probably done to death but the last post a few days ago wasn't answered...
will be converting the cellar over the xmas, the floor will be concrete but I'm not sure how I'm going to heat the area (6m x 3m x 2.2m headroom). the cellar will be used primarily as a play room and only during the day, for about 8 hours, as it's only accessible from the rear garden. I could extend a radiator into the room but that would mean heating the whole house unnecessarily, we won't be using the rest of the house, except the kitchen. the other alternatives are an electric heater or electric underfloor heating, but I'm worried about the cost. do the panel think running the gas central heating for the whole (3 bedroom) house and cellar would be more cost effective than an electric solution ?
I know it will be considerably more expensive to install underfloor heating but could anyone give me a rough idea of the running costs ?
I think that the first thing to do is to make sure that it's free of damp and then to insulate the walls and floor, making sure that there is ventilation behind the insulation. Putting in some kind of wooden/chipboard floor on pressure treated joists makes it easy to insulate the floor and also will be a lot more comfortable to walk on.
Once you have done this, you will have significantly reduced the need for heating anyway - at a guess to around 2kW on cold days depending on insulation chosen. There was a recent thread on insulating a garden outbuilding and the heating implications, and you can read about the principles involved there.
By taking the average monthly temperatures outside and the heat loss (which you can calculate) you can work out the typical heating requirement month by month. A cellar is going to be different because the ground temperature varies rather less. What you could do is to stick a max/min thermometer down there now and see how the temperature varies over the next few weeks. Treat that as the "outside" temperature when you do the sums. It's not going to be super-accurate, but you should be able to get close enough. Then you can work out the running cost for electricity.
As far as running from the heating system is concerned, you could do this by making zones out of the heating. You don't say how your heating is organised, but it is possible to convert the motorised valve arrangements to create separate heating zones. For this application, an ideal might be to have separate zones for the upstairs, downstairs apart from kitchen, kitchen and cellar (4 in all). It may not be easy to re-organise the pipework though, so a compromise may be needed - e.g. upstairs/downstairs/cellar. If you could post something about your system, it would be possible to give a more detailed explanation.
Since you have a cellar, I assume that the house is an older type.... If so, and it doesn't have cavities, or they are not insulated, then doing some zoning rather than heating the whole house makes a lot of sense.
1912 terraced miners cottage
2 storey at front, ground floor level with main road
3 storey at back, cellar door level with rear garden there are no cavities (45cm stone walls) and the cellar is below ground on 3 sides
heating is via a combi/radiators, looking at the pipe work I couldn't zone upstairs and downstairs without ripping up the flooring to access the pipes (not an option).
Given that the walls are stone, the normal impact is that the heatloss is quite a bit, but with different behaviour to a brick built house because the stone will store more heat. I suspect that the effect is that when you have been away and the house has been left without heating it takes a while to warm up, but once warm doesn't cool that quickly either.
I think that I would be inclined to continue heating the house as you have been - just when required. I guess that it's not realistic to insulate the walls of the house either and it wasn't in the scope of the question. You could try out the impact on energy consumption of running the heating when required vs. during the day as well to see what extra is used to do that. A simple way to do that, would be to read the gas meter daily and note outside temperatures at the same time each day for a week with heating on part of the day, and then repeat the exercise the following week with heating on all day. Assuming your use of hot water is reasonably constant day to day, you could pick days out of each week where outside temperature is about the same and compare. This isn't going to be super-accurate, but will give a reasonable idea.
For the cellar, I assume you have more or less a clean sheet of paper. I definitely think that insulating it is worth doing, because apart from reducing heat loss dramatically, it will mean that the space will warm up very quickly.
With a combi based system, if you can conveniently access the main heating flow and return pipes, and you can run pipework to that point, you could create one zone of the cellar and one zone of the rest of the house using two motorised valves. Running cost for that will be less than heaing the cellar with electricity, but you have to weigh up whether the installation work is worth it.
At least if you've insulated the cellar, you will have achieved the best situation if you do decide to go with electricity. In that situation, I think I'd go for oil filled radiators on the wall or fan heater fitted out of harm's way. Underfloor heating will take longer to warm the room,
Ensure there is good insulation throughout the house and especially in the cellar, which has massive cold bridging to surrounding land. Use at least
50mm of celotex attached to the walls, preferably more.
As a minimum, ensure rooms (except those with room thermostats) have TRVs.
If the pipework layout allows it, subzone the heating and use programmable thermostats. This way, each zone gets its own time and temperature control.
If you're willing to pay those costs, you may be willing to pay the costs of converting your heating system to S-Plan-Plus with subzoned control, which would be a grossly superior solution, will probably end up with a system cheaper to run than before and may even have a lower capital cost.
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