Your browser isn't supported
It looks like you're using an old web browser. To get the most out of the site and to ensure guides display correctly, we suggest upgrading your browser now. Download the latest:

Welcome to the MSE Forums

We're home to a fantastic community of MoneySavers but anyone can post. Please exercise caution & report spam, illegal, offensive or libellous posts/messages: click "report" or email forumteam@.

Search
  • FIRST POST
    • richardc1983
    • By richardc1983 4th Feb 09, 2:03 AM
    • 1,929Posts
    • 1,015Thanks
    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 87
    • helpjack
    • By helpjack 17th Oct 18, 8:07 AM
    • 40 Posts
    • 58 Thanks
    helpjack
    Ecodan Misery
    Ok, so interestingly, the first company don't appear on Mitsubishis approved list anymore. They were definitely there a couple of weeks ago and mitsubishi also confirmed this when I spoke on the phone.

    We still don't have any heating or hot water. Mitsubishi charged me £240 call out charge for 40 mins and I'm having to chase them for any update.

    I just wondered what other people's experience of service and maintenance is?

    I looked at their service plan and it's £40 a month and they still charge a £50 call out charge. This seems horrifically expensive for something that is sold as low maintenance and cost effective.
    • ian103
    • By ian103 10th Nov 18, 6:58 PM
    • 860 Posts
    • 379 Thanks
    ian103
    Just thought Id report back, after obtaining quotes for air to water, air to air, oil and replacement LOT 20 storage heaters, we opted for air to air. We had a mixed response as to whether the property was suitable for air to water so we dismissed this option (if we had been installing underfloor heating it would have been a good option) Well the impresssions after a month are good, property is finally warm this year after 5 bad years with storage heaters. Its controllable, reasonablly economic, its costing more than the old E7 heaters but we are no longer reliant on the log burner to keep the house warm. I dont think its for everyone but it works for us.
    • richardc1983
    • By richardc1983 11th Nov 18, 9:43 AM
    • 1,929 Posts
    • 1,015 Thanks
    richardc1983
    Just thought Id report back, after obtaining quotes for air to water, air to air, oil and replacement LOT 20 storage heaters, we opted for air to air. We had a mixed response as to whether the property was suitable for air to water so we dismissed this option (if we had been installing underfloor heating it would have been a good option) Well the impresssions after a month are good, property is finally warm this year after 5 bad years with storage heaters. Its controllable, reasonablly economic, its costing more than the old E7 heaters but we are no longer reliant on the log burner to keep the house warm. I dont think its for everyone but it works for us.
    Originally posted by ian103
    Hi Ian

    Good to hear. What kind of units did you end up going for?

    Richard.
    If you found my post helpful, please remember to press the THANKS button! --->
    • ian103
    • By ian103 12th Nov 18, 9:22 AM
    • 860 Posts
    • 379 Thanks
    ian103
    We opted for a local installer and he recommended Panasonic units, we selected the Etherea modelfor the indoor units as they offered energy saving options and the ability to purify the air (nanoe technology)
    • treecol
    • By treecol 12th Nov 18, 8:45 PM
    • 275 Posts
    • 31 Thanks
    treecol
    After getting our air to air unit installed back in the year, we had a lovely cool summer and now are getting used to using the unit for heat. Certainly when the weather was cold, it took longer for the room to get warm so we are learning as we go. Just wonder if - and I know this is probably a really dumb question, but if I increase the temperature on the unit from say 18 degrees to 24, will the unit use more electric? I notice when I first increase the temp, the motor outside seems to be working harder then seems to settle, so just wondering as I don't really know how these things work at their most efficient.
    • matelodave
    • By matelodave 12th Nov 18, 8:57 PM
    • 3,910 Posts
    • 2,466 Thanks
    matelodave
    The warmer you have it then the more energy it will use.

    Likewise the colder it is outside then the more energy it will use to maintain the same inside temperature.

    As they say you dont get owt for nowt.
    Love makes the world go round - beer make it go round even faster
    Look after our planet - it's the only one with beer
    • richardc1983
    • By richardc1983 12th Nov 18, 9:09 PM
    • 1,929 Posts
    • 1,015 Thanks
    richardc1983
    After getting our air to air unit installed back in the year, we had a lovely cool summer and now are getting used to using the unit for heat. Certainly when the weather was cold, it took longer for the room to get warm so we are learning as we go. Just wonder if - and I know this is probably a really dumb question, but if I increase the temperature on the unit from say 18 degrees to 24, will the unit use more electric? I notice when I first increase the temp, the motor outside seems to be working harder then seems to settle, so just wondering as I don't really know how these things work at their most efficient.
    Originally posted by treecol
    The unit will work harder like using the accelerator in your car. If your cruising along at 40 (18c) and then want to go to 70 (24c) you put your foot on the gas. An inverter unit will put it's foot to the floor to get to your chosen temp asap, once it's there it will take it's foot off and just use enough power to keep the temp there.

    A normal unit will floor it each time overshooting the set temp by 1c at full power then turn off room temp then drops 1c below the set temp then it will come back on and floor it at full power. Anything over your set temp is wasted energy so an inverter avoids this by slowing it's compressor down. Saving energy. Of course set it so it's comfortable but 24c does seem high, 22c is usually the comfortable temp and once it's achieved it will slow down the compressor however the heat loss from your house at 24c is higher than at 18c so it has to run faster to maintain the higher temp.

    Ensure your night setback temps when your in bed or not at home don't go below about 18c otherwise the unit will be running at full throttle for a long time to achieve your set temp.
    If you found my post helpful, please remember to press the THANKS button! --->
    • treecol
    • By treecol 13th Nov 18, 8:59 PM
    • 275 Posts
    • 31 Thanks
    treecol
    Thank you - makes much more sense now. So the room the unit is in is a very large hallway between the house and garage with a vaulted ceiling, but not used to live in as such. We do use it as a boot room/coat room so hence the heat and we do have a large group of us once a week in there for a couple of hours. So are you saying we would use less energy across the winter if we set the temp to say 18 degrees and leave it on all the time? At the moment we just put the heat on 1st thing in the morning for an hour before we go to work then again in the evening for around 4 hours. Are we wasting energy that way?
    The reason we haven't left it on is as this is the 1st winter with the unit, we didn't want sky-high electric bills. Thank you in advance for taking the time to explain.
    • richardc1983
    • By richardc1983 13th Nov 18, 9:02 PM
    • 1,929 Posts
    • 1,015 Thanks
    richardc1983
    Are you putting it Upto 24c at night or leaving it at 18c? A heat pump the lowest temp should be about 18c again it's all down to comfort. You would have to try it and see.
    If you found my post helpful, please remember to press the THANKS button! --->
    • treecol
    • By treecol 15th Nov 18, 1:20 PM
    • 275 Posts
    • 31 Thanks
    treecol
    No, just leaving it at 18c in the evening - we don't leave it on overnight. So that's what I'm trying to determine - do we leave it on at 18c all the time or turn only turn it on when we're in the house but off overnight.
    We're currently using it as we would our warm air central heating and only having it on when we're home during waking hours. But I'm getting the impression they are more efficient if used differently?
    • richardc1983
    • By richardc1983 15th Nov 18, 1:52 PM
    • 1,929 Posts
    • 1,015 Thanks
    richardc1983
    No, just leaving it at 18c in the evening - we don't leave it on overnight. So that's what I'm trying to determine - do we leave it on at 18c all the time or turn only turn it on when we're in the house but off overnight.
    We're currently using it as we would our warm air central heating and only having it on when we're home during waking hours. But I'm getting the impression they are more efficient if used differently?
    Originally posted by treecol
    Do you find the house comfortable at 18c, its not that cold yet so quite mild and really depends how well insulated your house is. A set back time for unoccupied times is how you would run underfloor heating. E.g if you turned off completely and your house dropped down to 10c in the night then it will take a long time to get back up to 18c.

    If 18c is your comfort temperature when you turn it on and your happy and warm at that then you could set back to 16c and that way its keeping a base temperature. If for example you turn it to 21c when your in (if thats your comfort temp) and then turn it off we would recommend that you turn it down to 18c when unoccupied so the house envelope and structure is not dropping too low. The unit then doesn't need to work as hard to get back up to your comfort temp.

    When a heat pump starts from cold so say 10c in the house and its cold outside the unit has to work really hard and at full output to get back to your comfort temperature, units that are borderline undersized may never achieve that temperature when it is really cold. When a unit is working really hard frost build up increases on the outdoor unit and defrosting can become frequent especially when the air is damp and cold. The greater the difference between the comfort temp and the actual return air temperature at the unit means the unit is having to work harder for longer to get to there.

    While the unit is in defrost cycle there is no heat being blown out of the indoor unit as the system goes into reverse to defrost the outside unit.

    All depends on what you are comfortable with, base it on your comfort temperature that you set it at when you are in the house. It may be that you have an ultra modern house that keeps the heat in, so you set it back to 18c and your house doesn't drop below that naturally in the night before you turn it back up to your comfort temperature then your saving energy and it just has to put the work in to get back to your comfort temperature of say 21c.

    If for example you don't use a night set back, live an old, poorly insulated cold house and your comfort temp is 21c and in the night the house drops to 10c. When you turn the unit back on the next morning its going to take a long time to get back up to 21c, depending on how cold it is outside and how much moisture is in the outdoor air. From a comfort perspective also this is not great. The unit will ramp right up to full output until it gets close to the comfort set temp. Using night set back of say 18c if the house drops below 18c the unit will come on and put just enough heat into the house to maintain that, the outdoor unit will be ticking away gently.

    It's also kinder on the components not to be running flat out and just ticking along.

    I will reiterate, if you are comfortable at 18c, then try a lower night set back e.g 16c which is the lowest recommended temperature for health. I wouldnt leave it at your comfort temperature 24/7. That would be like your comfort temperature being 22C and heating the house to that 24/7, it will waste energy while you are tucked up in bed. The trick is to keep the house from getting too cold. Set back is usually 2-3c lower than your usual temperature.
    If you found my post helpful, please remember to press the THANKS button! --->
    • treecol
    • By treecol 16th Nov 18, 12:17 PM
    • 275 Posts
    • 31 Thanks
    treecol
    Again, thank you. We had this installed https://www.appliancesdirect.co.uk/p/eiq-12k12kc24kwminv/electriq-eiq12k12kc24kwminv?refsource=APadwords&refsource=A %20%20padwords&gclid=EAIaIQobChMI8rbL7JfB2QIVKrvtC h3UZQv%20%20iEAYYASABEgJJ6fD_BwE

    at the recommendation of a board member here just so you know what we have. We have left the unit on 16c when we went out a while ago when we had that brief cold snap. I'm going to try leaving it on 18c when we're out and 16c at night compared to switching it on and off and see how the heat and energy compares. The room is entirely separated from the main house by doors so almost a sealed unit. Our bungalow is late 60's and well insulated but this extension is 90's and has a single wall on one side which is the draughty garage and a huge vaulted ceiling with limited insulation. There is also an entire wall of glass at one end too so whilst the house only drops to around 17 at night on the coldest nights, this room would be sub-zero.
    we will try your suggestions and report back,
    Thanks again.
    • matelodave
    • By matelodave 16th Nov 18, 12:46 PM
    • 3,910 Posts
    • 2,466 Thanks
    matelodave
    Ours is Air to water feeding underfloor heating so not at all comparable with an air to air unit but it's pretty easy to monitor it's consumption using an energy monitor to sse how tweaking your comfort and set back operations affects the system power consumptions. see here for what ours looks like www.energyhive.com/dashboard/dave (it's monitoring the whole house electrics but you can clearly see what the heatpump is doing). We set back to 17 degrees overnight and have different temperatures in different rooms at diffferent times of the day. Some nights it comes on and others it doesn't and it works harder on colder nights or days.

    However as said above air source heat pumps are very sensitive to outside temperatures as well the internal temperatures. So if it's cold out side it has to try and create heat from a lower base so has to work a lot harder - I've seen our external unit with quite a build up of frost on it especially on days when it very damp as well as cold. It gives out a big burst of vapour when it goes into derfrost mode.

    Ours probably has a significantly slower response time than an air-air unit, so if we let the house get cold it takes several hours to get it back up to temperature. even more if the house gets really cold - we have to set it to come on at least the day before we return home if we go away in the winter. I can temporarily increase the flow temperatures to try and speed it up but with a corresponding very high increase in energy consumption.
    Last edited by matelodave; 16-11-2018 at 1:14 PM.
    Love makes the world go round - beer make it go round even faster
    Look after our planet - it's the only one with beer
    • richardc1983
    • By richardc1983 16th Nov 18, 1:03 PM
    • 1,929 Posts
    • 1,015 Thanks
    richardc1983
    Again, thank you. We had this installed https://www.appliancesdirect.co.uk/p/eiq-12k12kc24kwminv/electriq-eiq12k12kc24kwminv?refsource=APadwords&refsource=A %20%20padwords&gclid=EAIaIQobChMI8rbL7JfB2QIVKrvtC h3UZQv%20%20iEAYYASABEgJJ6fD_BwE

    at the recommendation of a board member here just so you know what we have. We have left the unit on 16c when we went out a while ago when we had that brief cold snap. I'm going to try leaving it on 18c when we're out and 16c at night compared to switching it on and off and see how the heat and energy compares. The room is entirely separated from the main house by doors so almost a sealed unit. Our bungalow is late 60's and well insulated but this extension is 90's and has a single wall on one side which is the draughty garage and a huge vaulted ceiling with limited insulation. There is also an entire wall of glass at one end too so whilst the house only drops to around 17 at night on the coldest nights, this room would be sub-zero.
    we will try your suggestions and report back,
    Thanks again.
    Originally posted by treecol
    Do you mean 16c when you are out & then 18c when you are at home? There would be no point having it warmer when you are not there and then cooler when you are there. That would give no benefit at all.

    Could you also clarify where the 2 units are installed as the link you sent shows 2 indoor units on 1 outdoor unit. Also how large are the rooms the units are installed in? I think you said it installed in your hall so assuming normal hallway size I think 3.5kw per unit is reasonable.
    Last edited by richardc1983; 16-11-2018 at 1:11 PM.
    If you found my post helpful, please remember to press the THANKS button! --->
Welcome to our new Forum!

Our aim is to save you money quickly and easily. We hope you like it!

Forum Team Contact us

Live Stats

2,409Posts Today

8,508Users online

Martin's Twitter