We will see several questions to ask when choosing a heat pump in Switzerland?
How to choose a heat pump?
When it comes to installing a new heater because our old gas or oil boiler is about to give up the ghost:
A heating solution based on renewable energies is efficient and allows you to take advantage of a significant potential of free energy.
Many players are jostling for position on the market for the renovation of individual or collective housing.
If you go through free online quote sites, you receive several quotes quickly, and their analysis is your responsibility.
This article aims to shed light on the most important points to consider before purchasing your heat pump.
We will answer several questions that are not necessarily organized
But whose overall content will allow you to find all the information to make your choice.
What are the types of heat pumps?
The best known type of heat pump in Switzerland is the geothermal heat pump.
Its principle is based on an exchange of calories between :
- A glycol fluid that circulates in probes buried deep in the ground
- And the water in your heating system.
We speak of an exchange between the primary and secondary circuits, through a plate heat exchanger.
In this case, the heat is taken from the ground and then returned to the water of the heating network.
Then the heat pump air water, or pac air water, offers the same principle:
The difference is that the exchange is between the outside air and the water in the heating network.
No more probes buried in the garden.
This model consists of a simple outdoor unit with a fan that is often placed in the front, or a little more in the middle of the garden.
The growing success of the air-to-water heat pump is due to its often lower price than the geothermal heat pump, since a very expensive probe is not required.
There is also a model of PAC air water interior:
Nothing is outside in this case.
But we have to bring the air back to the heat pump unit, through galvanized steel ducts for example, or other material.
There is also the water-to-water heat pump:
It draws the calories from a water table, a river, a lake or other, and gives them back to the heating network.
It is rarer, but its coefficient of performance, or COP, is always much higher.
There is still the pac air air or heat pump air-air:
It takes the calories from the air and gives them back to the air in the room.
Its coefficient of performance is much lower.
This principle can be found in the most common air conditioning systems (Daikin reversible air conditioners or others) found in individual houses, in offices in the tertiary sector, or in collective housing.
Many other types of heat pumps also exist: these are less common types such as the gas heat pump or the stirling heat pump.
Can a heat pump be installed on all types of heating networks?
Heat pumps mostly provide low water temperatures for your heating.
Some can go very high, but this is at the expense of their coefficient of performance.
So we often prefer to stay:
- Towards 50°C at the pump outlet for low temperature radiators
- Or between 28 and 35°C for underfloor heating
If you have an underfloor heating network or distribution :
Then the heat pump is perfect, because the necessary temperatures are always low, around 30°C.
Indeed, the exchange surfaces are important (all the coils that run along the floor), the required temperature can remain low.
If you have a radiator heating system:
Each radiator has a surface dimensioned so that with the water temperature supplied by the current oil or gas boiler, it can heat the room in which it is located.
If a lower water temperature is passed, then it still provides thermal power.
But this is less, and it may not heat the room in question.
Unless the radiator in question is oversized.
In most cases its surface will not be large enough to ensure the heating of the room.
It may need to be changed in this case.
If you apply for a grant, you will definitely have to change it because the state will ask for information.
It is necessary to install low temperature radiators sized according to each room.
If necessary, it is advisable to carry out a thermal assessment of the dwelling.
If you have steel radiators in which 70 or 80 ° C pass, then it is unlikely that by passing 50 ° C their thermal power is sufficient.
They will have to be changed.
If your heat pump installer tells you otherwise:
This is because he intends to operate the heat pump on its maximum potential, at the expense of its coefficient of performance, or COP.
Or worse, he plans to put the electric resistance and you will have an electric heating in return: COP = 1, useless.
If you have cast iron radiators, then it is more likely that a temperature of 50°C is sufficient to bring the heat power to each room.
This is not always the case and only a thermal assessment will tell you (to be differentiated from an energy evaluation such as CECB)
How much electricity will I pay next?
The energy consumption of the heat pump comes partly from the air, earth, or water, and partly from the electrical grid. The coefficient of performance or COP of the machine you choose indicates how many kW are drawn from the free source, and how many from the grid.
For a COP of 5, this means that for 1kW drawn from the electricity supplier, the heat pump produces 4kW of thermal power for the home. In comparison, a direct electric heater draws 1kW from the grid and returns 1kW to the grid (with the same efficiency), i.e. a COP of 1 in theory.
If you only install a heat pump and you do not change anything else in the house (insulation, windows or other) then you can estimate the consumption by converting your fossil fuel or electric energy consumption into electric kWh, then use the COP data of the supplier and finally the current kWh price.
For example: 1000L of fuel oil represent 10 times more electric kWh. That is 10 000 KWh. If the COP is 3 then you will consume 10 000 / 3 or 3333kWh so at the price of 0.20 cts per kWh, your bill will be 3333 / 5 = 660 francs. Use our beautiful converter made in Vue.js to make your calculations.
Can the heat pump produce domestic hot water?
There are several solutions and it depends on the heat pump system.
There are advantages and disadvantages to producing domestic hot water directly with the heat pump that already provides the heating.
Heat pumps for heating can also heat DHW:
To do this, you need to install a 3-way valve in the system that will tell the circuit to switch to heating or hot water.
Most of the time, this hot water is stored in a domestic hot water tank
It is heated by means of a plate heat exchanger in which the water heated by the pump circulates.
Because you don't shower directly with the water created by the PAC.
The advantage of producing domestic hot water directly with the heat pump is that you have a single system for both heating and hot water.
The solution is rather less expensive.
The downside is:
- That we end up with a heat pump that runs in summer to make hot water
- And that can make a little noise on a terrace or other, because of the fan or the compressor.
It depends on the model.
So we have a product called a thermodynamic balloon, sometimes called boiler pac.
This consists of a mini heat pump grafted onto a DHW tank.
This mini heat pump runs independently of the main heat pump.
And everything is inside, so no more noise.
The disadvantage of this second system is
- that the room where the hot water tank is located is cooled down because it is necessary to draw calories from it to heat the water.
- And that these tanks are less durable than large heat pumps.
It is necessary to choose between external auditory comfort and durability of the material.
Does an air source heat pump work in very cold weather?
For the air-water heat pump, when the weather is very cold, with temperatures below -10°C, this complicates the matter.
Because there is less energy in the air.
As a result, the pump will consume more energy to try to produce the temperature required to heat the house.
The coefficient of performance or COP drops drastically.
An installer, or sometimes a supplier directly, will sell you a 4 COP model:
But at -10°C outside, with a water outlet temperature of 50°C from the heat pump, the COP will be around 2 or 2.3.
You have to put this figure into perspective because even if it is very cold in your region, it is very rare for it to be -10°C or less for several days without interruption.
In most municipalities the average annual temperature is around 5°C so everything is fine.
Some heat pump models claim COP performances of 3 at -25°C!
It is worthwhile to clarify this with the vendor or his technical team.
Do I need a maintenance contract for the heat pump?
The heat pump is like a car.
There is a service to be performed every X hours of compressor operation.
Otherwise, little by little, everything falls apart.
The coefficients are bad, the energy bill soars, until the breakdown.
By scheduling a technician visit after the first two years and then every two years thereafter, you can be sure that the machine is on the right track.
However, if your provider is qualified.
Large companies are sometimes able to send incompetent teams to your location
And you find yourself paying incredible bills that ruin your efforts to save energy on a daily basis.
What is the physical principle behind the heat pump?
The heat pump is simple, it's like a refrigerator that works in the other direction.
A refrigerator takes the heat from the food, and gives it back to the air in the house.
Yes, because the condenser on the back redistributes the heat taken from the food to the air in the house, even if you don't feel it heating up behind the fridge.
The heat pump does not take heat from the food, but from the outside air
Yes, because even when it is very cold and the outside temperature is very low, there is heat or rather energy in the outside air
And then it gives it back to the water of the heating network (or the ambient air of the house if it is an air)
But how does the heat pump take heat from the air outside ? It contains a refrigerant !
This one has the property to take the heat of the environment in which it is, when it evaporates.
So we need to evaporate it outside so that it takes the heat from the air.
To make it evaporate, we will put it at the pressure it wants to evaporate, thanks to a regulator.
He wants a different pressure for every temperature he's going to be outside so we have to regulate that.
When we have done this, the heat from the air outside goes into our refrigerant or regrigerant.
Now we have to take it back to give it back to the heating network water. How do we do it?
This time we must condense the fluid because condensation is a reaction that gives back heat to its medium.
So we have to make it condense at the level of the network water.
For that we use a condenser in which it passes.
And in the same way we will play on the pressure so that it condenses at the right temperature.
For this we use a compressor.
We have to condense it at the temperature we want for our heating water.
Around 50°C for a classic water radiator and 30°C for a floor heating system.
How can we achieve self-consumption with the heat pump?
Self-consumption is when we consume what we produce or we produce what we consume.
It's really very tricky to get.
To become self-sufficient and consume its own electricity, it is necessary to use solar photovoltaic panels for example.
Part of their electrical current will be used to power the heat pump.
For a new construction which aims at low consumption it is interesting to consider for your works.
For a renovation it is also interesting even if less easy.
The heat pump controller must have a function called PV Ready
So that it detects when we have production and then uses that power to operate.
A key issue is that the sun is mostly present when heating is least needed.
In summer for example or during the day when most people are at work!
So it is interesting to consider storing the solar power produced during the day with batteries.
However, it is still expensive in 2020, compared to the savings.
Do I have to insulate from the outside before installing a heat pump?
Not necessarily, but it is still recommended.
Heating a colander, with a state-of-the-art system, is a bit of a shame.
But not everyone has the means to do everything.
Therefore, insulating first is a smart move since it will reduce the power required by the heat pump to heat the home.
For Insulate your homea wall insulation as well as a roof insulation will do the trick
With a small amount of glass or rock wool or a state-of-the-art material if you have the means.
Make sure that the installer takes care to reduce thermal bridges.
For example, insulating the roof from the inside between rafters will create thermal bridges that are not always healthy for the structure.
This can create some condensation and cause the materials to rot.
How much will my heat pump installation cost?
Today, a complete installation with hot water, in air-water heat pump, is around 30'000 or 35'000 CHF all included.
Some foreign companies are undercutting prices and lowering the overall level.
Many human and industrial factors influence the price of a heat pump.
For a geothermal heat pump installation with sanitary water as well, count about 25'000 CHF more, because of the drilling and the installation of the geothermal probes by an accredited driller.
Can I size my heat pump by myself?
Yes, your installer most often relies on his supplier to do the math for him.
But the calculation is simple and if you still have notions of your younger years, you can do it yourself.
You will find all the calculations to do on the sheets on this link.
The formulas may seem impressive, but if you read a little, it is simpler than it seems.
So if you can count it should be fine.
Who to install my heat pump?
It is reasonable for the company in question to have at least one refrigeration engineer, as the installation of a heat pump really does require this skill.
A plumber does not know the refrigeration circuits and will rely more on his supplier to help you, perhaps lengthening the troubleshooting time.
Can I run my heat pump at night?
If it is coupled with a photovoltaic system, it is better to run it during the day to use the solar power.
If you have an outdoor air-to-water heat pump, running it at night will make noise outside at night, which is not ideal for the neighbors.
The noise of a heat pump is to be taken seriously as it is very much under the control of the municipalities.
If you don't have solar panels, you may want to use the peak or off-peak rates and therefore run at night to pay less.
However, electricity suppliers already offer lower rates for special heat pump electricity, which makes this assumption invalid.
Ask your installer for more information.
How do I heat my pool with a heat pump?
Today, most manufacturers offer systems that allow the pool to be heated with the same machine that heats the pool and the domestic hot water.
These systems can be a bit expensive to install, but they make little noise to perform their function.
There is also, to give in the low cost, a kind of heat pump for swimming pool, light, dedicated to swimming pools only.
These machines are generally large consumers since they must heat a large volume of water by drawing calories from the air.
Moreover they make noise, and in the canton of Vaud, in Valais or in Geneva, it is very controversial, very regulated and terribly feared.
I saw that there was a buffer tank in my estimate, but what is a buffer tank?
It is used, as its name indicates, to create a buffer between the heat pump and the hot water of the heating network which passes through the radiators in particular.
Qualified professionals always calculate a buffer tank according to your particular case.
Why install a buffer tank? If you have radiators, you should know that the volume of water flowing through them is very small.
When heat is needed for your home, the heat pump will have to start up to heat the volume of water that will flow through your radiators.
However, it is so low that the heat pump will heat it up very quickly, in maybe a few minutes
Then the demand will have disappeared and the pac will stop. The compressor stops.
But then the need returns quite quickly because the heat is returned to the home.
So you have to turn on the heat pump and the compressor and so on...
The compressor hates these nuisance starts and may suffer from them.
This is why for any heating request we will reserve a whole volume of water to be heated
To keep the heat pump running for a minimum of time, the time it takes to heat up this volume.
The hot water is then drawn from this tank, before the compressor is switched on again.
In general it has a capacity of 200 or 300 liters.
In conclusion, when it comes to changing your heating system, installing a heat pump is a viable solution.
Be sure to discuss the operating principle with your installer
And to check the sizing carefully so that the power consumption remains as low as possible.
Don't forget to check the heat output of your radiators according to their surface area and the water inlet temperature they receive.
Depending on the model chosen, the machine will be more or less noisy: check that the sound pressure at a distance of 3 or 4 meters does not exceed 25 or 30dBA.
High temperature heat pump models are a bad solution
Because this means that you are installing a heat pump on radiators that need a high temperature.
So you are putting the cart before the horse.
First, plan to insulate your facade from the outside, or to insulate your attic
And then change your windows for example, then you will put a heat pump with low temperature radiators or floor heating.
For your domestic hot water production choose between :
- The thermodynamic water heater that cools the room and makes noise
- And directly a hot water production integrated with the heating heat pump.
After studying mechanical engineering, Julian entered the world of climate engineering in 2009. After having built his experience in the ventilationand then in the heating with the largest manufacturers of German origin, he became an entrepreneur in the renewable energies and in particular a specialist in heat pump and solar panels photovoltaic systems for thehabitat individual.