R290 as a Drop In? - Short #234

HVAC School - For Techs, By Techs

Bryan Orr

Training, Careers, Airconditioning, Self-improvement, Hvac, Business, Education, Refrigeration, Heating, Ac, Apprenticeship

4.8 • 985 Ratings

🗓️ 1 April 2025

⏱️ 8 minutes

🔗️ Recording | iTunes | RSS

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Summary

In this short podcast episode, Bryan answers a listener-submitted question about using R-290 as a drop-in refrigerant for R-22 systems. It is NOT safe to use R-290 as a drop-in, but there are some similar properties between the two and some interesting thought experiments within this topic.

R-290 is propane, a hydrocarbon that belongs to the family of natural refrigerants. R-22 is an HCFC refrigerant that has undergone a manufacturing/importation phaseout in the USA. They are both single-component refrigerants, not blends. Both of them have similar operating pressures and oil carry. However, the latent heat of vaporization of R-290 is almost double that of R-22, which makes it extremely effective as a refrigerant.

The main issue with using R-290 is that it is highly flammable and explosive (A3), and it has very small charges (500 grams). Around 2010, some people started selling R-290 blends as drop-in alternatives for R-22. In theory, that combination would work very well, but it is not a safe or legal option.

R-290 is currently used in sealed, self-contained equipment. However, it could be the future, especially if our industry goes for refrigerants with lower GWPs and uses flame-free fittings and tubing cutters. It's also worth noting that A2L refrigerants do not contain R-290 or any other hydrocarbons, but it is possible that the industry will gradually embrace the more flammable refrigerants like R-290.

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Transcript

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0:00.0	Yep, yep, yahuy. This is the HVAC school podcast. The podcast that helps you remember some things.
0:08.9	You might have forgotten along the way as well as helps you remember some things you forgot to know in the first place.
0:14.0	And today is a Q&A podcast, a short podcast. Bob has a question. A question I have not gotten before.
0:20.6	But it may seem like a
0:21.7	simple question, but I have a little bit to say about it, I guess. But before we get to that,
0:26.2	let's thank our great sponsors. Carrier and Carrier.com. Navak and Navak global.com
0:32.3	and the breakfree power two bender model NTB7L. Seriously seriously this thing is really great bends even large size tubing up to 7 8's od
0:43.4	find out more at true tech tools.com use the offer code get schooled for a great discount at checkout
0:49.8	copeland and the copeland mobile app get full access to Copeland's online product information database on any device, any place.
0:58.6	And try out the new Copeland AI chatbot.
1:02.7	Cross-reference compressors and find local inventory, all on the Copeland mobile app.
1:07.7	Refrigeration Technologies at refrigetec.com.
1:12.9	All right. So the question that Bob asks here is dropping an R290 for R22. So what is
1:22.5	R290? R290 is propane. What is R2? R22 is chloro-difloro-methane, otherwise known as H-C-Fc, R-22. Of the classification, hydrochloro-fluorocarbone, H-C-Ferocerocarbone, H-C-FC. That's the more fancy name. So since we're just being fancy here, let's just do that. R290, also known as propane, in the family of natural refrigerants or hydrocarbons.
1:52.0	Chemical formula C3H8.
1:55.1	So why would even say this?
1:57.1	Why would Bob say can we use R290 as a drop in for R22? Well, the reason is,
2:02.8	is because R290 and R22 have very similar properties as refrigerants. In fact, if you took
2:08.5	R22 out of a system and you put R290 in, first off, don't do that. That is not good to do.
2:14.1	And we'll talk about that in a second. So if you only hear this far, but if you were to do that and you could do it safely, it would operate quite well. So in this scenario that we made up, let's say we have 40 degree of vapor decoil. 40 degree of vapor to coil at R22 is 68.5 PSIG. R290, 63.5. Very close. Both single component refrigerants, not blends,
2:37.8	and the latent heat of vaporization at 40 degrees Fahrenheit of R290, which is basically
2:44.8	its latent heat that it can carry, is nearly double that. 167.4 BTUs per pound versus 97.3 BTUs per pound for R22.
	...

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