Choosing Who To Call
This is a trade with a very low barrier to entry and a long history of telephone selling, which makes a few specific questions worth asking.
Short answer
Ask what equipment is used and whether the system is put under negative pressure. Ask whether the furnace, blower and coil are included or extra. Ask how many openings and how long the job takes. A quoted job that takes an hour and does not open the furnace cabinet is a vacuum pushed into a few registers.
The questions
What equipment: a truck-mounted or portable negative-pressure unit putting the whole system under suction, rather than a shop vacuum at each register.
Is the system put under negative pressure while working, so dislodged debris leaves the house rather than being redistributed.
Is mechanical agitation used — brushes, air whips — rather than vacuum alone.
Are the furnace cabinet, the blower wheel and the evaporator coil included, or extra.
How many access openings will be cut, and how are they sealed afterwards.
And how long is the job, because a whole-system clean on a Toronto house is hours rather than forty minutes.
The blower wheel is the tell
Ask whether the blower wheel is removed and cleaned. It is the single dirtiest component in most systems, cleaning it makes a measurable difference to airflow, and it is the item that separates a company doing the work from a company doing the visit. Many quotes exclude it and most homeowners never ask.
Warning signs
A very low advertised price for a whole house, which is a lead price rather than a job price, and where the upsell happens on site.
Telephone selling with a price before anybody has seen the house.
Before-and-after photographs that are not of your ductwork, which is a well-documented practice in this trade.
A sanitizing or antimicrobial upsell presented as necessary, particularly before the cleaning itself has happened.
An ultraviolet lamp sold on the doorstep.
And a job quoted at under an hour, which is not a duct cleaning.
What a good job looks like on the day
Floor and furniture protection, and the house left as it was found.
Access openings cut where needed and properly sealed with metal and mastic afterwards, not with tape.
The furnace cabinet opened, the blower pulled, the coil accessed.
Every register and boot cleaned, not just the accessible ones.
The negative air unit running and venting outside.
And a new filter fitted at the end, with the filter slot sealed.
Common questions
What is the key question?
Whether the blower wheel is removed and cleaned. It is the dirtiest component and the usual exclusion.
How long should it take?
Hours on a Toronto house. A forty-minute job is not a duct cleaning.
Is a very low advertised price a problem?
It is usually a lead price with the real work sold on site.