Garage Suite – Garden Suite Heating

The Weiss-Johnson Blog

Garage Suite and Garden Suite HVAC Professionals

The terms garage suite and garden suite have become interchangeable though some municipalities still define a garden suite as a suite built at grade level whether attached to a garage or not and a garage suite built above grade level on top of a garage. Whether you are building a garage suite or a garden suite there are HVAC challenges that if overcome will make the suite comfortable  as well as energy efficient.

With the increased need for affordable housing as well as a common desire to pay part of a mortgage through rental revenue we are seeing a marked increase in building garage suites and garden suites. We have vast experience in completing HVAC installations for garage suites and garden suites in both new housing as well as renovations and add ons.

Heating your garage suite or garden suite

Each garage suite and garden suite requires an independent heating and ventilation system. Below are the three most common ways in which this can be achieved


Forced Air Furnace 

  • The addition of a separate forced air furnace, and associated ductwork, can achieve this goal. With a typical garden or garage suite generally being around 600 Sq. Ft, we often use a small furnace for this space as there are normally only 6-7 heat runs in the suite. The primary ventilation system is typically a bath fan interlocked with the furnace. The reason for this is the mechanical room for most garage and garden suites is under the stairs and is quite small so an HRV is tough to fit in the mechanical room. The furnace and duct system for this type of install is usually in the $4800-$6000.00 range.
  • Often a tankless water heater is used by the plumbing contractor too because of the limited space in this mechanical room.

We typically recommend doing a hot box scenario when doing a garage suite so that we can help keep the floor warmer with the cold garage below. It is the most cost-effective way to install the ductwork. If you spray foam the space where are ductwork is under the garage suite, we must create a barrier between any ductwork and the spray foam as they can’t touch. We accomplish this by insulating all the ductwork but it is time consuming and can be quite expensive.


Electric Baseboard Heat paired with an HRV system for Ventilation

  • Electric Baseboard heat is sized and installed according to the heat loss of the suite.
  • An HRV is installed and ducted to exhaust from the bathrooms and to supply Fresh Air to the living areas of the suite. The HRV will be the Primary Exhaust system for the suite.

Initial cost is typically less than a Forced Air System. An HRV system with electric baseboard heat will run between $3800 -$5000

Operating costs will be higher for the homeowner. Electrical costs for the baseboard electric heaters will far exceed the cost for gas of a furnace. No humidification or air filtration is available with this option and this could be an issue for some.

Warranty. Electric space heaters don’t have great warranties when compared to a furnace.


Hydronic Heating paired with an HRV system for Ventilation

  • Hydronic, or in floor, heating is installed using a series of pipes located below a poured concrete slab. Heat transfers from the heated water/glycol and heats the concrete.
  • An HRV can be installed and ducted to exhaust from the Bathrooms and to supply Fresh Air to the living areas of the suite. The HRV will be the Primary Exhaust system for the suite.

This system is most expensive and virtually impossible to do in a renovation without incurring huge costs. Also cannot have any humidification/filtration added. It is however the most comfortable, even heat, for the occupant.


The Weiss-Johnson Blog Team

We are the Weiss-Johnson Blog Team! All blog posts are written by a collective of WJ employees. Each one of our articles is designed to inform our customers of all the happenings in the world of home comfort! Thanks for reading!

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