why is my boiler resulting in horrendous gas bills?

[haf]

Hi,
I moved into a new house 3 months ago and am stunned at my first gas bill (over £400 using 18000 kwh) and have concluded it must be my boiler. The property is 3 bed detached (1930's) and has conventional system with a Halstead Best50 boiler. What annoys me even more is that the house doesn't even get very warm (probably due to bad insulation, microbore, old style radiators).
The CH is switched on for about 7 hours a day only and the boiler does go off from time to time. My previous property was modern 4 bed detached with similar system and I had a £250 bill with more radiators on for 10 hours a day. I'm now thinking I need to replace my boiler with something more efficient - any advice on how i can work out if i have a inefficient boiler and what i can replace with - should i go combi?
ps aside from boiler the house only has one occasionally used gas fire and a gas cooker - also ocasionally used.
Haf

 

[Agile]

I would question your gas meter readings! Are you quite sure they are both actual readings?

You might get about 20% improvement with a modern condensing boiler.

You might get 40% by getting 200 mm of loft insulation and cavity wall insulation. Draught proofing will help too.

Tony

 

[croydoncorgi]

You might get about 20% improvement with a modern condensing boiler.

But be careful what you wish for! OK - a condensing boiler MAY give improved efficiency BUT only when it actually operates in condensing mode.

From your description of your 'billing problem', the high cost might be from a faulty meter, low gas pressure or the unfortunate fact that your '30s house is poorly insulated.

If it's the latter cause and the boiler is relatively new and not broken, your immediate priority should be to sort out your heat losses.

The reason for this is that your existing radiators need to be HOT to warm the rooms with so much of the heat leaking out (no loft insulation? no double glazing? poor seals on doors?...). They're probably also sized based on being operated at 78 degrees or hotter. As a result the water returning to the boiler will probably still be hotter than 56 degrees. If it is, then a condensing boiler will NOT operate effectively! The only time it will condense and deliver maximum efficiency is when the system is warming up and still cool or cold.

 

[chrishutt]

Just playing with your figures - the boiler has an output of 50,000 Btu/hr (?) = 14kW and an input of about 15.5kW. If it runs continuously for 7 hrs a day for 3 months the total will be 637 hrs. So the total gas consumption for the 3 months would then be about 10,000kWh.

However your gas consumption is over 18,000kWh, almost double that figure! So either you're running the boiler a hell of a lot more than you think or the gas meter is seriously faulty.

The above rough calculation ignores other gas consuming appliances, but you've told us that they're little used, and it ignores boiler running for HW outside the 7 hours of timed running for CH, but that can't be much more. On the other hand it assumes continuous running at full output which doesn't actually occur. On balance it probably overstates the gas consumption.

 

[ChrisR]

If your gas meter regulator (aka governor) is a cast ally round thing with a black plastic top with Dungs on it, it's possibly misbehaving. Transco are changing them ALL, but can't do them all at once so wait for complaints.

I've lost count now of how many duds I've seen. Yesterday's was giving 7mbar, instead of 21, so the user was paying 3x the right gas price. It's appaling but ofgem just say the customer has to complain not a corgi - but the customer has no way of measuring the pressure...

You CAN measure the gas consumption rate though. Assuming you have a meter calibrated in cubic feet, time one cu ft on the dial so marked. Or you may have to do a conversion - ask if help needed. You should be using 1 cu ft in about 70 seconds with (just) the boiler on.