Heat Pumps, Charging & Defrost #LIVE
HVAC School - For Techs, By Techs
Bryan Orr
4.9 • 1K Ratings
🗓️ 1 December 2019
⏱️ 54 minutes
🧾️ Download transcript
Summary
In this live episode, we talk about heat pumps, why Bryan likes them, why other people don't, charging and diagnosing them, and defrost.
Even though heat pumps work best in warmer climates, they can theoretically work as long as the temperature is above absolute zero (-460 degrees F). Viewers across the USA install heat pumps in their markets, even in places with cold winters like Wisconsin. Ideally, the discharge line should be around 100 degrees above the outdoor temperature in heat mode. Although this rule of thumb appears to work in many different climates, it is only really applicable on single-stage equipment.
When charging heat pumps from scratch, check the manufacturer data in heat mode. Airflow for comfort or efficiency is something else to account for when you're commissioning a heat pump; the CFM should be higher if you want the system to be efficient, but the building will be more comfortable if you have a lower CFM per ton. Airflow is especially important to control in heat mode, as small changes can noticeably affect head pressure.
When it comes to defrost, heat pumps typically use a time and temperature strategy. Defrost cycles usually run at a certain temperature for a fixed time period. Heat pump defrost boards usually look a lot more complicated than they really are; when you come across them, stay calm and remember that they're just like any other board.
We also discuss:
- Absolute zero
- Climate zones
- "Vapor line"
- Discharge superheat vs. over ambient
- W calls
- Supplementary heat and dehumidification
- Confirming airflow on a heat pump in heat mode
- Controlling mean radiant temperature (MRT) vs. blowing hot air
- Using in-duct psychrometers and manufacturer charts to assess system performance
- How reversing valves may fail or get stuck
- Thermal imaging applications
- Copeland compressors and mobile app
- Testing defrost boards
- Carrier vs. Trane & Rheem defrost strategies
- Demand defrost
- Suction pressure and compression ratio under frost buildup
Learn more about Refrigeration Technologies HERE.
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Transcript
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| 0:00.0 | This live podcast was recorded using the cast box app on a Saturday at 8 p.m. |
| 0:09.0 | eastern time which is our typical live podcast time if you want to participate in one of these |
| 0:13.8 | castbox podcasts live then by all means download the castbox app |
| 0:19.2 | subscribe to HVAC school look it up and subscribe turn on notifications and then when we go live it'll notify you or you can just open the app and look at the live cast button at 8 p.m. |
| 0:29.4 | on Saturdays if you want updates because we don't always necessarily go live on |
| 0:33.7 | Saturday things happen in my life on Saturdays that sometimes I can't control |
| 0:37.3 | then take a look at the Facebook group the Facebook group for HVAC school is where I kind of give those live updates and I know some of you don't like that some of you hate Facebook I get it |
| 0:46.7 | It's just how we do it for now. That's what works for me at this moment |
| 0:50.7 | But anyway, this is a live podcast and it is about heat pumps. It is about |
| 0:54.8 | charging them. It's about defrost and a few other things. We have some great |
| 0:57.7 | guests on Eric Kaiser and Eric Mellie and actually, is that it? I think that's |
| 1:01.4 | it on this one. But a thank you to our sponsors. Our sponsors are carrier and carrier.com, |
| 1:06.0 | Refrigeration Technologies, RefrigerateTech.com, they make viper cleaners. |
| 1:10.0 | They make a lot of really great stuff that you're going to like like |
| 1:12.5 | Nylog for example. Fieldpiece and Fieldpiece.com so many things from |
| 1:16.9 | Fieldpiece that are coming out that are just great. They work with Measure Quick |
| 1:19.6 | you combine it True Tech tools using the offer code get schooled for a great |
| 1:23.5 | discount and check out. |
| 1:25.0 | Speed clean, speed clean.com and then Navac and Navac global.com. |
| 1:29.8 | Those are our sponsors. |
| 1:31.1 | So here we go live episode using the cast box app about heat pumps. |
| 1:36.5 | All right, so today we're talking about heat pumps and yeah so heat pumps are what I cut my teeth on, it's what I've worked most of my life on. |
... |
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