The “No Permit Needed” Furnace Replacement
A 1992 detached two-storey house has a mid-efficiency furnace in the basement vented through a masonry chimney. The homeowner accepts a contractor’s proposal to install a high-efficiency condensing furnace, add an A/C coil, relocate the furnace 1.5 m, cut a new 350 mm by 250 mm return-air opening in the basement ceiling, and terminate new PVC venting on a side wall within 1 m of the property line. The contractor says no building permit is needed because it is “just a furnace replacement” and plans to start Monday. The homeowner asks you, as the municipal HVAC reviewer, whether to stop the work.
1. Is the contractor’s no-permit position defensible? Identify the facts that move this beyond a like-for-like replacement and explain the permit and scope consequences.
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It is not defensible on these facts. The Building Code Act treats heating, ventilating and air-conditioning systems as part of a “building,” and the OBC applies to construction and alteration of those systems. A true like-for-like appliance swap may be treated as exempt in some municipalities, but this project is not equivalent:
- The venting category changes from a mid-efficiency appliance on a masonry chimney to a condensing appliance with side-wall PVC venting. Vent termination near a property line, clearances, condensate disposal and combustion-air provisions all require review.
- The furnace is relocated, which changes clearances, access, duct connections and possibly structural or fire-separation details.
- A new return-air opening is cut in a floor/ceiling assembly. That is an alteration to the building envelope and may affect structure, fire protection and air pressure balance.
- Adding an A/C coil and new controls changes the system, not just the appliance.
The proper response is to stop work until a permit application is made, unless the authority has confirmed in writing that the specific scope is exempt. If work has already begun, require a permit before concealed work proceeds and inspect the concealed duct, vent and clearance details.
2. What plans, specifications and designer information should be in the permit package, and which site inspections would you attach?
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The package should be sufficient for a reviewer to verify code compliance without visiting the site, including:
- Floor plans showing furnace location, service clearances, vent route and termination, combustion-air source, condensate drain and trap, A/C coil location, duct layout, return-air opening size and location, and electrical disconnect.
- Equipment specifications showing heating and cooling capacities, fuel input, venting category, clearances to combustibles and manufacturer’s installation instructions.
- A heating and cooling load calculation and duct design basis, rather than equipment selected only by floor area.
- Designer information: the name and qualification of the person responsible for the HVAC design, and confirmation that the design complies with Part 9 and any applicable Part 6 requirements.
- Separate fuel-gas and electrical approvals where required.
Attach inspections for rough-in before concealment: venting and clearances, duct openings and firestopping, combustion air, condensate, structural cutting, and final inspection for operation, clearances, vent termination, controls and commissioning.
3. If the work proceeds without a permit, what enforcement and safety risks follow, and what is the most proportionate response?
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Risks include unapproved concealed work, unsafe venting or combustion-air conditions, structural weakening at the new opening, fire-separation breaches, and a building record that does not reflect the installed system. Enforcement exposure includes a stop-work order, double permit fees, ordered removal or correction of concealed work, and possible refusal of occupancy or insurance complications.
The proportionate response is not to assume the worst, but to stop work, require a complete permit application, and require inspection of anything already concealed. If the contractor resists, document the scope and the code basis. Allow the contractor to propose an equivalent alternative only if it is supported by a listed product or an engineer’s design. The goal is a compliant installation that can be inspected, not punishment for its own sake.