Boilers / hot water / heating question

[SavageHoutkop]

Mr SHK and I are finally in a position where we might be able to buy a house.
We've now lived in four different houses/flats.

As the selection of houses on offer is quite poor, we're likely to make some changes to whereever we buy. There are several things on the 'must have' list; one of which is a decent pressure shower. Our current rented property is single glazed, with an old boiler (c. 20 yrs, I believe) and the shower water pressure is poor (directly plumbed, not electric). I've also never yet met a good pressure electric shower.

The best house/flat, by far, in terms of insulation / heating / hot water / shower pressure was our fairly new build (c. 2003) flat - which had good insulation and no gas whatsoever. The running costs were also good. We only ever had one economy 7 storage heater on in the winter (with additional electric boost in the second bedroom, which we were using as a study, as the window frame there had left a good 2mm gap straight through to outdoors, and it was pointing in the wrong direction for any winter sunlight). The hot water was provided by an electric geyser (immersion heater? I'm not up to speed with the terminology) which was also economy 7 and had the option of an override for additional hot water. The tank was enough for us for showers + any dishwashing throughout the day. Occasionally we ran out (normally if we wanted a bath as well, and normally if the cold water tap was providing exceptionally cold water, in which case the override provided hot water fairly quickly)

I've heard it parroted frequently that gas is most 'efficient' in terms of heating and cooking. Cooking (on a hob) I might well agree, but for the others it seems to me what people mean is monetary efficiency - i.e. electricity expensive, gas cheap. Also, I think it's assumed that you'd want the whole house heated to (say) 22degrees; which is not what we do. We like to have the living room warm(ish); but other rooms not heated at all by default.

I'm not a fan of gas, it seems that it's very temperamental with high running costs; and of course it is also a fossil fuel and supplies depend on imports from possibly far off. Electricity, on the other hand, is possible to produce locally via PV / wind / whatever.

Any thoughts on whether or not to use a gas combi boiler; or to use an electric geyser? And whether or not one is actually more efficient? I've looked at the energysavingtrust but they seem to assume you already have, and will never change, from a gas boiler system.

I'm happy to have current running costs higher for electricity if it's simpler to run and breaks down less often! And of course there's the chance to have solar hot water heating and/or solar PV helping to power the electric appliances, whereas producing your own gas seems a bit harder (in the required quantities, anyway...)

 

[jugglingphil]

Solar water is very good even in this country. On a sunny winter's day it'll still heat up a tank of water. You will need a south facing roof. Can be used in conjunction with multiple other sources (gas, electric, wood, ground-source, etc).

SolarPV is a good investment while Govt is offering FiT, assuming you are planning not to move.

Not sure about gas v electricity, but it's an easier decision is you are generating your own electricity.

 

[annedonnelly]

Solar water is very good even in this country. ... You will need a south facing roof.

Not necessarily. I have solar hot water on an SW-facing roof. Solar PV will be going on the same roof soon.

Air/ground-source heat pumps are an option for heating. There was a topic here a few months ago.

 

[Over The Hill]

Lots of points there!

I think overall start point must be to get a nicely insulated property or to have it nicely insulated.

From there-

Gas V Electric.

Gas should be the cheaper of the two and is very much used on demand so quite efficitent in that way.

Electric - you have heaters that are basicaly an element which is on an expensive tarriff or storage heaters which is the same element heating a brick overnight with cheap leccy which you then get warm from then next evening. This is cheaper but it does end up heating the house at the wrong times so is inefficient in actula leccy used.

Shower
You basically need it pushing water out at mains pressure and not via a tank in the loft. Heating the water at the point of use with electric is fairly poor and does not have a good flow rate. You can have a hot water tank at mains pressure now (with an expansion device instead of the header tank).
Old gas boilers ran on a header tank so the pressure was low but modern combi boilers do away with the header tank and so run on mains pressure and shold have more go in them to be able to heat up a decent flow of water directly for a shower.

I would consider the greenest option to be the combi boiler as it is wasting nothing on storing heat, just chucking it out on demand in an efficient way.

yes they need a service but that is really a matter of £70 every couple of years.

You still will have lots of other things running on electricity that you can run from green sources.

 

[jugglingphil]

Not necessarily. I have solar hot water on an SW-facing roof. Solar PV will be going on the same roof soon.

Agreed, I was trying to over-simplify.
I have solar water on SE facing roof.

 

[Yellow Fang]

I've been wondering this for years. A condensing gas boiler seems to be the most efficient and green, but usually it seems you forced down the road of getting a combi-boiler, which does space and water heating. I don't actually want space heating, just hot water. I've also heard that condensing boilers and combi-boilers haven't been all that reliable in the past, as well as quite expensive to buy and install. I've read with combi-boilers, users often have to run the hot tap for quite a while before getting some proper hot water, because efficient space heating systems work at lower temperatures. Solar hot water is supposed to be quite good, although not cheap neither. Supposedly, it can provide 50% of your hot water needs, nearly all in summer. It's more complicated plumbing though and usually takes more space. I believe the Renewable Heat Incentive is about to be introduced, which should make solar hot water more cost-effective to install, although the present governments seems to be reviewing all the last government's green initiatives.

 

[SavageHoutkop]

I've been wondering this for years. A condensing gas boiler seems to be the most efficient and green,

I'm still not convinced on this one, taking into account where the gas comes from (at present, anyway, it's petrochemical). I reckon renewable energy is better, which puts you into electric (at the moment, anyway, unless the bio-gas or whatever it's called takes off). And, if large scale wind/solar/tidal whatever comes up, the problem is that it works some time but not all the time. Surely then there's a need for people to be able to use the energy when it is available to do work (heat the storage bricks in the heater, boil the water before storing in the well insulated tank for later use...) - so really similar to current 'economy 7' but perhaps not overnight but whenever the wind is blowing/sun is shining?

(I take the point that my current electricity use is likely to come from fossil fuels no matter who I pay my bills to - currently a 100% renewable supplier)

 

[Yellow Fang]

I'm still not convinced on this one, taking into account where the gas comes from (at present, anyway, it's petrochemical). I reckon renewable energy is better, which puts you into electric (at the moment, anyway, unless the bio-gas or whatever it's called takes off). And, if large scale wind/solar/tidal whatever comes up, the problem is that it works some time but not all the time. Surely then there's a need for people to be able to use the energy when it is available to do work (heat the storage bricks in the heater, boil the water before storing in the well insulated tank for later use...) - so really similar to current 'economy 7' but perhaps not overnight but whenever the wind is blowing/sun is shining?

(I take the point that my current electricity use is likely to come from fossil fuels no matter who I pay my bills to - currently a 100% renewable supplier)

Good point about storing renewable energy in water tanks. What I meant is that gas is greener than electric now, because combination boilers are about 90% efficient at converting fossil fuel energy to heat, while even the most efficient gas turbines are only about 50% efficient at converting fossil fuel energy to electricity.

 

[Yellow Fang]

Come to think of it, a solar hot water system with electric heater back up is probably not a bad way to go. The wind is stronger during winter when there's less sun. Wind power would be useful for heating your water up in the morning before the sun's had a chance to shine.There's nothing much else using electricity over night, so it looks like a win-win.