Hydronic Quick Design — Intermountain Sales & Marketing

Radiant Floor Inputs

Project Name / Address

Heated Floor Area (ft²) i

Construction Type i

New Construction 25 BTU/hr·ft²

2×6 framing · R-21+ walls · R-38+ ceiling · Low-e windows · Tight sealing

Moderate — 1980 to 2000 35 BTU/hr·ft²

2×4 or 2×6 · R-11 to R-19 · Double-pane · Average air sealing

Old / Leaky — Pre-1980 50 BTU/hr·ft²

Minimal insulation · Single or old double-pane · Poor air sealing

Floor Assembly i

Tube Spacing i

Climate Zone i

Site Elevation (ft) i

System Output — Radiant Floor

Enter floor area and construction type,
then tap Calculate System.

Heat Load

Floor area—

Adjusted BTU/ft² multiplier—

Design load—

Lochinvar boiler model—

Tubing & Manifolds

System flow rate—

Tube spacing selected—

Coverage per loop—

Number of loops—

Tube specification—

Number of manifolds—

Ports per manifold—

Design supply temperature—

Pumping & Zone Control

Boiler pump—

Zone pumps—

Supply / return pipe size—

Caleffi zone relay—

Thermostats—

Expansion, Fill & Separation

Approx. system volume—

Hydronic expansion tank—

Axiom system feeder—

Caleffi air separator—

Mixing station—

Condensate neutralizer—

Snowmelt Inputs

Project Name / Address

Total Melt Area (ft²) i

Site Elevation (ft) i

≤ 6,000 ft → 130 BTU/hr·ft² | > 6,000 ft → 150 BTU/hr·ft²

Pavement Type

Snow Sensor / Control

Automatic — Recommended

Pavement-embedded moisture + temp sensor · Auto activation · Hold-over mode

Manual

Owner-activated · Not recommended for reliability-critical applications

Boiler Arrangement i

Tube Spacing i

Standard design assumptions:
¾" PEX-A oxygen-barrier tubing · Spacing per selection above · 300 ft max circuit · 40% inhibited propylene glycol · 130°F supply temperature

System Output — Snowmelt

Enter melt area and elevation,
then tap Calculate System.

Snowmelt Load

Melt area—

Elevation / multiplier—

Snowmelt design load—

Lochinvar boiler model—

Boiler pump—

Tubing & Circuits

Number of circuits—

Tube spacing selected—

Tube specification—

Total circuit footage—

Manifold—

Glycol System

Fluid specification—

System volume—

Glycol concentrate needed—

Zone pump(s)—

Supply / return pipe size—

Hydronic expansion tank—

Axiom system feeder—

Controls & Accessories

Snow / ice sensor—

Control strategy—

Caleffi air separator—

Condensate neutralizer—

Slab edge insulation—

Under-slab insulation—

Combined System Inputs

⚠️ Important: Combined boiler sizing assumes both systems run at full load simultaneously — because during a severe storm they will be. Never size for one system at a time.

Project Name / Address

Radiant Floor Area (ft²)

Radiant Construction Type

Radiant Tube Spacing i

Climate Zone (radiant)

Snowmelt Area (ft²)

Snowmelt Tube Spacing i

Site Elevation (ft)

System Output — Combined

Enter radiant and/or snowmelt areas,
then tap Calculate Combined System.

Combined Load

Radiant floor load—

Snowmelt load—

Combined peak load—

Lochinvar boiler model—

Altitude-rated output required—

Boiler pump—

Radiant Floor System

System GPM—

Tube spacing—

Loops—

Manifolds—

Zone pumps—

Caleffi zone relay—

Radiant expansion tank—

Axiom feeder (radiant)—

Snowmelt System

Circuits—

Snowmelt manifold(s)—

Secondary pump (glycol)—

Glycol concentrate needed—

Snowmelt expansion tank—

Axiom feeder (snowmelt)—

Shared Components

Boiler configuration—

Caleffi air separator—

Condensate neutralizer—

Piping configuration—