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  • FIRST POST
    • richardc1983
    • By richardc1983 4th Feb 09, 1:03 AM
    • 1,981Posts
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    richardc1983
    Air to Air Heat Pumps/Air Con - Full Info & Guide
    • #1
    • 4th Feb 09, 1:03 AM
    Air to Air Heat Pumps/Air Con - Full Info & Guide 4th Feb 09 at 1:03 AM
    With all the posts ongoing here regarding heat pumps etc I have decided to start a new post I have put together with information on reverse cycle air conditioning (heat pumps), where people can ask questions, chat about heat pumps, discuss experiences, installs, electricity usage & anything else heat pumps related.
    Theres a lot of info here to take in, please do read it all as this may just


    How does it work?

    It's actually quite simple. Air conditioners work in much the same way as your refrigerator except there are two separate, but integral, parts to the system. There is an outside unit housing the compressor that is similar to the exterior back of your fridge. It draws warmth from the outside air in even the coldest of weather. That warmth is then transferred inside the home using a refrigerant process through a piping system powered by an indoor fan unit that is typically mounted to the wall. This is why the system is also often referred to as a heat pump rather then air conditioning. Both are in fact the same. Similarly, in summer, the reverse happens. Warm air is drawn from the interior room and expelled by the outside unit.

    Heat Pumps are capable of transferring up to 4kW of heat into a space while only consuming 1kW of electrical energy. The energy efficiency of a heat pump will decreases as the temperature difference between inside and outside becomes greater, even at low temperatures a heat pump can provide 3 times as much heat as a normal electric space heater would provide with the same amount of electricity input. This makes Heat pumps extremely energy efficient.

    "Not all Heat Pumps are designed to continue working where temperatures fall below freezing point"

    The principle of air conditioning always comes down to the same:

    absorb energy in one place and release it in another place

    The process requires an indoor unit, an outdoor unit and copper piping to connect both. Through the piping the refrigerant flows from one unit to another. It is the refrigerant that absorbs the energy in one unit and releases it in the other.
    Cooling mode (Heating mode is the same but in reverse)

    1 Indoor unit
    A fan blows the hot indoor air over a heat exchanging coil through which cold refrigerant flows. The cold refrigerant absorbs the heat from the air and cooled air is blown into the room.
    2 Copper piping
    The refrigerant circulates through the units and the piping and takes the heat from the indoor unit to the outdoor unit.
    3 Outdoor unit
    Through compression, the refrigerant gas is heated and its boiling point increases. In the outdoor unit the obtained heat throught compression is released to the outdoor air by means of a fan which blows the outdoor air over a heat exchanging coil.
    4 Refrigerant
    The liquid refrigerant flows back to the indoor unit.
    5 Indoor unit
    Back in the indoor unit, the refrigerant is decompressed and thus enabled to extract heat form the indoor air.



    Comparison of 2400w fan heater & Heat Pump Running Costs:

    http://www.bdt.co.nz/comfortmaster/data/guides/WinterRunningCostsComparison.pdf - this is for Mitsubishi Electric but savings made on other manufacters however these will vary.

    Inverter Technology:

    Here's some info about inverters, the same applies across all manufacturers however efficiency levels are different but the operation side of things is the same. There is an article at the bottom from Mitsubishi Electric where they have done a comparison test for a fan heater and heat pump. This is not unique to Mitsubishi Electric, similar costs will be seen across all heat pumps... its a very efficient technology. Different manufacturers will have different efficiencies. The best manufacturers are Mitsubishi Electric, Daikin, Mitsubishi Heavy Industries, Fujitsu, Sanyo, LG, any other manufactures are entry level and will not offer as good quality systems or efficiencies.

    Inverter systems save energy by using a variable controlled Compressor. The output is controlled to only provide the energy required to keep the room to the set temperature. By reducing the output required less power is used and this substantially reduces power consumption. Inverter control not only saves you money but also keeps you more comfortable.


    Inverter System or Fixed Speed System?

    What is a Fixed Speed Split System?

    This system only has a single speed compressor motor that is either on or off.

    It works similar to a fan heater that switches off when the desired temperature is reached and on again when the temperature drops to a set level. It speeds up or slows down to calculate the heat loss from the space to be heated ensuring it is only putting in the same amount of heat that the space is losing.

    What does Inverter Mean?

    Inverter technology uses a variable speed compressor motor similar to a car. It simply slows down and speeds up as needed to hold a selected comfort setting.

    Inverter technology provides a more precise room temperature without the temperature fluctuations of fixed speed systems.

    Inverter vs Fixed Speed:

    Inverter Systems are Approximately 30% more efficient than fixed speed systems.

    Inverter systems reach desired room temperature quicker.

    The speed control of the outdoor unit also means quieter operation, this is important especially at night in residential areas.









    Inverter Systems
    • Increased output to achieve set temperature faster.
    • Then varies the output to maintain a constant room temperature.








    Fixed Speed Type
    • Slowly gets to temperature as output rating is fixed.
    • Then turns on and off to maintain room temperature.
    Sizing of units:

    Read the following guide for sizing info: Excuse the references to Australia and New Zealand this contains useful info:

    http://www.bdt.co.nz/comfortmaster/data/guides/heatpump_sizing_quideline.pdf


    What type of unit is best suited for your property:

    Heat Pumps / Air Conditioners are manufactured with various indoor unit options. High Wall Type, Ceiling Cassette Type, Floor Mounted Type, Concealed Ducted Type, and Under Ceiling Type.


    High Wall-mounted

    The most popular residential unit choice. These units tend to be the quietest as well as taking up no floor space.

    Compact Floor Console

    The floor mounted are more designed for heating applications. They are ideal for space heater or gas fire/fireplace replacement. They can be recess mounted into the wall cavity giving a shallow profile for hallway installation.

    Ceiling Cassette

    The ceiling mounted units take up no floor space. These units have four way air direction and have adjustable air flow patterns. These units are more suited to larger floor areas & commercial properties.

    Ceiling Concealed (Ducted)

    These units are mounted in the ceiling space and are unseen in the conditioned space. The only visible presence is the supply and return air grilles.

    Ceiling Suspended

    These units are more suited to high stud large room areas. They tend to have high airflows and are more suited to commercial applications.

    Multi-Split Systems








    Multiple Indoor Units can be Connected to a Single Outdoor
    • Connect from 2 to 8 Indoor Units
    • Many Combination Patterns to choose
    • Energy Saving and Quiet Operation
    • Five Multi-Split Systems from 6.4kW to 16.0kW (Heating)
    Inverter Multi-Split system models are designed to allow several indoor units (regardless of capacity or type) to be connected to a single outdoor unit. This allows you to select the model best suited to each and every room in your property.


    Example: 3x Bedrooms and 1x Office

    ~


    Location of units:

    Indoors:

    Don’t locate units with obstructions in front.

    Result:


    Short cycling of air back to units room sensor making the unit think its wamer/cooler than it actually is.
    Air is not circulated correctly leaving cold/hot areas in room.

    Try to locate the indoor unit where the airflow is pointing to the other areas of the house that may require residual heating/cooling.

    Outdoors:

    Avoid paved areas unless a drain kit is fitted. Result: Units condensate and drip water. May cause slime build up or ice. If no other place please advise customer.

    Noise:
    Outdoor inverter units are very quiet and have scroll compressors, watch the following video and you will see mine in action:
    http://www.youtube.com/watch?v=-mUzYHEfQEY


    Defrost Cycles & Correct Sizing of Outdoor Unit:
    Defrost will happen in all climates, however the lower the humidity the less frequent it will defrost as it takes longer for it to build up on the outdoor coil.

    You will probably not even notice it defrosting, if you buy a decent brand system you will find that the defrost strategy is very good so that it doesn’t take long to defrost.

    When they defrost you will find that the system goes into reverse, taking heat from the inside circuit to the outdoor unit so it defrosts. This will last about 5 minutes depending on how much ice has built up but you have to look at the unit to notice it doing it as it doesn’t start making things cold inside. The unit just doesn’t heat during that time.

    Some units in New Zealand or other countries that have very cold winters have units optimised for that country, i.e. defrost cycles instead of stopping and going into reverse will inject hot gas into the outdoor unit whilst the unit is heating so that it doesn’t actually stop heating. Currently can only find info on Sanyo air to air heat pumps in this country that do this... not sure of a system that does this on a unit that will provide this on hot water but you can see the technology is there. As I say you don’t need it in the UK climate our winters are not as harsh as some countries.

    The best method for new builds is under floor heating, nice even temps throughout, however longer warm up times due to the lower water temperature but if left on during cold weather you will be fine.

    I personally prefer fan coil units as these double up as cooling/ac for the summer and provide very fast warm up times.

    Most air to water outdoor units can be used with fan coil units... you just use a fan coil instead of a water coil in the floor.

    Mounting of unit... must be installed in the open, no enclosure, so no garages, lofts or corners the unit must be in the open air.

    A user in another post:

    http://forums.moneysavingexpert.com/showthread.html?p=29040015#post29040015

    He installed it in the loft and it froze the loft in the cold weather and thawed and caused leaks into the house below, this happened twice and after this he decided to mount the unit outside and it performed better as it was effectively turning the loft into a giant fridge/freezer.

    Here’s some more info on heat pumps:



    Defrost Strategy

    When the outside temperature drops below zero all heat pumps must perform a “defrost cycle” to remove ice build up on their outdoor coils.

    Defrost strategy is determined by individual Heat Pump manufacturers. These strategies vary greatly between brands. Older style Heat Pumps initiated defrost by a fixed time or coil temperature. This system was not efficient as it often caused Heat Pumps to defrost too often or effected performance by not defrosting often enough. Defrost cycle is required when the outdoor coil is too cold or covered in ice preventing heat transfer and unit performance.

    All Heat Pumps must defrost. heats pumps utilise a Fuzzy Logic software program, a form of Artificial Intelligence contained in the chip of the outdoor unit and typically lasts between 3 to 5 minutes.

    The program measures and records:

    - Ambient Temperature
    - Outdoor Coil Temperature
    - Accumulated Continuous Heating Running Times
    - Defrost Initiation Time and Termination Times

    The program optimises this data based on history to produce defrost initiation only when absolutely required.

    This is important as Heat Pumps are unable to produce heat when they are in defrost mode. This is extremely important to real performance in low ambient conditions.

    Defrost Cycle Management

    Heat Pumps optimise its defrost cycle once selected in three ways:
    When the outside temperature drops below zero all heat pumps must perform a “defrost cycle” to remove ice build up on their outdoor coils.

    Defrost strategy is determined by individual Heat Pump manufacturers. These strategies vary greatly between brands. Older style Heat Pumps initiated defrost by a fixed time or coil temperature. This system was not efficient as it often caused Heat Pumps to defrost too often or effected performance by not defrosting often enough. Defrost cycle is required when the outdoor coil is too cold or covered in ice preventing heat transfer and unit performance.

    The program measures and records:

    - Ambient Temperature
    - Outdoor Coil Temperature
    - Accumulated Continuous Heating Running Times
    - Defrost Initiation Time and Termination Times

    The program optimises this data based on history to produce defrost initiation only when absolutely required.

    This is important as Heat Pumps are unable to produce heat when they are in defrost mode. This is extremely important to real performance in low ambient conditions.



    1. Compressor Control
    When a Heat Pump is defrosting it is not providing heat to the controlled space. It runs the compressor(inverter drive) at maximum speed during defrost to bring the outdoor coil up to temperature as quickly as possible. This melts any ice formed on the coil fins quickly and minimises defrost time. Minimising defrost time maximises heat output per hour real time.

    2. Dry Coil Defrost Cycle
    Once the outdoor coil is up to temperature and the compressor cycle has completed there is generally water between the outside coil fins. If the outdoor unit were to immediately resume heating the outdoor coil would freeze and prevent heat exchange. To prevent this the outdoor fan is run at maximum speed prior to resumption of the heating cycle. This is often characterized by steam blowing from the outdoor unit. This ensures the coil is completely dry before the heating cycle resumes.

    3. Time optimization through Fuzzy Logic
    Time between defrost cycles is continually being reviewed and optimized by the Heat Pump microprocessor software. Algorithmic calculations based on previous history is used to calculate the next defrost period.

    Fuzzy Logic or learning logic is a form of artificial intelligence. Defrost cycle termination is based on a combination of time and temperature. These parameters are used to calculate the next defrost period.

    Outdoor Humidity
    Outdoor humidity also effects heating performance. Areas that have a “dry cold” or low humidity such as “Mount Cook” will perform better at low ambient than say Taupo where ambient conditions can reach zero and “misty” moisture laden air conditions exists. The more moisture in the air the more moisture will freeze on the outdoor coil.

    Incorrect Unit Selection
    If a unit is selected that is too small the Heat Pump will run continuously and never reach set point. This continuous running will increase defrost requirements by reducing the outdoor coil running temperature and driving it into sub zero temperatures for excessive periods. The unit will defrost at the minimum intervals and may never catch up and achieve set point.

    Location of Outdoor Unit
    Location of the outdoor unit is essential for low ambient performance. Units located under houses, decking and in areas where airflow is impeded may create their own microclimate (i.e. giant fridge/freezer or in summer oven) and reduce the effective outdoor ambient temperature that the units operates in. Locating the outdoor unit too close to a wall and not observing clearances will also prevent the unit from delivering full output.


    Get the correct sized unit:
    Choosing the right sized Heat Pump is key to ensuring optimum comfort levels. Every home is as individual as its owner. The key to selecting the right Heat Pump for heating your home is choosing the correct unit size. Choosing the wrong size can cost you more in power consumption.


    Insulation and building orientation are key aspects in terms of potential heat loss a home is effected by. An older style home with poor insulation will lose indoor heat much quicker than a modern well insulated home that faces north.
    The quicker a home loses its heat, the bigger the Heat Pump system will need to overcome this heat loss.
    Last edited by richardc1983; 03-01-2011 at 3:00 PM.
Page 89
    • cazz04
    • By cazz04 11th Feb 19, 11:19 AM
    • 2 Posts
    • 0 Thanks
    cazz04
    Thank you, glad to here the high winds will not cause problems but possible PCB doesn't sound like a quick fix.
    • richardc1983
    • By richardc1983 11th Feb 19, 11:32 AM
    • 1,981 Posts
    • 1,031 Thanks
    richardc1983
    Thank you, glad to here the high winds will not cause problems but possible PCB doesn't sound like a quick fix.
    Originally posted by cazz04
    They are designed for the elements but if the install team did not screw a cover on properly then they are liable.

    If your landlord is slow in dealing with this then you should speak with the council who may be able to intervene and push things forward with your landlord.
    If you found my post helpful, please remember to press the THANKS button! --->
    • Dal Whinnie
    • By Dal Whinnie 19th Feb 19, 10:22 AM
    • 166 Posts
    • 56 Thanks
    Dal Whinnie
    This is a very interesting thread, Thankyou. I have had a phone call this morning wanting to arrange an energy inspection under the Government Renewable Heat Incentive scheme and about installing an Air Source Heat Pump.

    I am always very nervous about these calls but am interested in reducing energy costs and using renewables so should I proceed with this offer?
    • helpjack
    • By helpjack 20th Feb 19, 7:38 AM
    • 55 Posts
    • 62 Thanks
    helpjack
    Dal Whinnie

    Please don't respond to an unsolicited call. The technology is still being developed there are lots of opportunities for very costly mistakes. If you are interested do your research and find your own recommended company.

    The company I used were very experienced and still made mistakes which is costing me a small fortune to sort out now as they dissolved themselves to avoid dealing with it.

    Do you have gas already. If you do then just stick with that.

    In my situation, I needed to install a heating system anyway and as there was no gas where I lived and an ASHP seemed a good choice. The RHI is just a bonus. It is not worth changing an existing functioning system for.
    • richardc1983
    • By richardc1983 20th Feb 19, 7:46 AM
    • 1,981 Posts
    • 1,031 Thanks
    richardc1983
    This is a very interesting thread, Thankyou. I have had a phone call this morning wanting to arrange an energy inspection under the Government Renewable Heat Incentive scheme and about installing an Air Source Heat Pump.

    I am always very nervous about these calls but am interested in reducing energy costs and using renewables so should I proceed with this offer?
    Originally posted by Dal Whinnie
    Gas is still cheaper per unit than electricity in this country anyway. However a heat pump produces more heat per kw than a gas boiler does but the cost of gas is what wins.

    If you have mains gas stick with that if your boiler is very old then a heat pump would be more efficient.

    Certainly do not respond to cold callers.
    If you found my post helpful, please remember to press the THANKS button! --->
    • matelodave
    • By matelodave 20th Feb 19, 8:04 AM
    • 4,669 Posts
    • 3,004 Thanks
    matelodave
    Do not respond to cold callers and do not be persuaded to get one installed before doing your own research and making sure you thoroughly understand how they work, how the system should be designed and how to operate them efficiently before getting quotes from reputable MCS registered installers.

    Don't think that an ASHP is cheaper to run than a mains gas boiler, it isn't. Neither will it just replace the boiler on an exsiting system.

    It's unlikely that the existing radiators are properly sized to allow the heat pump to run efficiently so unless the whole system is redesigned to suit the heat pumps characteristics, you will be very disappointed with the performance and even more disappointed with the increased costs of running the system.
    Last edited by matelodave; 20-02-2019 at 8:11 AM.
    Never under estimate the power of stupid people in large numbers
    • Therooster100
    • By Therooster100 4th Mar 19, 9:51 AM
    • 18 Posts
    • 1 Thanks
    Therooster100
    Hi all,
    Looking into Air Source Heat Pump as the house (3 story 5 bedroom with 2 people living there) is fully electric as no gas in the area.
    I have tried finding some reliable installers but it is proving difficult. Where is the best place to look?
    • richardc1983
    • By richardc1983 12th Mar 19, 10:27 AM
    • 1,981 Posts
    • 1,031 Thanks
    richardc1983
    Hi all,
    Looking into Air Source Heat Pump as the house (3 story 5 bedroom with 2 people living there) is fully electric as no gas in the area.
    I have tried finding some reliable installers but it is proving difficult. Where is the best place to look?
    Originally posted by Therooster100
    What area are you in?
    If you found my post helpful, please remember to press the THANKS button! --->
    • matelodave
    • By matelodave 12th Mar 19, 10:44 AM
    • 4,669 Posts
    • 3,004 Thanks
    matelodave
    without too much effort I typed Air Source Heat Pump Installers into Google and got well over 20 who would service the area that I live in. A couple more clicks to enter my post code and I would have narrowed it down a bit further.

    I'd advise that you do your research first - do your own heat calculations so you've got some idea of the heating requirement for your house (even look at your EPC if you've got one) so you've got some idea of what size unit you require. Look at the heat requirement for each room as well, remembering that radiators have to be properly sized to take advantage of the lower flow temperatures.

    Get several quotes at least three, ideally more to compare specifications before just comparing prices. Investigate those that are significantly different. Compare unit size, configuration, radiator sizes and heating calculations. Do lots of research so you know how they work and how to use them - check on the MCS website and make sure that you get a full breakdown of what you are being offered.

    When you are satisfied that offered specifications do cover your requirements then you can compare prices and installers.

    An underpowered unit may cost less to install but wont do the job and will cost you dearly in running costs, especially if it has to use the boost/back-up heaters. Likewise a slightly oversized one might cost more initially. I'd err on the slightly too big rather than too small.
    Never under estimate the power of stupid people in large numbers
    • matelodave
    • By matelodave 8th Apr 19, 7:01 PM
    • 4,669 Posts
    • 3,004 Thanks
    matelodave
    Air source heat pumps.
    An air source heat pump (ASHP) is a system which transfers heat from outside to inside a building or vice versa.
    Originally posted by Ethan75
    ??????????????????? and ???????
    Never under estimate the power of stupid people in large numbers
    • richardc1983
    • By richardc1983 8th Apr 19, 8:12 PM
    • 1,981 Posts
    • 1,031 Thanks
    richardc1983
    ??????????????????? and ???????
    Originally posted by matelodave
    Words and pictures haha
    If you found my post helpful, please remember to press the THANKS button! --->
    • Mamahope
    • By Mamahope 28th Jun 19, 8:09 PM
    • 12 Posts
    • 2 Thanks
    Mamahope
    Is it fair to say that the running costs of an air/water heat pump are only actually cheaper in cases where the household would otherwise have conventional heating also on quite a lot?

    Last 12 months we only used 600L of oil (20yo boiler) and 35 nets of kiln-dried in our termatech woodburner (3-7kw output) (total for oil + wood = £361). Couple of showers a day, electric dishwasher, our core hours for heating mainly 4-9pm plus the occasional cold morning, rads off in most bedrooms except for perhaps 30 mins before bed (west Cornwall, south-facing, 3/4 bed semi, good insulation, like to open windows to ventilate even on cold winter mornings).

    Plus, If you're meant to run an air/water 24/7 does that mean you can't open the windows much in winter?
    Last edited by Mamahope; 28-06-2019 at 8:30 PM.
    • matelodave
    • By matelodave 20th Jul 19, 7:16 AM
    • 4,669 Posts
    • 3,004 Thanks
    matelodave
    We live in a rural area in the UK and recently installed an 18kW air source heat pump to switch from an oil boiler. So far it’s been great.
    Originally posted by Home Farm
    Glad to hear it - have you gone through a winter with it yet. Was the heating system upgraded or did you just bung the heatpump on in place of the old boiler.
    Never under estimate the power of stupid people in large numbers
    • fredwnelson
    • By fredwnelson 23rd Jul 19, 8:35 AM
    • 7 Posts
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    fredwnelson
    Economy 18
    Eon have informed me that the E18 tariff is being withdrawn. This currently enables me to run my ASHP system for 9.04 p per KwH. Does anybody have any advice as to which tariff or supplier to go for? The system runs 24/7 and uses 14000 kWh per annum
    • zeupater
    • By zeupater 23rd Jul 19, 10:41 AM
    • 4,945 Posts
    • 6,693 Thanks
    zeupater
    Eon have informed me that the E18 tariff is being withdrawn. This currently enables me to run my ASHP system for 9.04 p per KwH. Does anybody have any advice as to which tariff or supplier to go for? The system runs 24/7 and uses 14000 kWh per annum
    Originally posted by fredwnelson
    Hi

    14MWh of energy to run a heat-pump equates to an average heating demand of around 5kWh on a 24*7*52 basis ... either you live in a mansion, there's little insulation, the heat-pump is constantly needing to use resistance based immersion backup or maybe you're looking at heat provision in kWh.t as opposed to electricity used?

    ... can you provide more info ....

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • fredwnelson
    • By fredwnelson 23rd Jul 19, 11:19 AM
    • 7 Posts
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    fredwnelson
    Apologies it is 6700 on heating and 14000 in total. The house is modern, energy rating B, has amazing insulation and also Solar for hot water
    • zeupater
    • By zeupater 23rd Jul 19, 1:12 PM
    • 4,945 Posts
    • 6,693 Thanks
    zeupater
    Apologies it is 6700 on heating and 14000 in total. The house is modern, energy rating B, has amazing insulation and also Solar for hot water
    Originally posted by fredwnelson
    Hi

    So that's a space heat demand of upwards of 20000kWh/year in a modern house with 'amazing insulation' plus an additional 7300kWh of general electricity demand ?? .... and above that it's also got the benefit of solar thermal ??

    A modern large(ish) well insulated property would likely have a space heating demand approaching half of that figure, additionally, most would also be consuming around half of the additional electricity before taking steps to improve efficiency (LED TV, lights etc!) ....

    For comparison .... our property is around 3x average in size, has PV, solar thermal, small heat-pump, log burner & GCH for deep winter heat top-up / DHW backup with all of this supported by insulation levels far beyond the minimum required by regulations .... we average around 10% of that total level of electricity purchases plus an additional approx 1000kWh of gas and somewhere around 2000kWh of logs for direct space heating, so it looks like they're plenty of scope available to reduce 14MWh of electricity purchases if you're prepared to look for it! ....

    Anyway, regarding the tariff, have a look at least one of the price comparison sites, they should provide sole leads to what you're looking for.


    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • Cardew
    • By Cardew 23rd Jul 19, 2:17 PM
    • 27,974 Posts
    • 13,832 Thanks
    Cardew
    Apologies it is 6700 on heating

    Hi

    So that's a space heat demand of upwards of 20000kWh/year in a modern house

    HTH
    Z
    Originally posted by zeupater

    You appear to be assuming that the System COP of fredwnelson's ASHP is well over 3.0. If you look at the any of the independant trials of ASHPs only a few achieve a COP of 3.0.


    The requirement for an ASHP to run 24/7, or at least very long hours, means it compares unfavourably with conventional gas/oil CH systems in terms of overall heat requirement.


    Most people with gas/oil CH shut off, or turn down the thermostat, overnight or when they are out during the day. With the high water temperature available it will quickly bring the house up to the required temperature.



    The low water temperature of an ASHP means it has to run much longer hours producing heat that is not required at night or when occupants are out during the day.
    • fredwnelson
    • By fredwnelson 23rd Jul 19, 4:18 PM
    • 7 Posts
    • 0 Thanks
    fredwnelson
    Thanks for the responses. The ASHP is a Daikin Altherma 11Kw installed in 2013. Everything I have read says to leave the unit switched on 24/7 and manage through room stats which we do. We keep them at 18C. We also have a woodturner which we only use very occasionally on very very cold days
    • fredwnelson
    • By fredwnelson 23rd Jul 19, 4:21 PM
    • 7 Posts
    • 0 Thanks
    fredwnelson
    Thanks. Not sure where the 20000kwh derives. The house and small development won an award for Green Development of the Year in 2013. Insulation and build of the highest quality levels Energy rating of B (1 point off being A)

    The key issue is the change of tariff by Eon. I need to find out from them how to get the meter changed from E18 and what tariff will work best for me (probably not E7 or E10 methinks)
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