Boiler gas usage

Glastoun

Hi there, trying to sort out some heating issues in our house (3-bed semi) and one is the amount of gas we're using.

We have a Vokera Compact 24 boiler, with 4 downstairs radiators and 3 upstairs. The radiators are usually max out at 60C.

I put the thermostat on high (so it never clicked off) and ran the heating for 2 hours. It used 0.85 units of gas, which at our current (overpriced) tariff costs around £1.50. (32kwH at 4.75p per kwH)

Do these figures sound about right, or is our boiler using too much gas? Could a maintenance check adjust it to be more efficient?

anotherbaldrick

the boiler has an heat output of 23Kw (25Kw input) and you have used 28 Kw over two hours running it flat out. Sounds to be in the realms of possibility considering the possible system operation. When was the boiler last serviced ?


How well insulated and draught proofed is the house, this is where your fuel economies possibly are

Glastoun

anotherbaldrick wrote: »

the boiler has an heat output of 23Kw (25Kw input) and you have used 28 Kw over two hours running it flat out. Sounds to be in the realms of possibility considering the possible system operation. When was the boiler last serviced ?


How well insulated and draught proofed is the house, this is where your fuel economies possibly are

Not sure when it was serviced, we bought the house in the summer after moving from a well-insulated 2-bed flat, so the increase in bills was quite a shock. My initial calculations were that it had used £3.50 of gas in those two hours, but it's closer to £1.50 which doesn't seem so bad now. The radiators are definitely giving off a lot of heat, so.....

...potentially we could insulate the floors, loft and replace draughty front and back doors with PVC, just trying to work out what to do first and with the least disruption.

gasmanmartin

Glastoun wrote: »

...potentially we could insulate the floors, loft and replace draughty front and back doors with PVC, just trying to work out what to do first and with the least disruption.

Heat rises so do the loft first, easy job.

Also fix draughts from doors and windows, if you can feel a draught then there's a problem.

Floors would be the last thing to do

anotherbaldrick

Yes , the roof first . If it is already insulated top it up with an additional layer so that you have 10" depth . put some insulation over the trapdoor . Check around you might find DIY shops have it on offer , a mucky 1/2 day but well worth it.
Until you can change the doors and windows buy some foam weather strip to stop as much of the draughts as you can

Glastoun

The loft seems to have 100mm wool-type insulation between the joists, which have then been comprehensively boarded over, possibly glued in places.

I really don't want to be taking up those boards unless I absolutely have to, so is it okay to lay insulation directly on top of them? I remember reading about the circulation (or non-circulation) of air under the boards in this situation, to prevent condensation, but can't find the article again.

If I even topped up the insulation in half to three-quarters of the loft space, would that help, or would the same heat just keep on escaping through the missing quarter?

anotherbaldrick

Can't see that it would cause a problem if not one at present . In our last house I insulated across the whole area and made a walkway for tank access and area for storage by screwing timber bearers across face of roof trusses and spanning boards between above the insulation. I think if you are going to do it then cover the whole area you can get to