All electric - heating - and big mistakes!

lstar337

Returner wrote: »

Hot water can go to off-peak and I shall review the solar panel threads to see how best to time other appliances.

You could also get a solar diverter (such as immersun) which can divert excess generation from you PV panels to your hot water tank. This could be a welcome day time top-up, or just a reduction in your import over night.

Returner

My OH feels the same way you do Smiley Dan, that OFCH is a 20th century solution. Not that storage heaters are exactly cutting edge!

We took a passing look at heat pumps (both AS and GS) but were a little put off by the initial expense and also by a report from someone who, having installed an ASHP, found they never were quite warm enough. In truth, I don't know the details of their installation nor how well insulated they are. Certainly it would be wise to give thorough consideration before either is ruled out entirely. Thank you both for reminding me. What sort of temperatures do you get with your system Matelodave?

We've looked at an immersion diverter off the PV array and it's also in the mix as we formulate our plan.

This input from you all is unbelievably helpful, thank you so much for your time.

Andy_WSM

How about a couple of air to air heat pumps (air conditioning units that either heat or cool) for the main areas you need heated all day and panel heaters for the bedrooms?

air to air heat pumps can offer a COP of 4+ nowadays. I.E 1kW in 4kW of heat out.

Edit - sorry, can see Smiley Dan suggested this already.

matelodave

We get whatever temperature we want, it depends how hot you run it. The secret is to make sure that the emitters (radiators, underfloor, fan coils etc) are sized to provide sufficient heat at the system working temperature.

The hotter you run the system the more it costs - the optimum is about 35 degrees. My system is sized to give us 21 degrees indoors when it's -3 outside.

The system water temperature is about 40 degrees at 0 degrees and 30 at +10 degrees outside and we can wind it up to 55 degrees if we want to but I've never done that.

We have had a few nights when it's dropped to -15 outside and we've been quite warm enough although I guess that the inbuilt back-up heater kicks in when it gets down that low. We've not used any backup or alternative heating however cold it's got.

Our bungalow is 30 years old, insulated cavity brick, 15 year old double glazing and about 300mm of loft insulation. The floor isn't insulated and it's not particularly draught free.

Smiley_Dan

Another advantage of A2A heat pumps is that they come with the emitter... you don't use rads (hence the name - air to air).

matelodave

When I suggested A2A it was met with "we're not having one of those on the wall/ceiling", so that was that idea out of the window (no pun intended).

If returner want's some more info on what we've got and how much it cost then PM me and I'll give some more info. We've had our system for four winters now and just going into the fifth.

We are all electric and my wife doesn't stint on the heating or the tumble dryer and we are at home all day. Our electricity cost on a full rate tariff is still less than £900 a year.

Pincher

If you have good insulation, I wouldn't worry too much about it.
If you just switch on the panel in the rooms you are using, it shouldn't be too excessive, if you have good insulation.


I am paying 10.6p per kWh for single rate electricity.


With Economy 7, you would be losing money over the summer period on higher peak rate.

matelodave

Pincher wrote: »

If you have good insulation, I wouldn't worry too much about it.
If you just switch on the panel in the rooms you are using, it shouldn't be too excessive, if you have good insulation.


I am paying 10.6p per kWh for single rate electricity.


With Economy 7, you would be losing money over the summer period on higher peak rate.

Probably not if he's got solar panels to offset the amount he has to use off the grid - it's a balancing act to ensure that you use as much of your own generation as you can and then use cheap stuff overnight, So washing, heating ironing & cleaning should either be done when the sun shines or during the low tariff times at night.
It's not so easy during the winter because you won't get much PV generation so you need a heating/hot water system that optimises your use of off peak electricity - ie storage heaters and a well insulated hot water tank.

A heat-pump isn't really suited to E7 as it needs to run during the day although it would capitalise on PV in the summer to heat the hot water. In my view a heatpump on a single a tariff deal using PV in the summer for hot water is probably the cheapest unless you can really adjust your lifestyle to do as much as you can overnight.

Unfortunately there really is no clear cut solution - it depends on your life style and how long you intend to stay in the house. There's not much point in spending £10k and then moving a year or so later unless you have added that £10k to the value of your house.

Ours cost about £6k four years ago which is about £3k more than a compete oil set up. I reckon we've saved at least £2k so far in fuel bills (£500+/yr). My original payback would have been about six years but now we are getting RHI (four years later than promised) it will be paid back by April next year. The RHI will then pay my total annual fuel bill with a bit left over for the next six years.
We should still benefit from lower fuel bills until we fall off the twig or move

Robwiz

I wouldn't install oil fired central heating either. Or any wet system for that matter. Think about it, you're using a pump rated at 1 kW just to circulate water round the system. A well-insulated house has an average heat loss of 2 kW, so it's more efficient to use the energy as direct heat.

There's nothing wrong with NSHs on Economy 7. Just because they are old tech doesn't mean they can't be effective. I'd use them to just take the chill off the house, providing a background temperature of 16º to 18º. At night rate, your cost per kWh of heat is comparable to gas (if you're on the right tariff!).

We had an air to air heat pump installed last March in the kitchen/diner. On a day like today, when it's 12º outside, the AAHP is running with a set temperature of 21º off the solar PV and I'm still exporting 0.26 kW to the grid. We aren't using any other heating yet.

The good thing about an AAHP is that its efficiency (around 5 in my case) means that your cost of heat is one fifth of the electricity unit price. So mine is costing about 2.4 pence/kWh of heating.

When you change your meter back, it's worth checking you're with a supplier who offers the best tariff for your usage pattern.

Returner

I can't thank you all enough for the time you've taken to add your thoughts to my initial query.

We've decided that we are going to revert to E7, utilizing the old heaters, for this winter which will give us many months to thoroughly research all our options.

We live in interesting times, don't we, with so many choices available to us? In my case, rather too many choices in fact! I'm intrigued by the A2A systems and have much reading to do. No doubt that will then generate another gazillion questions...