HVAC School - For Techs, By Techs

Do you think of the building envelope as a duct? Do you test it? In this podcast episode, Joe Medosh talks to us about envelope testing and why it's the future of building health and comfort. The building envelope is the largest duct in the entire home. However, so many HVAC techs forget about it; they attempt to optimize comfort in the HVAC system and ducts, not the home itself. Techs use Manual J and S, but they don't use the infiltration rate in their calculations. Infiltration in the envelope is a major culprit of discomfort in the home, especially through and around windows. We use blower doors to determine leakage. During the blower door test, we depressurize the home by a pressure difference of -50 Pa, and we can then calculate the air changes per hour by taking the CFM, dividing it by the volume, and multiplying that number by 60. The pressure pan is another tool that we use to determine leakage. Pressure pans are semi-quantitative tools that help you figure out where leaks are coming from; you won't find out how much CFM leakage you have, but you will find out if there is CFM leakage. The commercial HVAC industry has already used "fresh air" in buildings via economizers. However, the residential HVAC industry does not bring fresh air in via the HVAC system. Joe proposes solutions to seal homes but allow fresh air to enter the home in a controlled manner; when we bring that fresh air in, we could implement dehumidification measures to avoid fungal growth. Joe also discusses: Windows and energy savings myths Measuring volume in the home Common sources of leakage in the home Gas appliances and combustion/CO risks in tighter homes Outdoor air and retrofit applications Backdraft Balancing ventilation Check out Retrotec at retrotec.com or purchase Retrotec products from TruTech Tools at trutechtools.com/retrotec. (Use the code "getschooled" at checkout for a discount!) If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Ductless expert Jesse Claerbout talks about his best maintenance practices for ductless air conditioners and heat pumps. This episode is part 2 of the two-part series. Ductless outdoor units tend to have clean condensing coils. The only real issues are grass clippings (and cottonwood, in some locations). which typically don't affect performance too sharply. Jesse likes to clean outdoor units with plain water; he does not use cleaners. Drain cleaning is a little more involved than condenser cleaning. When cleaning a gravity drain, Jesse uses a shop vac to get rid of standing water. He does not run water through the drain line until after he begins reassembling everything after cleaning. Three main lines need to be insulated: the suction line, expansion line, and drain line. A proper ductless maintenance procedure will include checking the state of those lines' insulation. Condensate pumps can be a necessary evil in ductless unit maintenance. The cleaning procedure is straightforward, but it requires a lot of work and leaves plenty of room for techs to cut corners. Much of the difficulty comes from exposing the reservoir, which is the component that truly needs cleaning. You can clean it from the poly-tubing, but you must use a shop-vac to clean it thoroughly. When you finish, make sure that the blower wheel sounds right and that no parts are rubbing against each other. Let the unit run for 15-20 minutes before taking line temperatures so that all the parts can dry. Check the charge (preferably without gauges), air temperature split, and your amperage to make sure that the unit works as it should. Overall, the most important goal of ductless maintenance is to establish a cleaning regime that works for your business and the customer. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Ductless expert Jesse Claerbout talks about his best practices for maintaining ductless air conditioners and heat pumps. This episode is part 1 out of 2. Ductless maintenance can be a bit more extensive than regular split system maintenance. Ductless filters are plastic; they are not high-MERV and can simply be washed off with water. Customers can clean their own filters with nothing but water from a hose or sink. Blower wheels are a bit more challenging than filters; the blower wheels are long, have small cups that are prone to buildup, and carry an electrostatic charge. Due to the blower wheels' challenging nature, technicians require special training to deal with the additional labor, and customers require special education. As such, we at Kalos charge for special blower wheel maintenance. We pull the blowers from the systems and clean them (though the process of getting a blower wheel off the blower shaft is complicated). You can wash the blower wheel outside with a safe cleaner; make sure the wheel is dry when it goes back inside. Removing the blower wheel gives you full access to the drain pan. During a ductless maintenance procedure, remember to clean out the drain pan thoroughly with a safe cleaner. If you clean ANY component indoors, use a drop cloth, especially if you're cleaning on carpet. We clean evaporator coils and the housing with spray bottles (preferably) or pump sprayers. Clean WITH the grain, not against it, and use only water or mild, non-toxic cleaners. A botanical cleaner works well, especially for customers who may have allergies. Rectorseal also has a cleaning kit (Desolv) that comes with a good coil cleaner, a cleaning bib that surrounds the ductless unit, and a pump sprayer. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, we cover some common misconceptions about run capacitors, some easy ways to test them, and some tips on working with them. A run capacitor is a power storage device; it contains oil to dissipate heat and some thin metal plates wrapped in a spiral. Capacitors also contain plastic insulation between the metal plates to keep the power separate; electrons should NOT cross the insulation, and there should be a charge difference between the plates. Current also does NOT flow through the capacitor; capacitors merely store and discharge power. Capacitors also do NOT boost voltage. You may notice higher voltage between terminals, but the capacitor is not involved in that voltage boost. You see that voltage increase because of the inductive motor's back EMF. Back EMF only occurs on systems with a running motor. On a single-phase PSC application, the run winding is the primary, and the start winding is the secondary. A run capacitor that is too large will draw more current on the start winding. You may see a slight drop in overall amperage on the common wire, but large capacitors increase the current on the secondary winding. The start winding is not designed to carry excess current. Connecting capacitors in series REDUCES capacitance. Therefore, most of the time, we connect capacitors in parallel. Many electrical circuits nowadays are connected in parallel (compare to Christmas lights, which are connected in series). Bryan also covers: Capacitor basics (terminals, microfarads, etc.) "Common" confusion Capacitance and current relationship Start capacitors and potential relays Hard start kits PTCR products Series vs. parallel capacitors Testing capacitors (in the circuit, under load, with a capacitor tester, etc.) Calculating capacitance and evaluating capacitance ratings If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

James from Rectorseal talks about the IMC codes relating to tamper-resistant caps and why you may consider installing them now. Tamper-resistant caps, also known as locking refrigerant caps, fit on refrigerant ports to prevent unauthorized access. Even though these caps can RESIST attempts to tamper with the equipment, they are not (and cannot be) fully tamper-proof. Many new construction companies used to put the caps on ONLY to pass inspection; they then take the caps off to reuse them several times. That's an inhalant abuse risk, and it's also a liability issue for other contractors who service the equipment. So, the IMC requires locking-type, caps to be fastened to the equipment after charging or recovery. Unfortunately, it's impossible to enforce the code, even as it currently stands. Moreover, many technicians want manufacturers to make their equipment easier to service. Components like tamper-resistant caps make it harder to service equipment. Almost no standard tools can remove those caps, and you will need special tools for tamper-resistant cap removal. The code, however, does not define what a "tamper-resistant" cap is; a key could fall under that umbrella. However, tamper-resistant caps are still worth considering because they prevent inhalant abuse. Inhaling refrigerants is a gateway for harder drugs, including heroin. Even though tamper-resistant caps may not stop adolescents from doing drugs at all, we remove our industry from that controversial subject. It is also a good idea to give your system caps that make it harder for people to steal refrigerant, especially as refrigerant prices rise. James also discusses: The purpose of code commentary Inhalant abuse prevention Code compliance Built-in vs. added components required by code IMC vs. AHD Explaining tamper-resistant caps to customers Check out Rectorseal's Novent refrigerant caps HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Many techs know just enough about economizers to bypass them. In this podcast episode, Jerry Eavenson and Bryan talk about the basics of what an HVAC economizer is and how it functions. Economizers typically work on the air side of package units and help pull fresh air into a structure. Economizers are almost exclusive to commercial HVAC. Climate also plays a role in their usage; you will not find many economizers in hot and humid places like Florida. An economizer is generally an energy-saving device that brings fresh air into a building if it is of a higher quality than the return air. These economizers determine if the outside air is better than the return air via enthalpy controls. Enthalpy controls evaluate the humidity and temperature of the air. When you set up an economizer, you can easily go wrong if you don't understand the sensors that are involved in the setup. Many economizers have dry-bulb or enthalpy sensors (wet-bulb), and these sensors are not interchangeable. You typically have to know the model number to differentiate the two types, but the model information is readily available on the internet. Typically, your differential set points will depend on your climate zone. You may come across fixed-enthalpy or differential controls. When it comes to economizers, acquiring documentation is the best move. As with all types of HVAC equipment, reading the manual is the key to understanding what an economizer does. Jerry recommends identifying the controls, sensors, and functions of the equipment. Economizers may vary greatly across models within a manufacturer (let alone across manufacturers). Jerry and Bryan also discuss: Heat loads of commercial spaces Variable frequency drives Sensors Economizer setup Honeywell Jade Cooling stages Controls Dehumidification-only application possibilities Return duct sizing Climate zones If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Dan Holohan is the father of modern steam heat training. This episode is a narration of his in-depth steam article "A Steam Heating Primer" from HeatingHelp.com. Read that article HERE. Check out more about Dan's work at heatinghelp.com. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

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

This special podcast episode focuses on the tragic life and times of Spark Ranger Roy Sullivan. Roy Sullivan was a park ranger who was born in Virginia in 1912. He grew up in the 1920s when the mining industry was in full swing and had scrapped up the beautiful mountain landscape. In 1935, Shenandoah National Park was founded, and Roy decided to become a park ranger. He wanted to help restore the land and protect it from human destruction, such as the mining industry. One of Roy's duties was to scope out the forest on the new fire lookout tower. That new tower had yet to have a lightning rod installed. One day, a lightning storm approached while Roy kept watch, and lightning struck the tower. Roy survived the strike, though he was badly burned in the incident. In July of 1969, Roy encountered lightning once again. That time, Roy was driving a car. Although many people believe that the tires are insulators, most people are protected from lightning by the Faraday Cage effect; the current travels through the metal around you until it reaches the ground. Roy, unfortunately, forgot to close his window and had a lightning charge from a nearby tree strike him through the window. Roy got struck with lightning yet again while doing yardwork a little while later after a transformer was struck by lightning. He was allegedly struck by lightning several times after that, including on a fishing trip where he ALSO had to outrun a bear after getting struck by lightning. However, even though Roy had the scars, these lightning strikes are unconfirmed. Sadly, Roy died by a[n allegedly] self-inflicted gunshot wound. However, the legacy of the Spark Ranger continues through his ongoing world record for "Most Times Struck By Lightning." If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast, Bryan and Jamie talk about the electronic expansion valve (EEV). Bryan and Jamie describe how EEVs work and the reason they exist. In the process, the hosts also review a wide range of metering devices. We made this podcast to address the rising demand for EEVs in the aftermarket element of the HVAC business. Like the TXV, the EEV is a metering device. Metering devices create a pressure drop as refrigerant moves from the liquid line to the evaporator. Traditional refrigerators typically use capillary tube metering devices because they require a constant temperature and operate in a fixed temperature environment. However, TXVs are a bit more variable but open linearly and are dictated by a minimum stable superheat value. EEVs are also variable, but they can influence the superheat more directly; the superheat always exceeds the minimum stable superheat. Therefore, EEVs can increase efficiency by reducing the evaporator temperature and compression ratio by increasing saturation temperature. Even though EEVs dominate the grocery refrigeration market because of their head pressure control, we can use them in residential HVAC too. The EEV controls superheat more precisely than a TXV, and their algorithms can maximize efficiency and fill the evaporator coil with the most refrigerant possible. There are two types of EEVs: the pulse-width EEV and the stepper motor EEV. The stepper motor has "steps" to modulate the degree to which it opens or closes. The pulse-width EEV either opens or closes, much like a solenoid valve. Bryan and Jamie also discuss: Hot pull down Ideal compression ratios and efficiency Minimum stable superheat Compressor cooling accessories Downsides of oversizing TXVs Evaporator superheat vs. suction superheat Technological advancements for EEVs, especially for Danfoss EEVs Less obvious advantages of EEVs over TXVs If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.