Re: Software for Central Heating Control

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On 3 Jan 2006 15:18:53 -0800, rowan@xxxxxxxxxxxxxxxxxxxxx wrote in message
<1136330333.861087.125500@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>:

>I'm having a loft conversion done at present, and I'd like to take the
>opportunity to upgrade my central heating control system,

<lots of interesting questions snipped>

>What is the best hardware?

Good question. For example, it would (IMO) be inappropriate in most cases to
substitute a computer-operated low-water-shutoff when extremely reliable
electromechanical ones have long been available inexpensively and are
installed and understood by HVAC professionals.

So consider accomplishing as much as you can with conventional equipment and
use uP/plc/pc-control only where you have to. So, for example, use
conventional, commercially available communicating thermostats (Aprilaire,
RCS, etc) and have the setpoints varied under software control.

The arena in which  software decision making may be most appropriate is in
realtime  fuel-switching decisions. For example, in some places in US, the
cost of electricity depends on time of day, time of year and total usage.
Last month, the doubling of the price of natural gas over the last year in
my area (Central US) has led to resistance electrical heating being less
expensive than the most efficient possible heating with natural gas. It has
been less expensive than heating oil and propane for some time. Use of heat
pumps (instead of resistance) cuts the energy cost roughly in half again and
geothermal in quarter under some circumstances. Each has different advantage
and ranges of applicability, as well as and installation and maintenance
costs.

The software I use (CyberHouse by Savoy, now not available to consumer) has
an energy use module that can download energy cost from the web in real
time, monitor power consumption on nine circuits  and control Cutler Hammer
circuit breakers. Savoy's efforts in this area were funded in part by US
Government grant, and the original installations were in Texas in about
1999.

(This question was crossposted to multiple groups, which may  result in some
confusion.)

... Marc
Marc_F_Hult
www.ECOntrol.org