Air-Pressure Difference Monitor

Submitted by admin on Mon, 01/04/2016 - 15:11
Indoor Air Pressure Monitor

Air-Pressure Difference Monitor

This air-pressure differential monitor provides an accurate, reliable and affordable means to visually monitor a very low positive, or negative, air pressure difference between a room and:
1. Another room or floor level.
2. Soil gasses under the lowest floor.

Undesirable air-pressure differences in buildings can cause air movement and leakage in ways that adversely affect health, comfort, energy costs, and the longevity of buildings.
— Air Pressure and Building Envelopes by Dr. Joseph Lstiburek.

Maintaining an indoor air-pressure difference at, or near, zero is recommended by ASHRAE Standard 62.2-2004, United States EPA, Building Science Corporation, and the EPA’s Energy Star program.

Simple to use: An image disappears when the air-pressure differential reaches the rated pressure.


General Applications

Limiting indoor air pressure equal to less than 2.5 Pascals (0.01 inche of water column) helps to solve problems, without creating new problems, in the following applications:

  1. Minimizing entry of radon gas, water vapor, insecticide fumes, etc. from the soil through pores and cracks in the lowest floors and walls.
  2. Minimize the escape of warm humid indoor air through walls and attics during the heating season.
  3. Minimize the entry of hot humid outdoor air through walls and attics during the air-conditioning season.
  4. Minimize entry of microbes, dust, and other air pollutants from outdoors through unfiltered openings.
  5. Enable air exhaust fans to work at full capacity to remove odors and pollutants.
  6. Prevent back drafting (reverse flow) of natural-draft (non-powered) chimneys.
  7. Prevent entry of sewer gasses whenever the water trap in a sewer drain has evaporated.
  8. Sewer drain pipes have a "U" shaped section designed to hold enough water to block entry of sewer gasses into your building.
  9. Sewer gasses will flow into your building if the water barrier in the "U" shaped section is lost due to evaporation and the indoor air pressure is less than the air pressure in the sewer pipes.

Hospitals use Air-Pressure Difference Monitors to help prevent the spread of infectious microbes.

Building Contractors use the Pressure-Detective during construction and renovation to monitor the difference in air pressure between their work area and rooms occupied by their clients.


  • Affordable.

  • Rugged and reliable.

  • Recalibration is never required.

  • Simple construction.

  • Provides a clearly visible indication when the air pressure differential is greater, of less than, the rated pressure.


  1. No mechanical parts to wear out.

  2. Maintains accuracy because there is no mechanical friction.

  3. Less expensive than electronic air-pressure monitors that can detect an equally low air pressure differential.

  4. Recalibration is never required.

  5. Not affected by vibrations.


Pressure-Detective™, Model APM 7 @ $97 each plus
$8 for shipping and handling within the USA via U.S. Post Office Priority Mail.

For orders from outside the USA, call or write for details.

Approximate size: 10 inches (254 millimeters) diameter x 3 inches 
(76 millimeters) deep.

You will also receive the following:

Instructions for monitoring and control of indoor air pressure.

A six-foot length of 5/8 inch O. D. clear 
plastic hose is included with each unit. The hose can be extended under a door,  through a 3/4 inch 
diameter hole to another room, or to the soil gas under the lowest floor.

 1. Air Pressure and Building Envelopes
 2. Moisture Movement through Air leakage vs. Diffusion
 3. Meeting Your Ventilation Requirements
Your Satisfaction is Unconditionally Guaranteed!

To discuss your requirements and/or order products, contact:
Jon Traudt

Health & Energy Company
3316 Augusta Avenue
Omaha, NE 68144-4113

Office: 402-697-1205

Cellular: 402-680-4429

The First Place Prize, Practical Category, in the 1992 Innovative Radon Mitigation Design Competition was awarded to Jon Traudt for "Ventilation Rate and Indoor Air Pressure Control". The international competition was sponsored by the United States Environmental Protection Agency (EPA) and the Association of Energy Engineers. The prize winning design by Jon Traudt was based on EPA's recommendation to block entry of soil gasses by keeping the air pressure in the lowest rooms slightly higher than the pressure of gasses in the soil. Radon mitigation is only one of the many benefits you can obtain by controlling your ventilation rate and indoor air pressure.
Our air pressure sensors are patented. United States Patents Numbers 6,328,647 and 7,213,464.