Overview
Code requirements and best practices for installing mini-split outdoor condensing units in Michigan climate. This information will be critical during Stage 6 (After Build / MEP & Finish) when installing the HVAC system.
Two-System Topology
Per 2026-05-14 — Mini-Split Topology: Two Separate Systems (Single-Zone Garage + 2-Zone Loft), this build installs two outdoor condensers on a shared concrete pad at the rear-wall location: one for the 18k single-zone Hyper-Heat (garage) and one for the 21k 2-zone (loft). All clearance, setback, electrical, and condensate requirements below apply to each condenser; inter-unit clearance (typically 12-24” between condensers per manufacturer specs) must also be observed on the shared pad. The two units will be installed at different times to anchor separate 25C tax credits — see Mini-Split HVAC Order for sequencing.
Related: HVAC Strategy
Mounting Height & Pad Requirements
Michigan Residential Code (IRC)
- Minimum elevation: At least 3 inches above ground to permit free drainage of defrost water
- Compliance: Must conform to manufacturer’s installation instructions
Michigan Climate Recommendations
- Concrete pad: Required for stability and proper drainage
- Must be level
- Should extend slightly beyond each unit’s footprint
- Sized to host both condensers with required inter-unit clearance — typical MrCool 5th Gen footprints are ~36”×14” each, so a pad ~6’×3’ provides both units plus ~18-24” between them and ~12” perimeter clearance
- Single pour for both is preferable to two separate pads — cheaper, fewer freeze/heave failure points, easier service path
- Snow/flood protection: Stand or platform highly recommended
- Elevate 12-24 inches above ground level
- Height should exceed typical snowfall accumulation
- Platform must be rated for combined snow + equipment load (two condensers ~250 lbs combined plus snow)
- Protective hood/awning: Install 40 inches above each unit to protect from heavy snow and ice accumulation
- One continuous angled shelter sized to span both condensers is acceptable as long as the per-unit overhead clearance is maintained; matches the “leftover Burnished Slate metal roofing scraps” approach noted in Outdoor Unit Weather Protection
Clearance Requirements
From Building Walls
- Code approach: IRC defers to manufacturer’s installation instructions (no fixed distance specified)
- Typical manufacturer requirements:
- 12 inches minimum from wall or other obstructions
- 28 inches minimum from front (service access side)
- 12 inches minimum from rear
- 40 inches minimum overhead clearance
Between Adjacent Condensers (Two-Unit Pad)
- Inter-unit clearance: 12-24 inches minimum between adjacent condensers, per MrCool 5th Gen install manual. Required to prevent each unit’s exhaust from being drawn into the adjacent unit’s intake (recirculation) and to allow service access between them.
- Service-side orientation: Orient both units so their service-access faces (front, ~28” clearance) point outward from the pad rather than toward each other where practical. If units must face each other, increase inter-unit spacing to at least 30” to maintain service clearance for both.
- Verify per-unit specs: Final inter-unit spacing must reference the specific 5th Gen 18k single-zone Hyper-Heat install manual and the 5th Gen 21k 2-zone install manual at time of order — MrCool spec sheets occasionally tighten or relax this.
Service Access (IMC Section 306.1)
- 30” x 30” level working space required on control side for servicing
- Additional clearances per manufacturer’s specifications
Why Clearances Matter
- Insufficient clearance increases operating costs
- Reduces system efficiency
- Shortens equipment lifespan
- May cause airflow restrictions and performance issues
Property Line Setbacks
General Information
- Not uniform: Requirements vary significantly by municipality in Michigan
- Typical range: 3-5 feet from property line (common standard)
- Fire safety minimum: 3 feet is a common fire safety standard across jurisdictions
- Some jurisdictions: May extend to 5-6 feet depending on zoning
Michigan Residential Code (MRC 2015)
- No specific setback for HVAC condensing units in state code
- Exhaust openings: Must be 3 feet from property lines (MRC M1506.3)
- Defers to: Manufacturer clearances and local zoning ordinances
- Note: 2021 MRC adoption delayed by court order (July 2025); 2015 codes remain in effect
Clare County Setback Research
Jurisdiction: Clare County Community Development handles all building/mechanical permits for City of Clare (as of July 25, 2016).
Contact Information:
- Clare County Community Development
- 225 W Main St, Harrison, MI 48625
- Phone: 989-539-2761
- Hours: 7:30 a.m. - 4:00 p.m. (closed noon-1 p.m.)
- Website: clareco-buildingdev.net
City of Clare Contacts:
- Zoning/Code Enforcement Officer: Terry Acton
- Building Official: Mark Fitzpatrick
Our Situation:
- Garage rear wall is 6 feet from rear property line
- Typical 3-foot setback requirement would leave 3 feet for unit placement
- Unit width (~3 ft) + wall clearance (1 ft) = 4 ft total depth needed
- Assessment: 6 feet is likely sufficient, but must verify with county
Questions to Ask Clare County:
- What is the required setback for mechanical equipment from rear property line?
- Are there noise restrictions for HVAC equipment near property lines?
- Does the township have additional zoning requirements beyond county code?
Common Requirements from Other Jurisdictions (Reference)
Based on research of various municipalities:
- 3 feet: Common fire safety minimum (Bay Area cities, many others)
- 5 feet: Seattle, Albany CA, some Michigan townships
- Enclosures: Cannot extend more than 4 ft into setbacks; must be 3 ft from lot line
- Noise limits: 50 dBA at property line (when within 10 ft of neighbor’s living areas)
Noise Considerations
- Keep at least 10 feet from:
- Neighbors’ patios
- Bedroom windows (yours and neighbors’)
- Property lines where noise could be an issue
- Typical noise limits: 45-50 dBA at property line
- Hyper-Heat units may be slightly louder during defrost cycles
Required Action
⚠️ Critical: Contact Clare County Community Development (989-539-2761) to confirm specific setback requirements before finalizing placement.
Electrical Requirements (NEC)
Service Receptacle (NEC 210.63)
- Requirement: 125V, single-phase, 15A or 20A receptacle
- Location: Within 25 feet of outdoor unit, on same level as equipment. One receptacle within 25 ft of the shared pad serves both condensers — does not need to be duplicated per unit.
- Accessible: Must be in an accessible location
- GFCI protection: Required (effective January 1, 2023 for mini-splits)
- ⚠️ Important: Receptacle must NOT be connected to load side of either equipment disconnect
Dedicated Power Supply (Two Independent Circuits)
- Two separate 240V branch circuits to the shared pad — one per condenser, each with its own outdoor disconnect:
- Garage system (18k single-zone Hyper-Heat) — fed from main panel
- Loft system (21k 2-zone) — fed from loft subpanel
- Each circuit sized per the respective unit’s nameplate (MrCool 5th Gen single-zone 18k typically 20A 240V; 21k 2-zone typically 25-30A 240V — verify at order time)
- Each unit gets its own NEMA 3R or 4 weatherproof outdoor disconnect mounted on the exterior wall adjacent to the pad
- See dedicated loads for branch-circuit allocation rationale
- Follow manufacturer’s electrical requirements per unit’s install manual
Condensate Drain Requirements
Two Condensate Drains
Each outdoor condenser has its own condensate drain. Plan two separate drain routes from the shared pad, both meeting the requirements below. The two drains may merge downstream of each unit’s trap before reaching the disposal point, but each unit needs its own trap.
Piping Standards (Michigan Plumbing/Mechanical Code)
- Trap/check valve: Required in drain line (per unit)
- Pipe size: Minimum ¾ inch internal diameter
- Cannot decrease in size from drain pan to disposal point
- If merging two drains, downstream segment sized to handle combined flow
- Material: Approved corrosion-resistant material
- Slope: Minimum 1% slope (⅛ inch per foot) toward disposal point
- Disposal: Must convey to approved place of disposal
Freeze Protection (Critical for Michigan)
- Exterior drain lines: Require insulation and/or heat trace
- Preferred solution: Route condensate drain to heated/protected location
- Winter operation: Ensure drain system functions during heating mode (defrost cycles produce condensate)
Auxiliary Protection
Required where overflow could damage building components:
- Auxiliary drain pan, OR
- Water-level detection device
Michigan Climate-Specific Considerations
Snow Management
- Unit placement: Avoid locations where snow drifts accumulate
- Roof eaves: Don’t place where snow/ice can slide/fall onto unit
- Access paths: Ensure year-round access for service/maintenance
- Prevailing winds: Consider wind direction for snow accumulation patterns
Cold Weather Performance
- Hyper-heat models: Recommended for Michigan (rated to -13°F or lower)
- Defrost cycle: Ensure proper drainage during defrost operations
- Base pan heater: Some units include this feature for freezing conditions
Seasonal Maintenance Access
- Plan for snow removal around unit
- Consider lighting for winter service access
- Maintain clear path from service entrance
Installation Sequence & Coordination
Pre-Installation (Stage 3 - Framing)
- Determine exact pad location (sized for both condensers)
- Verify property line setbacks with local building department
- Plan lineset and condensate routing through wall for both systems (two lineset paths, two condensate paths)
- Install wall sleeves/penetrations during framing — one set for the garage system (single head), one set for the loft system (two heads)
During Exterior Finish (Stage 5 - Siding)
- Install exterior electrical boxes — two outdoor disconnects (one per condenser)
- Complete lineset and condensate penetrations for both systems
- Coordinate with siding for proper flashing on all penetrations
Installation Phase (Stage 6 - After Build)
- Pour shared concrete pad sized for both condensers (outside main contract scope - see Open coordination items)
- Install mounting stand/platform (if using) — must support both units
- Order #1 (loft 2-zone, target 2026 tax year): Set loft system condenser on pad; complete electrical connections; route and connect 2-zone linesets; install condensate drain with freeze protection; commission per MrCool instructions; place in service before 12/31/2026 for 25C credit
- Order #2 (garage single-zone, target 2027 tax year): Set garage system condenser on existing pad with manufacturer-specified inter-unit clearance; complete electrical connections; route and connect lineset; install condensate drain (may merge with loft drain downstream of trap); commission per MrCool instructions; place in service in 2027 for separate 25C credit
- Install protective hood/awning spanning both units (one continuous shelter acceptable if per-unit overhead clearance is maintained)
Open Items & Decisions
Outdoor Unit Location Decision
Under Consideration: Center-back placement vs. side wall placement
| Factor | Side Wall (24’) | Center-Back (40’) |
|---|---|---|
| Lineset length | Longer (40+ ft to far units) | Shorter (~20-25 ft max) |
| Electrical run | Shorter (near panel) | Longer (across building) |
| Cost impact | Higher (copper lineset expensive) | Lower (wire is cheap) |
| Efficiency | Lower (longer refrigerant lines) | Higher (shorter lines) |
| Service access | Wall-mounted or ground | Ground level (easier) |
| Property setback | Side yard | 6 ft to rear property line |
Current Preference: Center-back placement for shorter lineset runs and better efficiency.
Blocker: Must confirm rear property line setback with Clare County before finalizing. See Clare County Setback Research.
From Initial Build Coordination
- Ask about pouring small slab for mini-split heat pump (currently outside contract scope)
- Coordinate timing with other exterior work
- If center-back placement confirmed, adjust slab location accordingly
To Be Determined
- Confirm setback with Clare County (call 989-539-2761) — stage:: 3
- Finalize placement location based on setback confirmation — stage:: 3
- Stand/platform height based on typical snow accumulation (12-24” recommended)
- Condensate drain routing (ground-level simplifies this if center-back)
- Protective hood style and mounting method
- Service access pathway design (year-round access to back of building)
- Check for roof overhang/snow shedding hazard at center-back location
Permit & Inspection Requirements
Typical Requirements
- Building permit for HVAC installation
- Electrical permit for outdoor unit circuit
- Mechanical inspection after installation
- Final inspection before commissioning
Pre-Installation Checklist
- Confirm local property line setback requirements
- Obtain necessary permits
- Schedule required inspections
- Review manufacturer’s installation manual
- Verify all clearances meet code and manufacturer specs
References & Resources
Related Project Documents
- HVAC Strategy - Overall HVAC system design
- Initial Build - Contract scope and coordination items
- Insulation Strategy - Envelope performance (affects sizing)
Code References
- Michigan Residential Code (MRC) Chapter 14 - Heating and Cooling Equipment
- International Mechanical Code (IMC) Sections 304.1, 306.1
- National Electrical Code (NEC) Section 210.63
- Michigan Plumbing/Mechanical Code - Condensate drain requirements
Manufacturer Resources
- Consult specific equipment installation manual for exact clearances and inter-unit spacing
- Follow manufacturer’s specifications for electrical, refrigerant, and condensate requirements
- MrCool DIY 5th Gen installation manuals (single-zone 18k Hyper-Heat + 21k 2-zone) — download from MrCool DIY Direct when units selected
Notes
- Initial code research conducted October 2025
- Clare County setback research conducted January 2026
- Center-back placement option added January 2026
- Two-condenser shared-pad topology adopted May 2026 (see 2026-05-14 — Mini-Split Topology: Two Separate Systems (Single-Zone Garage + 2-Zone Loft))
- Always verify current code requirements with local building department before installation, as requirements may change and vary by jurisdiction
- Michigan Residential Code 2015 remains in effect (2021 adoption delayed by court order July 2025)