Can an older house switch to geothermal heating?

Does geothermal heating work in existing homes?

A ground-source heat pump does not care how old the house is. It cares about how much heat the building needs on the coldest days and how that heat is delivered to the rooms. A drafty house with little insulation needs a bigger heat pump and a bigger loop, which raises cost. A tighter house needs less of both. The same geothermal heating system can also cool the house in summer, which may let an older home drop a separate air conditioner.

That is why the order of work matters. Cutting heat loss first usually lets you buy a smaller system, and a smaller system costs less to buy and to run. If you have not had one, a home energy audit gives you the heat-loss picture that any installer should size from. The insulation upgrade priorities guide lists where the savings tend to come first.

What does the existing heating system change?

Older homes usually have one of three setups, and each one affects a geothermal retrofit differently.

• Forced-air ductwork. Often reusable, but old ducts are sometimes too small for the airflow a heat pump wants, so duct changes can be part of the job.
• Hot-water radiators or baseboard. Heat pumps deliver lower water temperatures than a boiler, so radiators may need to be larger or supplemented to keep rooms comfortable.
• Electric baseboard with no ducts. Adding a full duct system or hydronic distribution to a finished house is the biggest cost and disruption.

Low supply temperatures are a strength of the technology, not a flaw, and the same idea runs through the Drake Landing design, where homes were heated with a low-temperature district loop and an air handler in each house. For the principles, read about low-temperature hydronic heating and radiant floors.

Is there room on an older lot to drill or dig?

Older neighbourhoods often have mature trees, buried services and small yards. A horizontal loop needs a lot of open ground. A vertical loop needs far less surface area but a drilling rig, access for a truck and an approved location away from buried lines, septic systems and property boundaries. Some contractors can use compact rigs for tight sites.

Ask your contractor how the loop type was chosen and whether the soil and bedrock where you live suit it. The guide to horizontal and vertical ground loops explains the trade-offs. Rules on drilling, water wells and setbacks differ by province and municipality, so confirm what applies locally before you sign anything.

What does a retrofit cost, and is it worth it?

Retrofit costs are higher than for a new build because of loop drilling, interior work and often some duct or distribution changes. The final figure depends on house size, loop type, ground conditions and region, so quotes decide, not rules of thumb. See the geothermal heat pump cost guide for the main drivers.

Payback depends on what you heat with today. A house on electric baseboard or oil has more to save than one on cheap natural gas. Federal and provincial programmes for heat pumps have existed in various forms, and their terms change, so check the Government of Canada energy-efficiency pages, your provincial energy ministry and your utility for what is open now.

If the house is poorly insulated or the budget is tight, a cold-climate air-source unit may suit better. Our comparison of air-source and ground-source heat pumps sets out when each one wins.

What is the practical route to a retrofit?

Start with an energy audit and any envelope work that pays for itself. Ask two or three installers for a heat-loss calculation, a loop design and a written scope that names duct and distribution changes. Compare those, not just the total price. Then walk through the geothermal installation process so you know what each stage involves, from drilling to commissioning.

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