Is This Correct???

nursemolly

Hi,
I have a Worcester Greenstar  boiler which is 30kw, my gas with Scottish Power is 10.1p per kw..so am I correct in thinking my central heating is going to cost  approx £3 an hour !!!
Possibly £15 a day if the heating is on for 5 hours a day.......
Many thanks
NM

MWT

No, modern boilers modulate the burn to reduce their consumption to what is needed, close to impossible for your boiler to operate at full power all the time as you cannot distribute the heat that fast...

nursemolly

MWT said:

No, modern boilers modulate the burn to reduce their consumption to what is needed, close to impossible for your boiler to operate at full power all the time as you cannot distribute the heat that fast...

Thanks..any idea what the average per hour might be for 3 bed semi....just trying to work out rough averages

razord

nursemolly said:

MWT said:

No, modern boilers modulate the burn to reduce their consumption to what is needed, close to impossible for your boiler to operate at full power all the time as you cannot distribute the heat that fast...

Thanks..any idea what the average per hour might be for 3 bed semi....just trying to work out rough averages

Afraid you'll need to test this yourself. Take a read, turn the heating on for an hour, and take another read.

You might need to run for more than a single hour to get an actual meaningful value though, unless your meter has decimal places.

[Deleted User]

And it might vary depending on how hard the heating needs to work, so that depends on starting temperature, outdoor temperature, TRV settings etc

k_man

nursemolly said:

MWT said:

No, modern boilers modulate the burn to reduce their consumption to what is needed, close to impossible for your boiler to operate at full power all the time as you cannot distribute the heat that fast...

Thanks..any idea what the average per hour might be for 3 bed semi....just trying to work out rough averages

There are many variables, e.g insulation level, thermostat temperature, how often people come in and out, windows left open etc etc.

Do you have previous bills or meter readings for last year?

dunstonh

nursemolly said:

MWT said:

No, modern boilers modulate the burn to reduce their consumption to what is needed, close to impossible for your boiler to operate at full power all the time as you cannot distribute the heat that fast...

Thanks..any idea what the average per hour might be for 3 bed semi....just trying to work out rough averages

Look at your meter readings.  Not the estimates but the actual readings.

If you get readings that are a year apart, then you can see what your typical annual use is and divide it accordingly.   

You should not look at a day in isolation.  As that could be a warm day when the boiler never fires up for heating.  And the temperature of water coming in is higher so needs less heating.  You should also not just look at the summer months in isolation.    Hence why you need the whole year.

lohr500

Impossible to estimate as it depends on too many variables. 

How long have you lived in the house and do you have actual meter readings for say October to March last year?
If so, the meter readings will show you how much gas you used during that period last year.

If you assume similar weather conditions for this coming winter and you use the central heating for the same amount of time, then you can work out the likely consumption for the next six months by taking the October to March readings and applying the 10.1p per kWh cost.

The_Fat_Controller

It's one of those "how long is a piece of string" questions.

There are many factors involved, how cold was the house to start with, what temperature you are trying to achieve and over what time.

[Deleted User]

Get a smart meter and download the free App BRIGHT. This is my 30 minute usage for a 24kW boiler last December. Most gas boilers are massively over-sized for domestic homes.

MWT

Dolor said:

Most gas boilers are massively over-sized for domestic homes.

Which is where a lot of waste comes in as the minimum level the boiler can modulate down to is usually related to the maximum rating so an over-sized boiler can't run at a low enough level to avoid frequent cycling which is wasteful.

Longer runs and low flame are greatly preferred to short, frequent bursts.

It made a very noticeable difference when we changed form an over-sized 28kW boiler to a properly sized 19kW boiler.

Sadly too many fitters do not do the work to properly size the boiler and just fit what they have or what they can get cheaply at the time.