What heating to install?

[hightower]

I've got an ex-authority 4 bed semi in Cornwall, built in the 50's, heated currently by a single mutli-fuel burner in the lounge which also has a back boiler for domestic hot water. The hot water tank has a single 3kw immersion heater in it. We're looking to put cavity wall insulation in this summer, and I'm topping up the loft insulation too. I want to put in some form of central heating, which will also provide DHW within these constraints:

i. We don't have mains gas ii. We have limited outside space (I should be able to site an oil tank OK)

Aside from oil, I've been pondering GSHP, or potentially an electric boiler combined with solar PV to take the overall sting out of the electricity bills (I appreciate it's only over the summer I'll be saving, but every bit helps). We're on a water meter, so we don't tend to need a massive amount of DHW anyway. We have a piss-poor electric shower at the moment, which I'm also hoping to incorporate into some 'whole house' solution.

Given that I'm prepared to listen to anything sensible or otherwise, any suggestions would be great....

Cheers

Rich

[Doctor Drivel]

The easiest is to fit an "outside" oil boiler. Some oil combis are very good on DHW flowrate. This would eliminate the tanks and cylinders and give high pressure showers.

You could go LPG, which is expensive to run, but cheap in capital cost to fit. A Rinnai or Andrews multi-point water heater to do the DHW (they have amodel that can be fitted on and outside wall "outside") and a small LPG CH boiler inside for CH.

They are "very" expensive to fit. You have to do the payback calcs well to justify one.

PV panels are not worth it. Direct wet solar DHW heating is cheaper and far more effective.

You could go thermals store and use overnight cheap electricity to heat it. It would need to be around 1,000 to 2,000 litres in capacity to take you through the day in DHW and CH.

The more you insulate and make the house air-tight the less heat you need. Then once the insulation level gets so high and the heat demand is so low electric heating become feasible. Less capital cost too.

Initially concentrate on insulating. Can you also externally insulate as well? Also fit double or triple glazed low "e" glazing and over 1 foot of insulation in the loft.

[Owain]

If you can get mains gas into the house at a realistic price this is probably the best option bearing in mind running costs and adding to the house value.

I don't know if it's legal in the UK, but in Italy it's quite common for bulk gas (Calor type) tanks to be buried under the garden, which may help with the space issue.

Photovoltaic solar is hard to make cost-effective if you have mains electricity. Solar water heating may be useful.

Owain

[David Hansen]

On 28 Jun 2006 03:04:41 -0700 someone who may be "hightower" wrote this:-

Are you aiming to save money in the short term, or are you looking at longer term investments with an emphasis on reducing your carbon dioxide footprint?

Don't neglect to insulate the pipes.

Do you have enough ground to lay the outside coil? They can be installed vertically, but this is even more expensive as it involves drilling.

Used with off-peak electricity they can provide a useful input to a thermal store.

A quick win is to use the sun to heat water. This can be another input into a thermal store.

Solar works in winter too, though obviously at lower output. In summer a properly designed and installed system should provide almost all your hot water, in winter it might only provide say 20%.

Use it as a backup, but have as the main shower either a gravity one or a venturi one. No need to burn electricity just to pump water.

If you want the cheapest electricity bills then shop around, if you are more interested in carbon dioxide emissions then go for one of the renewable tariffs from the smaller suppliers. The latter either offer a rising percentage of 100% from renewable sources (measured over a year).

[normanwisdom]

I'd do some calcs and probably crank up the insulation to get as much in as space will allow - including between rooms i.e. unused rooms stay cold. And draughtproofing wherever poss. You might then find that the high but reduced running costs of all electric are well offset by the low capital and maintenance costs, esp if you add in solar heating and source cheap fuel (waste wood) for your multi fuel. Could you re-direct hot air from the multi? I'd replace the piss poor shower immediately with a 9 or 10 kw model. These are quite adequate and cheap to run but not fashionable on this group - just ignore the adverse comments! And they are always available whatever the state of the rest of the system. Don't bother with DG it's a waste of money - do the calcs if you doubt this. Instead have thick curtains, roller blinds etc.

cheers Jacob

[The Natural Philosopher]

Two sensible and well tried practical solutions suggest themselves.

(i) Big combi if you don't mind only having one shower and no other hot water at any one time ;-)

(ii) mains pressure system boiler, pressurised HW tank, and so on.

I don't think the latter is any more expensive than adding a heatbank to a combi.

With a smallish house well insulated, both will be pretty efficient.

Given it sounds like you are on a tight budget, and don't have a huge family..the Combi solution sounds most sensible.

[Doctor Drivel]

There are high flow combis that do more than one shower.

Adding a heat bank to a combi achieves nothing as the heat bank can provide mains pressure DHW at very high flowrates.

An oil one.

[Dave Liquorice]

Multiple thick curtains or roller blinds don't help with drafts. Very few of the energy conservation things have rapid paybacks but are you doing it for pure economic reasons (smaller primary energy bills) or just to reduce the amount of energy you consume?

[Mary Fisher]

I agree with both those points. And solar water heating doesn't just work in the sun, as we've discovered since January when we installed our own.

Mary

[hightower]

Thanks for all the responses so far, the general consenus appears to be:

i=2E REALLY concentrate on insulation

ii. Oil (no mains gas!!) combi and radiators would be about the cheapest 'whole house' solution for heating and DHW

iii. GSHP and solar would be a long term investment, but given our lack of outside space it would need a bore hole +++=A3=A3=A3=A3. It'd give us a nice warm environmentalist feeling inside, but we need to look at the money side of it for sure :) Solar water may be worth looking into, although our need for hot water is lower than our need for heating.

iv. People REALLY seem to hate electric boilers :))

We're trying to heat the house efficiently, reduce the carbon footprint in general, and hopefully make a few long term cost savings too, which is why I worry a bit about oil. We're too close to other people to go for other 'green' energy sources, so maybe oil is the most obvious short to medium term option....??

Thanks again for your time.

Cheers

Rich

[Dave Plowman (News)]

So you've moved on from recommending twin combis? What is the next harebrained scheme you're going to try wasting other's money on?

[Doctor Drivel]

Sad isn't it. I wonder if he has worn out those loafers yet.

[David Hansen]

On 28 Jun 2006 09:41:20 -0700 someone who may be "hightower" wrote this:-

Note that there are environmentally friendly forms of insulation, as well as the "standard" ones. One place to get these is

there are limits to what can be done with an existing building.

For hot water this depends on numbers, usage patterns, location of boiler in relation to demand locations and several other factors. Combination boilers are not the silver bullet that some claim they are.

If a combination boiler can be located next to the most used hot tap (the kitchen one) and feed a properly insulated hot water cylinder next to the place with heavy but irregular use (the bathroom area) this can be the best of all worlds. However, this is a matter of how much you wish to re-arrange the house around heating systems.

is a good place to start on heat pumps. With no mains gas they can be viable compared to alternatives, but it depends on the circumstances.

Solar PV is still not a financial investment. Rather it is an environmental investment to reduce one's carbon footprint and/or encourage further developments.

Solar heated water can charge up a thermal store, which is then used for heating and hot water. These are not cheap, but if starting from scratch are worth considering. It might be worth having several large solar panels if they are charging a thermal store.

One of the advantages of a thermal store is that it can take many inputs. A wood burning stove might be such an input. Are there any sources of fuel locally?

You might still want an oil fired boiler, but instead of a complicated combination boiler this would be a far simpler and smaller one, sized to keep the thermal store charged rather than heat water instantly.

I would build in flexibility. This will be more expensive in the short term, but will pay back in the long term. Partly this depends on how long you think you will be in the house.

How able are you to deal with these things? If you can't then "unusual" systems may be more expensive or impossible to maintain with local fitters.

[The Natural Philosopher]

I think that you have summarised 100% correctly.

Which is encouraging.

[The Natural Philosopher]

Not on theory there aren;t. You could surround the whole house in 6 feet of polystyrene if you wanted too..and inject foam under the suspended floor...use quadruple glazing and heat exchangers in the ventialtion shafts..;-)

No, but they represent a cheap and effective way of getting reasonably decent amounts of hot water at mains pressure around a small house..

Easier to use a system boiler if you want a pressurised hot water tank.

I like the idea of heat pumps because they reduce thermal pollution as well.

I think the best way to utilize solar power is to simply have a black painted preheater for water under glass somewhere. UFH pipe under double glazing sprayed black?

[The Natural Philosopher]

I agree with both the above. I have SG, and thick lined curtains. Its warmer than DG and no curtains. However the windows are new, and very well sealed.

Draughts are the first thing to tackle in any energy saving move. Its usually cheap, and VERY effective.

Then roof insulation, because its cheap and easy. All the insulation in a loft is usually less expensive than ONE DG window.

Then walls, because it makes a heck of a difference.

Then floor, because its a big area.

Then and only then tackle those teeny weeny windows that actually represent a small fraction of the total heatloss area.

[Doctor Drivel]

Gosh! He actually made some sense there. Amazing.

[Doctor Drivel]

These have an annual service charge. And can do this:

have a high flowrate combi like an Alpha CD50. it will fill a bath pronto.

Plastic pipe. Oh dear.

[David Hansen]

On Thu, 29 Jun 2006 00:05:04 +0100 someone who may be The Natural Philosopher wrote this:-

Indeed. However a four bedroomed demi-detached house may well necessitate rather more thought going into providing a hot water service than the "bung in a combi" merchants appear capable of.

[Mark]

Maybe your existing back boiler could be configured to run a central heating system. I'd have thought that would be the cheapest option.

Mark