Re: Ultimate Central Heating Thermostat

["steve" <steve@xxxxxxx>]

>
> *Multi-zone via Dallas one wire temperature monitors

Done but using Quantech stuff

> *Predicts rate of rise and fall of house temp in order to anticipate
when
to
> run boiler

Wanted to due this but couldn't figure out the maths. Current system tracks
occupancy in each zone and predicts when heating would be required &
come on
45 mins early and off as appropriate.

> *Specify house warm by time and warm until time
> Support for multiple programmes - week mode, weekend mode, alternate
week
> mode

Not required as house only heated when occupied or predicted to be
occupied.

As zoned and ideal temps found all adjustments of set points have been
removed from code. Outside temp is also monitored and shuts off heating
when
12 deg or above. This i have found can save money. As external temp rises
it
is unesseccary to heat as internal temp will rise on its own.

> Display to show current temp, set point, boiler on/off
> Buttons to override on/off, adjust set point
> RJ45 network connection to provide web interface to thermostat and
Comfort
> Zone inputs from Comfort to permit occupancy/alarm/telephone control
> Zone outputs to allow 12v control of boiler (e.g. via Comfort)
> *Additional outputs to allow independant heating of other rooms as
required
> Serial input from Comfort, to permit Comfort to use thermostat web
interface
>
> I've asterisked a couple of the features I think I want, because I
wondered
> if anyone on the list has any experience of getting these sorts of
things
to
> work. My current thermostat does a reasonable job of anticipating the
rate
> at which the house heats and cools, yet often seems to let the
temperature
> fall 1/2 degree too low before switching on. I'm thinking of
implementing

Problem with current system is that although modules have i believe an
internal resoulution of .1 inc. I only have access to whole deg which is
not
ideal as i believe you can feel a 0.5 deg change.

> some sort of weighted average of temp increase rates held against
ambient
> temperature, so the system will know that if the current temp is 18C,
it
> will take x mins to reach 20C. That way I can set it to have the house
at
> 20C by 7:30am, and on colder days the system will come on earlier to
> compensate.
>

Tried this simply by:-

If time < 8 oclock and temp < 18 then heat
If time < 7 oclock and temp < 17 then heat
If time < 6 oclock and temp < 16 then heat

Making heat come on earlier if colder.



> I'm keen on making it multizone simply because my current single zone
system
> is easily fooled by heat from external sources - e.g. coal fire in
lounge,
> oven in kitchen. I'm not sure how best to implement multi-zone. One
plan
> would be to have one 'current' zone that the thermostat attempts to
maintain
> at the set point. The trouble with that though might be that different
rooms
> need different set points depending on where the temp probes are
located.
> Also if the 'current' zone were to be switched based on monitoring
zone
> activity from Comfort, it might make the 'rate of temp increase'
algorithms
> a touch tricky.
>
> Another solution might be to have the system to keep an eye on all
zones.
If
> some start escalating out of control (e.g. lounge and kitchen temps
soar),
> but other zones remain in keeping with established parameters for rate
of
> heating and cooling, then perhaps the thermostat could selectively
ignore
> zones once it determines it has lost control of their temperature.
Some
> safeguard would be needed to ensure that once any zone reached a
maximum
> safe set point the heating is shut down on the assumption that 'a
fault
has
> occurred'.
>
> Finally, the conservatory is on the main central heating system, but
> naturally cools more quickly in the winter when the heating is off,
> producing a draft into other warmer rooms. To combat this, we use a
> convector heater to supplement the central heating in that one room.
If
the
> thermostat were set to associate an X10 address with a particular
zone, it
> could ensure that zone was maintained warm when the main system was
off.
Not
> sure if this makes it all too complicated though.
>
> Ray Barnett
> Systems Developer
>
>
>
>
>
>
>
>



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