Short #32 - "It's Undersized"

HVAC School - For Techs, By Techs

Bryan Orr

Training, Careers, Airconditioning, Self-improvement, Hvac, Business, Education, Refrigeration, Heating, Ac, Apprenticeship

4.8 • 985 Ratings

🗓️ 4 December 2018

⏱️ 14 minutes

🔗️ Recording | iTunes | RSS

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Summary

When we replace equipment, we sometimes wonder if the old unit was undersized. Here are some things to consider before replacing that old A/C with a bigger one.

When we do load calculations, we figure out how much heat to remove or add to a home based on the building's design. We need to account for how much heat is entering or leaving a building and heat gains on the inside of a space. Heat gains can come from human body heat or electronics running, and heat losses are quite rare. Those factors are perhaps even more important for correct sizing than mere square footage.

In general, I don't recommend putting a bigger unit in. Focus on getting the equipment to work properly before considering an upsize, as the improper cooling could be caused by a mechanical issue and not an undersized unit. If you want to dig deeper and consider upsizing a unit, you have to consider a few things.

First of all, you want to look at the sensible and latent loads. Is the unit too small on the sensible or latent side? In either case, you can adjust the blower to try to address these first. If humidity is the issue, you do NOT want to oversize the unit.

Is leakage a factor? Check the integrity of the duct system and if you have cracks, can lights, or other sources of leakage. How's our ventilation? Attic ventilation is also a huge factor that will determine how well an A/C unit works.

We also discuss:

Shade and impact on radiant gains
Ductwork, wire, and copper pipe sizing
Heat load reduction (lighting, ventilation, etc.)

Learn more about Refrigeration Technologies HERE.

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Transcript

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0:00.0	Hey, this is a short episode of the HVAC School Podcast, I'm Brian, and this is the
0:06.8	podcast that helps you remember some things that you might have gotten along the way,
0:09.2	as well as helps you remember some things you forgot to know in the first place.
0:12.3	And today we're talking
0:13.1	about well that system is undersized and that's something that I hear too often and
0:17.8	we're gonna talk about why I'm sick of hearing that and what you can do about it but
0:21.9	before we get into that I want to thank our sponsors.
0:24.0	Navac, they make all kinds of great tools, a lot of them that we use at Kailos.
0:28.0	I've especially been enjoying the battery-powered flaring tool from Navac. you can find it by going to true
0:33.8	tech tools dot com to rut tech tools dot com big thanks to refrigeration
0:38.0	technologies for all of their support they make nylog they make big blue they the Viper Cleaners, they even make some hand wipes.
0:45.4	They come in a nice little convenient tub, they smell great and they do the job, like all of the
0:49.8	different products made by refrigeration technologies. You can find out more from them by going
0:54.0	to refrigate.com. I want to thank Air Oasis for their support. They make some really good
0:58.9	air purification products, the nano and the bipolar. you can find out more Air Oasis.
1:03.7	dot com forg slash go and then last but not least I have to mention our new sponsor of
1:08.9	the podcast field piece it might be a surprise to some of you, but I have always enjoyed many Field Piece tools, and especially lately I've been enjoying their vacuum pump and their recovery machine.
1:20.0	And I've mentioned this to many of you, I did a video on this. I really think they're excellent
1:23.8	excellent tools. So the VP85 is the vacuum pump that we like. We use a lot of those at Kailos.
1:29.4	It's got a really nice oil change on the fly. It's very quiet. I love where the ports are oriented kind of at a
1:35.0	45 degree angle on the side. It's a DC motor and then also the MR 45 is a recovery
1:41.2	machine. Again both of them very light very quiet very easy to use I really like the digital display on the MR. 45 for recovery it makes the process a lot easier in fact you can even recover
	...

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