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Building Pressure Relief

Building Pressure Relief

Building Pressure Relief

Building Pressure Relief
Hi Friends,

I design HVAC systems and often include means to relieve building pressure. A common practice for almost all HVAC engineers .

My question is where in the CODE BOOK (IMC OR UMC)does it states to provide building pressure relief if we are not using economizer?

I am working on a 10,000 sq. ft child care center. Owner wants me to use bunch of furnaces and condensing units. Every class needs 250 to 300-cfm outside air. I know I must provide relief damper but does the code really mandates providing means to relieve outside air if we are not using economizer?

Thanks in advance

RE: Building Pressure Relief

"Codes" are a Minimum Safety Standard - there is a lot that is not in any "Code" that the design engineer has to actually do some real design to accomplish a successful building HVAC system. The "Codes" are not supposed to be a design guide/checklist - the Code is the minimum bottom line that you can't go below before you are breaking the law. You have a basic HVAC design issue - you will be supplying X amount of outdoor air into a (hopefully) sealed building - so now you have to relieve that amount of outdoor air you are blowing into the building. Is there enough washroom exhaust that runs at the same time as the furnaces to relieve the amount of outdoor air? If not, then you'll have to provide other means of keeping the building from over-pressuring and not be blowing exterior doors open or getting whistling noises at all the exterior doors.

RE: Building Pressure Relief

You need to balance OA intake and exhaust or your building will be positive or negative. ideally use ERV to recover energy.
The OA and EA rates are given by code and you need to do whatever the higher of the two is for each space.

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