[EXTERNAL] R32 Single Phase Co...centration Calculator Training
September 21, 2026
 

Overview

This training session covers the application and use of the R32 Single Phase Concentration Calculator to ensure proper refrigerant charging and safety compliance for high comfort series products.

Product Specifications
Harrison provided technical details regarding the product line, which includes models ranging from 310 to 510 for auto units, as well as domestic water tanks. Key installation parameters include:
* Most indoor units have built-in refrigerant sensors; however, high wall units require an optional detector installed within four inches of the floor.
* The standard release height for most indoor units is 7.2 feet, while wall-mounted units typically have a reference height of 5.9 feet.
* Piping configurations are divided into three segments: the first branch pipe (gas 5/8, liquid 3/8), the second segment (gas 5/8, liquid 3/8), and variable sized branch pipes to the end unit depending on model size.
* The specific branch pipe model for single phase mini VRF is HFPU-102F.
* Water tanks use a special wide branch pipe (H7D43861A) and must be connected as the first branch pipe in a system.

Safety Calculations
The primary purpose of the R32 Single Phase Concentration Calculator is to determine if a shutter box is required based on room area and refrigerant concentration levels.
* Concentration Factor (SF1): A critical threshold exists at 0.50; if the SF1 value exceeds this number, a shutter box must be added to mitigate leakage risks according to UL and ASHRAE standards.
* Room Area Logic: Smaller rooms increase concentration risk; therefore, larger square footage requirements may necessitate a shutter box unless air circulation is sufficient or room areas are aggregated. For ducted systems serving multiple rooms, the total square footage can often be combined for calculation purposes per UL standards.
* Water Tank Constraints: Water tanks require stricter calculations because they lack air circulation during leaks. For example, with a charge of 10 pounds, a water tank requires a minimum area of 443 square feet, whereas standard indoor units only require 147 square feet.

Technical Uncertainties
Lance raised practical concerns regarding common installation scenarios in apartments where mechanical closets may not meet minimum area requirements. Questions remain regarding whether louvered doors allow for the inclusion of surrounding hallway or living room square footage in calculations to satisfy safety standards without adding additional hardware like shutter boxes.

Outline

Introduction and Purpose

- Lance Dyer introduces the training session led by Harrison Li regarding the R32 single-phase concentration calculator.
- The primary goal is to assist in designing systems with A2L refrigerants and ensuring alignment with ASHRAE standards.
- Participants are encouraged to use the chat for questions while Harrison demonstrates the Excel tool and product applications.

R32 Product Application Overview

- Harrison Li explains that the calculations apply to High Comfort, H5, and S5 series products.
- Most indoor units have built-in refrigerant sensors, but high wall units require an optional detector installed within four inches of the floor.
- Piping configurations consist of three parts: initial branch pipe (number 1), mid-section (number 2), and final branch pipe (number 3).
- For water tank systems, the water tank must be connected as the first branch pipe in the sequence.

Refrigerant Concentration Logic

- Concentration levels are calculated based on the total system charge and room volume/area.
- The key safety threshold is a concentration factor (SF1) below 0.50; exceeding this requires a shutoff box.
- Wall-mounted units require larger minimum areas than other units because their lower release height results in smaller volumes.
- For ducted systems serving multiple rooms, total area can often be combined for calculation purposes under certain standards.

Using the Excel Calculator

- Users can calculate total refrigerant charging by combining factory charges with additional charges from liquid piping length and indoor unit models.
- The calculator allows users to input different room areas and reference release heights to determine if a shutter box is necessary.
- Blue cells indicate user-input data, while pink cells indicate selection options within the spreadsheet.

Water Tank Specific Requirements

- Water tanks have stricter requirements because they do not provide air circulation during a leak like standard AC units do.
- A system with 10 pounds of charge requires a much larger minimum area of 443 square feet for a water tank compared to standard indoor units.
- Future generations of 38-gallon water tanks will include built-in shutoff boxes as standard to address these space constraints.

Installation Practicalities and Compliance

- Placing a water tank in a small mechanical closet may necessitate adding a shutoff box if there is no sufficient ventilation via louvered doors.
- Using louvered doors may allow engineers to consider the adjacent open floor area as part of the required volume for safety calculations.
- Any design decisions involving louvered doors or combined room volumes must be approved by professional engineers and local authorities having jurisdiction (AHJ).

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Transcript:

Lance Dyer  00:00
Good.

Speaker 1  00:04
Marvelous Monday. Oh yeah.

Lance Dyer  01:00
Hey everybody! It's 230. I think we got like 50 or 60 people that are coming on, so I'm going to give it a few more minutes. I see Harrison's jumped on, so Harrison will be doing the presentation here. Harrison, we're going to wait a few minutes. Make sure everybody needs to get on. Get on. Maybe we can record this as well.

Harrison Li/李华骞  01:29
Yeah, yeah.

Lance Dyer  01:33
It shouldn't take too long. Obviously, if you have questions, we want to make sure you feel comfortable with it. But I sent it out, so everybody should have been able to download it. And I think Harrison probably end up going through the tabs at the bottom and kind of explaining a little bit about the the program and how it can assist you in Designing systems-it's definitely something that you know with A2L and changes that have been made. It's a way to kind of provide assistance, I guess, on you know selecting maybe. sure that we've got the right charge in the system. Number one and number two to make sure that it it aligns with with Ashray. So got some folks that are still on morning time, and some that are in afternoon. So, give it another couple minutes. I guess before we get going, Harrison, I'm going to ask everybody. First of all, did any anybody have any problem downloading the calculator? Everybody has it. I know it was attached to the invitation, so you should have access to it. Secondly, if you have any further questions after we go through this, we can certainly go through those. But I would thank Harrison. While you're doing it, if somebody has a question, I'll just be monitoring the chat, or you can just drop in and stop it. So that works for you. You want to get started, Harrison?

Harrison Li/李华骞  04:43
Okay, yeah, I can do that now. Okay, so good afternoon and good morning, everybody. So today I will have an introduction for the mostly for the application for the H2L, the R32 refrigerant calculation, so actually we have also a design course, but that's relatively complicated. So today's training will mainly based on the how to calculate the R32 concentration and use that to our product. So as Les mentioned, So we received a Excel tool for calculating that. But before that, I will have a brief introduction about the application of R32 refugium. So I prepared a PowerPoint. So that's mainly focus on high comfort series, but the theory is the same. We can also use that for not only high comfort theory, but but also H5 or even S5 series. So firstly, if we look at the product line we have for high comfort, so we start from 310, and then we have 410 up to 510 for the auto unit, and we also have a domestic water tank, which is also applicable for high comfort series, and the all the other two indoor units we have are the four vehicle set, mini four vector, three ducted, the high static ducted, multiple station air handle unit, and the high wall unit. So except the high wall unit, all the other type of indoor unit they are have built in refrigerant sensor as standard, but for the high wall unit, we need to choose the detector as an optional part and install that stray below within four inches for the wall wanted unit, and this is the basic parameter for the high comfort series odder unit. We can see the cooling operation is down to um five Fahrenheit with a windshield. Without that, it will be 23 Fahrenheit, and the cooling can be down to minus 13 Fahrenheit, and this is a basic piping info for the schematic. You can see that it divided to three parts. So the first part is the order you need to the first branch pipe. The way name is number one. So if you look at number one, the gas pipe is half, and the gas pipe this is the gas pipe for the boiler tank, and the normal gas pipe for the indole unit is five eight, and the liquid pipe is three eight, and the second part is the pipe after the first branch pipe. We name it number two over here, and the gas pipe is five eight. The liquid pipe is three eight, and the last part we name is number three. That's the branch pipe to the end indoor unit. The number three, the pipe size depends on the size of the indoor unit, so there is a table that we can check it to see that what the exact piping size for the indo unit. So, so the the logic is smallest smaller indoor unit, strong smaller piping size, and if you look at the branch pipe model, they are always the same. The the the branch pipe model is HFPU dash 1o 2f for all the single phase mini B R F. So we can sometimes if we if we don't use the selection software, we can check this table to see what which branch pipe we need to use and what pipe size we need. And one thing to be note is that if you have a water tank in the system, the water tank has a special wide branch pipe. The model is like this: H7D43861A. So this is shipped with standard as standard in the accessory bag of the water tank. So when you receive that, please make sure to make this branch pipe as the first branch pipe. It means that the the water tank should be the the first one to connect with the other unit. It cannot be over there or over there. So must be the first one. This is one thing to be note when we have a water tank in the system. And come to the concentration calculation. So normally we can use our high selection software to get that number. But if you don't want to use the some software, maybe like our contractor side, they are not that familiar with the computer things. Maybe they don't want to use the software. Also, they can use this table to see if that will meet the requirement.

Harrison Li/李华骞  10:19
For example, so this is the intel unit, like four-week set, mike four-week set, ducted, slim ducted, and multiple sitting unit. It just accept a high wall unit because for for the default installation or release height, except wall mounted unit, all the other type of in the unit we use 7.2 as the default release height. So since the default release height is the same for them, so all these results are the same. You can use the same table for checking that. So for example, so if the system there is 10 points, 10. point one four pounds in total for the refrigerant charging in that system. So in this case, the minimum error requirement for that room will be 147 square feet as minimum. It means that if you have a room size which is larger than this. In that case, you don't need to add a shutter box. But if the system error is smaller than this number, then you have to add a shutter box to the system. So the same logic, we make a same table for the one multi tab in the unit. So since the normally the Walmart is unit is high on the wall, which is lower than the ceiling, right? So normally the the the reference installation height is 5.9 feet. So we use this number to calculate the minimum error requirement. We can see that the same refrigerant charging for the system, the same 10.14 pounds in the system, and if this is a wall-mounted indoor unit, then the minimum error requirement will be 180 square feet, so which is larger than the other type of indoor unit. The other type is only 147, but for the wall matt, since the release height is lower, so then the volume is smaller. Then we need a larger minimum error. So we can check this table to see. So what's the total refrigerant charging of the system than the minimum error we require in this case, and this is also a table for the water tank. So for the water tank, since it's not like normal indoor unit, it cannot have air circulation when there is a leakage detected because it doesn't belong to air conditioning. There is no fire. Since there is no fire in the water tank, so the concentration for a certain area when there is a leakage detected, it cannot be reduced by the fire. So the the formula for calculating the water tank will be stricter than the other type of indoor unit. So we look at the same refrigerant charge for the system. The minimum error requirement for the water tank is 443, which is much more larger than what we need to have for the indoor unit. So normally we required a shuttle box for the water tank. So for the next generation, when we developed the 38 gallon water tank, we have built in shuttle box as standard to solve this problem. But now we have to consider it when we have a water tank, and also we take a special. It's not real special cases, but normally when we have a ductile system like the ductile type in a unit or multiple season air hunter unit. So in in this case, there are several rooms that will be served by one in the unit. In this case, by URL standard, it indicates very clearly that we can add all the room areas together to consider them as one room and do the calculation, which will be easier for us, and for archery standard, it doesn't indicate very clear. But in full some some chapter for archery institution, they have also indicates that if you use a ducted type indoor unit, like ducted indoor unit or multi position that several serve several rooms, they can be calculated together. The room error. It means that we can have a large room area. For example, so if it's a single family house, which is 3,000 square feet, and we can use this 3,000 square feet as the the room area for calculate that. And by adding the shuttle box to the system, please note that the shutter box cannot be exist in the main pipe and the sub pipe together. It means that when you add a shutter box in a main pipe, so you cannot add one over here.

Harrison Li/李华骞  15:43
So if you want to add for each room, and then you cannot add that to the main pipe. That's one thing to be note. And if you have the shuttle box to the wall matted, you need please always remember to add the refrigeration detector. Otherwise, the shuttle box will not work. Okay, then we can come to this Excel file. I will explain how to use the Excel. So for the Excel, the first one is the version info, which is not that important. So then come to the high comfort and H5 reference charging info. So normally we can get this information through the high selection software. But if you don't use the software, you can also manually calculate them by using this Excel file. Firstly, so the the total reference charge con consider consist of two parts. One is the refrigerant before shipping, so we have some refrigerant inside, and also when we install that on site, it will have additional refrigerant charging, which caused by the length of the piping, the liquid pipe, and also the type and the model of the indoor unit. So, for example, we have 60. We have these two model in the system. The other unit we use is the full 10 high comfort series, and the other unit we use are the 210 multiple air handler unit. So for the 210 multiple air handler unit, we can see the pipe. So the liquid pipe is three eight, and the liquid pipe to the WU 210 is also three eight. So all the pipes, no matter the other unit to the first branch pipe or the branch pipe to the indole unit, they are all the same pipe size. They are all three eight, and we assume that the liquid pipe length in total is 60 feet. So we put 60 over here, and then we got the total additional charge for the liquid piping is 1.86, and then we select the model we have for the system. So one is a VU 210, and another is also OVU 210. And if we have multiple, we can also choose them over here, select them over here, and we got the additional refrigerant charging for the indoor unit. Then we add them together. We get the total refrigerant additional charging is 3.62 for the system. And then we add the default factory charging 6.4. We plus them together. The total refrigerant charging for the system will be 10 pounds, 10. 10.02 pounds in total. This is how we get the total refrigerant charging by using this Excel file, and then we can check the minimum room error requirement. So we switch to this table. So you can see that the 10.02 will automatically be there. So they will use this number and directly comes here. And if you have multiple rooms, you can also use the verification room two or room three. So I just put it over there. In that case, if you have multiple rooms that want to verify together, you can use these two. Otherwise, if you only want to check this one, you can only you can use this one. Just use this one. So the refrigerant amount for the total system is 10 pounds. And for example, so so we have two same units, right? And let's make an assumption: the minimum area, maybe these two units serve for two different room, but the smaller one is 200 square feet, and there is a reference reid 7.2. So when you choose different type of inner unit, they will give you different reference number. This is for reference, and you can put that over here. If you do not remember this number, you can just look at this and put that over here. Actually, except one multi-type indoor unit, for the other type of indoor unit is always 7.2. So let's switch back to the two-10 multi-precision error handle unit. The reference release had a 7.2 over here. So we put 7.2 as well over here. This the the the the the cell that which is in blue that need to be filled in by us, and which is in pink that need to be selected by us. For the others, we do need to put that.

Harrison Li/李华骞  20:57
So this one is 7.2 as the release height, and the room error is 200 over here, and the SF1 we check here is only 0.36, which is smaller than 0.5, and they tell us we don't need a shut off box in this case. So if required a shutter box, they say no. So in this case, we don't need to do the calculation for adding the shuttle box because we don't require shutdown blocks. So since the minimum error for the room is 200, so now it's good. But if I make the room to 100, now this size will double. So from the 0.362 now to 0.73, so now it's larger than 0.5, so it will tell you that you require a shuttle box. Then you can go Harrison.

Lance Dyer  21:54
Harrison, what does S what does SF1 stand for? What's what

Harrison Li/李华骞  22:00
is it? That's that's called a concentration factor.

Lance Dyer  22:07
Okay, so that's the concentration factor, and as long as we're below point or 0.50, then we will not require a shut off box.

Harrison Li/李华骞  22:17
Correct.

Lance Dyer  22:18
Okay, so the 0.50 is the key number to keep in mind. So, when you do the calculation here and you put in the square footage, if it's above 0.50, then you you know that a shut off box is going to be required for that particular indoor unit. Correct?

Harrison Li/李华骞  22:39
Yeah, that's correct. Okay. Because the the the actual logic is that we want the concentration smaller than 50% of the RFR number. So that's the reason why there this is point five to evaluate that. So LFR is so this one. The LFR is lower flammability limit than in RE and UR standard. So this number is 19.1 pounds per 1000 cubic feet. So when we use the air conditioning with air circulation. The minimum, the maximum, a low level refrigerant is 50% of this concentration. So that's the reason why we always use plant file to make the adjustment. So if you see that, so the

Lance Dyer  23:38
larger the larger the indoor unit. So, if you picked an AVU 48 as an example, and you're still at a 7.2 release height because it's still an AVU model,

Harrison Li/李华骞  23:56
right? So, the different model of the indoor unit actually it will so so if we we don't talk about the wall multi type, we talk the other type of in the unit. The release types are all the same, right?

Lance Dyer  24:10
Right.

Harrison Li/李华骞  24:11
So in this case, the different model will only have influence on the second part, the releasable refrigerant part charging, because when there is a leakage, the refrigerant. If you have a shutter box, then you close the valve. The refrigerant that still in the heat exchanger of the indoor unit will be different since the the model is different, right? But if you don't talk about this one, if you don't add the shutter box before adding the shutter box, you will use the total refrigerant charging for the system for calculate the concentration. So no matter what model you have, it will not have no influence on the SF number. This will all always be the same.

Lance Dyer  24:54
Okay. So

Harrison Li/李华骞  24:54
so you can see that always 0.47 as long as the room area is the same, the release height is the same. This one will not have have no influence on this value.

Lance Dyer  25:06
So do you do you find when you do these that the the room area square footage is is the number that really in a lot of cases sort of dictates whether or not you're going to need a shut off box? Is that one of the, like in other words, if the room, the smaller the room, the more chance you're going to need a shut off box, correct?

Harrison Li/李华骞  25:27
Yeah, yeah, yeah. That that's a like a. So so if if you see it's 150, this is point four nine, right? And if I make that 75, that will be, or around one. This is so. If you reduce that one time, this this will increase one time.

Lance Dyer  25:48
Right.

Harrison Li/李华骞  25:50
150. And if you do that, the double size. This will reduce, uh, 50%

Lance Dyer  25:59
So that's why you said when you have a full, if you have two or three rooms off of the same air handling unit that's ducted, you can take into consideration all of that square feet, right?

Harrison Li/李华骞  26:11
Right. So the larger room and the the lower risk of us. Okay.

Lance Dyer  26:21
And what happens if you have a tank and an indoor unit?

Harrison Li/李华骞  26:26
So they need to be calculated separately. So you need to calculate. So this this table is for normal type indoor unit only. For the time, since the formula is very complicated, so we didn't make a this Excel file. So if you have a tank, then you have to check this this table to see if you require a shuttle box. So like I mentioned, if the total refrigerant charging for the system is 10 parts, then you will require 443 square feet as minimum for water tank. All

Lance Dyer  27:02
right, so that's that's crucial to know because many times these tanks go inside of a mechanical closet that might be on the first floor of like a you know the main floor like in the hallway. A lot of apartments where these units are going to be going, that tank ends up inside of a mechanical closet, and that mechanical closet is nowhere near 400 square feet. So, what happens in a scenario? So, do they? So, what happens if that closet has a louvered door instead of a solid door? And can they take into consideration because it's a louvered door? Can they take into consideration the rest of the of the open area of the first floor in terms of square footage? Does that count?

Harrison Li/李华骞  28:02
For this part, the actually doesn't make that very clear. But normally, basically, all for the manufacturers, we think that we can consider them as a whole error as long as they has a lower door. But when we design that, we need to make a conversation with the consultant engineer to get an approval of them.

Lance Dyer  28:27
Okay. And does the louver door have to have a certain inches of slots? You know, a certain amount of square inches of airflow.

Harrison Li/李华骞  28:36
We don't define that actually in the standard, but so this this is like a gray error, which is not that clear. But normally we can make that happen by using this way, and this also again this need to be approved by the engineer and AHJ.

Lance Dyer  28:57
Okay. All right, I'm just I'm just trying to make sure because I know that there's a lot of people on this call that they're designing these systems for smaller applications, right? Many times the tanks are not in like a big garage or a full basement below the home. A lot of times in apartments, they just have a mechanical room where they put the water tank, and sometimes they even put the multi-position air handler in the same closet as the as the tank. So I'm just trying to utilize Common installation practices, just to sort of make sure that we all kind of understand that.

Harrison Li/李华骞  29:49
Yeah, and yes, we found this issue after we have this product. So for the next generation, we are trying to make the set of bugs built in as standard in the water tank. Yeah, but but now now if we find that the minimum error doesn't meet our requirement, then we need to consider to add a shadow box to the water tank. So like a a two calculator. So when I hide that from ChatGPT, they tell me that maybe around this number value, 432 square feet. So which should be enough, but this is not a like a standard. Maybe someone's house, the the garage is smaller than this one, so you need to consider that. So we are just in the boundary.

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