What's the Difference Between an RTU and a Split System? (Commercial)

RTUs (rooftop units) and split systems are the two dominant commercial HVAC configurations in the GTA. They serve different building types and have very different cost, maintenance, and lifespan profiles. The right choice depends on your building's roof structure, available space, zoning needs, and long-term plans.

Rooftop Unit (RTU) — At a Glance

All components (compressor, evaporator, gas heat, blower) packaged in a single cabinet on the roof
Single duct connection through the roof penetration
Typical capacity: 5 to 25+ tons cooling, 100k to 400k BTU heating
Common in: strip malls, retail boxes, warehouses, single-tenant offices, light industrial
Lifespan: 15–20 years
Replacement cost: $14,000 – $48,000+ per unit installed (see [commercial RTU replacement guide](/blog/commercial-rtu-replacement-toronto-property-managers))

Split System — At a Glance

Compressor and condenser outside (ground or roof), evaporator and air handler inside (typically mechanical room)
Refrigerant lines connect the two — installed by professionals only
Typical capacity: 1.5 to 30 tons cooling depending on configuration
Common in: multi-tenant offices, restaurants needing zone control, hotels, residential-converted-to-commercial buildings
Lifespan: 15–20 years
Replacement cost: $9,000 – $40,000 depending on size

When RTUs Win

Building has flat roof with structural capacity for HVAC equipment
Single zone or simple multi-zone setup acceptable
Want all equipment outside the leased space (frees up tenant area)
Preference for simpler service access (everything on the roof)
Short-term lease with multiple tenants — RTUs make zone changes simpler

When Split Systems Win

Roof can't support an RTU (sloped, lightweight construction, heritage building)
Multi-zone requirements with VRF (variable refrigerant flow) capability
Lower noise requirements (compressors can be ground-mounted away from tenants)
Custom airflow needs (industrial process cooling, server rooms)
Heritage facade preservation — outdoor units can be ground-mounted out of sight

VRF / VRV — The Modern Split System Evolution

Variable Refrigerant Flow (VRF) systems are advanced split systems with one outdoor unit serving 8–32 indoor units, each with independent zone control and inverter-driven capacity modulation. Increasingly common in newer GTA office buildings and hotels. Higher upfront cost, dramatically better part-load efficiency, and individual tenant zoning. Brands: Daikin VRV, Mitsubishi City Multi, LG Multi V.

Cost Comparison

Single 10-ton RTU: $22,000 – $35,000 installed
Equivalent split system (10-ton condenser + air handler): $18,000 – $32,000 installed
10-ton VRF with 8 indoor heads: $35,000 – $60,000 installed (higher capability)
Crane mobilization for RTUs: $1,500 – $5,000 per crane day

Maintenance Differences

RTU: roof access required for all service. Single point-of-failure (whole unit replaced when major component fails). Bird/debris exposure on filters and coils.
Split: ground or basement access for outdoor compressor. Indoor air handler accessible without ladder. Components can be replaced individually.

Which Should You Choose?

For most simple GTA commercial buildings (strip malls, single-tenant offices, warehouses, retail), RTUs are the standard and cost-effective choice. For multi-tenant buildings, restaurants with multiple zones, or buildings where the roof can't support an RTU, split systems make more sense. For new construction or major renovations of multi-tenant buildings, VRF is increasingly the right answer. ZK Mechanical designs and installs all three across the GTA — see our [commercial HVAC services](/services/commercial-hvac) for full scope, or [contact us](/contact) for project-specific recommendations.

Frequently Asked Questions

What is a rooftop unit (RTU)?

A rooftop unit is a self-contained commercial HVAC system that combines the compressor, condenser, evaporator, gas heating section, and blower in a single cabinet installed on the roof. A single duct penetration connects it to the building below. RTUs are common in strip malls, retail boxes, warehouses, and single-tenant offices because they keep all equipment outside the leased space and simplify service access.

What is a split HVAC system?

A split HVAC system separates the outdoor components (compressor and condenser) from the indoor components (evaporator coil and air handler), connecting them with refrigerant lines. Split systems are common in multi-tenant offices, restaurants, hotels, and buildings where the roof can't support a heavy rooftop unit. They allow more flexible zoning and quieter outdoor unit placement.

Which is more expensive — RTU or split?

Like-for-like, RTUs typically cost slightly more installed than equivalent split systems — RTUs include integrated gas heat in a single cabinet and require crane lifting. A 10-ton RTU runs $22,000 to $35,000 installed; an equivalent 10-ton split system runs $18,000 to $32,000. VRF systems cost more upfront ($35,000 to $60,000 for a 10-ton 8-zone) but deliver multi-zone capability that simple RTUs cannot.

How long does a commercial RTU last?

Commercial rooftop units typically last 15 to 20 years with proper maintenance in the GTA. Units that skip annual maintenance often fail closer to 12 years. After 15 years, repair costs spiral and you're typically missing 30%+ efficiency gains from current equipment, making replacement the better long-term decision.

Can I convert from RTU to split system or vice versa?

Yes, but it's typically a major retrofit. Converting from RTU to split requires installing indoor air handlers, ground-mounting the condenser, running refrigerant lines, and either repurposing or removing the rooftop ducts. Converting split to RTU requires roof structural assessment, removing indoor equipment, and adding a curb. Most building owners stick with the original configuration unless a major building renovation is happening.