Energy Saving Trust Q&A Centre

Hi

I've posted this elsewhere, and I'm still confused. I work from home quite often, and spend 95% of the day in one room at a desk. I didn't want to spend money in winter heating the house all day, when I don't need to. I therefore (after researching a bit) bought a 3 bar (400w per bar) halogen heater.

Generally I only have 1 bar on, though in the current Arctic temperatures, I sometimes have 2 on, right next to me.

I am hearing though, that having my gas central heating on (I have a Potterton Performa 28 combi boiler) all day is still cheaper than this one heater!?!
Can this be true? I know I can turn other radiators on and off, but frankly it's a pain, as some of them are quite old, and when my other half comes back from work, we want the whole house warm anyway.

Can anyone give me a definitive answer?

Thanks

A_Robson wrote: »

Hello Everyone

I live in a 1967 chalet bungalow that has required lots of insulation and I have done all the normal stuff:

1. New boiler
2. Cavity wall insulation
3. 5cm Selotex style foam stuffed up the 10cm gap between the roof tiles and the plasterboard.
4. 20cm of space blanket stuffed under most 1st floor rooms and in all three lofts. Additionally silver foil fixed to centre loft V beams.
5. All windows double glazed
6. Self fit "thick foil behind the radiators - I think it helps

However here is the question. The upstairs area has 3 bedrooms and 1 bath room. It is breeze block with old wood cladding. I am soon to replace the wood cladding with Cedar. Now I have a once in a life time chance to place some insulation between the wood and the blocks. However is it worth it?

The area front and back is approx 80m2
The cost of super quilt would be approx £950
Lets discount the cost of fitting
Would I save much and what would the payback be?

I have asked around and nobody knows where to start.

Any advice or estimations?

Andrew

Hi

I take it that the upstairs is blockwork with a cavity which is then clad, not blockwork-cavity-cladding ?

Whichever, as you haven't supplied any technical data, you'll need to work out your heat losses though the current 80m2 of wallspace, look at the additional u-value of the new insulating layer, calculate a new heatloss at the same average internal/external temperature difference, find out what the difference in heatloss would be in terms of kWh/heating season, apply the cost of your fuel, apply the efficiency of you boiler (probably take 5% off manufacturers claimed data) and you have the saving per year from which you can calculate the payback.

HTH

Berger wrote: »

Hi

Not really, we have an open fireplace which we use occasionally, but nowhere near my desk, and wouldn't be useful for me. No gas supply to this room, would need significant work; as we're hoping to move next year, not worth it.

So if I turn off all radiators in the house except in the room I'm in, is the gas my boiler uses to heat the system somehow reduced significantly? How does that work? Surely it's the same burners for the same amount of time?

Hi

If your heat requirement in that room is only 400/800W then running the central heating and turning all of the other radiators off will probably not be efficient/practical. Modern CH boilers can modulate their output from full power to around 25% of their rated maximum, so if you have say a 30kW boiler it could attempt to match it's output to as low as 8kW, which would be far too high for the radiators in a standard room .... the boiler will therefore be cycling on/off at a high frequency and become far less efficient than it could be .... probably not a practical solution for one room.

The only thought on the gas is that if you're running the heating in the evening anyway, what would the cost of running it for the extra hours be ?. If you're currently using an average of say 600W, that's around 5kWh of electricity/day costing around 50p to 60p, which could buy around 15kWh of additional gas heating/heatloss .... If your house isn't too large and is well insulated it might be an idea to test how much extra gas is used by taking some meter readings.

You could possibly look at installing a small ASHP (Air to Air) for the room, but if you're looking at moving within the timescales mentioned it would never pay for itself, you might as well run your CH full blast and be comfortable. If you're not going to move this could be a viable one-room option.

HTH

##Note ..... Just checked, it looks like the potterton boiler you have is non-condensing/non-modulating with an efficiency of 78.2% (ish - when new) .... therefore it will not be able to adjust it's output to meet requirement.