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Hey Ed, Can I Use Different Outdoor Design Conditions if I Live in a Heat Island?


In this edition of "Hey Ed", Ed discusses if you can use different outdoor design conditions if you live in a heat island

Hey Ed, can I use different outdoor design conditions if I live in a heat island? There’s a specific reason that we should always stick to the design temperature that’s listed in manual J, and it has more to do with runtime than it does anything else, often people will mistake the design temperature that's in manual J with the hottest day of the year and it's simply not the case, the design temperature represents either 1 percent or 99 percent of what we will expect to see whether it’s heating or cooling, we want runtime and I can't emphasize enough when it's just run time when really hot out, we had plenty of days in the summer where it's humid in most climates but it's not that hot out, and if we don't have the sensible BTU’s to make the system run, then we can’t get the water, the moisture out of the air if we artificially inflate those outside design temperatures what we end up with is a piece of equipment that doesn’t run enough on part load days and we’re not able to maintain the comfort that we desire and that’s the way I see it.

In this edition of “Hey Ed”, Ed discusses if you can use different outdoor design conditions if you live in a heat island

Ed Janowiak is the Manager of HVAC Design Education at ACCA.


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Posted In: Hey Ed, Technical Tips

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