Re: [xap_automation] Heating Control

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

Hi Neil,

Not quite sure what you're wanting here. Presumably you are saying
that the current thermostat is reading low because it is influenced by
the outside temperature. Assuming you have reasonably insulated walls I
can only assume the localised temp is being influenced by a large area
of windows or by a draught, or it's behind a curtain . The thermostat is
switching based on the temp it sees locally of course. Replacing the
thermostat with another located in the same place will very likely just
produce the same result.  Far better would be to re-site the thermostat
to somewhere more reactive to the actual room temperature.   The normal
system of having the main , and only thermostat in a colder area of the
home is typical because if you can satisfy that area then it is assumed
you can also satisfy all other areas too. If you have it switching in
your warmest area then the cooler areas can never demand enough heat to
reach setpoint.   Handling multiple demands in different rooms requires
zoning of the heating system or more usually now thermostatic radiator
valves - which might be a sensible solution for you ? 28.5 deg C is very
hot !!  There are some networkable thermostats available too that I
believe will aggregate the demand back to the boiler (Sensible Heat)

If you are actually asking if there is some device that you could
use instead of the thermostat that would switch the boiler (and taking
input from xAP TOM10) then you could use Floorplan and a xAP
controllable relay to achieve this.  Cheapest would be attaching a relay
to your PC's parallel output port but this I think is a do it yourself
job - ensure you have a protection diode across the coil or you will
damage teh parallel port. . I am not sure if the parallel port outputs
can supply enough current to switch relays - you would have to
investigate this, there may be some prebuilt kits too although the
relays might not be rated sufficiently to use directly to the boiler. .
KevinT has some xAP software that would drive this. There are a number
of other prebuilt devices that attach to a PC and give relay outputs - I
think again KevinT has some xAP software for some. You could do this via
a xAP Netiom too or a controller like HomeVision etc.    Please note the
boiler is probably switching mains voltage directly and so the relays
must also be mains rated - you may need to use two interconnected relays
to get up to this rating. Also you must take appropriate precautions
when wiring the mains switching as it can be lethal of course.    Beware
that some  HVAC switching systems use 24V rather than what I expect is
mains switching in your case.  You only effectively have to replace some
normally open (closed to generate demand) relay contacts , assuming
there are just two wires there, but they must be mains 230V rated.

Kevin

Neil Frost wrote:
> Next question...
>
> I'm using xAP TOM10 to report some room temperatures. These are
> displayed using FloorPlan.
>
> The current thermostat in the lounge is on an outside wall, as it gets
> colder so I have to turn the thermostat down. It was down to 17deg C
> last night and the room was actually 28.5deg C.
>
> Is there a bit of kit that I can replace my existing thermostat with
and
> get it to switch the boiler on / off based on the temperature of the
room?
>
> The thermostat uses 2 wires wired straight into the combi boiler...
and
> is a basic "turn it round to select the temperature, and you can
hear it
> clicking on and off"
>
>
> Thanks
> Merry Christmas
>
> Neil
>
>
>
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