Ductless and VRF – Good, Bad, & Ugly #LIVE

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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Author:

Bryan Orr

Company: HVAC School

Position: Founder

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HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

In today’s podcast, Bryan talks with legendary Hydronics author and trainer Dan Holohan about the history of steam heating and some practical applications of old ideas. Recently, Dan has been working on more novels, having published two of them over the past few months.

Steam heating is a “lost art” nowadays; it has become increasingly uncommon and has been disappearing since the Vietnam War. Many people who understood steam heating either retired or died after the Vietnam War. Many elements of steam heating are difficult to understand or surprising. (For example, steam pressure has a surprising relationship with velocity: low-pressure steam moves through piping much more quickly than high-pressure steam.) So, Dan Holohan is on a mission to revive that knowledge and teach the newer generations about the lost art.

There are many older steam heating systems still operating today, especially in the older large buildings in New York. Dan learned a lot about steam heating when working on these old systems and optimizing them. Most of the time, he optimized those systems by removing unnecessary accessories, not by adding components like steam traps.

Many old boilers used coal as a heat source. Nowadays, many old boilers have been fitted with conversion oil burners with thermostats, but they are still piped for coal. Some systems now have multiple risers or massive vents on the main riser to prevent the thermostats from getting too hot too early and satisfying the thermostat too early. We call that master venting, which reduces pressure and allows steam to move very quickly and efficiently.

Dan also discusses:

The 2-PSI standard
Transportation metaphors for BTUs in steam
Harmful renovations for old boilers
Replacement vs. restoration mindsets
Gaps in steam boiler education
Monopolizing the market if you HAVE the education
Boiler piping and venting
Two-pipe vs one-pipe steam

Find out more about Dan and hydronic heating at HeatingHelp.com.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium. Subscribe to our podcast on your iPhone or Android. Subscribe to our YouTube channel. Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.