Buying a new house and have some concerns about the energy bills

andrewjf

We are in the process of moving house. Our new property is a bungalow, which has had bedrooms built in the roof space. This does appear to include adequate insulation.
I asked the owners to see their monthly energy bill. To my dismay, they are paying £197 per month. Compared to the current cost on my property which is £105.
On looking at their boiler, it's 20+ years old. I suspect it's not a condensing boiler, and from what I've read, modern condensing boilers are 95% efficient. Compare this to an older boiler which is 60-70% efficient. 
Now I'm trying to get some feeling for how much an older less efficient boiler can add to a monthly gas bill.
Also note that I'm on a cheaper tariff than them. I calculated that if they were to switch now, they could immediately save £30 per month, even with their existing boiler. But that still that leaves a discrepancy of £60/month between me and them. It's worrying me because I don't want to buy a house that will cost a fortune to heat.
And yes, the current owners are really paying almost £2400 a year on energy bills! To heat a 4 bed bungalow. We currently have a 4 bed 2 storey house.
So let's say I get the boiler replaced, that's going to be £2k. Would you say this would bring down the monthly energy cost to a reasonable level, maybe comparable to what I'm currently paying?
Thanks.

theoretica

Also take into account how warm you might like the house.  If they felt the chill or were home more than you then that would increase heating bills significantly. My parents keep their thermostat at 22 - mine is at 18 during the day... our bills are very different!  Can you get the make/model of the boiler and look up its supposed efficiency? 

andrewjf

theoretica said:

Also take into account how warm you might like the house.  If they felt the chill or were home more than you then that would increase heating bills significantly. My parents keep their thermostat at 22 - mine is at 18 during the day... our bills are very different!  Can you get the make/model of the boiler and look up its supposed efficiency? 

Yes that is also a factor. But my wife and kids will be in the house all the time, so will want the heating on a lot. We tend to keep the thermostat to under 20 degrees. The boiler is a Vailant, but as I said it's over 20 years old. The current occupiers have lived there for 20 years, and haven't replaced it. Don't know the model, but I strongly suspect it's non-condensing. 
But their annual energy bill is eye-wateringly high!

stewie_griffin

Do you know what their annual usage is and if this is based on actual meter readings. The amount they pay per month is largely irrelevant. In general however bungalows use more energy than standard houses of similar size. The one you're moving in to is slightly different since there are bedrooms in the attic.

dogshome

Just where is all this money going to - Electric or the gas ?

Bungalows are known for being expensive to heat unless super insulated, but the leccy consumption should be about the same for a house or bungalow, depending on the occupants lifestyle - National average 3000 Kwh a year.

Not stated, but I get the impression the current owners are a retired couple, as the residents in this 3 bed semi house are - Annual Elec 2970 Kwh

andrewjf

stewie_griffin said:

Do you know what their annual usage is and if this is based on actual meter readings. The amount they pay per month is largely irrelevant. In general however bungalows use more energy than standard houses of similar size. The one you're moving in to is slightly different since there are bedrooms in the attic.

Are attic bedrooms a lot less energy efficient? I've watched videos on roof space conversions, and they've insulated the rafters correctly. 
The monthly payment is of concern to me because as I said, I looked at their tariff, and adjusted it to a better deal from an alternative energy supplier. It worked out as £30 per month cheaper. But it's still a really big difference between what I'm paying now, and what they are paying, or could be paying on a cheaper tariff.
But yes, I agree, knowing their annual usage would be a good thing to know. I'll ask them for those figures.

[Deleted User]

The attic bedrooms i visit (also in a bungalow) a lot are very well insulated so maybe focus attention on replacing the boiler in the first year to an up to date one, maybe some/all radiators too.
I wouldn't get too anxious yet - the first year in properties allows you to learn about its habits so you can adjust where needs be from there on in.
Likewise gardens - resist the urge to make big changes, learning what it 'does' through the first year gives you a better insight than jumping in too early.

tacpot12

The efficiency of the boiler is very much dependent on what flow/return temperature it is set to; if it is set too high, a condensing boiler won't be able to operate in condensing mode, so you will lose all the efficiency gains from a new boiler. If the flow/return is set so the boiler can operate in condensing mode, but the radiators in the house are not large enough then the house will not be warm enough. To be most efficient, condensing boilers have to have radiators that are sized for them. It is likely that the bunglow does not have the larger radiators that a condensing boiler will require to operate at full efficiency. 

You could plan on replacing the radiators with large ones when the existing ones are at the end of their life. This is probably the most economical arrangement. 

Don't despair though - all is not lost. New boilers are also "modulating" as well as "condensing". This means that when running to heat the house, the boiler can reduce the heat output and hence the amount of gas consumed. This ability to turn down the gas will save you money when the house only needs a bit of heating, e.g. in Spring and Autumn. Note that this ability is quite difficult to achieve if you also have a hot water cylinder that is heated by the boiler. When heating the home, you want the boiler to modulate down to the lowest amount of heat it can, when heating hot water, you want the maximum output of the boiler so your controls need to switch between modulating and unmodulated modes. 

 Make it clear to the heating engineer that installs your new boiler (you will need one soon enough if the Vaillant is 20 years old) that you want full power for heating hot water and modulated power for heating the home. If your heating engineer says it can't be done, get another engineer in as it is certainly possible, and highly desirable. 

andrewjf

tacpot12 said:

The efficiency of the boiler is very much dependent on what flow/return temperature it is set to; if it is set too high, a condensing boiler won't be able to operate in condensing mode, so you will lose all the efficiency gains from a new boiler. If the flow/return is set so the boiler can operate in condensing mode, but the radiators in the house are not large enough then the house will not be warm enough. To be most efficient, condensing boilers have to have radiators that are sized for them. It is likely that the bunglow does not have the larger radiators that a condensing boiler will require to operate at full efficiency. 

You could plan on replacing the radiators with large ones when the existing ones are at the end of their life. This is probably the most economical arrangement. 

Don't despair though - all is not lost. New boilers are also "modulating" as well as "condensing". This means that when running to heat the house, the boiler can reduce the heat output and hence the amount of gas consumed. This ability to turn down the gas will save you money when the house only needs a bit of heating, e.g. in Spring and Autumn. Note that this ability is quite difficult to achieve if you also have a hot water cylinder that is heated by the boiler. When heating the home, you want the boiler to modulate down to the lowest amount of heat it can, when heating hot water, you want the maximum output of the boiler so your controls need to switch between modulating and unmodulated modes. 

 Make it clear to the heating engineer that installs your new boiler (you will need one soon enough if the Vaillant is 20 years old) that you want full power for heating hot water and modulated power for heating hot water. if your heating engineer says it can't be done, get another engineer in as it is certainly possible, and highly desirable. 

Thanks for taking the time to provide that full response, you've given me a lot of good information there.
One thing I don't understand is that this heating system has a hot water cylinder, but does NOT have a water tank, like mine does. So I guess the water is heated by the boiler and pumped directly to the cylinder?
This differs from my system, which is an 'indirect' design, where the central heating pipe goes through the cylinder and heats up the water. There's a diverter valve next to the cylinder.
But then with a bungalow, you probably have less options due to restricted space, especially if the roof's been converted to bedrooms. I suppose a lot of these properties have combi boilers (are they better in terms of economy?)
Sorry, I'm a bit of a worrier, and their energy bill has really freaked me out. I cannot believe how much they are paying per month. In all other respects, this house is perfect.

Talldave

I think you're worrying too much. A 20 year old setup isn't going to be ideal and can be improved upon. The heating flow's probably crap because the radiators are full of crud, there probably aren't any TRVs and no programmable thermostat meaning the place is heated like a sauna 24/7.  The hot water could be on continuous too, topping up unnecessarily all day.

They might not have LED bulbs and pay a stupid rate for electricity too, no doubt on a dual fuel deal.

The only expense/aggro that might put me off would be having to install or replace double glazing.

Robin9

The fist you have to do anyway is get the electric and gas suppliers sorted. Seperate suppliers are usually best - just make a guess for the consupmtions - as has been said bungalows can be high energy users - use (say) 4,000 kWh for elec and15,000 kWh for gas - it will alll sort itself out after a year anyway.