Variable Ventilation Controls on Cambrige MAUs

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Here is a short 2 minute and 30 second video about 3 available options on Cambridge Engineering’s Make Up Air Units. Watch the video to learn about our Modulating Gas Controls, Variable Frequency Drives and Automated Profile Damper controls.

Thanks for watching.

Indoor Air Quality…It Really is Important

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According to the Environmental Protection Agency the average American spends 93% of their life indoors…. 87% is spent indoors at their work and home and the other 6% is spent in their automobiles. With that much time spent inside we should all be more concerned with Indoor Air Quality.

Recently Cambridge Engineering’s Doug Eisenhart published a post about IAQ that focused on the effects of temperature and productivity of a workforce because ambient air temperature is an IAQ factor. Doug was spot on with his comments about productivity and its correlation to temperature.

Along with temperature the quality of the air from indoor pollutants is also an important IAQ factor that needs our attention. Pollutants such as volatile organic compounds (VOC), particulates and carbon dioxide, to name a few, can not only affect short term productivity but can also have long lasting negative health consequences to those working in that environment.
One way to alleviate these types of IAQ problems is to have the building properly ventilated through the use of mechanical ventilation of filtered outside air. By using High Temperature Heating and Ventilation (HTHV) products that use 100% outside you have the ability to not only heat the space but also ventilate the space in an effort to help reduce the types of indoor air pollutants that can sometimes cause serious health problems. HTHV products, when combined with appropriate air filters offer a very energy efficient way to heat and ventilate a structure during the winter months when bringing in outside air is the most problematic.

There is plenty of information available that can provide guidance on indoor air quality and ventilation. Here are two that I have found useful:

1. OSHA publication titled – Indoor Air Quality in Commercial and Institutional Buildings can be located on OSHA’s website at

2. ASHRAE publication titled – Indoor Air Quality Guide: Best Practices for Design, Construction and Commissioning is a free publication located on the ASHRAE website at–publications/bookstore/indoor-air-quality-guide. The guide is designed for architects, design engineers, contractors, commissioning agents, and all other professionals concerned with indoor air quality.

ASHRAE also has available for purchase their ANSI/ASHRAE Standard 62.1-2016 Ventilation for Acceptable Indoor Air Quality. Standard 62.1 specifies minimum ventilation rates for new and existing buildings that are intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. This publication is located on the ASHRAE website at–publications/bookstore/standards-62-1–62-2.

Let us know what you think about the IAQ subject and look for more post on Indoor Air Quality in the future.

People Comfort – How Does It Effect Your Bottom Line?

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For the last 3 years my team has been traveling North America visiting with Cambridge Engineering’s, Sales Representatives to spread the word about options available to Building Owners, Building Operators, Design Engineers, Contractors and Utilities when recommending and selecting heating and ventilation solutions for their building or retrofit projects.


We have been attempting to call out 3 core concepts for the key influencers when considering improvements to their buildings.

1.) Safety – Use of 100% outside air, direct fired HTHV and MAU technology is inherently safe. Ventilation and Heat are provided by the same blower that cannot be separated. These technologies can improve indoor air quality. Ventilation is the key to safety, preventing the buildup of products of combustion.
2.) Energy Efficiency – HTHV technologies provide the highest btus/cfm ratio thus creating more net useable btus or heat to satisfy the air load and the conductive load in high bay warehouses, distribution centers and manufacturing facilities.
3.) Lowest Total Installed Cost – HTHV technologies deliver 3 system in 1 piece of equipment. HTHV technologies deliver A.) Heat, B.) Fresh air ventilation and C.) Even temperatures throughout the building. This 3-in-1 system reduces total equipment cost and the installation costs associated with connections necessary to install multiple pieces of equipment. Engineers may call this a cleaner design.

During our recent Contractor Advisory Board, an influential Design Build Contractor, Paulson-Cheek (Atlanta, Georgia), called us out on our failure to identify THERMAL COMFORT as a primary value in his selection and use of HTHV equipment in his high bay building designs. I’d like to share a brief video from Marshall Cheek regarding his comments on this subject:

Marshall’s callout on Thermal Comfort was very insightful. We often undervalue the importance of building occupant comfort in a cost competitive new construction or retrofit building environment. Understanding the importance of creating a safe and comfortable working environment for people engaged in the real physical activity such as: warehousing, distribution center and manufacturing facilities, compels us to add this 4th leg to the table.



Are people more productive when their workplace is comfortable? One ergonomics expert, Chris Adams, who in addition to being a Human Factors Engineer & Industrial Designer, has been providing human factors engineering to NASA, states that: temperature has a major impact on productivity. According to one of Chris’s articles, 71.5 F is the optimal temperature for 100% productivity. His report details the following information:

As temperature increases at:
• 77 degrees fahrenheit we’re about 98% productive
• 82 degrees fahrenheit  = 95%
• 87 degrees fahrenheit = 90%
• 92 degrees fahrenheit = 85%
As temperature decreases at
• 66 degrees fahrenheit we’re about 98% productive
• 63 degrees fahrenheit = 95%
• 59 degrees fahrenheit = 90%

Soliciting solid Building Owners and Building Operators’ input during the design phase of one’s building project makes sense, according to this report. Adding personnel comfort level to our discussions and being able to articulate the impact that consistent temperatures may have on people’s productivity is beneficial.

Inherent Equipment Safety, Energy Efficiency, Lowest Total Installation Cost and People Comfort are all important topics of discussion when discovering what is most important to owners and operators. People Comfort is high on my list of questions. What does a 5% gain in productivity mean to an organization in real dollars? Answer this question and compare it to an investment decision and it makes for better decision making in an equipment selection.

Thanks for sticking with me to the end here. How important have you found thermal comfort to be in your conversations regarding HVAC design? Does the same hold true for people working in the warehouse? Should it? 71.5d egrees fahrenheit sounds good right now as it’s 100 degrees fahrenheit in St. Louis as I write this blog post.

Is an HVAC Smoke Detector Required on a 100% Outside Air Unit?

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Have you ever received a request to include an HVAC smoke detector with Cambridge heaters? Typically, engineers or building inspectors will make this request, interpreting building codes to require an HVAC smoke detector be installed on any air handling system with a capacity greater than 2,000 cubic feet per minute (CFM).

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