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  • FIRST POST
    • richardc1983
    • By richardc1983 4th Feb 09, 2:03 AM
    • 1,889Posts
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    richardc1983
    Air to Air Heat Pumps/Air Con - Full Info & Guide
    • #1
    • 4th Feb 09, 2:03 AM
    Air to Air Heat Pumps/Air Con - Full Info & Guide 4th Feb 09 at 2:03 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 4:00 PM.
Page 83
    • skhell
    • By skhell 20th Sep 16, 5:28 PM
    • 4 Posts
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    skhell
    Considering all points your going to need some form of cooling so I would just go with an air conditioning heat pump system. So you could look at a multi split system where you have several indoor units connected to one outdoor unit, the only thing with these are all indoor units have to be on the same mode either heating or cooling but you can have individual room set points so bedroom at 21 and lounge at 23 etc. There is also a VRV or VRF systems available that connect to one outdoor unit via fan coils and you can have the flexibility to have different operation modes in diff rooms so your lounge could be at 23C cooling and your bedroom at 21C heating - the heat recovered from the lounge cooling is recycled and used to heat the bedroom.
    Originally posted by richardc1983
    I think heating and cooling at the same time will not be needed. At least until now I never had the need for it.

    In Spain and other Europe countries where Air Con is essential they use the air con to heat in winter as standard. So I would personally go for a multi split system or the more expensive VRV or VRF.
    A multi split AC system is one the solutions that I am considering. They are more affordable and very efficient.

    What is the difference between a VRV/VRF system and a multi-split AC system? I have read about it, but can't seem to understand the differences...
    • richardc1983
    • By richardc1983 20th Sep 16, 5:43 PM
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    richardc1983
    A standard split is 1 indoor connected to 1 outdoor unit. A multi split is several indoor units connected to 1 outdoor unit - thus multi.

    The folllowing technologies are the same but two diff manufacturers Mitzi and daikin named them separately. VRF - variable refrigerant flow, VRV - variable refrigerant volume are connected the same way as a multi split unit. Multiple indoor to one outdoor, the difference is that they are 3 pipe systems so instead of having just liquid and gas pipes back to the outdoor unit you have a third pipe, this third pipe allows for heat recovery and this system is ideal when simultaneous heating and cooling is required in a building - e.g. Office or hotel complex. This can also be utilised if heating is not required for water heating which is why I recommended this option also. Cost though is more for vrv vrf. Manufactures to look at for multi systems deffo have a look at LG who are now very good and affordable along with the higher end stuff which is Mitsi, daikin etc.
    If you found my post helpful, please remember to press the THANKS button! --->
    • Cardew
    • By Cardew 20th Sep 16, 5:47 PM
    • 27,114 Posts
    • 13,226 Thanks
    Cardew
    Agree with Richards points above.

    One point not mentioned is the potential problem of noise, both for yourself and neighbours. An issue that needs to be considered in the design of the house.
    • richardc1983
    • By richardc1983 20th Sep 16, 5:56 PM
    • 1,889 Posts
    • 1,006 Thanks
    richardc1983
    Agree with Richards points above.

    One point not mentioned is the potential problem of noise, both for yourself and neighbours. An issue that needs to be considered in the design of the house.
    Originally posted by Cardew
    Outdoor units are generally very quiet now unless u go for cheap rubbish.
    If you found my post helpful, please remember to press the THANKS button! --->
    • skhell
    • By skhell 21st Sep 16, 9:03 AM
    • 4 Posts
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    skhell
    Excellent explanation of the VRV/VRF systems. Now I know the differences between these systems and a AC Multi-split system.

    About the external noise, I have also considered that. This could also be a problem if using a heat-pump, but I think it will not be a problem. In the house where I live now, we have two Daikin standard split units, and although they are entry line models, they are very very quiet. Also, I guess that all neighbors have or will have AC units
    • Uclan
    • By Uclan 9th Jan 17, 12:00 AM
    • 12 Posts
    • 0 Thanks
    Uclan
    It is interesting to read the comments on this forum having not visited it for 4 years. I had my heat pump installed nearly 4 years ago and in that time it totally contradicts most of the negative comments on here. It is quiet. It is cheap to run. It heats up a 178sq. metre 4 bedroom house in less than half an hour. It heats up a 210 litre tank of hot water up to 55 degrees in less than an hour and up to 60 degrees once a week with the help of a timed immersion. It heats up 11 bedrooms in the house by use of radiators not by underfloor means. In the four years I have used it it has not had one call out. If it had needed it the system was covered for parts and labour for 3 years. It is now covered by anextendedwarranty. I get 116 pounds every 4 months for the next 7 years in RHI payments. This would have been more but I had previously been given 850 pounds grant.
    My payments for last year were 96 pounds a month to EON. This included all my electricity usage i.e computers, dishwasher,washing machine etc. At the end of the year I was 180 pounds in credit on my bill.
    Having previously lived in a duel fuel house we were paying about 150 pounds a month and that was 7 years ago.
    I own a caravan and that is double glazed etc. and has gas central heating. The radiators get very hot quickly but the caravan is still bloody cold because of its poor insulation.
    That is the key. Insulate a house properly and your heat pump will work. Find an installer and a recommended heat pump and the system will work.
    I have used both gas and a heat pump and if I had a choice I would choose a heat pump every time especially in a well insulated new property.
    Why? For the simple reason that a heat pump is far healthier. No more dry throats and headaches associated with the 80 degree temperatures of agasheated radiator and no
    • Uclan
    • By Uclan 9th Jan 17, 12:34 AM
    • 12 Posts
    • 0 Thanks
    Uclan
    [carry on as I pressed the wring button- now where was } singed fingers from touching them. No danger of gas leaks or explosions or carbon monoxide poisoning.
    We should be looking to install a combination of heat pumps and solar panels,which I do not have, in all newly built houses. If we did this then we could fetch down the costs and enable the industry to expand asit hasdone in Europe. The price of electicity should also be reduced and cheaper gas should be used to produce that electrity.
    I forgot to mention the fact that when my wife and I were working I used the system and still do when required on a timed system i.e. if we finished at 5 then I put the timer on to come on at 4.30. The house was always warm as it is every morning when I put it to come on every morning in the winter.
    As for the myth of the 24/7 heat pump it is set to on put is controlled at different times by a thermostat as we are both at home most days. It is set to 20 degrees from 6.30-8.00am and after that down to 19 degrees from 8.00 to 16.00 when it is set to 21degrees til 22.30. If it is colder then you can increase or decrease the temperature as apropriate. Between these times once the temperature is reached the heat pump will switch off. It is set at 17 degrees from 22.30 til 6.30. All these temperatures can be easily adjusted to suit us.
    This is how my system works. The house is over 7 years old and has not been updated to accommodate the system. These are just the facts.
    • Uclan
    • By Uclan 9th Jan 17, 12:42 AM
    • 12 Posts
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    Uclan
    Sorry about some of the joined up writing and spelling errors. Just to clarify I get 116 pounds every three months.
    • Cardew
    • By Cardew 9th Jan 17, 10:02 AM
    • 27,114 Posts
    • 13,226 Thanks
    Cardew
    It is interesting to read the comments on this forum having not visited it for 4 years. I had my heat pump installed nearly 4 years ago and in that time it totally contradicts most of the negative comments on here.
    Originally posted by Uclan
    You are obviously getting satisfactory results from your system. However not everyone is so lucky!

    A recent BBC report highlighted the poor performance of heat pumps and referred to the EST report for field trials on Heat pumps - particularly on ASHPs. http://www.energysavingtrust.org.uk/...mp-field-trial

    Or try this http://www.energysavingtrust.org.uk/Media/node_1422/Getting-warmer-a-field-trial-of-heat-pumps-PDF

    The study was a year long and had 29 ASHP systems from a number of manufacturers.(who installed the systems)

    It is quite a long report but of the 29 ASHP systems the annual COP for 19 of the systems was 2.2 or less(the highest number had a COP of 1.6). So if that is an average spread across 12 months - little wonder systems are struggling in this current weather. In fact with the requirement for wasteful defrosting cycles, it is quite easy to envisage a situation with some systems where there will be a COP of less than 1.0 and people would be better to switch off the ASHP and rely on Granny's old 1/2/3 bar fire!!!!!!

    It is also pertinent to point out(as I have before!!) that when considering the COP of ASHPs firms never take into account that the heat produced when occupants are out of the property, or in bed, is wasted. For instance it might be necessary to keep the ASHP running 24/7 because of the inability of the system with low temperature water to quickly bring the house up to temperature. It might be that, say, 30kWh will be produced when occupants are out or in bed.

    With gas/oil CH with water at 80+C there is no need to heat the house when occupants are out/in bed, as 20-30 minutes will bring a house up to heat. Yet in the inevitable comparisons of running costs, the 'unwanted' 30kWh is always used to swing the comparison in favour of heat pumps – and still fails!

    Now the trial was for 29 systems with the manufacturers involved over 12 months, all with a vested interest in getting good results and the results are frankly a disaster.

    Virtually all the adverts talk of a COP(system efficiency) of 3 or greater, yet only one verified result achieved 3.0(there was an estimated 3.2)

    Small wonder there are so many people on MSE complaining about their system’s performance and costs. Especially given there is normally reluctance for people to admit that something that has cost them £thousands is a disappointment.

    It can’t just be the setting up of the system or none of the 29 systems in the trial – with the manufacturer at hand – would have performed so poorly; it must be more fundamental.

    If the manufacturer monitored systems produced such poor results, I wonder what results a random check of properties with unsuitable or poorly installed systems would produce!!!

    The ‘experiments’ owners are having to carry out in order to improve performance require some considerable technical knowledge. I shudder to think how many of the population could cope. The system should be set up by the installation company and be simple for the user to operate.

    Frankly IMO it is irresponsible to recommend that anyone spends £thousands on installing an ASHP system where the results seem to be a lottery, and virtually nothing meets the manufacturer’s claimed performance.


    • richardc1983
    • By richardc1983 9th Jan 17, 10:19 AM
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    • 1,006 Thanks
    richardc1983
    It is interesting to read the comments on this forum having not visited it for 4 years. I had my heat pump installed nearly 4 years ago and in that time it totally contradicts most of the negative comments on here. It is quiet. It is cheap to run. It heats up a 178sq. metre 4 bedroom house in less than half an hour. It heats up a 210 litre tank of hot water up to 55 degrees in less than an hour and up to 60 degrees once a week with the help of a timed immersion. It heats up 11 bedrooms in the house by use of radiators not by underfloor means. In the four years I have used it it has not had one call out. If it had needed it the system was covered for parts and labour for 3 years. It is now covered by anextendedwarranty. I get 116 pounds every 4 months for the next 7 years in RHI payments. This would have been more but I had previously been given 850 pounds grant.
    My payments for last year were 96 pounds a month to EON. This included all my electricity usage i.e computers, dishwasher,washing machine etc. At the end of the year I was 180 pounds in credit on my bill.
    Having previously lived in a duel fuel house we were paying about 150 pounds a month and that was 7 years ago.
    I own a caravan and that is double glazed etc. and has gas central heating. The radiators get very hot quickly but the caravan is still bloody cold because of its poor insulation.
    That is the key. Insulate a house properly and your heat pump will work. Find an installer and a recommended heat pump and the system will work.
    I have used both gas and a heat pump and if I had a choice I would choose a heat pump every time especially in a well insulated new property.
    Why? For the simple reason that a heat pump is far healthier. No more dry throats and headaches associated with the 80 degree temperatures of agasheated radiator and no
    Originally posted by Uclan
    Its good you are getting good results from your heat pump system. Installed correctly (like any other heating system) you will experience good results. I fully support heat pumps systems BUT argue that if you have mains gas supply to the property you would be better off with a condensing gas boiler. Gas is still cheaper per unit than electricity and will be for some time into the future. Electricity is expensive in the uk. A heat pump is the best solution if you don't have mains gas.

    You say you run your heat pump at 55C well you could also run a combi boiler at 55C you don't need to run it at 80C and you would get the same results as your getting from your heat pump, only your bills would be even cheaper. I have a friend who was misold a heat pump when she came to replace her old boiler, her bills tripled, even though she had all the upgrades to radiator sizes and system installed correctly as verified by various experts and consultants. The company who installed it went out of business so its now at her cost to remove the system and replace with a gas boiler.

    While there is mains gas, use it it will always be cheaper in this country. If there isn't then install a heat pump. If you don't like the high temps that a gas combi/condensing boiler "can" produce then reduce your flow temp, the lower the better as its even more efficient. I run my gas combi boiler with a max flow temp of 60C the opentherm does the rest as the house comes upto temp it reduces the flow down temp to as low as 30C if need be.
    If you found my post helpful, please remember to press the THANKS button! --->
    • zeupater
    • By zeupater 9th Jan 17, 5:41 PM
    • 3,816 Posts
    • 4,728 Thanks
    zeupater
    It is interesting to read the comments on this forum having not visited it for 4 years. I had my heat pump installed nearly 4 years ago and in that time it totally contradicts most of the negative comments on here. It is quiet. It is cheap to run. It heats up a 178sq. metre 4 bedroom house in less than half an hour. It heats up a 210 litre tank of hot water up to 55 degrees in less than an hour and up to 60 degrees once a week with the help of a timed immersion. It heats up 11 bedrooms in the house by use of radiators not by underfloor means. In the four years I have used it it has not had one call out. If it had needed it the system was covered for parts and labour for 3 years. It is now covered by anextendedwarranty. I get 116 pounds every 4 months for the next 7 years in RHI payments. This would have been more but I had previously been given 850 pounds grant.
    My payments for last year were 96 pounds a month to EON. This included all my electricity usage i.e computers, dishwasher,washing machine etc. At the end of the year I was 180 pounds in credit on my bill.
    Having previously lived in a duel fuel house we were paying about 150 pounds a month and that was 7 years ago.
    I own a caravan and that is double glazed etc. and has gas central heating. The radiators get very hot quickly but the caravan is still bloody cold because of its poor insulation.
    That is the key. Insulate a house properly and your heat pump will work. Find an installer and a recommended heat pump and the system will work.
    I have used both gas and a heat pump and if I had a choice I would choose a heat pump every time especially in a well insulated new property.
    Why? For the simple reason that a heat pump is far healthier. No more dry throats and headaches associated with the 80 degree temperatures of agasheated radiator and no
    Originally posted by Uclan
    Hi

    Although I really like to think that heat-pumps in the right settings are a great solution, I really don't follow much of the content in the above post and the ones which followed ...

    Previous posts (2013 etc) described coming from a cheap Chinese made unit which the builder originally installed, to a more efficient brand (8.5kW Ecodan ?) ... if so there must be some pretty interesting technologies and materials involved in the property design in order to achieve the rate of temperature changes described, especially with a Delta-T of 35C ... we can't meet those rates of change with 30kW and a Delta-T of 50C and we're massively insulated ....

    ... Whilst talking about 'massively insulated', we find that overnight heat-loss reduces the hall temperature by well below 1C, therefore I really can't see the benefit of such a wide temperature variation pattern as described in the quote below ...
    ... As for the myth of the 24/7 heat pump it is set to on put is controlled at different times by a thermostat as we are both at home most days. It is set to 20 degrees from 6.30-8.00am and after that down to 19 degrees from 8.00 to 16.00 when it is set to 21degrees til 22.30. If it is colder then you can increase or decrease the temperature as apropriate. Between these times once the temperature is reached the heat pump will switch off. It is set at 17 degrees from 22.30 til 6.30. All these temperatures can be easily adjusted to suit us ...
    Originally posted by Uclan
    .. All this is achieved from one 8.5 kw heat pump ..
    Originally posted by Uclan
    ... unless it's an ultra low thermal mass building I can't follow how a single 8.5kW heat-source could reach the thermostat set-points and allow the contents and structure to be raised and maintained without 24Hr operation, so I'd guess that 24/7 heating is actually being employed, providing background heating at 17C/19C (satisfying the majority of requirement) with a boost to increase the air temperature to 20/21 for a third of the day ....

    ... looks like myth-busting 24Hr operation could be a little premature but what would be interesting would be to look at object and internal structure surface temperatures and how they change during the day - we have huge variations throughout the house, but once allowed to be absorbed nothing really varies much over a day unless we provide literally hundreds of kWh.t into the property per degree C difference ....

    HTH
    Z
    Last edited by zeupater; 09-01-2017 at 5:43 PM.
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • Cardew
    • By Cardew 9th Jan 17, 7:18 PM
    • 27,114 Posts
    • 13,226 Thanks
    Cardew
    Hi
    Previous posts (2013 etc) described coming from a cheap Chinese made unit which the builder originally installed, to a more efficient brand (8.5kW Ecodan ?) ... if so there must be some pretty interesting technologies and materials involved in the property design in order to achieve the rate of temperature changes described, especially with a Delta-T of 35C ... we can't meet those rates of change with 30kW and a Delta-T of 50C and we're massively insulated ....

    HTH
    Z
    Originally posted by zeupater
    Well said zeupater.

    A less polite person might have said the posts were a load of rubbish; with totally unsupportable figures.

    The irony is Uclan is talking about myths!
    • Uclan
    • By Uclan 9th Jan 17, 9:56 PM
    • 12 Posts
    • 0 Thanks
    Uclan
    Those are the facts. I haven't mentioned which company manufactured my heat pump as I am nottrying to promote or sell anything. The heat pump was setby the installer on purchase. All I do is run it on temperature set at the temperatures mentioned. The water comes on twice a day in the afternoon and early morning. I have a smart meter installed which shows my electric usage. My bills are on line and a graph shows what I have used over a year. I have no reason to lie as you have said I have suffered the indignities of a cheap heat pump.
    I am not promoting a said product I am just stating facts. I do not understand how my house can be heated to 23 degrees or more if needed by radiators that are luke warm but it is. Nor do I understand how 11 rooms can be heated for less than the cost of one 2kw electric fire. But as say they say proof is in the pudding or should I say heat pump. If anyone wants to see how it works they are quite welcome to visit . I do not work for any company but realise that a product used extensively and sucessfully in Europe has no reason not to work here. I agree that it has to be sized and installed properly and that the house must be well insulated.
    Finally I
    • Uclan
    • By Uclan 9th Jan 17, 10:11 PM
    • 12 Posts
    • 0 Thanks
    Uclan
    Sorry. I wish this site would stop putting my comments up before I have checked it. Finally as I have said those are the facts . Perhaps I am just 1 of the lucky few with a successful installation. I'll take that. But cost aside if I had a choice of heat pump or mains gas in a new well insulated house I would no hesitate in choosing a heat pump, as long as it had been installed properly and was a well known make. I have had both systems and there is no comparison especially health wise.
    • Uclan
    • By Uclan 9th Jan 17, 11:44 PM
    • 12 Posts
    • 0 Thanks
    Uclan
    The heat pump is set to 17 over night and unless it is really cold does not come on til morning unless it is heating the water between 3 a.m. and 4 a.m
    As mentioned when my wife and I were both working we used to run it on the auto timed system. Please don't mention the old heat pump as I still have nightmares about that heap of sh**. The sad fact is that heat pump and similar rubbish is still for sale on Ebay and from a plumbers in the W. Midlands.
    • bazer
    • By bazer 10th Jul 17, 10:29 AM
    • 3 Posts
    • 0 Thanks
    bazer
    Comparisons!
    Hi,, you seem to be well versed in these ASHPs, I have have several quotes, prices (that vary massively (approx. £13.000 for starters) and various sizes of HP and makes! Initially I was told a EcoDan Mits. 8.5kw was suffice. Now I have been steered towards a 11.2kw Ecodan, but the latest quote is for a Daikin 16Kw LT Split. So I ask if you feel I am getting a - ripped off (as I believe the units are approx. £5,000 Solar tank £1,500 + labour, parts etc.
    b - if there is a preference on which is a better unit EcoDan or Daikin16Kw LT Split ? I wouldn't hold you to this!!
    c - The sizing of unit seems to differ significantly!! is it better to have a oversized unit taking it steady of a lower sized unit working harder? I would assume the first option!
    Hope you can help, or anyone else Thanks Bazzer
    • lovesgshp
    • By lovesgshp 10th Jul 17, 3:26 PM
    • 1,261 Posts
    • 709 Thanks
    lovesgshp
    What sort of size is your house bazer in m2. Is it rads or ufh.
    The quotes you are getting seem to range from a house size of 120 m2 to one nearer 300 m2.
    A lot of this will also depend on insulation levels, double glazing etc.
    You should go slightly undersized, as this will help the pump keep peak efficiency.
    Do not know much about the pumps you mention as we mainly deal with the IVT AirX here in Italy, but believe it is also available under the WB brand in the UK. Both outclassed all the others in Nordic tests for performance and COP.
    As Manuel says in Fawlty Towers: " I Know Nothing"
    • Paula0014
    • By Paula0014 24th Oct 17, 2:53 PM
    • 1 Posts
    • 0 Thanks
    Paula0014
    Mitsubishi Ecodan new system
    Hi

    I wonder if anybody can help me, I had a completely new wet heating/hotwater system installed in December of 2014 for an Ecodan Mitsubishi 8.5kw Air source heat pump, 180L preplumb air source heat pump cyclinder 10 radiators a mixture of stelrad (4) and Milano Aruba vertical double (6).

    7 weeks ago the system showed a U1 fault and both the heating and hot water stopped working. After a number of visits the issue has boiled down to bits in the system, the water is brown and so dark it has stained the flow gauge which needed to be replaced before a reading could be taken, seems extremely odd as the system is not even 3 years old. The pipes to and from the cylinder and the heat pump have been flushed, it seems that the heat exchanger has been blocked by a build of of these bits which has caused the U1 to be triggered. Chemical has been added to break the bits down and a further limited flush to this area completed giving a flow of 10l enough for the heating and hot water to work, but it is only a matter of time before the bits build up again and the U1 returns without a proper solution. Mitsubishi have been contacted and they say it is an installtion issue, both companies are Mitsubishi registered installers.

    The installation of the system did not go at all well back in 2014 with multiple issues with the workmanship. I have moved to another company to complete the maintenance and now this investigation work. The new company think the system was not flushed before commissioning which is possible but would that have casued this issue? They are recommending a full power flush ontop of a bill for nearly £900 already. I am unsure if this is the best option as the theory is a powerflush was not completed but is that the cause or is there a lurking root cause which will just come back? The question I have is do other people think this is a sensible next step or are there alternatives I should look at before doing this? The new maintenance company has looked at getting the water tested from the system to see what the bits are but cannot find anywhere who could do this for them.

    Your advice would be very welcome to help me make the decision of the next steps to take, I have asked the original installers if they completed a powerflush and am currently awaiting their reply.
    • wrightk
    • By wrightk 7th Dec 17, 8:30 AM
    • 930 Posts
    • 511 Thanks
    wrightk
    Hi all sorry to jump in on this. Have read as much as i can on this thread. Currently live in 3 bed end terrace 1920's council property. Have been offered a heating upgrade to ashp. We are off grid and have charnwood multi fuel stove 15kw with back boiler feeding 7 rads. The details are sketchy at the moment but i presume it will be air to air aource.the building is externally rendered with external insulation and solid 12inch block walls. I wondered whether this is a suitable option? Will post more details when i get them
    Thanks
    Even a stopped clock tells the right time twice a day, and for once I'm inclined to believe Withnail is right. We are indeed drifting into the arena of the unwell.
    • matelodave
    • By matelodave 7th Dec 17, 9:04 AM
    • 3,176 Posts
    • 1,896 Thanks
    matelodave
    I doubt you'll be offered air-to-air. It will probably be an air-to-water. Is gas not available where you live?

    Hopefully by now councils & housing associations will be a bit more careful about designing heat-pump systems than they used be and wont just hang an undersized unit on the end of your existing system. The MCS specs are a lot stricter than they used to be especially if the council want to claim the RHI.

    If the system is designed properly, the place has reasonable insulation (wall, loft and double glazing) and you learn how to use it properly then there's no reason why it shouldn't be ok.

    However I guess you wont have much say about the design or what gets put in but if it was me I'd really like to have a complete system design given to me that I could get checked before I made a decision.

    My bro is in a similar postion, he lives on an estae with a centralised area heating system which is now well past it's sell by date and will not be repaired or replaced.

    He's had notification that he'll be offered an air source heat pump instead although he doesn't know how the system will be designed yet and the housing association are "still in negotiations" so he's just waiting to see what transpires.
    Last edited by matelodave; 07-12-2017 at 9:08 AM.
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