Relative costs of mains Gas/LPG/Oil

[IMM]

Absorption units are available. But expensive.

[IMM]

The next phase of boilers under R&D, looks promising and appear likely to be introduced, is the Zeolithe heat pump, which runs on natural gas, or LPG gas, for the provision of domestic heating and hot water. Currently these units are floor mounted and resemble a typical boiler in appearance. Zeolithe heating appliance's use less energy and are more environment-friendly than electric heat pumps and gas boilers. It provides considerably higher output levels than the current conventional and condensing boilers. Carbon-dioxide emissions are reduced by approximately

20 to 30%.

[Ian Stirling]

Of course, if you could get small 24*7 generators, doing the CHP thing and putting the exhaust heat into the house, and the low-grade residum into the heat source, plus using the shaft power to run a compressor, then that would pretty much beat anything.

[Steve Firth]

Heh, I'm working on something similar. Generators work best at constant load so I'm fixing up an immersion heater as a ballast load and planning to run the exhaust through a coil in a separate calorifier.

[IMM]

And the payback period would be a lifetime. Better spend the money on high insulation, air-tightness and passive solar, etc.

[IMM]

The calorifier will have to be a strong, expensive stainless job. The exhaust may rot a lesser one very quickly. It will generate much heat (the IC engine produces more heat than turning power), so you will require a vast amount of hot water storage to make it anywhere near viable.

[The Natural Philosopher]

Becasue the efficiencuy loss of a small gas engine to run the pumps cancels out the lower running costs. Fuel cells may ultimately change that.

>

[IMM]

electrictity.

They may, but be prepared to wait a long time.

[Ian Stirling]

Conventional IC engines are pretty close to breakeven, if they are run on cheap fuel, and the result compared to electricity. If you add in the heating, it can be an overall win. (neglecting maintainance, and capital costs, which is the biggie.)

Insulation is indeed generally easier, as are many other measures in general.

[IMM]

The problem with Combined Heat & Power is that it is expensive to run using even the most economical diesel or natural gas generator. Most of the time there is little power being used in a house, with power usage tending to be bursty, yet the unit has to run in case of demand and to run the numerous times clocks in a house.

The only way to make it feasible is to store the output of the generator in stored hot water, which requires a "very" large thermal store.

I believe an engine which is a cross between a turbine and an IC engine is being developed in Holland. The inventors are English. This promises to be an excellent choice over piston units being initially developed for large scale CHP applications. The inventors initially developed it for vehicles, and say it is scalable, as piston engines are, to almost any application. Fuel consumption in vehicles is predicted to be around 3 times better. So in

10 years you may be getting 120 mpg with vastly reduced emissions in a mid sized car. or running your house on one. It can run on many fuels, so natural gas powered and connected to the grid, we need far fewer power stations.

It is best to ignore machines and concentrate on the building fabric and use solar gain. Merely installing highly insulated shutters, that are closed at night (the Victorians used shutters a lot) can save a hell of a lot of heat that would normally drift off out into the night via the windows. So solar gain during the day and keep it in at night. Then there is the security aspect too.

[Pete C]

Either that or one of these micro CHP sterling engine boilers. If they are 20% efficient at generating electricity and drives a 600% efficient heat pump then you'd get 200% efficiency overall (80% +

120%). Should cut gas bills in half which isn't too bad.

cheers, Pete.

[G&M]

But most heat pumps are 400% at best.

then you'd get 200% efficiency overall (80% +

[Rob Graham]

4 bedroom/sitting room/living kitchen cottage nr. Edinburgh; oil CH £300 p.a.

Rob

[Pete C]

This'll do it:

if you have a broadband connection:

cheers, Pete.

[N. Thornton]

Some info about heat pumps:

Electrically powered compression type pumps can do 3x to 4x heat transfer, but this is a max figure, and drops as outdoor temp falls. Thats the gotcha.

Gas powered absorption pumps are hopelessly inefficient, and are simply a non starter for space heating.

Air source is way cheaper, and sounds diyable. Does someone here know more about it?

BTW one form of heating that can pay is flat plate solar space heating. You'll still need the convetional CH though.

Regards, NT

[Pete C]

Hi,

There are ones available in Japan that have a heat transfer of around

6 or above:

Toshiba:

Hitachi:

Daikin:

Mistubishi:

Although they are less efficient towards 0°C, they are more efficient in milder weather and when run at less than the rated capacity, so it evens out more.

The biggie for air source is that when the temperature drops to 0°C frost can form on the evaporator outdoors, which needs to be thawed off and reduces efficiency.

It might be possible to have a semi-ground loop. Air would be used when it's temperature is above 0, and the ground loop at other times. A smaller pipe in the earth or large pond could be used as the ground loop.

Also when the air temperature is above that of the ground loop, the ground loop could be warmed using the air. This could all be done with a normal outdoor unit with a small pump to circulate liquid warmed by the ground loop over the coils when required. The liquid could be distilled water maybe with some potable antifreeze.

cheers, Pete.

[G&M]

I only get blank pages for these Excite pages. Is there a trick to seeing the real page ?

This one is fine, albeit in Japanese. We had an older model in a place I used to work and all it did was either ice up on cool or spew it's guts on heat. Certainly didn't manage 6:1 but I'll investigate further.

[Pete C]

Hi,

Seems to work OK here on IE and Opera. Try:

Or go to select Japanese ->

English and enter them in as follows:

cheers, Pete.

[N. Thornton]

Good refs there.

Has anyone tried mechanical frost removal? Would seem far more energy efficient. Also solar reflectors pointed to the cold element would reduce this at least a bit, and presumably help with efficiency. Cant say I've tried any of this though. Solar space heating is cheaper and pays back ok.

extra complication, extra cost, thats the problem.

Regards, NT

[Pete C]

Not really, apart from a small ground source of some type it just requires a small pump and some tubing. Rather than use the ground source to supply all the heat, just use it as a buffer to even out temperature swings.

This should allow a heat pump to operate more efficiently as the average monthly winter temperature in the UK rarely drops below 0°C :

Even the average monthly temperature last summer was 17°C, so it could be used for air conditioning or even normal air cooling too.

With some simple temperature control on the pump the ground source could only be used when necessary and it's temperature change reversed when the air temperature allows.

cheers, Pete.