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Calcimator

Humidification Load Calculator

Calculate humidification requirements including moisture load, steam capacity, water consumption, and energy cost.

Inputs

CFM
%
%

ASHRAE 55: comfort 30–60% RH; ASHRAE 170 healthcare 30–60%; museums 45–55%; avoid >60% (mold risk)

°F
°F
%

Results

Moisture Load

9.7 lbs/hr

Humidifier Capacity

10 lbs/hr

Steam Required9.7 lbs/hr
Water Consumption1.16 GPH
Energy Cost$0.34
How to Use This Calculator
  1. Enter Ventilation Airflow, Outside Relative Humidity, and Target Indoor Humidity.
  2. Set Outside Temperature, Inside Temperature, and Infiltration Rate.
  3. Review Moisture Load (lbs/hr) and Humidifier Capacity (lbs/hr).
  4. Use Steam Required (lbs/hr) and Water Consumption (GPH) to inform your decision.

How the result changes with Inside Temperature

Inside TemperatureMoisture LoadHumidifier Capacity
626.64 lbs/hr10 lbs/hr
678.05 lbs/hr10 lbs/hr
7310.06 lbs/hr15 lbs/hr
7812.04 lbs/hr15 lbs/hr

What each input means

Ventilation Airflow
Outdoor air ventilation rate that introduces dry air needing humidification.
Outside Relative Humidity
Winter design outdoor relative humidity. Cold air holds very little moisture even at high RH.
Target Indoor Humidity
Desired indoor relative humidity per ASHRAE 55-2023 (thermal comfort) and ASHRAE 62.1. ASHRAE 55 comfort zone: 30–60% RH at 70–75°F; healthcare facilities per ASHRAE 170: 30–60%; museums/archives: 45–55% RH for preservation.
Outside Temperature
Design outdoor winter temperature for humidity ratio calculation.
Inside Temperature
Indoor setpoint temperature.
Infiltration Rate
Additional air infiltration as percentage of ventilation airflow. Accounts for leaky building envelope.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Ventilation Airflow = 2000, Outside Relative Humidity = 30, Target Indoor Humidity = 40, Outside Temperature = 10 = 6 input(s) provided
  2. Calculate Moisture Load
    Moisture Load
    9.7 = 9.7
  3. Calculate Humidifier Capacity
    Humidifier Capacity
    10 = 10
  4. Calculate Steam Required
    Steam Required
    9.7 = 9.7
  5. Calculate Water Consumption
    Water Consumption
    1.16 = 1.16

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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