• Heating via air

    Heating via air

    with hot water or electrically

Heat Recovey Ventilation Systems are an efficient way of providing ventilation with hardly any heat losses for relatively airtight buildings. Whereas they are primarily not heating systems, in some cases they can be used for space heating or back up heating.

In order to give you a better guideline when MVHR/ HRV systems are recommended and what needs to be taken into account if they should be used for space heating, we have produced the following chart:

A – Feasibility for commercial buildings

Is the building heated and needs ventilation, e.g offices, schools, nurseries, care homes, swimming pools, etc.Is heat being produced that needs to be expelled, e.g. in a plant room, and can other parts of the building take advantage of the heat, e.g. offices?Is the building unheated and needs ventilation for the expelling of smells only?
MVHR is feasible.
–> Please contact us for details
MVHR could be feasible.
–> Please contact us for details
 Extract ventilation.
Unfortunately we do not supply these systems.

B – Feasibility for dwellings

Will the building be fairly air tight (below 5 m3/(h m2) at 50Pa)? This could also be the case if a building is being renovated with window exchange.Are high humidity levels a problem? Or is noise protectionin habitable rooms needed, e.g. bedrooms due to traffic noise? Or is air quality an issue?Otherwise
MVHR is feasible; if no trickle ventilators will be installed, MVHR is necessary.
–> Please see below for details.
MVHR could be feasible.
–> Please contact us for a detailed analysis
Continuous or intermittant extract ventilation or extract air heat pump are possible.
Unfortunately we do not supply these systems

C – Choice of MVHR system and heating method for dwellings

Dwelling with whole house central heatingPassivhaus or Low Energy Building with only part of the building heated, e.g. via stove or part underfloor heating/ radiatorsPassivhaus (best thermal efficiency standard) without central heating system
We recommend to use a highly efficient MVHR system. For Passivhaus buildings PH certified MVHR systems are mandatory. A post heater is normally not needed.A Passivhaus certified MVHR system with post heater is highly recommended. Special attention to the design and the specification of ducting is needed. Heating in wet rooms and kitchen is necessary.A Passivhaus certified MVHR system with post heater is necessary. Special attention to the design and the specification of ducting is needed. Extra heat source in wet rooms an kitchen is necessary, e.g. heated towel rails or underfloor heating.
A detailed thermal analysis (possibly room-by-room)needs to be done by an experienced consultant at the early design stage of the building. Please note that there will be varying degrees of temperature differentiation from heated to unheated rooms.
A certified Passivhaus Designer has to be involved for thermal calculations via the PHPP (Passive House Planning Package). The PHPP needs to show that heating via air is possible. In more complicated cases a thermal room-by-room analysis is needed.

D – Choice of Post Heater

Post heaters can be installed for the whole house (close to the MVHR unit) or for individual floors.If hot water is generated via a renewable source or by the use of a cheap electric night tarrif and there is there plenty of hot water stored…if not…
 Type of heater:A water based post heater is probably the best choice, all supply ducts after the heater need 25mm+ insulation.An electric post heater is probably necessary, all supply ducts after the heater need 25mm+ insulation.
 OutputThe output depends on the ventilation level and the temperature of the hot water, which should ideally be 70 deg. Celsius. Between 180 and 220 l/hr of hot water are needed.The output is generally 2kW. Heaters with less or more capacity can be provided.
ControlsThe heater is usually controlled by a room thermostat, operating either a dedicated pump or a motored valve, which enables or disables the water flow through the heater.The heater is usually controlled by a room thermostat and a special controller, which measures the air temperature and disables the heater when there is no air flow.