Installing new central heating system - which is best?

[Lindyboo]

During this summer we hope to install a new central heating system. The current one is oil-fired – combi-boiler we’re told is about 8 – 10 years old. The rad’s were done piecemeal DIY by the previous incumbent (balanced system) and are tatty and were second-hand before they were installed – some barely get warm.

Having previously been townies, we’ve no wider experience of practical heating solutions in rural properties. We find that the oil-system is running at £300 per 6 weeks (600 litres consumption) which we feel is very high. So, my questions are:

1. Is this running cost high for oil-fired water and heating (detached, 3 small bedrooms, kitchen, 2 very tiny bathrooms and 2 small sitting rooms – by small, I mean that the largest room is approx 18 x 10 ft and the smallest about 5 x 4 ft)?
2. If it is high, would it be likely that a new boiler and rads would run more efficiently?
3. Anyone know how oil compares to solid fuel for running and installation costs? We have 2 open fires which we intend to replace with log/coal burners so want to look at using them for heating and water.
4. I read that a study done in 2006 found that the cost of electric heating (not economy 7 etc) worked out at around 50% of other types, when the cost of maintenance and installation was included, for systems installed from scratch, over a 10 year period. Also that it was more eco-friendly, as all of the energy is converted into heat. Anyone out there have recent experience of electric heating?
5. We intend to have a kitchen extension built and are considering underfloor heating for that room. Any advice on costs or the best type to have?

Ta very much.

 

[Penners]

Although the price of heating oil has skyrocketed in the last 12 months or so, your figure of 600 litres costing £300 is still very high. A rough current figure seems to be about 45p/litre (inclusive of 5% VAT).

And I can only say that by our standard, £50 a week for heating a modest-sized 3-bedroom house sounds extremely high. I think our house is larger than yours, and we cook with oil, as well as heat. I expect a 3000-litre tankful of oil to last us the entire winter.

Of course, a lot of this depends on how long you run your heating for, each day. We have ours on for an hour-and-a-half in the morning, and five-and-a-half hours in the evening.

I've no idea how oil compares with solid fuel, costwise. I would only say that oil is much more controllable, enabling you to turn it on an off at will. That's much more difficult with solid fuel.

As for electricity, I don't have much experience of electric central heating other than some years ago when my offices used to be heated with nightstore heaters - they cost a flippin' fortune. But as the cost of other fuels has increased, I don't know how the comparison stands these days. But frankly I would be very surprised if electric heating truly works out at only 50% of the cost of other fuels.

However, I do believe that the best way to use electric heating - if you decide to go that way - is to use it underfloor. But do make sure that you've got really effective insulation underneath it.

 

[Essex]

Have you insulated as far as is practical? and sealed possible air leaks (remembering to make sure there is adequate ventilation commensurate with your and the properties needs). Please don't consider electricity, it takes 2 1/2 to 3 units of oil to produce 1 unit of electricity, so there would be a real increase in your carbon emissions.
If you are repiping the heating consider zoning so that the bedrooms are on a different loop and can be on at different times to the rooms downstairs.
There are very good condensing oil boilers available which will also be more efficient.
Underfloor heating on the ground floor is great, but you may not want to dig up your floors.
Also a weather compensator may be worth considering.
We have reduced our oil use by about 50% by these measures.

 

[MdB]

Our house is 4 bed detached with thin uninsulated walls. We are spending around £800 a year on gas (tank in garden) heating the place. Speaking to neighbours, they pay around the same for oil. Our current heating system is on its last legs so we are going to replace it when we do some major building work shortly. We looked into the various options and thought that electric night storage would cost roughly the same to run but neither my wife nor I liked it as an option. We have decided instead to go for a heat pump which we think will be of the order of £300 to run though the installation costs are quite a bit more than the other options.

Something to note with night storage is that it doesn't have to just run at night to get cheap electric. Most people have heard of economy 7 but there is also economy 10 which gives a bit of cheap electric from 1pm to 4pm and in the evening from 8pm to 10pm as well as at night from 12am to 5am. This helps get heat into the system closer to when its needed.

 

[Flyfisher]

May I ask how you arrived at the £300 figure for the heat pump running costs? Have you calculated the calorific value of your £800 of gas compared with £300 of electricity, even allowing for the 3-400% efficiency of a heat pump.

I ask because I'm went through the same thought process but, with a little prompting from NT, concluded that a heat pump would cost around the same as mains gas because of the higher cost of electricity in the first place.

My rough calcs were:

Gas - average 2.34p/KWh
Elec - average 7.4p/KWh
Thus, Elec = 3.2x gas per KWh

So, if the heat pump is 320% efficient the running cost will be the same as gas. This is only approximate, of course, because there will be efficiency differences in utilising the KWh. The efficiency of heat pumps also varies depending on the differential temperatures involved, which can change throughout the year.

Another way of looking at this is that, roughly, £800 of gas will buy 34,200 KWh of energy, whereas the same amount of electricity would cost £2530. For the heat pump running costs to be £300 the efficiency would have to be more than 800% - on average - which, as I understand things, is simply not possible at present.

From what I've read, 320% is a much more likely figure, so the probability is that there'll be little change in the overall running costs and, therefore, no saving to pay back the capital cost of the system. On this basis, I've given up on heat pumps and am going for gas.

I would dearly like to be proved wrong though!

 

[MdB]

I think the difference is between bottled gas and mains gas but I did go through the figures at one stage. Remind me what the calorific value of gas is and I'll redo the sums.

 

[Flyfisher]

Ah, yes, bottled gas would make a difference.

My calcs were based on the following formula:

Gas Units (Cu Ft) x 2.83 x 1.02264 x 39.1344 / 3.6

where:

2.83 = metric conversion factor
1.02264 = volume conversion factor
39.1344 = calorific value
3.6 = kilowatt hour conversion factor

As per a British Gas bill.

My gas price per KWh figures were averaged over a year. Actual pricing (from the same bill) is 4.266 p/Kw for the first 12.526 KW used each day and 2.173p thereafter. Electricity price was 8.739 for the first 2.466 KW per day and 7.31 thereafter. But that's probably a level of detail unnecessary for a basic comparison.

 

[Penners]

Memo to self: must learn Swahili.

 

[nickc]

I agree with Fly. I went through exactly the same decision last year and was very keen to go for GSHP but it just didn't add up. Capital cost was huge (£30k for large farmhouse once all the extras are included) and the basic flaw is, as pointed out, that electricity is about 3 times cost of gas which removes the much heralded 3-4 x efficiency of a pump. Also, remember to take account of the extra interest you'll be paying on the capital cost (assuming you have a mortgage, if not then the loss of savings interest). When this was taken into account, my pay-back time became 95 years! even using ICE Energy's projected annual saving figure.

If mains gas not an option then oil probably still best. Definitely get a zoned system so you can heat the bedrooms only in morning and evening but keep downstairs warm if you are in. Honeywell do a good remote (wireless) system.

Worth looking at biomass boilers but only really an option if you have the space for a large external hopper and don't mind looking at it).

I have 2 large woodburners which are great for supplemental heating when the house is occupied all day. Wood is generally the cheapest form of heating but you need a good supply of dry (i.e. seasoned logs) and lots of energy to lug them around.

 

[Flyfisher]

I also agree about the biomass boilers. After, regretfully, discounting GSHP I looked at these but, as nickc points out, fuel storage is an issue. This was a shame as we have a woodchip supplier quite close to us but I recall that a 5 ton hopper was the recommended minimum size. I concluded that these were really better suited to small-scale industrial installations, or perhaps schools, than for domestic use.

I found it all a bit depressing that everything pointed back to a 'normal' boiler/radiator system and was resigned to an oil boiler with multi-fuel stoves. My recent discovery of a gas main much closer than I thought has moved me towards a gas boiler now, but the multifuel stoves remain in the plan.

 

[MdB]

Current usage:
LPG tank in garden driving an old boiler which is say 70% efficient. Cost is currently £800 per year which refills the 1200 litre tank twice. Price of gas is £0.32 a litre which with tank rental makes the £800.

2400 litres expanded at 250:1 ratio converted into m^3 is 2400 x 250 x 0.001 = 600m^3 of LPG

LPG has a calorific value of 94MJ/m^3 which with our 70% boiler gives 600 x 94 x 0.7 = 39500 MJ of energy pumped into the house to heat it. Divide by 3.6 to give 11000 kWh.

Future usage:

LPG - Continue as before but with new boiler which is 90% efficient. Cost is £800 x 0.7 / 0.9 = £622 per year to run. Install costs around £3500.

Oil - In round figures I have been lead to believe that the cost of running on oil is roughly the same as LPG. I may be wrong on this. Our neighbours with similar houses but running on oil have similar fuel bills to us so I think this is reasonable. Cost £622 per year. Install costs around £5000.

Night storage electricity - Assume £0.08 per kWh and 100% efficiency. 11000 x £0.07 = £770 per year. Install costs around £800.

Heat pump - Assume £0.07 per kWh and 320% efficiency. 11000 x £0.07 / 3.2 = £240 per year. Install costs around £8000.

Summery:
LPG - £3500 + £622 per year
Oil - £5000 + £622 per year
Night Storage - £800 + £770 per year
Heat Pump - £8000 + £240 per year

We haven't made any final decisions yet on what to go for though the heat pump is top of the list. If anybody can find any obvious holes in the above sums then I would be very interested in hearing it.

 

[Nemesis]

Free champers and advice:

We have been inundated by the response to our Champagne and Canapé Saturdays here at Ice Energy. All three dates were fully booked within 24 hours and so we've had to add more dates and find a larger venue.

We have now booked the National Self Build & Renovation Centre on Saturday 23rd February 2008 which will allow us to have many more visitors and will give you free entry to the centre (normally £8).

http://www.iceenergy.co.uk/

 

[Flyfisher]

Wow - LPG has 2.4x the calorific value of mains gas? Clearly, that makes a big difference to my earlier calcs.

Just a couple of comments on your calcs:
1. 11000 kWh of heating doesn't sound very much based on my previous experience of a 4-bed detached house that used about 34,000 kWh of gas per year (DHW all year, heating in winter only and empty house during the day, no cooking). Coincidentally, the cost of that gas was also about £800 per year, which shows how much cheaper mains gas is compared with LPG.

2. Your figure of £3500 to change your current boiler to a more efficient LPG one sounds rather high, or does this include other CH works as well.

From your summary figures I calculated the following:

Interest Rate 5%

_______Capital____Ann___Ann____Int_on__Actual____Break
________Cost____Cost__Saving__Capital__Save/Yr__Even(Yrs)

Current___£0_____£800___£0______£0_____£0_______n/a

LPG____£3,500____£622__£178____£175____£3______1167

Oil_____£5,000____£622__£178____£250___-£72_____-69 (never!)

Elec____£800_____£770___£30_____£40___-£10______-80 (never!)

GSHP___£8,000___£240___£560____£400___£160______50

(apologies for the lines, it was the only way I could get the table to line up because spaces are removed and tabs don't work)

The breakeven calc is a bit simplistic and doesn't take account of reducing interest payments on any borrowed capital but it gives a rough picture. The 5% rate is also only approximate.

But, interestingly, all this seems to suggest that your current LPG system is not too bad as none of the alternatives would appear to repay the capital investment within their lifetimes (I'm assuming a GSHP won't last 50 years).

The numbers seem to suggest that sticking with your current system until it needs replacement is the most economic option for now and a new LPG boiler would be best when that time comes. I wasn't really expecting that conclusion!

It's the cost of the capital that has the dominant effect. You must either borrow the money (and pay interest) or spend existing savings (and lose interest).

 

[Penners]

Your figure of £3500 to change your current boiler to a more efficient LPG one sounds rather high

As does £5000 for an oil-fired boiler. Surely you can get a high spec condensing boiler for around a third of that price.

 

[Flyfisher]

I assumed the extra £1500 for the oil upgrade was for the oil tank costs, but I agree that the remaining £3500 still seems a lot for the boiler itself.

 

[Penners]

I admit I didn't think of the cost of a tank.

However, all-in-all your figures make pretty depressing reading - particularly for someone of my age, who would never see a break-even point, no matter what what kind of heating nstallation he put in.

But there is an additional aspect of the equation that one might consider, and that is the possible enhancement of the value of the property. If you put in a nice kitchen range boiler - say an oil-fired Rayburn, or similar - I wonder if the value of the house would increase sufficiently to cover the cost of the unit.

 

[Flyfisher]

particularly for someone of my age,

Given the payback timescales it seems that age is almost irrelevant. None will payback before the system needs replacing anyway.

The property value enhancement point is a good one, although like all increases in property value, it's only really applicable if you can actually access that value.

But you raise the important point that such decisions are not purely economic; there are quality of life issues to consider as well. When we finally get around to having a decent heating system installed the running costs (whatever they are) will be much higher than currently, so the payback time will be huge - but the big difference is that we'll be warm (hopefully!).

 

[Penners]

the big difference is that we'll be warm (hopefully!).

Quite so. But even that isn't quite the whole story. As you observed, there is an unquantifiable "quality of life" element in the equation.

You can create a warm house simply by having a boiler hidden away in a boiler room, and adequately sized radiators in every room. So you achieve an ambient temperature of perhaps 20 degrees. Quite sufficient for comfort.

But it's still not the same as having a nice log fire or a kitchen range to warm your bum on. Those give a more comforting, cosy kind of heat. Illiogical, but undeniable!

 

[MdB]

A few comments to make a bit more sense of my figures.

Current LPG is for heating only. The hot water was done by oil fired Rayburn but is now electric. I've ignored hot water heating in all my calcs to keep it simple. This may be part of the reason of why our heating costs are lower. The other reason may be that there is only two of us so some of the rooms only get a bit of heat. Also the ones we do heat only have small radiators so can't output all that much heat. The house is poorly insulated apart from the roof but has very few drafts (probably too few) so the heat is kept in. This winter it is looking like we will get away with less than two full tanks worth so the figure of 11000kWh may be an over estimate.

LPG install cost includes replacing most of the radiators

Oil install cost includes replacing most of the radiators and a new tank. We are near a stream so the tank has to be an expensive one.

Night storage costs are just for the heaters so is lower than the other options.

Heat pump install costs includes underfloor heat pipes.

I will be doing a lot of the labour in the above myself so that hasn't been included in the prices.

We have to rip out most of the current system anyway when are major building work starts so payback period doesn't really come into it. What is important is total cost in the longer term which the heat pump wins after about 10 years.

 

[Flyfisher]

As you observed, there is an unquantifiable "quality of life" element in the equation.

You can create a warm house simply by having a boiler hidden away in a boiler room, and adequately sized radiators in every room. So you achieve an ambient temperature of perhaps 20 degrees. Quite sufficient for comfort.

But it's still not the same as having a nice log fire or a kitchen range to warm your bum on. Those give a more comforting, cosy kind of heat. Illiogical, but undeniable!

Not only undeniable but not too illogical, I'd say. We're a bit torn on a range for the kitchen/sitting room but if we don't have one we'll have a stove instead., for exactly the reason you mention. What is - on the surface - completely illogical is my overwhelming habit to come into our existing kitchen and stand in front of the old Rayburn whether it's actually on or not, such is the 'comforting' nature of the thing (Hmm, perhaps there's a message there for our eventual decision).

We're currently thinking radiators to keep the chill off the place, say low 60s F and stoves for the main living areas. I've never liked overly warm bedrooms, preferring to rely on an electric blanket, although I am looking forward to not having frost on the inside of the windows in the coldest mornings.