Small Suites With Big Comfort Problems
A 3-ton rooftop unit is the right tool for a small commercial space, but only when it is the right size. The calls we get from small suites usually fall into two groups. Dental operatories and clinic rooms that will not hold steady temperature or humidity. And small retail units where someone installed an oversized RTU that short cycles, leaving the space clammy and the compressor wearing out early.
A 3-ton RTU delivers about 36,000 BTU of cooling. That suits many small storefronts, dental suites, medical offices and service businesses, once the actual load is checked.
Fit by Use
| Building use | Why 3 tons often fits | What changes the math |
|---|---|---|
| Dental or medical suite | Small floor area, steady occupancy | Equipment heat, sterilization rooms, filtration |
| Small retail storefront | Modest floor area | West-facing glass, door traffic |
| Small office or service business | Few occupants | Server closet, kitchenette |
We confirm with a Manual J load calculation, not a square-foot rule. When the load comes in higher, a 5-ton rooftop unit may be the better fit.
Clinics and the Dental Operatory
A dental operatory needs quiet, steady temperature and clean air. That means a unit sized to the load (so it runs longer, gentler cycles), MERV 13 filtration where the blower can handle it, and an install scheduled after hours. On our Davisville dental clinic project, the right-sized unit and after-hours install meant no lost patient day.
How Much Does a 3-Ton RTU Cost?
3-5 ton units run $9,500-$16K installed, typically in 3-5 business days. That includes crane, curb check, gas and electrical connections and commissioning on standard roofs. Curb adapters and permits are listed separately if needed. Brands include Lennox, Carrier, York, Trane, Daikin, Rheem and American Standard.
Quick Answers
Is a smaller unit always cheaper to run? A right-sized unit is cheaper to run than an oversized one, because it short cycles less and controls humidity better.
Can a 3-ton unit replace an old 5-ton? Sometimes. Many small suites were fitted with oversized units years ago. If the load calculation says 3 tons, going smaller saves capex and hydro.
For installation details see commercial rooftop unit installation, and for model options see packaged rooftop units. We install small RTUs across North York, Davisville, Leaside and the GTA, alongside the rest of our Toronto commercial rooftop units.
