pump on the manifold is linked to these also.

is the honeywell timer have batteries as well? i'm desperately trying to remember the in's and out's of that particular model! If it needs to have a permanent live and neutral then 2 wires won't be enough, the instructions with the room stat should have a wiring diagram. If you can tell me what is written in the instructions as to what wires are needed, i may be able to de-code it a little for you

hi eggers,sorry for delay in replying my router jacked in .the honeywell does not have batteries.in the back cover it has a diagram for fixed wiring only,incoming mains,live.neg.earth.it then has 1.2.3.4.a wire in no 1 with o on the end.a wire to no 2 says off and has a letter n on the end.no 4 says on and has a letter n on the end.on the other side of connectors it shows nos' 1 2 4 with a switch diagram across them,and underneath it says. 24-230v-3(3)A.hope this is of some help,please note i do have 2 spare wires which i installed when fitting heating system just in case i ever changed the stat.so there is 4 wires in total+earths.thanks.
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hi eggers,
a bit more info which may be helpful,i have checked the wiring for the danfoss tp5000,which i am replacing.in the stat it has 1, 2, 3,
n/c. com. n/o
brown wire(live) from no 2 goes to live(mains)in wiring centre,blue wire with brown sleeve on it from no 3 to no 5 in wiring centre which feeds the live on a 2 port valve and live on manifold pump.thanks.

com is the com live from the programer,
n/o is normally open, that it the heating on,
should work providing the unit is recieving power from either a battery or a permanent live and neutral

com is the com live from the programer,
n/o is normally open, that it the heating on,
should work providing the unit is recieving power from either a battery or a permanent live and neutral

hi eggers.
so in the honeywell i have N.L.1.2.3.4.
if i remove the danfoss and connect the brown live to live in the honeywell
where do i connect the blue wire which has a brown sleeve on it which is connected to no 3 n/o in the danfoss.thanks.

Brown to number 1 (if this will be permanently live, you can bridge to L)
blue sleeved brown to number 4
nothing into terminal 2 as it is not relevant to your system
terminal 3 is redundant
but remember the honeywell needs a permanent live and neutral as well

Google "plumbnation.co.uk/site/honeywell-st9100c-7-day-single-channel-programmer-/honeywell-st9100c-sales-brochure.pdf"

(please confirm this is the unit you have!?!)

hi eggers
sorry for delay in replying,having trouble with master phone socket waiting for talk talk to come out and change it.thanks for the link,yes that is the model i have, so i need 4 wires in total.thanks again much appreciated.