Hi, my central heating (Vokera Combi) is controlled by a Danfoss 103
mechanical timer. Having got up at 4am today by work callout and
frozen my knackers off and also my first baby being due in January I
thought it'd be nice to have more thermostatic control of my
tempoerature so the little'un doesn't freeze.

I don't want to redecorate (again!) so wired thermostats are out -
basically I just want to replace the Danfoss with a remote thermostatic
timer.

Am I correct in thinking that these units are all pretty much
interchangeable, as they're just a "clever switch" so will have e.g.
live, neutral and a switch line? Can I for example replace my existing
timer with something like this: -

http://cgi.ebay.co.uk/Towerstat-RF-R...QQcmdZViewItem

Are there any gotchas I should look out for, incompatibilities etc? (
I do have some thermostatic valves which I know can conflict with
thermostat controllers, but I guess I can just set them to full in the
room with the thermostat).

Any recommendations for suitable controllers? First glance the eBay
one seems to do what I want, but anything I can pick up from B&Q/Wickes
etc?

Many thanks


Simon

Simon wrote:

Hi, my central heating (Vokera Combi) is controlled by a Danfoss 103

Partially answering my own question, it seems there are 2 types, volt
free (common switching) and 240v switching, and it appears the Danfoss
is the former. It also seems that the switch I pointed to on ebay is
240v switching and therefore no good (without rewiring - my boiler is
in the attic and the timer in the hallway). So looking again there
seem to be Drayton RF2/RF3 on eBay which may fit the bill.

Opinions again? Or suggestions for volt-free remote thermostats (with
timer) from local shops?

Thanks, Sy

"Simon" wrote in message
ps.com...
Simon wrote:

Hi, my central heating (Vokera Combi) is controlled by a Danfoss 103

Partially answering my own question, it seems there are 2 types, volt
free (common switching) and 240v switching, and it appears the Danfoss
is the former. It also seems that the switch I pointed to on ebay is
240v switching

well according to the sellers description its "now volt free"

and therefore no good (without rewiring

but any rewiring required (if any) would only be connection changes at the
boiler and/or the timer.

Do a survey of the connections to the Danfoss. Compare with the published
Danfoss wiring diagram. Do a survey of the connections at the boiler.
Compare with the published Vokera wiring diagram. All available online.
Work out the changes needed (if any).

Come back if you are still stuck.

Jim A

In an earlier contribution to this discussion,
Simon wrote:

Simon wrote:

Hi, my central heating (Vokera Combi) is controlled by a Danfoss 103

Partially answering my own question, it seems there are 2 types, volt
free (common switching) and 240v switching, and it appears the Danfoss
is the former. It also seems that the switch I pointed to on ebay is
240v switching and therefore no good (without rewiring - my boiler is
in the attic and the timer in the hallway). So looking again there
seem to be Drayton RF2/RF3 on eBay which may fit the bill.

Opinions again? Or suggestions for volt-free remote thermostats (with
timer) from local shops?

Thanks, Sy

Where do you want your timer/thermostat to be? If you can put it in the
hallway in place of the Danfoss 103, it doesn't even need to be wireless -
you can just use the same wires (but probably won't need all of them) as the
Danfoss uses. In that case, something like a Honeywell CM67 would be a good
bet. It is batttery operated, has volt-free contacts, and has a number of
useful features including:
* opimised start - where *it* decides when it needs to turn the heating on
in order to achieve the desired temperature by the time you specify [extra
cost option - but well worth it!]
* automatic frost stat
* holiday setting - allowing you to turn the heating off for a number of
days but to turn it on again just before you get back, so you come home to a
warm house
* party setting - allowing you to over-ride the programmed temperature for a
specified number of hours. Intended to keep the house warmer later when
you're having a party - but can also be used to save energy while you're out
shopping, etc.

If you need it to be somewhere different, a wireless one would be best. You
can probably put the (wired) base unit where the Danfoss 103 currently is,
and put the wireless temperature sensing part wherever that needs to be. As
others have pointed out, the one you mentioned in your previous post does
appear to have volt-free contacts anyway, so would probably be suitable.
[The fact that it's mains operated doesn't preclude it from having volt free
contacts - what matters is that its switching contacts are entirely separate
from its power supply - so that they can be used for switching anything, be
it mains or low voltage.] I don't know how similar it is to the Honeywell -
but there is a wireless version of the CM67 if you're interested.

As you are aware, a room stat should be in a room whose temperature is *not*
controlled by a TRV, because the two would otherwise conflict. If you have a
TRV, it would probably suffice just to remove its thermostatic head.

A programmable stat - wired or wireless - will allow you to set different
temperatures at different times of day - so you can, in effect, keep the
heating on but on a low setting overnight - which would address your 4am
problem. You should be able to buy one at your local Plumb Center (sic) -
although they're usually cheaper on line.
--
Cheers,
Roger
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