Ductless and VRF - Good, Bad & Ugly #LIVE

HVAC School - For Techs, By Techs

Bryan Orr

Careers, Business, Self-improvement, Education

4.9 • 1K Ratings

🗓️ 16 November 2019

⏱️ 59 minutes

🔗️ Recording | iTunes | RSS

🧾️ Download transcript

Summary

Some great live guests join the podcast to discuss the advantages, disadvantages, and challenges of ductless and VRF equipment.

We started off working on ductless equipment with Mitsubishi, especially installing them in lanais. Sunrooms have large amounts of radiant heat coming in, and the heat load often warrants getting an A/C system just for the sunroom/lanai. We even began oversizing them a bit (which was a lesson learned). We also learned that mini-split ductless systems tend to have filthy blower wheels because moisture tends to build up on them. However, bib kits make cleaning the blower wheel in place an easy process.

High-wall ductless systems also work in houses, not just sunrooms. However, they may have issues dehumidifying effectively. To remove more latent heat, you have to ramp down your blower and ramp up your compressor to get your coil colder. Overall, Bryan is not a large fan of using multi-zone ductless units in residential applications UNLESS they are replacing window units.

VRF systems are typically used in commercial applications. The systems typically use cassette-type units or low-static fan coils, unlike high-wall ductless units. Although VRF and high-wall ductless units tend to have different sets of advantages and disadvantages, both of them struggle a bit with humidity and may need supplemental dehumidification.

Overall, while VRF and ductless systems are desirable because they can control sensible capacity, those modulation capabilities can also lead to serious problems in wet climates.

We also discuss:

Condensate pumps
Blower wheel set screw issues
Ductless and VRF filtration
Sensible heat ratio (SHR)
VRF serviceability
Dehumidification vs. efficiency
Regional VRF manufacturing practices
EER vs. SEER
Daikin dry mode
What should HVAC systems really control?
Engineering commercial buildings
VRF refrigerant loss
ICM493 controls

Learn more about Refrigeration Technologies HERE.

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Transcript

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0:00.0	This episode of the HVAC School podcast is a live episode about Duckless and VRF
0:09.6	recorded live using the Cast Box app. If you don't have the cast box app, then go ahead and
0:14.3	download it. It's free and you can participate live. You can call in you can
0:17.5	listen live and also you can listen to the podcast there as well. It's a nice app.
0:20.8	It's the cast box app available on Android and iOS. Thank you to our sponsors carrier,
0:27.2	Navac, refrigeration technologies, Speed Clean, and field piece without those
0:34.3	sponsors without those companies who put their hat in the ring and
0:37.9	support good training and allow me to speak freely because frankly on this
0:41.8	podcast we speak very freely we do especially on these live
0:44.1	episodes and we talk about difficult things we're not pulling our punches and it's good to have
0:50.5	companies that recognize that real training means that you're not just pulling a party line,
0:55.0	you're not just saying exactly what everyone wants to hear,
0:58.0	you're talking openly,
0:59.0	and that's what this podcast does,
1:01.0	and I thank you to our sponsors for recognizing that and not trying to
1:05.7	control everything that said. Obviously we try not to be overly negative or anything like that.
1:10.3	We want to be positive for the trade that's what we're here to do. So here we go, Duckless and VRF good, bad and ugly.
1:16.4	This is the HVEC school podcast and today we're talking about Duckless VRF and inverter-driven equipment in general, even
1:26.1	unitary equipment and what makes them good, bad, or ugly and then just sort of some of the
1:31.9	things that I've run into and maybe some of you have run
1:34.2	into that I think are worth having as part of this conversation again anybody
1:39.1	wants to join just hit the phone button if you do join by hitting the phone button then just mute
	...

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