ASHP – Should do better - Must Do Better

lovesgshp

harryhound wrote: »

Bosch certainly liked them!!

Over here in UK they were pushed by Ice Energy (in the ground source format) which created the rather bizarre situation of Ice Energy (who at least had some experience even if they did over sell) facing Worcester-Bosch across a gangway with both of them trying to sell the same kit.
W-B seem to be only marketing the lower output models (single phase ).
Worcester-Bosch had a nice film of their managing director having a new pre-made grid of heat gathering plastic pipes being dug into his lawn. This would probably have been a compact collector system, which is used for smaller gardens, would probably been combined with a heat recharge system
I think the gas fitters on their stand were somewhat bemused.
We have had so many gas fitters here giving excessive heat information requirements, so can see why they are bemused. Takes a thermal loading analysis of the property to convince them that it needs far less than they think!!!

Presumably the situation has now settled down with Ice Energy handling the wealthier clients?
May just be that Ice Energy have the full range availability, plus able to offer the better guarantee. The W-B only has 2 years, so you spend what you prefer, even though they are the same unit basically

I wonder who designed this:

GSHP: UK, 1998 [25] An IVT Greenline 4 was installed with two 2kW immersion heaters in a large detached home in the UK, and monitored for around one year. Outlet temperatures were 45°C for under-floor space heating, and 50°C for hot water. The COP of this system was limited by the choices made during installation. COP of the heat pump was 3.16 during this time, but was reduced significantly due to a circulation pump set to run continuously. If this pump ran only when the heat pump was operating, the COP was estimated to be 3.43. The heat pump was sized to only provide 50% of the annual heating demand, so usage of the low- efficiency immersion heaters was significant. These consumed 2.8MWh of electricity, compared to 5.0MWh from the heat pump itself – reducing the overall system’s performance factor to 2.39. This would have increased to 2.52 if the circulation pump was optimised. The monthly COP was not seen to vary between summer and winter, as summer demand was mostly for higher temperature hot water.

This was one of the earlier models. The HT Plus performs far better.

Cardew

Edale wrote: »

I think the heat pump consumed 5mwh of electricity giving a heat output of 3.16 times this or 15.8mwh, add the immersion heaters and you have an annual heat requirement of 18.6mwh. This sounds more realistic for a large detached home than 7.8mwh it would be using your calculation.

You are correct.

It was the expression '5MWh from the heat pump' that threw me. It should surely be '5MWh to the heat pump'

lardconcepts

I'm glad I found this thread, and thanks especially to Cardew for his rational thoughts and figures in all of this.

I've only seen economy electricity tarrifs mentioned once here. We've moved to a tarrif called "twinheat" which gives 4 hours from 4 to 8am and 3 hours from 2:30 to 5:30pm, which has shaved about 40% off our bills (doing simple things like pushing "delay start" on the dishwasher and washing machine before we go to bed, showering before 8am which we do anyway, so no lifestyle change and a 40% saving. Bargain). There's another one called Economy 14 which give 11 hours overnight (9pm to 8am) and 3 in the afternoon.

With a long "overnight" burst on 6.2p rather than 13.7p electricity, wouldn't this greatly improves the viability of an air-to-water heat pump?

As an aside, we've had a complete nightmare working from the list of MCS accredited installers. They seem totally disinterested, and the ones which show any enthusiasm run a mile when you ask for calculations/previous installations/guarantees of effectiveness etc.

BTW, we're on LPG for heating & cooking, and electric immersion (45 mins a day) for hot water, and although people keep saying we should switch to kerosene, with the saving being only just over a penny per kwh (according to http://www.nottenergy.com/energy-costs-comparison3 ) and oil fluctuating more wildly than LPG, once you take into account boiler change it's not worth it.

Cardew

lardconcepts wrote: »

I'm glad I found this thread, and thanks especially to Cardew for his rational thoughts figures in all of this.

I've only seen economy electricity tarrifs mentioned once here. We've moved to a tarrif called "twinheat" which gives 4 hours from 4 to 8am and 3 hours from 2:30 to 5:30pm, which has shaved about 40% off our bills (doing simple things like pushing "delay start" on the dishwasher and washing machine before we go to bed, showering before 8am which we do anyway, so no lifestyle change and a 40% saving. Bargain). There's another one called Economy 14 which give 11 hours overnight (9pm to 8am) and 3 in the afternoon.

With a long "overnight" burst on 6.2p rather than 13.7p electricity, wouldn't this greatly improves the viability of an air-to-water heat pump?

As an aside, we've had a complete nightmare working from the list of MCS accredited installers. They seem totally disinterested, and the ones which show any enthusiasm run a mile when you ask for calculations/previous installations/guarantees of effectiveness etc.

BTW, we're on LPG for heating & cooking, and electric immersion (45 mins a day) for hot water, and although people keep saying we should switch to kerosene, with the saving being only just over a penny per kwh (according to http://www.nottenergy.com/energy-costs-comparison3 ) and oil fluctuating more wildly than LPG, once you take into account boiler change it's not worth it.

What a great first sentence;) - Thanks!

Just a couple of comments on your question about 'viability':

For anyone on Economy 7, or your 'twinheat' tariff, it is easy to work out the 'break -even' point i.e. the percentage of cheap rate electricity you need to consume for that tariff to be viable.

You just work out what you paid for that tariff with your level of consumption and compare this with all consumption charged on a 'normal' 24/7 tariff.

After you had an ASHP fitted the same exercise could be carried out - but it would cost several thousand pounds to find out!

Given that an ASHP has to run for long periods during the day(sometimes continuously) my guess would be that a 24/7 tariff at around 10p/kWh would be the better bet.

bernithebiker

I reckon that tariffs will be increasingly going this way - lots of different rates for different times.

As elec. demand continues to increase, the peaks will become 'peakier'. Everyone will want to use their heating, cooking, etc. at the same time.

So companies will have to do more to encourage people to push demand into the night/early morning so as to avoid having to build yet another power station.

A good solution would be to have an ASHP with some other source of heat like keeping your old boiler or wood burners. Run the ASHP at night as much as possible then either turn it off in the day or burn wood, etc.

The French partly get round this by imposing a power limit on every house. You contract gives you 6, 9, 12 or 15kW. Each is progressively more expensive. If you exceed this, it trips the whole house. Can be a right pain in the XXX. Like this, the French know that peak demand CANNOT exceed a certain level. In the UK peak demand is potentially limitless, meaning more power has to be ready on standby.

We use a tariff called TEMPO. 6 prices. 3 types of day, 300 blue day/night rate (about 6 and 5p), 40 white (about 11 and 10p) and 25 red (50 and 24p). Obviously red days are in the winter, on the coldest days.

Clearly this type of tariff is not good for electric heating, including ASHP, unless you have an efficient alternative backup.

Basically, more and more, if you don't want to chuck away hundreds of quid for nothing, you will have to be a bit more proactive/savvy, with how you heat.

lardconcepts

Berni, Cardew - thanks for your replies.

ASHP was just a conclusion I came to once I'd read a fair few books, sites and studies. But having explained our situation, is there anything YOU would recommend instead? Hell (and us) will freeze over before I consider oil and I've ruled out woodchip as it's already in such short supply it's being shipped over from Canada and the market is ensuring rapidly rising prices. Even plain unseasoned logs are rising in price, and now forestry commission has put a stop to "collect your own", it's not so easy to come by.

One idea I had was to built a small cheap conservatory to house the ASHP outside unit, to reduce the effects of the low winter temperatures with a bit of daytime passive solar gain. Madness or not?

It seems to me that EST and other renewables groups are more focussed on what's now and sexy, rather than what's practicle, economic and actually sustainable. So... is there a technology to heat the house I'm missing?

Cardew

There are lots of other threads where the various methods of heating are discussed; but there is no magic solution.

IMO we are just going to have to get used to ever increasing fuel bills and accept that the era of cheap energy is finished.

I say 'cheap energy' because that is exactly what it has been. Even now the average family spends £1,000 a year(£20 a week) on heating, hot water, lighting and powering all appliances.

Compare that with how much is spent on the average family car, taking into account depreciation, tax, insurance, servicing/repairs. Even before putting in any petrol I suspect it is double the cost of energy for the house.

Anyway back to ASHPs. Even if they were guaranteed to work properly all the time, they are still extremely expensive to install and you will take a long time to recoup the £7,000+ they cost.

lovesgshp

There is always the probability of a heat pump costing more to run, if not set up correctly initialy, or if the consumer alters settings without understanding the system. We had a client here (an engineer) who changed the internal thermostat to full house heating overide and then complained his elec bills had increased too much.
One must remember that in normal use a heat pump works more in the evening/night except in adverse weather conditions. Running hours should be circa 12-14 a day in winter, depending on room temp settings etc.
Electricity usage here is about 30% on peak rate and the rest on lower rate.

lardconcepts

Cardew wrote: »

For anyone on Economy 7, or your 'twinheat' tariff, it is easy to work out the 'break -even' point i.e. the percentage of cheap rate electricity you need to consume for that tariff to be viable.

You just work out what you paid for that tariff with your level of consumption and compare this with all consumption charged on a 'normal' 24/7 tariff.

Well, that's just what I did!
I thought you might be interested in the following:

Last year, when I found I could enter our own readings for any time period, I did so, and then again for roughly the same time this year.

Let me know if you see any obvious flaws in the working out:

Actual electricity bill, standard tariff: 01/04/10 to 29/04/10
405 standard units * 11.223 = £45.78
29 days * 12.23 = £3.54
Total ex: vat £49.02

Actual electricity bill, twinheat A: 15/04/11 to 10/05/11
peak 156 * 14.015 = £21.86
off-peak 228 * 6.311 = £14.39
(total units: 384)
standing charge 26 days * 16.95p £4.41
Total ex vat: £40.66

So in fact we used a lot MORE electricity than this time last year and we're still saving over tenner a month (26 vs 29 days)

If we assume identical use: 228/26 * 29 = 428
428 * 11.223 = £48.02
29 days * 12.23 = £3.54
Total ex: vat £51.56

So let's say a £10.90 saving per month, the meter cost £50 to swap, after 5 months we're at break-even and every year after, we're saving about £130 with absolutely zero change of lifestyle. (In fact, we should be rewarded for being greener because balancing load and using more off-peak is better, which is why it's cheaper .

Cardew wrote: »

After you had an ASHP fitted the same exercise could be carried out - but it would cost several thousand pounds to find out!

You're not wrong there! We'd nearly given up waiting when we finally got a quote for an ASHP - for a 3 bed small detached, the quote was just under £13,000. Then we saw this bloke demonstrating a "low impact" GSHP which drilled down several times, but at angles from one small entry point. Nice idea, but £25,000.
And I couldn't work out his sums - the owners were apparently spending £2,500 a year on oil heating, and would "break even in 6 years". That's including a £120 a year service charge. Couldn't quite get my head round that one.

Cardew wrote: »

Given that an ASHP has to run for long periods during the day(sometimes continuously) my guess would be that a 24/7 tariff at around 10p/kWh would be the better bet.

I did a lot of searching, the best I could get without a stupidly high first few units and standing charge was 11.2p.

Anyway, hope the above is of some use - I think our dabble into the world of heat pumps is over, at least until the cost comes down and the honesty of installers goes up...

Cardew

lardconcepts wrote: »

Well, that's just what I did!
I thought you might be interested in the following:

Last year, when I found I could enter our own readings for any time period, I did so, and then again for roughly the same time this year.

Let me know if you see any obvious flaws in the working out:

Actual electricity bill, standard tariff: 01/04/10 to 29/04/10
405 standard units * 11.223 = £45.78
29 days * 12.23 = £3.54
Total ex: vat £49.02

Actual electricity bill, twinheat A: 15/04/11 to 10/05/11
peak 156 * 14.015 = £21.86
off-peak 228 * 6.311 = £14.39
(total units: 384)
standing charge 26 days * 16.95p £4.41
Total ex vat: £40.66

So in fact we used a lot MORE electricity than this time last year and we're still saving over tenner a month (26 vs 29 days)

If we assume identical use: 228/26 * 29 = 428
428 * 11.223 = £48.02
29 days * 12.23 = £3.54
Total ex: vat £51.56

So let's say a £10.90 saving per month, the meter cost £50 to swap, after 5 months we're at break-even and every year after, we're saving about £130 with absolutely zero change of lifestyle. (In fact, we should be rewarded for being greener because balancing load and using more off-peak is better, which is why it's cheaper .




You're not wrong there! We'd nearly given up waiting when we finally got a quote for an ASHP - for a 3 bed small detached, the quote was just under £13,000. Then we saw this bloke demonstrating a "low impact" GSHP which drilled down several times, but at angles from one small entry point. Nice idea, but £25,000.
And I couldn't work out his sums - the owners were apparently spending £2,500 a year on oil heating, and would "break even in 6 years". That's including a £120 a year service charge. Couldn't quite get my head round that one.



I did a lot of searching, the best I could get without a stupidly high first few units and standing charge was 11.2p.

Anyway, hope the above is of some use - I think our dabble into the world of heat pumps is over, at least until the cost comes down and the honesty of installers goes up...

You don't say where you live, but presumably Scotland????

Why are you worried about the "stupidly high first few units". The tier system(primary/secondary units) is no more expensive for you on your level of consumption, and will enable you to get cheaper tariffs.

That said, as you are not getting a heat pump, with the percentage of electricity you use on cheap rate, there is no point in moving from heat wise.

£13,000 for an ASHP system is just a joke. You can invest that sum in a long term notice account at 4% after Tax, and that produces £520 a year. Borrowing the money costs even more.