Welcome back to Teaching the Unteachables, where we dive into teaching and learning
methodologies for professionals like you. This episode brought to you by
Stanfield Training Solutions, your source for HVACR training solutions.
Learn more at hvacrfundamentals.com.
Well hello everyone, thank you for joining Did You Know? the ESCO HVAC
podcast. So today we're joined by esteemed author Carter Stanfield. How are
you sir? I'm doing great. Author of Fundamentals of HVACR, published by
Pearson. Carter is very involved with education as well as authoring in the
industry and we both have a passion for understanding where things come from. I
always say that you can't know where you're going unless you know where you
came from and that's very true when we start talking about this A2L transition.
And really it's a, when we look at it, it's more about the low GWP transition
because yes we're seeing the A2L transition but we're also seeing an A3
transition as well. And so today we're going to spend some time talking about
where the standards come from, particularly ASHRAE Standard 15 and
Standard 34. And Mr. Stanfield has spent a lot of time breaking these down and
Carter if you could help us understand a little bit about this transition and why
we're doing the things that we're doing. Sure. So I like to emphasize it you
mentioned knowing where things come from. I like to look at the the original
documents to things. So while I love presentations given by people, I like to
see the original documents where their information came from. Absolutely. So when
it comes to refrigerant, ASHRAE 34 is the standard that really all codes and
even the UL qualification refer to. So ASHRAE 34 is the document that gives the
refrigerants their numbers and also it's where our safety standard comes
from. So the A1 through B3 and all the numbers and A2L, all that comes from
ASHRAE 34. So I like to be able to refer to the original document and see
exactly how they define things. This is particularly important now as we try to
understand what an A2L is versus say an A1. Yeah absolutely. A lot of people
don't realize you know where these transitions come from. We get a lot of
calls at the ESCO office and sometimes complaints about these transitions going
why are the manufacturers of equipment doing this to us again? And it's
actually never been the manufacturers of equipment. Like when we talk about this
A2L transition, we're really talking about the HFC phase down that came
through in two different ways. It came through with a Kigali amendment to the
Montreal Protocol as well as a portion of the AIM Act. So not only do we have an
act of Congress but we have an international treaty that is phasing
down the use of hydrofluorocarbon refrigerants. And so in doing that we
have to look at what are the next generations of refrigerants, how do we
safely handle them, and what other refrigerants could we see going forward?
Because this is just one step of a variety of transitions that I'm sure
we're going to see. Now many of us seen the CFC phase out. We've seen the H CFC
phase out. We're now in the HFC phase down and remember it's not a complete
phase out but it is a phase down by 85% by 2036. So what that means is we have to
start looking at what other refrigerants do we have to work with. And you know
we'll take chemists like Dr. Chuck over at Comoros who says that the periodic table
doesn't really grow. We just have to reuse the elements that we have. And in
doing that unfortunately we we end up with refrigerants that will have some
mildly flammable and even highly flammable characteristics going forward.
But then like how do you work with them? How do the manufacturers design the
equipment? How did the tool manufacturers relook at and sometimes
redesign their tools? There's a lot of safety that goes into that and we have
to have something to start with. And that's really where ASHRAE 34 comes into
play. Yeah ASHRAE has been doing refrigerant safety for quite a while and
again it is really the backbone of most of the refrigerant safety standards.
ASHRAE 15 which is also widely documented is used in many codes and
essentially all the rules for refrigerant mechanical rooms, mechanical
rooms and refrigerant systems in them basically refer back to ASHRAE 15. The
issue that we've had with ASHRAE 15 is that it's primarily a commercial standard.
Right. People don't have mechanical rooms in their houses. So ASHRAE 15.2
covers low-rise residential structures and specifically really lays out all
the safety requirements for installing and servicing A2L systems. It does also
cover A1 systems but its primary purpose for being has to do with installation
and service of A2L systems. And it was developed sort of in parallel with the
UL, the number? 60 335-3-40. Okay thank you. Absolutely. And that UL standard
actually came from an IEC standard of the same name, the same number. That's
why they came up with that number because they harmonized the standard
with the IEC standard. There's something that you know when we talk about
worrying about global warming and getting rid of our high global warming
refrigerants, this is not just a US thing. This is an international thing. That's
right. The reason it's important to manufacturers is that we don't want to
be on an island. We don't want to be the only people in the world using a
particular type of refrigerant or having particular kinds of systems. The
manufacturers both of the refrigerant and equipment want to be international.
They want their products to be able want to be able to sell their products
someplace besides the United States. So that gives some impetus. It's not just
the government. There's also you know financial and industrial things
at play here. And again it's an international movement. So it's not
something that our government could just say okay well we don't want to do this
anymore because we don't believe in it. We'd be bucking the whole world and
basically it's sort of like isolationism. When we start talking about the the
three different levels of mitigation what we're really talking about is the
refrigerant concentration levels based on the flammability of the refrigerant.
And when we start breaking down those refrigerants, so we started in ASHRAE 34
to see what those flammable characteristics are, and then in 15-2 we
can actually look at well when does that mitigation come into play because these
smaller systems under four pounds and that's a rough estimate based on the
refrigerant itself, under four pounds in these residential systems they actually
don't even have mitigation. But once we reach that potential for combustion we
actually we start adding mitigation to it. And so what we're going to see in
particular residential systems is mitigation controls which is going to
add a refrigerant leak detection sensor and a control to be able to mitigate
those gases in the event of an actual significant leak. Yeah so on the the
mitigation levels the UL standard and also the ASHRAE 15.2 refer to levels that
charge levels they call M1, M2, and M3. I believe the M stands for mass. That
makes sense. You know I haven't verified that with anybody. I'm just trying to
come up with some reason why they use that. And then when they talk about the
maximum charge and that sort of thing they also use M. But anyway M1 is six
times the lower flammability limit, M2 is 52 times the lower flammability limit,
and M3 is 260 times the lower flammability limit. So the weight amount
varies with refrigerant because it depends on the refrigerant's density and
the lower flammability limit of the refrigerant. Right. And it does it's it's
just under four pounds for R32 and honestly I don't know right off the top
of my head what it is for 454B. But it's in that same range. And to get a
perspective on this I looked up I thought about P-TAC units. Yeah. And I
looked up a Friedrich P-TAC unit of 12,000 BTUs and their charge was 1.8
pounds of R32. So well under this four pounds. Yeah. Meaning that those units
and say window units like you'd buy your big box store don't require any kind of
special mitigation. When you go between M1 six times lower flammability limit up
to M2 52 times a lower flammability limit you do require mitigation. And
there's lots of ifs, ands, and buts, lots of different things that alter what the
what mitigation is required. So that gets kind of detailed. And then there's
more mitigation required between M2 and M3. And at M3 the 262 times of lower
flammability limit basically that's outside of the UL standard. So that would
require a whole different document. Exactly. And that's going to be large
quantities of refrigerant large systems. Probably the only time we're going to
see that is going to be in large VRV VRF installations. And it really comes down
to once we get to that point we're going to add additional controls like pump
down solenoids and ways to be able to do additional isolation of the refrigerant
itself. Yeah. The again the mitigation varies a lot depending on the quantity
of refrigerant and also where the system is applied. That's the only thing about
standard 15. The requirements for what you're allowed to do and what you're
required to do vary based really on three things. The occupancy, that's the
building, the refrigerant, and oh the system. Oh yeah. Okay. Yeah. So I'll start
from here. The mitigation varies depending on the type of occupancy.
That's the type of building it is. The type of system, the type of refrigeration
system, and the refrigerant classification. So when we talk about occupancy we're
talking about say institutional would be hospitals and things where you have
people that cannot easily move. Be relocated. That getting everybody out is
going to be a chore. Sure. And then when you talk about systems they've got
several different kinds of systems but it really comes down to whether
something is a high probability or low probability system. Now by high
probability they're talking about the possibility or probability of refrigerant
getting in the airstream in the building if there's a leak. So in our typical
direct expansion systems are all high probability systems because refrigerants
in the coil that the air blows over. Exactly. In the space. Yeah. So an example
of a low probability system would be say like a chiller where the refrigerant
cools water and then the water is pumped around. Even if you did have a leak the
chance of the refrigerant getting in the air is extreme. Minimal. Yeah. So the
standards are different for those. So until recently the standard ASHRAE 15
would not allow flammable refrigerant in a high probability system. So the
first allowance of any kind of flammable refrigerant in a high probability
system came about in the 2019 revision of the ASHRAE standard 15. The ASHRAE
standard 34 recognized A2L refrigerants in 2016 but it was not until 2019 that
they said in standard 15 that you could use A2L systems in a high probability
system and there's again lots of parameters. So that's where we get into
the mitigation and the amount of mitigation and the type of mitigation
varies based on the quantity of refrigerant and the application. Yeah a
lot of people don't realize that like you'd mentioned before a lot of our
window units and P-TECH units have already made the transition to A2L
refrigerants. Pretty much any window air conditioner you buy right now has R32 in
it. Same way with the P-TECHs. Yeah you'd have a hard time actually finding a
window unit that doesn't have 32 in it. Exactly and because of that charge limit
of around four pounds most of those window units have a pound or under of
refrigerant so they have no additional requirements for mitigation. In our
residential and light commercial applications we're going to see factory
leak refrigerant detection sensors as well as the controls that go with them.
If it is a non-communicating system it's going to have a independent control
module which is basically going to be connected between the thermostat and the
indoor unit so that in the case of a detection we're actually going to go into
a mitigation state which is going to turn off the outdoor unit. It would turn
off any heat source inside whether it was electric furnace or whether it was a gas
furnace it would actually turn off those ignition sources and turn on the blower
to dissipate those gases. If it's a communicating system most of our
manufacturers have incorporated that control into the indoor board and so
literally it's a matter of just connecting the sensor that comes with
the coil down to the control board of the indoor unit and now it's actually
ready for a mitigation capable system. Yeah I didn't know that that's that's a
good information. Yeah I've spent a lot of time on how we're actually utilizing
the mitigation controls so if it is a non-communicating system you're going to
have an additional control board. If it is a communicating system the the same
refrigerant detection sensor is just going to be plugged into the primary
control board of that indoor unit. At least that's what I've seen with the
manufacturers that I've went through so far and then when we get into our VRV
VRF because it's already a communicating board on the indoor unit that is able
to communicate to the outdoor we're just adding the additional refrigerant
detection sensor and it plugs directly into the control board. So as our systems
make the transition it's going to be a little bit of a learning curve
understanding what that installation looks like and in the installation
manuals that I've seen for our residential like commercial split
systems they actually give you all of the dimensions for if this system is
installed in this cubic amount of space mitigation is required and here's how
you make the connections. So it's pretty basic but it is definitely a transition
that we're going to be making and it takes a little education and so the
whole conversation today was where does that education come from. Most of it
comes from standard 15 and standard 34. It's interesting that you mentioned the
room volume it is one of the kind of significant changes. There the
manufacturers part of the UL standard is they have to with the equipment when
it's checked for the UL requirement they have to actually supply the
installation instructions that they're going to package with the equipment and
they have to provide tables rather than just formulas for technicians to be able
to determine whether or not a particular piece of equipment will safely work in a
space and they do that two ways. One of these they give they tell you equipment
with this charge can go in a space no smaller than and they give you you know
the volume and the other is they say it will if your space is this size the
maximum charge you can have is and they give you a number. You're also going to
be required to calculate total charge meaning in a split system or a many
split system adding charge for the for the line set. Now of course that's not
that new but now it's a really legal requirement and something that a lot of
speakers have mentioned in their A2L presentations is a lot of behaviors and
procedures that have been best practice are now required practice if you want to
do it safely. Exactly so that's all that's a little bit of education doing
best practices are going to get you through a lot of the hurdles otherwise
your installation manuals and training from your manufacturers and industry
partners like all of us are here to help educate you and keep you current. So
Carter if you're looking for more information where are some ways that
people can locate Fundamentals of HVACR and Carter Stanfield? So I have a blog
hvacrfundamentals.logspot.com and I have a website hvacrfundamentals.com
and then if you you can also google Stanfield training solutions and I
believe my website will come up. Also you can go to Pearson. Pearson has a website for
the book so you can google the book title Fundamentals of HVACR and you
should be able to find that Pearson website. Fantastic Mr. Stanfield we sure
appreciate you joining us today. Thank you very much.