Pool heat pump FAQs
Frequently Asked Questions for Swimming Pool Heat Pumps
What are “Inverter Driven” heat pumps?David Morris
Pool heat pumps generally fall into two types:-
- Inverter driven
Inverter driven heat pumps are a newer generation of heat pumps. They are variable speed which allows the fan and compressor to run at different speeds according to the demand from the pool.
On/Off heat pumps can only run at 100% or turn off. They are not variable speed.
The advantage of inverter heat pumps over on/off models is:-
1. More efficient = lower running costs: When inverter heat pumps run at reduced speed their efficiency (COP) rises drastically. Inverter driven heat pumps can have efficiencies (COPs) of up to 14.
This means that for every 1kw of power used, they can return up to 14kw of heat to the pool. The maximum COP for on/off heat pumps is around 5 to 6
2. They are generally much quieter as they do not need to always run at 100%. Once the pool reaches the desired temperature, the inverter driven heat pump can slow itself down and run at a reduced speed eg 30%. When running at a reduced speed, the noise is significantly reduced.
3. Built in "soft-start". When inverter heat pumps start, they gradually increase their speed from zero up to the required running speed. This gentle start up avoids the power "spike" that can be encountered with on-off type heat pumps.
This "soft-start" feature of inverter driven heat pumps prevents issues such as the house lights flickering when the heat pump starts or electrical breakers tripping on the consumer unit.
At the moment, both on/off and inverter driven heat pumps are available.
Do your prices include VAT?David Morris
Yes our prices include VAT and are the total amount payable including free UK delivery.
Our VAT registration number is 114 3502 61
Can I use a heat pump to heat my koi pond?David Morris
See our Koi Page for more information on using heat pumps on koi ponds.
I use salt in my pool rather than chlorine, will this damage the heat pump?David Morris
No, all of our pool heat pumps have titanium heat exchangers which are resistant to damage from salt, chlorine or bromine used in pools.
In fact salt pools generate chlorine from the salt water and so are effectively the same as chlorine based pools. Only the method of generation of the chlorine is different.
What is the difference between R410a and R32 refrigerant gas?David Morris
At present, pool heat pumps use either R410a or R32 refrigerant gas to operate.
The refrigerant gas is contained inside the heat pump in a pressurised and sealed circuit. The compressor pumps the refrigerant gas around the refrigerant circuit in the heat pump so that the refrigerant gas can absorb heat from the air and transfer this heat to the heat exchanger in the heat pump to heat your pool water.
Both R410a and R32 gases are environmentally friendly
They are also very efficient and there is virtually no difference in the operating efficiency of the two gases.
R32 is slightly more environmentally friendly than R410a gas and has a lower GWP rating (global warming potential). This is only relevant if the refrigerant gas were to leak into the atmosphere. Under normal operation, the refigerant gas remains in the sealed refrigerant circuit - like your fridge and should never leak.
The disadvantage of R32 gas is that is is highly flammable and also runs at a higher pressure than R410a. Many airlines therefore will not carry heat pumps that contain R32 gas whereas they will carry those with R410a gas.
Both gases are well serviced and maintained by engineers.
As there is no operating difference between the two gases and they are both well supported, we believe that it should not be a major factor in selecting a pool heat pump.
Can I plug the heat pump into a standard 13A mains socket?David Morris
Mini heat pumps (eg Hot Splash) can be plugged into a standard 13A socket.
For larger models, we recommend that armoured cable is used to run the electrical supply to the heat pump.
Armoured cable provides protection from the cable being accidentally damaged and is therefore safer than standard electrical flex cable.
The heat pump should be connected to an RCD device for safety reasons.
Larger heat pumps will draw more than 13A and so a dedicated electrical supply may be required.
It is best to get a qualified electrician to connect your heat pump to the electirical supply. The electrician will also ensure that the heat pump has a proper earth
Will it damage my heat pump to put it outdoors?David Morris
No, all of our heat pumps are designed to go outdoors and are weatherproof.
They will operate perfectly well in all weather conditions including heavy rain and wind etc.
We recommend that you cover your heat pump with one of our specially designed winter covers during winter when the heat pump is not in use. This will give your heat pump some additional protection against the weather.
I have an indoor pool, should I put the heat pump inside the pool enclosure to act as a dehumidifier as well as heating the pool water?David Morris
For indoor pools, it is possible to put a heat pump inside the pool enclosure or in a plant room.
In order to do this, the air expelled from the heat pump is blown out of the building by using a through the wall vent kit. (this is only available for some models of heat pump)
A grille, preferably at the other end of the building would allow fresh air to enter the building to replace the air being blown out.
This method will blow the moist pool air out of the building helping to dehumidify the air. The heat pump will gain some benefit from using the warmer pool room air.
The disadvantage of this method is that the air in the pool room will soon be the same temperature as the outside air.
This is not normally desirable for an indoor pool, particularly in winter !
For this reason, it is normally best to put the heat pump outdoors and use seperate dehumidifiers to dry and warm the pool room air.
We sell “all-in-one” type units (eg the Heatstar Gemini) that can provide pool water heating, dehumidification and air heating.
Please contact us for more information.
Can I put my heat pump under a tree?David Morris
You can put a heat pump under a tree as long as the tree is more than 2-3 meters above the heat pump.
This is so that the air coming out of the heat pump (on vertical fan models) does not hit the leaves of the tree and then recirculate back into the heat pump. This would cause reduced efficiency.
While the heat pump is operating, the fan will prevent leaves from entering the heat pump.
In the winter, we recommend that you cover the heat pump using one of our specially designed winter covers.
This will prevent leaves from entering the heat pump in Autumn.
Should I keep a solar cover on my pool when using a heat pump?David Morris
Absolutely ! It is almost compulsory to use a solar cover when using a heat pump to heat your pool.
A solar cover provides several benefits:-
- It can heat the pool on its own by up to 8 degrees C
- It reduces water evaporation by 98%
- It acts as an insulation layer and greatly reduces heat loss
- It reduces pool chemical consumption by up to 30%
- It prevents leaves etc from entering the pool
- It saves you money by reducing your heating costs
- Reducing your heating costs will also reduce your carbon footprint
Not using a solar cover is like not insulating the loft in your house. As your heat pump puts heat into the pool, it will be lost into the air when a solar cover is not used.
An uncovered pool will lose about 2-3 times more heat than a covered pool.
Covering the pool is particularly important at night as the air temperature will drop causing a temperature difference between the pool water and the air.
The temperature difference will cause your pool to lose heat at a greater rate than during the day.
We recommend that you keep a solar cover on the pool at all times when the pool is not in use.
The solar cover will work in conjunction with your heat pump to make an efficient combination for heating your pool and minimising energy requirements.
We sell good quality solar covers and rollers
How long will the heat pump run for each day?David Morris
Just like the boiler in your house, the heat pump will run for different amounts of time each day depending on the weather.
On warm summer days when the pool is up to temperature, the heat pump may not need to run at all. Whereas on cooler days, the heat pump may run for a few hours.
In extremely cold weather (eg below +5c) the heat pump may need to run for 12 hours a day or more.
When you keep a solar cover on your pool, this will give the pool some heat gain on warm days and will supplement the heat pump.
As the weather gets colder the heat pump will need to run for longer.
You can control how long the heat pump runs for each day by using a time-clock on your pool pump.
Other factors that affect how long the heat pump will run for each day include:-
- The power of the heat pump – a more powerful heat pump will heat the pool more quickly and so will switch off sooner than a smaller heat pump
- How well insulated your pool is
- If you have a high water table around your pool, then this will drain away the pool heat and cause your heat pump to run for longer to replace the lost heat
- The pool water temperature that you require – a higher pool water temperature will need the heat pump to run for longer to maintain the temperature
- Pool cover – an uncovered pool will lose 2-3 times as much heat as a covered pool
As a guide, on warm summer days the heat pump would typically run for between 0-3 hours
On cooler days between 3-8 hours should be sufficient but this depends on the factors mentioned above
What does “3-Phase” and “Single Phase” mean?David Morris
This refers to the type of electrical supply that the heat pump needs.
Most properties in the UK have a stamdard 100A single phase power supply (ie a live and neutral wire) .
Some larger properties or commercial properties in the UK may have a 3-phase power supply
Smaller heat pumps are normally single phase and 3-phase is generally used for larger models, Single phase heat pumps are available up to around 35kw. Over this all heat pumps will be 3-phase models
Single phase power is 220v to 240v and uses one live wire and one neutral wire.
3-Phase power supplies are 380v to 415v and use three live wires (and sometimes also a neutral wire)
If you are not sure what electrical supply you have, ask your electrician to check this before ordering your heat pump.
3-Phase power is more common in mainland Europe eg Portugal, France and Spain than in the UK and is fitted as standard to most new properties in some parts of mainland Europe.
As a guide, for larger heat pumps (eg over 24kw), then if 3-phase power is available in the pool room, it is better to use a 3-phase pool heat pump.
If in doubt, please call us for more advice.
I have seen the same heat pump cheaper on another web site. Will you match the price?David Morris
Our prices are some of the cheapest on the internet and we always aim to provide highly competitive prices.
However if you see the same product cheaper elsewhere, then please let us know and we will always try to match or beat any pricing you have seen
How do I turn the heat pump on and off at the required times?David Morris
Most of our heat pumps (apart from mini heat pumps like the Hot Splash and Sunspring models) include a water flow switch. This means that they will only operate when your pool pump is turned on and water is flowing through the heat pump.
You can therefore control when your heat pump operates simply by using a time clock on your water pump.
Some heat pump models also have a timer built into the digital control panel. This allows you to turn the heat pump on and off at set times independently from the pool pump. Note that the pool pump always needs to be operating for the heat pump to work.
I have an existing gas boiler, should I replace it with a heat pump or keep the gas boiler as well?David Morris
If you have an existing heater (eg gas, oil, electric etc), then we recommend that you install the heat pump alongside your existing heater.
This will allow you to run both the heat pump and the existing heater if required for a rapid pool heat up, or to provide a backup heater in case the heat pump develops a fault (unlikely). You can also switch to your existing heater when the air temperature becomes too cold for the heat pump to operate efficiently eg right at the end of the season.
If you want to install the heat pump alongside your existing heater, then the water should flow through the heat pump and then the existing heater before returning to the pool for maximum efficiency
Should I cover the heat pump in winter?David Morris
We recommend that you cover your heat pump during the winter. However, you must use a suitable cover. The cover must allow the heat pump to breathe so that mositure and condensation can escape, otherwise corrosion can occur to the components in your heat pump causing permanent damage.
We sell a special range of heat pump winter covers that are custom made for each heat pump model and incorporate ventilation mesh panels to allow air circulation.
Smaller heat pumps can be disconnected and carried into a garage or shed for the winter.
Is it a good idea to install a heat pump in a greenhouse?David Morris
Generally not. We would not advise installing a heat pump in a greenhouse.
Whilst this may seem like a good idea, the benefits are minimal.
This is because heat pumps have quite powerful fan motors and transfer a lot of air.
Within a few minutes of operating, the heat pump will have extracted all of the air in the greenhouse.
You also need a vent to allow fresh air to enter the green house to replace the expelled air.
Within a couple of minutes the temperature of the air in the greenhouse will be the same as the external air.
The air is not in the greenhouse for long enough to warm sufficiently to provide much benefit.
If the air flow to the heat pump is restricted, it may in fact cause lower performance.
Heat pumps normally work best outdoors with a good supply of fresh air.
Can I install a heat pump in my pool plant room?David Morris
Most heat pumps should be installed outdoors as they require a good flow of fresh air to operate properly. Some models can however be installed in a pump-house or plant room using the through the wall ducting kit or by cutting a hole through the wall of the plant room to allow the air to be blown outside
A permanent grille must then be installed in the opposite wall of the plant room to allow fresh air to enter the plant room at the same rate as it is leaving.
Generally there is no advantage to putting a heat pump inside a plant room other than to protect it from the weather and possibly for aesthetic reasons.
There are not normally any performance advantages from putting a heat pump inside a plant room. Any surplus heat in the plant room will be expelled within a couple of minutes of the heat pump being turned on and fresh air drawn in from the outside. This causes the temperature inside the plant room to become the same as the outside air temperature negating any performance benefit
Feel free to call us for more advice on this topic
Please see our Installation Tips page for more information
What is a COP?David Morris
The COP is the Coefficient of Performance. It is the ratio of energy input to output. Eg a unit with a COP of 5 would provide 5 units of heat for every one consumed.
For example a heat pump with a COP of 5 would use about 4kw of electricity and output 20kw of heat (ie 5 x 4kw =20kw).
Bear in mind though that there is no international standard for stating COPs and therefore each manufacturer will state the maximum COP obtainable for their units under optimum temperature and humidity conditions. In reality you may not therefore always acheive the COP rating stated.
This is another reason why you should always oversize your heat pump
How are the units delivered?David Morris
The units are delivered on a lorry with a tail lift. The units are on a pallet and will only be delivered to your driveway. You must arrange to carry the unit to where you require your pump to be located. Note that the units are heavy and will require two or three people to move them safely.
Do you supply to mainland Europe?David Morris
Yes, we can ship to anywhere in UK, mainland Europe and beyond.
We regularly send heat pumps to France, Spain, Portugal, Czech, Netherlands etc
We have sent units as far as Egypt and Zimbabwe
Please email us with your required heat pump model and address and we will get a competitive shipping quote for you.
What physical size are the heat pumps?David Morris
Each product listing states the physical sizes of each model.
What size heat pump do I need for my pool?David Morris
There are many factors that should be considered when sizing a heat pump for your swimming pool.
At HeatPumps4Pools we gather the information on how you wish to use your pool and take into account a wide range of factors so that we can give you a heat pump that will meet and exceed your requirements.
If you would like us to recommend suitable heat pumps for your pool, then please complete our Heat Pump Sizing Form
this will capture a wide range of information about your pool including:-
- Pool Dimensions (length, width, average depth in feet or metres)
- Swimming season (eg May – Sept, or all year round etc)
- Desired water temperature (28c is typical)
- If the pool is kept covered when not in use (ie with a solar cover or thermal blanket)
- The number of hours per day that the pool is uncovered
- If the pool has a single or 3-phase electrical supply
- Indoor or outdoor pool
- Pool location (eg UK, France, Spain etc please provide address if you would like a shipping quote)
- Existing pool heating system
- Domestic or Commercial use
- If the property is rented or a holiday home
- Above ground or in-ground pool
We will then give you our recommened pool heat pumps.
Of course you can always call us if you prefer to run through this by phone !
We can provide our expertise to consider all of these factors and help you choose the best size unit for your pool.
We therefore recommend that you contact us to discuss the size of heat pump that you require before making a purchase.
Each of our product listings has a sizing chart that shows the maximum number of cubic metres (m3) of water that each heat pump model supports.
As a start, compare the volume of your pool in m3 to the sizing chart. If your pool volume is near the maximum size supported, then choose the next model up.
Always allow some “headroom” with the power of your heat pump. This will ensure that the heat pump can still produce enough heat to maintain your required pool temperature on colder days.
Inverter heat pumps should also be sized larger than "on-off" heat pumps so that the unit can run at a reduced power output to give the maximum efficiency of an inverter driven pool heat pump
For rented properties or holiday homes, it is advisable to oversize the heat pump to allow a faster heat up time before guests arrive. We also have heat pumps with lockable keypads to prevent guests from adjusting the pool temperature.
Feel free to call us and we are more than happy to run through the sizing of your pool heater.
Is a heat pump difficult to install?David Morris
Not at all, the heat pump needs a solid concrete base or can be laid on paving slabs. The unit then needs an electrical supply and it is best to get a qualified electrician to install this.
The plumbing is straightforward and the pipes are glued together. The heat pump only needs a flow and a return pipe.
You should install 3-valves to create a “bypass”.
The heat pump should be installed after the filter and as the last item before the water returns to the pool.
If you want to install the heat pump alongside your existing heater, then the water should flow through the heat pump and then through the existing heater before returning to the pool
See our Installation section for lots more tips on installing your heat pump
What warranty is offered on the units?David Morris
Each product listing states the warranty offered.
Most of our new heat pumps include an on-site parts and labour warranty.All heat pumps shipped outside the UK are supplied with a parts-only warranty. Outside the UK you will need to employ a local contractor if required and we will courier any necessary spare parts to you
What size pipe outlets are on the units?David Morris
Most units have 50mm pipe outlets. They are normally also supplied with 50mm to 1.5″ adaptors as 1.5″ is the most common size of pipe in the UK.
In Europe, 50mm is the most common size of pipe.
Each heat pump listing states the pipe outlet size
We can supply adaptors to go to different pipe sizes if required.
What is the difference between the digital and analogue models?David Morris
Analogue units use a simple knob to set the required temperature whereas digital models have a digital panel where you set the required temperature.
Once the required temperature is set on either types, the heat pump will then automatically maintain the pool at the required temperature.