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Drain Cleaning - More To It Than We Think Nov 19, 2020

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Mike Klokus and Corey Cruz from Kalos come on the podcast to talk about drain cleaning. They discuss their tips and some best practices.

Approximately 50% of the calls in the light commercial division have to do with drains, and drain cleaning is a common PM procedure. The procedure starts off when you pull the panel off the air handler and look in the drain pan. Muck can accumulate in the pan and in the back and side channels. Pay attention to the unit orientation and the drain pitch before you even start cleaning. If you need to get underneath the channels, you can use bottle brushes.

Dedicated drains are associated with only one unit. However, communal drains have multiple units running into a single drain line and have a special set of considerations. You don't want to pour something caustic into the common drain and have it overflow on the lower levels. It's also best to know where the drain leads; you don't want chemicals to wash out into a garden. Water can also create a slippery surface and cause someone to fall.

Generally, the top 3 drain cleaning methods use a shop vacuum, compressed air, or plain water; each one has its place, but they also have drawbacks. While water is ideal for cleaning, it's not always available and practical. Shop vacs are good, but the suction is limited. Compressed air is better at unclogging than cleaning, and it can cause you to blow away piping if there's a loose pipe fitting.

Mike, Corey, and Bryan also discuss:

Condensate safeties
Using shop vacs and extensions
Weight in the drain pan
Cleaning with chemicals
Copper vs. aluminum for bacterial zoogloea
Priming the drain line
Condensate assembly cleanings in residential HVAC
Capping vents (don't do it)

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Open v Closed Refrigeration - Short 102 Nov 17, 2020

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In this short podcast episode, Bryan talks about the differences between single-phase and two-phase refrigeration. This particular episode is about the fundamentals of physics, chemistry, and science in general.

When we talk about phases, we're referring to the changes in the states of matter. We typically think of the states of matter as solid, liquid, and gas. In refrigeration systems, the refrigerant usually changes from a liquid to a vapor in the evaporator and then from a vapor to a liquid in the condenser; that is an example of two-phase refrigeration. We get two-phase refrigeration anytime we're changing the state of matter in order to accomplish refrigeration.

When you change the state of matter, you transfer a lot more heat than with a single-phase system. You get more heat in and out between phases due to latent. Between a solid and a liquid, the energy that goes towards the phase change is the latent heat of fusion. Between a liquid and a gas, the energy that goes into the phase change is the latent heat of vaporization. It takes a lot more heat to condense or boil water than it does to change its temperature by one degree, so we take advantage of that capacity to absorb heat into the boiling refrigerant.

There are also forms of single-phase refrigeration, including John Gorrie's open-refrigeration machine. Gorrie's machine was just compressing and decompressing air; it was not changing the state of the air. In single-phase refrigeration, we can't make use of the extra energy from changing states. In those cases, condensers would be gas coolers.

However, when you think about it, the process of refrigerating the space is a form of single-phase refrigeration; we don't change the phase of the air. So, we merely use two-phase refrigeration to drive single-phase refrigeration.

Learn more about Refrigeration Technologies HERE.

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Changing Refrigerant Regulations w/ Bluon Nov 12, 2020

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In this episode, Bryan talks with Peter Capuciati and Bryan Johnson from Bluon. They discuss how refrigerant regulations keep changing and how technicians can make sense of it.

We've begun phasing out R-22; the refrigerant can no longer be imported or manufactured in the United States. We can still recover and reclaim R-22, but the recovered refrigerant on the market can't meet the usual demand. R-22 went through a phaseout because of its ODP; R-410A has 0 ODP and was the main replacement.

However, refrigerant regulations are still changing, as R-410A will soon be ready for a phase-down due to its high GWP. There are two main replacement options for R-410A: R-454B and R-32 (A2L refrigerants). There is also R-466A, but it cuts out even earlier than R-410A on high-pressure and has worse heat transfer capabilities. Right now, R-32 is perhaps the best refrigerant (beside ammonia, which is toxic), and it's even an ingredient in the R-410A blend. However, HVAC technicians and customers alike are apprehensive about the flammability.

Although these regulations can be confusing and frustrating, the Bluon team recommends holding off from making capital decisions. While regulations are changing, it may not be a good idea to make a definitive equipment swap without knowing the final rulings. As a technician, it's good to benchmark the equipment. If you need to convert equipment, make sure to tune it to the specific refrigerant that's going in.

Peter and the Bryans also discuss:

Ozone-depleting potential (ODP) vs. global warming potential (GWP)
Equipment efficiency and its effect on GWP
R-32 and flammability risk aversion
AR5 vs. AR4
Refrigerant blends as replacements
Converting various equipment designs
Benchmarking
Bluon support and training

Check out more information about Bluon HERE.

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Single Phase v Two Phase Refrigeration - Short 101 Nov 10, 2020

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Learn more about Refrigeration Technologies HERE.

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Floating Head Strategies Nov 05, 2020

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CO2 Architecture Oct 29, 2020

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Don Gillis joins us again to talk more about common types of CO2 systems and how they differ

Heat Pumps in Cold Climates Oct 27, 2020

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In this episode, we are joined by three people who know a lot about heat pumps and cold weather. We also cover everything from the way technologies have changed, some of the pitfalls to keep away from, and why heat pumps work even in really cold climates nowadays.

Chad Gillespie: Chad is a senior manager, part of Mitsubishi Electric's Performance Construction Team. He currently leads a national team of business development managers tasked with growing the new construction market for high-performance heat pumps. He has also worked in the construction industry for 26 years and has been with Mitsubishi Electric for 9.

Dana Fischer: Dana is a residential area manager at Mitsubishi Electric. He supports and promotes the installation of high-performance, ductless heat pumps in homes across Maine and New Hampshire. Prior to his work at Mitsubishi Electric, he was a program manager for the Efficiency Maine Trust.

Scott Libby: Scott is the owner of Royal River Heat Pumps. He has over 35 years of experience and training in the residential HVAC industry. His team sells Mitsubishi Electric exclusively; they are one of the largest heat-pump-only contractors in the country.

Heat pumps are becoming more effective and comfortable, so they are now more appealing for cold climates. Although we previously relied on gas and oil in colder climates, we have seen people using heat pumps with success in New England and even Norway. We partially have R-410A and high-speed compressors to thank for those technological advancements to heat pumps.

Chad, Dana, Scott, and Bryan also discuss:

Offsetting fossil fuel usage
Compressor advancements
Heat pump performance during the polar vortex
Leaky vs. tight buildings
Load calculations and equipment selection
Seasonal loads
Single-zone vs. multi-zone heat pumps
Design software
Flaring tools
Triple evacuation
Responsible refrigerant handling
Auxiliary heat
Mitsubishi Kumo station

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Demand Cooling + Liquid and Vapor Injection Oct 22, 2020

Show notes

Trevor Matthews is back and dropping more compressor knowledge on us. This time, he talks about demand cooling and liquid and vapor injection.

In low-temperature applications, the discharge temperature would get very high and lead to oil breakdown and thermal overload, so demand cooling is a means of cooling the compressor. Demand cooling injects saturated refrigerant into the compressor body to cool it down. You're not jamming liquid into the compressor; the refrigerant flashes, which achieves a cooling effect.

A demand cooling system consists of a module, temperature probe, liquid line solenoid valve, and injection valve. On the Discus compressors, the sensor will go in the port in the compressor head. When installing these, it is important to make sure high-quality goes to the valve. It's normal to have some frost at the outlet during operation; look for frost to make sure the demand cooling system is working properly.

Scroll compressors use liquid and vapor injection almost exclusively nowadays. However, there is a difference between liquid and vapor injection for scroll compressors. A liquid injection system helps the compressor avoid high discharge temperatures (and high compression ratios). The vapor injection improves capacity and efficiency.

When troubleshooting demand cooling or liquid/vapor injection systems, you need to keep a few things in mind. For example, you need to make sure you have the right amount of tees when you retrofit a compressor with a vapor injection system. You may also have to repipe the vapor line and add a DTC (discharge temperature control valves).

Trevor and Bryan also discuss:

What happens when we change refrigerants
Return gas temperature and mass flow rate
Compressor head cooling fans
Motor operation and spinning indicators
Visual inspection
Vapor injection vs. mechanical subcooling
KVE vs. K4E
Part replacement
DTC vs. EEV w/ CoreSense diagnostics

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Intro to CO2 w/ Don Gillis Oct 15, 2020

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Don Gillis with Emerson joins us on the podcast to teach us the basics of CO2 as a refrigerant. He explains how it works and its applications.

Carbon dioxide is a colorless, odorless gas that is becoming an important refrigerant for commercial refrigeration (R-744). It is desirable because it has a low critical point and high triple point, so we can use subcritical (below the critical point) and transcritical (above the critical point) CO2. Carbon dioxide also has a very low global warming potential (1), is inexpensive, and is very efficient at transferring heat.

Above the critical point, we see transcritical fluid, which is a high-pressure fluid. Below the critical point, you get lower pressures. We don't see CO2 in our everyday air conditioners because it doesn't have the typical pressure-temperature relationship above the critical point (over ~88-degree ambient conditions). It is also more common in regions with colder ambient conditions like Canada.

We rarely encounter the triple point in other refrigerants, but it is crucial in CO2 refrigeration. The triple point is the temperature and pressure at which a substance can exist as a solid, liquid, and gas. The triple point of carbon dioxide is very high, so we can come across it in normal equipment operation. We don't want dry ice in the system, so we want to charge the CO2 system with our pressure well above the triple-point pressure.

Don and Bryan also discuss:

John Gorrie's original machine
Recovery (or lack thereof)
Sublimation of dry ice (solid to vapor CO2)
Risk of asphyxiation in confined spaces
Leak detection
Saturation and operation pressures of CO2 compared to HFCs
Liquid vs. gas tanks
Piping and fittings
CO2 grades and moisture content
Sales and distribution

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Building Performance QA with Sam Myers Oct 01, 2020

Show notes

Sam Myers of Retrotec joins Bryan and Kaleb on the podcast to discuss building performance. He also answers some of our listeners' questions.

Checking airflow is important for building science as well as HVAC. However, "airflow" is vague and can refer to static pressure readings (which isn't actually "airflow" at all), air from whole-home ventilation systems, or CFM per ton. We can also look at total system airflow with flow hoods. Equipment settings also matter when it comes to measuring airflow as it relates to building performance.

Leakiness (of the ducts or structure) is a common building performance issue. Blower door tests can determine the building pressurization and are a great tool for determining leakiness. However, we usually only do comprehensive "airflow," duct leakage, and building envelope tests during renovations or other large-scale projects; we don't typically check "airflow" and duct leakage when we do small repairs like capacitor replacement.

When balancing airflow, we usually rely on room-by-room load calculations. However, Sam finds that finding a pressure differential between rooms can be a bit more reliable. The main drawback is that a pressure differential won't tell you if a room isn't getting enough air, but the opposite problem is far more common and can be addressed.

The duct system's location also has a lot to do with a building's ventilation or sealing strategy. If the attic is in an unconditioned space in a humid climate, it may be best to seal the area to control the dew point.

Sam, Bryan, and Kaleb also discuss:

Airflow measurement instruments
Total system airflow
Balancing and isolating rooms with comfort issues
Grilles, diffusers, and vents in zonal duct design
Using your senses during balancing
Ventilating vs. sealing the building envelope
Infiltration and air mixing
Split-level homes
Blower doors
Building performance in commercial HVAC

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

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