Changing a room thermostat / wiring

[Left Nothing]

Hi All,

I currently have a Drayton RTS1 room thermostat wired in. In an attempt to better control my CH I am looking at replacing the above with a Danfoss TP7000 (the replacement for the TP75 series).

The wiring to the RTS1 has 5 wires connected as follows:-

2 x N 1 x L 1 x C(all) 1 x Earth

There are 3 (+ earth) connections on the RTS1 being N, L and Call.

Looking at the Danfoss website

and getting the PDF for the 7000 series, the two models I am looking at are the TP7000 and the TP7000M (the M being mains powered).

The wiring for the TP7000 is listed as being; COM, ON and OFF

The wiring for the TP7000M is the same as above with an additional N and L

Now the question is, which wires would I connnect to where? I am assuming for the TP7000 the wiring would be:-

N --> COM C --> ON

The remaining wires not being used?

and for the TP7000M;

N --> COM C --> ON N --> N L --> L

Does this look right or am I missing something here? (there is a wiring diagram in the PDF from Dandoss's site)

Also, can anyone recommend the best place to get one from? The cheapest I have found so far is from

@ 47.39 ukp but this doesn't say if it is the battery or mains powered version. Most places I have looked only stock the older TP75 but SWMBO likes the look of the 7000 series better.

Any help / comments appreciated!

LN

[Christian McArdle]

There's no point in connection a neutral to the switch common. It will cause the heating to go permanently off.

L(CH On) --> COM C --> ON (TP7000M only) L(Perm) --> L N --> N

The old "Live" is probably not permanent live. Old analogue room stats had connections for CH On (from programmer), Call for heat (to zone valve), and neutral (used to power a heater to affect hysteresis). I have no idea why you appear to have two neutral connections, though. It is possible you have an odd installation.

Unfortunately, if the wiring is conventional you probably don't have a permanent live available, which may preclude the use of the TP7000M, unless you either rewire, or disconnect the 'L' line from programmer "CH On" and connect to permanent live. This will prevent the old programmer being used as a master control, however. (Obviously, the new thermostat would have to be programmable as it will disable the programmer's CH timing functionality).

Christian.

[ARWadsworth]

One possibiliy is that 5 core flex is been used, the one with 2 black wires. It is often easier to double up on the neutral than identify the black cables. I know that the cables are usually numbered, but not all are.

If the neutrals are doubled up back at the boiler/wiring box it would be possible to seperate them to give the permant live required

Have a look at the other end of the cable (if it is just one cable/flex to see if this is possible)

-- Adam

adamwadsworth@(REMOVETHIS)blueyonder.co.uk

[Left Nothing]

[Replacing a RTS1 thermostat with a Danfoss TP7000]

[SNIP]

There are two set's of cable running to the thermostat, one set is the L, N & Earth, the other is the N & Call.

Does this help any?

It is a 4B detached house built in '96 by Jelson's. AFAIK, the wiring for the CH has not been altered since it was built. (not to say it is 'conventional' but in general Jelson houses are pretty well built e.g. Solid wood doors, breeze-block / plaster on all walls up&down etc)

The timer is in our utility room with the room thermostat in the hall. Am I correct in assuming that all these wires will go back to the timer/controller? or will some go to the valves upstairs in the airing cupboard?

Is there any easy way to tell?

LN

[Left Nothing]

Looking at the PDF from

for the TP7000 again, the three connections are COM, ON & OFF. Should the 'OFF' be connected to N ? (If I am reading the diagram correctly, 'COM' is switched to 'ON' or 'OFF')

See my other post on this, there are two sets/cores of cable running to the box, N/L/E and N/Call. Is one set going to the CH programmer and the other to the zone valve (I assume this is the motorised valve(s) located next to the HW tank?)

I would prefer to be able to switch off the CH if needed from the programmer...

LN

[Christian McArdle]

It is possible that one cable is from the programmer with the L (actually CH On, not permanent) and N.

The other cable might go directly to the zone valve, particularly if it isn't mounted in the same place as the programmer. This would explain the doubled up neutrals.

Christian.

[Christian McArdle]

NO!!!!!!!

Do not under any circumstances connect any neutrals to any of the switch connections.

Christian.