Not everyone knows that mechanical ventilation - already present in many homes - can be a nice stepping stone to a true heat pump. With it, you can achieve nice energy savings. It doesn't even require an outdoor unit, making it a relatively minor operation to get this done. What is a ventilation heat pump and how does it all work?
Many homes have mechanical ventilation. In its simplest form, the air in certain areas of the house, such as the bathroom and toilet areas, is extracted and exhausted at a central point through an air duct to the outside. Due to the negative pressure created in the house, new, fresh air is automatically supplied to the living room and bedrooms, for example, via grilles near the windows or in the outside wall.
Say goodbye to heat
In this way, the air in the house is continuously refreshed, but with the major disadvantage that a lot of heat is blown outside with the exhausted air. The boiler then has to work hard to bring or maintain the house to the desired temperature. Which of course is a great shame and unnecessary.
With balanced ventilation with a heat recovery system, the situation is already much better, because here a lot of heat is first recovered from the extracted air, before this air is blown outside. With this heat, fresh incoming air taken from outside is then neatly reheated. The boiler now has to step in much less often. In this case, however, additional air ducts are needed, not only for the outgoing but also the incoming air flow, both with their own fans. Because these two airflows are balanced, this is called balanced ventilation.
No outdoor unit
A ventilation heat pump can be used in either situation. A major advantage is that a ventilation heat pump does not require an outdoor unit at all, let alone a ground source. After all, the heat is extracted from the (outgoing, warm) ventilation air. This also makes this type of heat pump very suitable for apartment buildings and condominiums. Basically, the mechanical ventilation box is replaced by a heat pump of about the same size and thus quite small. It hardly takes up any space, which can be important in existing situations.
It is of course questionable whether sufficient heat can always and at all times be recovered if there is only an outgoing air duct (ventilation type C). After all, (cold) outside air is then supplied via, for example, window and wall grilles. Therefore, a hybrid ventilation heat pump can also be chosen. At peak times, the central heating boiler will then step in and provide hot tap water. All in all, this works to save energy, but the house or apartment can certainly not yet be off the gas.
Extra return
If there are both inlet and outlet air ducts (Type D ventilation), then much more is possible. This time there are intake valves scattered throughout the house and no more grilles in windows or walls. Because both airflows are now fully controlled, the heat recovered from the outgoing air can be transferred immediately to the fresh incoming airflow for pre-heating.
Not surprisingly, a "regular" heat recovery system is already possible with this type of ventilation. But a ventilation heat pump manages to recover even more heat, because it can cool the exhaust air enormously, much colder than the outside air in many situations. In addition, some ventilation heat pumps can draw some additional energy from the condensation of ventilation air, which adds to the efficiency.
Insulation and release points
So, depending on the situation, a compact ventilation heat pump can be installed that supports the existing boiler (hybrid heat pump), or an all-in-one ventilation air/water heat pump (all-electric). With the latter, you energy-efficiently combine the ventilation of the home with the heating of that same home, plus there is an (often) internal boiler for hot tap water. So this allows a home to get rid of gas.
As always, it is important that a licensed installer look at the entire chain. First of all, it is and remains important that a house or apartment is adequately insulated. Because all the heat that you lose through poor insulation is of course definitively lost and then the ventilation heat pump still has to work extra hard. It is also necessary to look at the heat release points of the central heating system. With a ventilation heat pump, the heating water gets less hot than with the traditional central heating boiler and the existing radiators or underfloor heating must be able to cope with that.
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