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How to Calculate Cooling Capacity for a DOAS unit

This is an easy calculation if you know the cfm (airflow to be conditioned) and have a psychrometric chart handy.  The formula for calculating total cooling is: Qt = cfm x (Hf-Hi) x 4.5 Where: Qt = Total capacity in btu/h Hf = Enthalpy of the leaving air Hi = Enthalpy of the entering air 4.5 = constant 
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How to design a DOAS unit as sole source heating and cooling

When possible, it makes life easy to have a separate DOAS system from the space HVAC system. In this case, each system has one specific job: -The DOAS’s job is to bring in 100% Outside Air, when the space is occupied, and delivers neutral temperature air. -The main heating & cooling system can be (in most cases) 100%
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How to Avoid a VRF Piping Nightmare

Refrigerant copper piping isn’t new. It’s been in use for years and has stood the test of time. What you might not know is how important the insulation can be. Check out this article to make sure you’re following code and not sidestepping potential problems.

How to Avoid a VRF Refrigerant Nightmare

If you haven’t designed a VRF system yet, you need to be aware of what code violations can get you into the most trouble. Check out this article to learn about ASHRAE Standard 15 and how to avoid a VRF refrigerant nightmare.

How to Avoid a VRF Zoning Nightmare

One of the biggest benefits of VRF is the built-in zoning that is available. But if you don’t design the system properly you can run into major problems. Check out this article to learn how to avoid a VRF zoning nightmare.

HVAC swimming pool design

Did you know that the HVAC equipment for indoor pool applications should not be installed directly above the swimming pool area? Warm moist air, which might contain airborne chemicals like chlorine, could migrate into the system causing operational problems and premature failure. For more information on HVAC swimming pool design, see the attached “Swimming Pool Design Guide”
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How do you select and design a custom coil replacement?

Here is a step-by-step process for replacing a custom coil and A) Making sure it fits and B) Making sure it works.Step #1: Gather the physical coil dimensions (more info will be needed at coil verification measure)Tube size (typical: 3/8″, 1/2″, 5/8″, or 1-1/8″)Number of Rows (1 or 2 rows typical for heating, 3-8 rows typical for cooling)Fins per
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How do you fix a humidity problem?

Humidity, the 8th wonder of the world, is a tough nut to crack. Unlike sensible heat transfer, it’s very difficult to measure its movement into buildings through cracks, doorways, and other openings.But, there are ways to combat these higher than expected humidity levels.Here are 11 ways to decrease the relative humidity in your space. The answer could be one of
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How many tons of air conditioning is this DX or Chilled Water coil?

If you are measuring a Direct Expansion (DX) or Chilled Water coil in the field, or just quoting a replacement coil, you can quickly estimate its nominal tonnage based on the square footage of the FIN area of the coil. This is a useful “rule of thumb”, which will help ensure that you have all the
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How much system water per ton of cooling for process chillers?

Did you know that York recommends a MINIMUM of 6 gallons of system water per ton of cooling for process chillers? This is double the amount of water that York recommends for standard air conditioning or comfort cooling applications. See the attached engineering supplement from York for more details!Related Posts:What type of chiller is ideal for
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