None of the Lochinvar products are appropriate DIY installs. Combi boilers and condensing commercial water heaters require licensed contractor install in nearly every US jurisdiction, plus typically Lochinvar manufacturer training for the contractor on the specific model.
NOBLE / KNIGHT Combi Boiler install
- Wall-mount on framing capable of supporting 90-130 lb unit
- Direct vent PVC: 2" or 3" Schedule 40 PVC per manual; equivalent length tables in the install manual must be followed
- Sidewall termination: 12" above grade, 12" from windows/inlets, 4 ft from gas meter or LP tank
- Concentric vent option: single penetration for intake + exhaust
- Gas line: ¾" minimum to NKC110/WHN85; ¾"-1" to NKC199/WHN155/WHN199 depending on length from meter
- Condensate drain: condensate trap with floor drain or condensate pump. Add condensate neutralizer if discharging to copper plumbing
- System fill: 12-15 PSI cold; auto-fill valve recommended; expansion tank sized per system volume
- DHW shutoffs: isolation valves on both inlet and outlet for plate exchanger descaling
- 120V outlet within 6 ft
- Combustion air: sealed combustion via dedicated intake pipe; no room-air requirement
SQUIRE Indirect-Fired Tank install
- Floor-stand on standard pad; 40-120 gallon footprints
- Boiler loop circulator (typically 1/25 HP, often Taco 007 or Grundfos 15-58) on the boiler-to-tank loop
- Piping: 1" supply and return between boiler and tank coil; minimize fittings
- Aquastat: Honeywell L4081 or equivalent; mounts on tank well; signals boiler on DHW call
- DHW priority wiring at boiler controls — DHW call overrides space heat call until tank satisfied
- Tempering valve downstream of tank — tank stores at 140°F to suppress Legionella; tempering valve mixes to 120°F at the fixtures
- 120V for circulator only — tank has no burner, no flue, no electrical for heating
- T&P relief on tank outlet
- Anode rod (SIT only): magnesium anode standard; replace at year 5. SSU stainless has no anode
AWHP Heat Pump install
- 240V 30A dedicated circuit
- 700+ cubic feet of unconditioned air space — basement or garage; closet install requires louvered doors with 240 sq in vent area
- Condensate drain — gravity drain or condensate pump (~$120)
- Ambient temperature 40-90°F for full heat pump operation
- Drain pan required indoor or above living space
- Service clearance: 12" sides, 24" front, 18" top
EnergyRite Commercial install
- Atmospheric B-vent chimney sized per BTU input (ERN-301 typically 6" Type B; ERN-852 may require 8-10")
- Commercial-grade gas line: 1.25" minimum on ERN-501; verify with engineered piping calc
- Combustion air: 50 cubic feet per 1,000 BTU input — ERN-501 (500 MBH) needs 25,000 cubic feet OR engineered combustion air supply ducts
- Commercial drain for tank draining and T&P discharge
- Mechanical room requirements per IBC/IFC: fire-rated walls, adequate clearances, ventilation
ARMOR Condensing Commercial install
- PVC venting — sidewall or roof termination; equivalent length per manual
- Condensate neutralization required for code compliance (acidic condensate)
- 120V controls + dedicated outlet
- Gas line sized per engineering calc
- Condensate pump and drain often required where gravity drain isn\'t available
- Service clearances per manual — front access for heat exchanger service
Permits and inspections
All Lochinvar installs require permits in nearly every US jurisdiction. Commercial installs trigger commercial mechanical, gas, plumbing, and electrical inspections. Coordinate with your local AHJ early.
Bottom line
Lochinvar install = contractor work. Combi requires Lochinvar-certified installer for warranty. Indirect is the most accessible — any competent boiler installer can integrate a SQUIRE. AWHP heat pump is the most homeowner-friendly Lochinvar product. Commercial always requires engineered design and licensed mechanical contractor.