Re: Re: Gas boiler control

["Pete Shew" <ukha_d@xxxxxxxxxxxxxxxxxx>]

Patrick, the hous is an old one (c 1790) and we bought it after most of the
renovation had been done. Well insulated and dry lined for the most part,
but still with old single glazed casement windows, open chimneys and a few
draughts. No room thermostat anywhere, Tom. Where would you put one -
multiple stats and occupancy sensors might make sense.

Sadly the house was refurbished by someone without a thought for automation
or even communication. Not even phone or TV points :-( I have been
retrofitting to some extent but it's tricky. I may be able to get some data
from the burglar alarm for occupancy but I'm not hopeful.

So, I was thinking of using the zone controls much as now on timers, but
try to reduce unnecessary boiler burn time by looking at the delta
temperature. When the return is much cooler than the supply, it should
indicate open rad thermostats, so demand is there. If the return approaches
the supply the there is no need to keep the supply so hot.

I wonder if all that is required is to try to keep the return, rather than
the supply, at a target temperature. This will require higher burn at high
demand times and lower burn with consequent lower supply temperature when
the demand is low.

Pete

*********** REPLY SEPARATOR  ***********

On 08/04/2004 at 22:07 Patrick Lidstone wrote:

>Although I make do with one boiler, Pete :-), I do run a homebrew
>predictive controller, based on weather data collected locally and
>medium range weather forecasts. My overall personal approach is aimed
>primarily at keeping the house at a comfortable temperature for the
>prevailing conditions, rather then saving energy per-se (although
>hopefully it does that too). I don't have any means of comparing the
>relative efficiency of my controller with conventional controls,
>because I haven't run the boiler using an ordinary
>controller/thermostat arrangement for any length of time, but the
>overall energy input has to be lower if only because the target
>temperatures are more tightly controlled than they would be
>otherwise. It sounds like you already have a reasonably efficient
>multi-zoned system, which has to work in your favour. If you live in
>a modern building, the thermal coefficients are likely to be such
>that you are unlikely to benefit from the heat-storage effects of the
>building fabric, although, conversely, if it is south facing, you may
>see significant transient temperature rises from solar radiation (aka
>the sun), which strategically positioned sensors can compensate for,
>reducing the heat input cycle. If you live in a thick-walled
>building, there may well be savings to be had from the medium range
>predicative element because of the building fabric's "storage
heater"
>factor. I think I also probably make decent savings from combining
>boiler control with occupancy detection/alarm status - the room
>temperature is set back when the house is unoccupied for short
>periods, and set back yet again for medium and long periods
>unoccupancy. The inconvenience of coming home to a cool house is
>dealt with by sending a text message or using a wap browser to set
>the system back to normal operation in anticipation of inpending
>return. A zoned heating system also lends itself nicely to
>automation. If my heating system was multizoned, I would extend the
>occupancy concept to aim for a specific target temperature in the
>last known occupied zones (which allows for people sitting still
>whilst watching tv etc quite nicely), whilst setting back unoccupied
>zones.
>
>HTH a bit
>
>Patrick
>
>
>
>
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