Intelligent Heating Control Software

["News on aioe.cjb.net" <rowan@xxxxxxxxxxxxxxxxxxxxx>]

I'd like to install a more intelligent control system for the heating in my
house. Currently the system consists of:
- an oil fired boiler which heats domestic hot water and water filled
radiators. Mains gas is not available in our village.
- a standard indirect hot water cylinder with an immersion heater which we
only use when the boiler can't keep up with demand (usually at Christmas
when we have a lot of visitors). The immersion heater has an X10 switch on
it so I could have it come on at night on off peak electricity if I wanted.
- one or two radiators in each room, fitted with thermostatic radiator
valves
- a two-zone 24 hour time clock with up to three on-offs per zone per day
(one zone is the domestic hot water, the other is all of the radiators)
- a hot water cylinder thermostat
- a boiler thermostat
- there is no room thermostat at present
- when I had a loft extension done, I had them put in separate zone valves
(3 in all) for bedrooms, living rooms and study, but these are all wired in
parallel at present.

This system has the following shortcomings:
- the boiler is old and inefficient, and due for replacement
- I hate thermostatic radiator valves. It seems to me that they are
inaccurate, inconvenient, and impossible to automate
- if the time switch says there should be room heating, but the thermostatic
valves say it's warm enough, the boiler continuously idles at operating
temperature, using oil needlessly.
- I can't have higher temperatures in the morning and evening, and lower
(but not off) in the middle of the day. I'd like to be able to do this.
- I can only have different temperatures in different parts of the house by
tweaking thermostatic valves.
- I can't have heating off in the middle of the day in the bedrooms, but on
in the living rooms.

I'd like to be able to overcome all of the above, as well as add new
features such as:
- add one or more outdoor sensors (maybe temperature, sunshine, wind
strength and direction) to help automatically get the temperature
"comfortable" in all weather conditions
- ability to control the heating remotely by phone and/or internet (e.g. to
turn the heating on an hour or two before we arrive home from holiday).
- prioritise room heating or hot water depending on the circumstances
- optimise the operating temperature of the boiler for best possible
efficiency in all levels of demand

What software (preferably open source) is there available to help me do
this? Preferably I'd like something that enables me to build and experiment
with my own control algorithms. I'd also like lots of logging so I can
investigate the performance of various algorithms under varying conditions.

All suggestions welcome! If there's a better place to ask this question,
please let me know.

Thanks - Rowan