Drayton thermostat - changing from standard to wireless unit


Postby gfenton » Sat Jan 19, 2008 2:39 pm

I'm trying to replace the bog standard central heating thermostat with a wireless programmable model - the existing one is a Drayton RTS 1 (so has 3 wires, N, L and #3 - call for heat).

I'm trying to add a Drayton +3RF (on the theory that as it's the same manufacturer it should be easy...) but running into problems with the wiring.

The +3RF has 4 connections (N, L, #1 - common and #3 - call for heat), but crypically in the instructions (below) it says if the '3RF is used without a separate programmer, or the programmer is set constantly on it would be acceptable to link 'L' to '1' provided the output voltage required is 230V ac'; I have a combi boiler (and have set the timer switch on the boiler to be on for all 24 hours) which I had thought took normal mains input, but doing this results in the new wall unit failing to come on at all (so doesn't send a signal to the boiler to come on etc).

I guess you could read the quote as saying attach the wire to N [u]and[/u] 1 but that doesn't seem to make sense, especially as the wire in the wall is a single piece so can't be split - could attach another short piece to it, but that sounds a bit shoddy.

Any ideas?? Otherwise I have a nice remote thermostat unit (2 parts) that can't turn on the boiler...
Last edited by gfenton on Sat Jan 19, 2008 7:36 pm, edited 1 time in total.
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Postby ericmark » Sat Jan 19, 2008 7:06 pm

I will try to explain. Live is bridged to Common (1) and switch wire is normal open (3) terminal and neutral to neutral of course. Yes you do need a bit of wire to link the Live and (1).
The old thermostats had a heater built into them to reduce the differential between the on and off temperature with modern digital units the neutral is not required. Often even on the old units people would not bother to connect the neutral. This has resulted in no neutral to the thermostat in some cases. Non radio control tend to use batteries so if no neutral it is not a problem but it would use too much power with radio controlled units. The same thermostat can be used for air conditioner units and boilers using 24 volt control circuits as well as 230 volt so has volt free change over contact hence extra contacts.
ericmark


Postby sparx » Sat Jan 19, 2008 7:29 pm

Hi, presuming your original room stat has L, sw-L, N + E then the cable going out from boiler should just go to the wireless recvr. part of new system using:
N to N term.
Live to Live & loop on to L1,
Sw-Line (call) to term. 3.
this gives mains to run the unit plus switched mains back to boiler.
Do read the instructions sheet thoroughly as the 2 units have to learn to 'talk' to each other once you have powered them both up, Tx. battery needs to be fitted at the right point in the process i seem to remember.
Just a ? why did you go radio route much cheaper to just replace stat with programmable type on original wires???
have had probs with wireless types as range not as good as makers say!
regards
SPARX
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Postby gfenton » Sat Jan 19, 2008 8:07 pm

Cheers for the ideas - the theory was to be able to better control the temperature in the rooms we use most often - it's a fairly new build 3 story house with the garage part of the ground floor and cleverly (?) the builders put the thermostat onto the wall with the garage so it is pretty much a waste of time in terms of setting it to any temperature. I guess at this point a basic programmable one would have been a whole lot easier - guess I'm a sucker for punishment?

I'm pretty sure it's not a problem around the remote unit talking to the wall unit - as part of the start up you have to get the wall unit to fire the boiler before turning on the wireless unit - and this is the part I can't get to work (the wires themselves are ok as the dial thermostat works). Plus I managed to get the wall unit to 'hear' the wireless (but couldn't get the wall to talk to the boiler) when it was wired L, N and #3. You're right about the batteries (very odd).

I think we're talking about the same things but just to check - there are 3 wires in the current unit (plus the earth, attached the cable box in the wall) - live, neutral and call for heat (#3) - and per the instructions the #1 is the 'common' (also described as 'switched live from wiring centre'), so you mean to splice from the live onto here? If so, that's the part I don't currently have (as there's only 1 live in the current set up).

So one final electrical thicky question - the wire within the cable is a single copper core (unlike a basic plug cable, which is about my level) so I can't splice it into 2 sections - so should I look for a particular type of cable (which is only going to be about 1cm long) and is there anything I should be thinking about when I'm making the join?
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Postby ericmark » Sat Jan 19, 2008 10:56 pm

As to connecting the link it is just a case of putting two wires in same clamp. And I seems we have found the wiring fault. Because it is central heating control it does come under but Part P and Part L building controls if you bother is up to you. As to location of old thermostat that seems correct! With new builds the boiler is normally of a variable output and during the winter months each room is controlled by the TRV as the spring arrives the boiler will rely on the anti cycle but in the summer one wants the while system to turn off and that’s where the room thermostat comes in turning the whole system off in the summer. So it needs to monitor outside temperature more than inside temperature which is what you say it does so is correct as builder placed it.
Of course in the old days when boilers only turned off and on and no TRV’s were fitted the job of the room thermostat was completely different today many systems don’t have room thermostat and rely on owners turning off the heating in the summer.
ericmark


Postby gfenton » Sun Jan 20, 2008 10:12 am

Interesting re the thermostat position - hadn't thought of it that way (although it does seem a little strange to use a thermostat to set a temperature for the house as a whole in the coldest location).

I don't think the issue is putting 2 wires into the same clamp - it's that I have 4 clamps to fill (N, L for the wall unit and #1 common and #3 call for heat to go to the boiler) but only 3 wires in the existing setup (N, L and call for heat).

So my question was should I try to splice the existing L between L and #1 (so getting power to the boiler through the common) - which seems difficult given the wire is a single core cable, or should I get a particular type of wire to join into the L and attach that to the #1 (and following on from that is there anything else I should be thinking about when I make the join)?
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Postby sparx » Sun Jan 20, 2008 11:00 am

Hi agn,
if you read my first reply it says LOOP a piece of wire (brown) from L in to L1 so Live goes into L then out again to L1, you can't 'splice ' a wire even if stranded type.
BTW make sure the live from boiler is always live and not going off at set times as if it is the set up won't work as each time it comes back on the radio link will not self start.
The wire live core (red?) used to go to old stat. may have come from a boiler term that is not directly connected to the boilers incoming main Live, ie it may be off sometimes, this needs checking & if so will need putting to Live in.
one final point you do know that boiler controls come under part-p notifiable works? see gov. list of 'controlled services' so you may need to get proff. help,
regards SPARX
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