How do I convert inH₂O to PSI?

Formula : PSI = inH₂O × 0.0361273 Examples : 1 inH₂O = 0.036 PSI 2 inH₂O = 0.072 PSI (typical duct) 5 inH₂O = 0.181 PSI 10 inH₂O = 0.361 PSI (gas manifold) 27.7 inH₂O = 1 PSI inH₂O to PSI converter →

How do I convert inH₂O to Pascals or mbar?

Formula : Pa = inH₂O × 249.1 mbar = inH₂O × 2.491 Examples : 1 inH₂O = 249.1 Pa = 2.49 mbar 0.5 inH₂O = 124.5 Pa = 1.25 mbar (residential duct) 2 inH₂O = 498 Pa = 4.98 mbar (commercial duct) 4 inH₂O = 996 Pa = 9.96 mbar (high static) inH₂O to Pascal converter →

What is normal static pressure in HVAC?

Residential systems : Total external static pressure : 0.4-0.8 inH₂O (target) Supply side : 0.2-0.5 inH₂O Return side : 0.1-0.3 inH₂O High static pressure problems (>1.0 inH₂O total): Reduced airflow Higher energy costs Shortened equipment life Possible compressor damage Low static pressure (<0.3 inH₂O): May indicate oversized ductwork Can cause noise issues Commercial/Industrial : 1-4 inH₂O typical (design dependent)

When should I replace an HVAC filter?

Pressure drop method (most accurate): MERV 8 : Replace at 0.5 inH₂O MERV 11-13 : Replace at 0.7-1.0 inH₂O HEPA : Replace at 2-3 inH₂O Without gauge : Monthly inspection Every 1-3 months residential More often if pets, allergies, construction Measure with : Magnehelic gauge or manometer across filter

Why use inH₂O instead of PSI for HVAC?

Appropriate scale : HVAC pressures very low (0.1-2 inH₂O = 0.004-0.072 PSI) Historical : Water manometers traditional measurement tool Precision : Easier to read 0.5 inH₂O than 0.018 PSI Industry standard : ASHRAE, building codes specify inH₂O Instruments : Magnehelic gauges, manometers calibrated in inH₂O Conversion : ~28 inH₂O = 1 PSI (HVAC uses tiny fraction of PSI)

Inch of Water Column (inH₂O) - Unit Information & Conversion

Symbol:inH₂O

Plural:inches of water column

Category:Pressure

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What is a Inch of Water Column?

Inch of water column (inH₂O, in wc) measures low pressure by water column height. 1 inH₂O = 249.1 Pa ≈ 2.49 mbar ≈ 0.0361 PSI. Used in HVAC duct pressure, building air systems, clean rooms, differential pressure. Common in US residential/commercial HVAC.

History of the Inch of Water Column

Traditional low-pressure measurement from water-filled U-tube manometers. Natural unit for HVAC since pressures small compared to atmospheric. Standard in US building codes, ASHRAE guidelines. Water gauge principle dates to 1700s.

Quick Answer

What is Inch of Water Column? Inch of water column (inH₂O, also in wc) measures low pressure by water column height in inches. Standard for HVAC duct pressure, clean room differentials, building air systems. 1 inH₂O = 249.1 Pa = 2.49 mbar = 0.036 PSI. Typical duct: 0.5-2 inH₂O. Use our pressure converter for conversions.

Definition

1 inH₂O = 249.1 Pa = 2.491 mbar = 0.2491 hPa = 0.0361 PSI = 0.00249 bar = 0.0736 inHg = 1.868 mmH₂O

Also written as: in wc (inches water column), "H₂O, inAq

Physical meaning: Pressure exerted by 1-inch column of water at standard conditions

Common Uses

HVAC: Duct pressure, fan static pressure, filter pressure drop. Building Systems: Room pressurization, clean room differentials. Industrial: Low-pressure gas systems, ventilation. Testing: Air tightness testing, pressure differential measurements.

Real-World Examples

HVAC Duct Pressures

Residential supply duct: 0.1-0.5 inH₂O
Residential return duct: 0.05-0.2 inH₂O
Commercial supply: 0.5-2.0 inH₂O
High-velocity duct: 2-6 inH₂O
Industrial exhaust: 1-4 inH₂O

Fan Static Pressure

Residential furnace blower: 0.4-0.8 inH₂O
Bathroom exhaust fan: 0.1-0.25 inH₂O
Commercial air handler: 1.0-4.0 inH₂O
Inline duct fan: 0.5-2.0 inH₂O
Industrial ventilation: 2-10 inH₂O

Filter Pressure Drop

Clean MERV 8 filter: 0.1-0.2 inH₂O
Clean MERV 13 filter: 0.2-0.4 inH₂O
Dirty filter (replace): >0.5-1.0 inH₂O
HEPA filter (clean): 0.5-1.5 inH₂O
HEPA filter (loaded): 2.0-3.0 inH₂O

Building Pressurization

Office building: +0.02 to +0.05 inH₂O (positive)
Hospital corridor: +0.01 to +0.03 inH₂O
Hospital isolation room (negative): -0.01 to -0.03 inH₂O
Clean room (Class 100): +0.02 to +0.05 inH₂O
Pharmaceutical clean room: +0.03 to +0.08 inH₂O

Gas Appliances

Natural gas manifold: 3.5 inH₂O (typical)
Propane manifold: 10-11 inH₂O
Gas water heater: 3-4 inH₂O
Residential furnace: 3.2-3.7 inH₂O

Inch of Water Column Conversion Formulas

To Pascal:

1 inH₂O = 249.088908 Pa

Example: 5 inches of water column = 1245.444542 pascals

To Kilopascal:

1 inH₂O = 0.249089 kPa

Example: 5 inches of water column = 1.245445 kilopascals

To Megapascal:

1 inH₂O = 0.000249 MPa

Example: 5 inches of water column = 0.001245 megapascals

To Hectopascal:

1 inH₂O = 2.490889 hPa

Example: 5 inches of water column = 12.454445 hectopascals

To Bar:

1 inH₂O = 0.002491 bar

Example: 5 inches of water column = 0.012454 bars

To Millibar:

1 inH₂O = 2.490889 mbar

Example: 5 inches of water column = 12.454445 millibars

To Atmosphere:

1 inH₂O = 0.002458 atm

Example: 5 inches of water column = 0.012292 atmospheres

To Technical Atmosphere:

1 inH₂O = 0.00254 at

Example: 5 inches of water column = 0.0127 technical atmospheres

To Torr:

1 inH₂O = 1.86832 Torr

Example: 5 inches of water column = 9.341602 torr

To Millimeter of Mercury:

1 inH₂O = 1.86832 mmHg

Example: 5 inches of water column = 9.341602 millimeters of mercury

To Inch of Mercury:

1 inH₂O = 0.073556 inHg

Example: 5 inches of water column = 0.36778 inches of mercury

To Pound per Square Inch:

1 inH₂O = 0.036127 psi

Example: 5 inches of water column = 0.180636 pounds per square inch

To Kilopound per Square Inch:

1 inH₂O = 0.000036 ksi

Example: 5 inches of water column = 0.000181 kilopounds per square inch

To Kilogram-force per Square Centimeter:

1 inH₂O = 0.00254 kgf/cm²

Example: 5 inches of water column = 0.0127 kilograms-force per square centimeter

To Kilogram-force per Square Meter:

1 inH₂O = 25.4 kgf/m²

Example: 5 inches of water column = 126.999999 kilograms-force per square meter

To Millimeter of Water Column:

1 inH₂O = 25.4 mmH₂O

Example: 5 inches of water column = 126.999999 millimeters of water column

Frequently Asked Questions

Formula: PSI = inH₂O × 0.0361273 Examples:

1 inH₂O = 0.036 PSI
2 inH₂O = 0.072 PSI (typical duct)
5 inH₂O = 0.181 PSI
10 inH₂O = 0.361 PSI (gas manifold)
27.7 inH₂O = 1 PSI inH₂O to PSI converter →

Convert Inch of Water Column

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Inch of Water Column Quick Info

inH₂O

Symbol:inH₂O

Category:Pressure

System:Various

Convert Inch of Water Column

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Inch of Water Column (inH₂O) - Unit Information & Conversion

🔄 Quick Convert Inch of Water Column

What is a Inch of Water Column?

History of the Inch of Water Column

Quick Answer

Definition

Common Uses

Real-World Examples

HVAC Duct Pressures

Fan Static Pressure

Filter Pressure Drop

Building Pressurization

Gas Appliances

Inch of Water Column Conversion Formulas

Frequently Asked Questions

How do I convert inH₂O to PSI?

How do I convert inH₂O to Pascals or mbar?

What is normal static pressure in HVAC?

When should I replace an HVAC filter?

Why use inH₂O instead of PSI for HVAC?

Convert Inch of Water Column

Inch of Water Column Quick Info

Related Pressure Units

Popular Conversions