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Taking the plunge Daiken Altherma HT
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No the COP doesn't take into account defrosting.
The technical forums frequently state that it is defrosting that 'kills the COP'
In that case, the spec sheets relating to the cop at low ambient temperatures are pretty meaningless.
If the low temp cops are published at 1.5 in the spec sheets, then it certainly looks possible (or even probable) that they could drop below 1 during certain ambient temperature ranges, when of course it would then be better to use granny's old 2kw bar heater (or several!).
As Swipe said, at very low temps, the problem goes away (if it's not snowing), because then there is so little moisture in the air, there's nothing to cause deposition of ice. But then, at -15 and below - the cop, as measured/per the spec sheets, is pretty low anyhow. I see why 'bi-valent' is the current buzzword! I'd incorporate a stove with a backboiler for the cold days, and turn the heat pump off at the first sign of ice.
Nevertheless, there's £850 up for grabs for people who install Air to water HPs atm. Shame it doesn't apply for air to air, or exhaust air pumps.0 -
grahamc2003 wrote: »In that case, the spec sheets relating to the cop at low ambient temperatures are pretty meaningless.
If the low temp cops are published at 1.5 in the spec sheets, then it certainly looks possible (or even probable) that they could drop below 1 during certain ambient temperature ranges, when of course it would then be better to use granny's old 2kw bar heater (or several!).
As Swipe said, at very low temps, the problem goes away (if it's not snowing), because then there is so little moisture in the air, there's nothing to cause deposition of ice. But then, at -15 and below - the cop, as measured/per the spec sheets, is pretty low anyhow. I see why 'bi-valent' is the current buzzword! I'd incorporate a stove with a backboiler for the cold days, and turn the heat pump off at the first sign of ice.
Nevertheless, there's £850 up for grabs for people who install Air to water HPs atm. Shame it doesn't apply for air to air, or exhaust air pumps.
Pity you guys don't get the same incentives as here. 55% of costs paid back over 5 -10 years through the tax system. That includes installing double glazing/extra insulation etc. Even applies to air/air units.
Also special reduced electricity rates.As Manuel says in Fawlty Towers: " I Know Nothing"0 -
hi graham,
no, the company installed the whole system, and yes, it probably does come from china, the same as most other units which have been installed in scandanavian countries over the last few years.
also, the firm is local and have all the accreditation necessary for any future RHI.
i am well satisfied with the equipment , and at the moment it is just operating the DHW. the real trial will be over winter but if performance so far is anything to go by, all will be satisfactory. will keep all posted!0 -
The other Achilles Heel of Electric Heat Pumps is the properties they are matched to. I live in a 1960s semi which was built in an era when energy efficiency meant a hot toddy and Long Johns.
I'm currently running oil and if I were to put in an EHP then I have little doubt my energy costs would increase - rather than decrease. As a minimum, I'd suggest that unless a house is built to 2006 Building Regulations, then putting in an Electric Heat Pump is taking something of a gamble.
At an installation where mains gas isn't available and the house doesn't comply with 2006 standards, I'd suggest putting in a High Efficiency Oil Boiler and adding Solar where practicable as possibly a more economically attractive alternative at many installations.
Finally, don't forget that whilst we are often told of the Scandinavian experience of heat pumps... many of these homes were built from the outset for Electric Heat Pumps. Even then 25% of homes in a country such as Denmark have oil fired central heating, whilst in urban areas, many will be heated by municipal energy schemes.
At the right installation, Electric Heat Pumps are a fantastic choice; at the wrong installation they are a liability.
Regards
Ulsterman0 -
its early days yet with my ASHP set up, it is only set for DHW, 45c , but the running costs are quite encouraging. i have one of those "owl' electricity monitors on the heat pump only and the household consumption for one week, three showers a day, washing machine three times a week, washing up and shaving etc. works out at £2.40p per week average over the three weeks.0
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also just been told, gas boilers will not be allowed to be installed in new build properties from 2015, so it looks as if the race for heat pumps is on!0
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rogerbanana wrote: »also just been told, gas boilers will not be allowed to be installed in new build properties from 2115, so it looks as if the race for heat pumps is on!
Looks like the race may be a marathon0 -
jeepjunkie wrote: »I'm sure if you looked a study for gas central heating systems you would find good systems and poor systems, indeed you could survey everthing in life and fret about it no end...
At the end of the day we are no longer buying wood, coal, LPG and leccy to power oil rads [none of which were particularly effective but expensive] We are simply paying one bill for a cheap to run ASHP system that has transformed the house. House at a constant temp with loads of DHW. I can also shop around leccy suppliers for the best price should I wish...
As with most things in life you get what you pay for and £12k or whatever is sod all when compared to the house value and improvement to our life.
From much of my reading on the internet the anti ASHP brigade seem to be people that don't have them and are just trying to increase their post count or got it very wrong therefore we are all doomed...
Lastly, if the system did not work as expected the wife would start moaning and guess what... peace perfect peace...
It is not being 'anti ASHP' to point out that many systems are being fitted to houses that are not suitable, and/or by installers who are incompetent.
Every manufacturer seems to quote figures of an 'output of 3 or 4 units for every 1 unit input' when the reality is very far different.
You could hardly call the Energy Saving Trust 'anti-ASHP' yet their 12 month trial of 29 ASHP systems - with manufacturer's involvement - produced just one system with a confirmed system COP = 3.0. The average being below 2.0 and down as far as 1.2.
The results were so disappointing that the trial has been extended by a further year to see what lessons can be learnt.
If someone is fortunate enough to get a system that performs as promised - then good luck to them; although they have no way of verifying the performance.
Even on MSE many people have complained of huge electricity bills and systems unable to cope with really cold weather - some have simply ripped out their ASHP and used other methods of heating.
Has anyone heard of an ASHP salesman who has turned down a potential sale on the grounds that the house is not suitable?0 -
jeepjunkie wrote: »My time here is wasted along with everyone else who has great experiences with ASHPs...
:wall:
Only because you make it so.
As an owner, you should be a great resource to this discussion, but while you adopt a very odd 'I own a HP, I think it's great, and if you don't own one you can't have anything useful to say' attitude, then no wonder you find it a waste of time. I personally find your puerile animated yellow things irritating and a waste of time, but I suppose I've just got to live with them.
Instead of ad hominem attacts, can't you just reply to the (valid) points raised from professional studies of heatpumps, the concerns they raised and why they are incorrect?
On a specific point, could you tell us how your heatpump handles ice deposition, and operations at say -10C? Does it have a resistive heater for when things get very cold and the hp is unable to extract the demanded heat from very cold air?0 -
jeepjunkie wrote: »My time here is wasted along with everyone else who has great experiences with ASHPs...
Cardew, may I ask if you have a heat pump and live off gas grid?
I bet if I were to back in a year it will be the usual gripes about how expensive Oil and LPG is and that a log burner is the answer to their prayers.....!?
:wall:
You would do well to read the Energy Saving Trust Q&A responses on ASHPs in this thread
https://forums.moneysavingexpert.com/discussion/2867980 Post#91 onwards.
It seems your attitude is I have an ASHP, with which I am happy, so don't criticise ASHPs. So yes your time is probably wasted on this thread.
Would you be happy if your £12,000 system was on of the eight systems in the trial that had a system COP of 1.6 or less - one at 1.2? Or perhaps your system is that low??
Read how many people on MSE and all over the web have been 'unlucky' and their system is a disaster. Huge bills and inability to cope with cold weather - some have simply ripped them out.
All the manufacturer's sales blurb talk about 3 or 4 units for each unit input - the reality for the majority is that their systems don't achieve anything like that figure.0
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