correct, but this being the UK crap houses do exist...
Dan and Alec... to come full circle I think there are too many variables in the equation for my particular property.
I would honestly challenge you to right-size the rads for my house Dan. (Really... I challenge you!)
It is a 60's bungalow with 9" solid walls, so no cavity to insulate. The loft is very well insulated, and I am applying internal insulation on a room per room basis. The kitchen is done, the main bedroom is next, followed by bathroom then lounge and remaining bedroom.
The house is subject to massive variations in solar heat gain, as it is quite sprawling, with all rooms accessing a central hall, but the overall house footprint being several rectangles attached to one another means it has a long total run of external walls.
The main bedroom gets the morning sun, and goes fully into shade in the afternoon. The kitchen and second bedroom are the exact opposite, and the lounge is long and narrow with it's longest wall being predominantly north facing, so it has little if no solar gain, and massive heat loss.
The house sits on an incline, and takes the wind head-on. Heat migrates between rooms via the hall, as we like to keep the doors open between rooms.
I am currently also converting the garage, and that will have to be to building regs, so it will be the only room in the house with proper floor insulation (100mm of PIR). It will also have 100mm of wall insulation compared to the 75mm that will be going around the rest of the house.
Add to this that I will be adding forced air ventilation with heat recovery in the next couple of years, and that complicates matters even further. I might even include a heating matrix in the inbound air path to give partial blown heating to assist the rads.
My plan at the moment is just to regulate the coldest room with the thermostat, and then run every other room on liquid TRV's. I had considered electronic radiator stats/valves (Z Wave) and multi-room control via software/internet, but the systems are expensive, and don't tend to support OT.
Out of the control methods we have discussed, I think OpenTherm clearly comes out on top for reasons Alec reiterates... you are keeping the flow going for the most part, and carefully throttling the heat output of the boiler. It
has to be much kinder to the boiler than harsh On/Off cycling of either a manual stat, or some sort of slow pulse-width modulation control such as TPI. OT by it's nature is bound to offer tighter regulation of the set temperature, combined with better fuel economy. This is all regardless of the addition of WC.
Please tell me if I have any of this wrong gents. I SO wish the house had cavity walls, and a more compact floor-plan, but unfortunately it doesn't, and we really don't want to move, so it's about making the best of a bad lot.
