Welcome to the Windshield Chronicles, a mental sequence of operation.
This episode sponsored by Sunrise Refrigeration.
Learn more about Sunrise Refrigeration at SunriseRef.com.
Dennis Sukup, thank you for joining us once again.
Let's dive a little into building and designing a box.
Cliff, walk-in box is one of my favorite things.
Something I love to do every day.
Even my guys are amazed.
I just went out and finished a big 42 foot long glass door box for a new liquor company
here in Las Vegas.
And I love sizing and designing walk-in boxes.
So I think one of the most important steps is first off, you got to meet the customer.
You got to know your audience.
Know the customer.
What is he doing?
What's his business?
How is he going to use this box?
Because once I start the layout, I want to see how he's going to load it.
So I know which way to swing the doors.
Do my hinges go on the left?
Do my hinges go on the right?
You don't want to be banging into the door when you're coming with a hand cart full of
food.
You want to have a natural flow.
So that begins part of the layout when I draw it on paper before I go to the manufacturer.
But above and beyond that, one, now I need to know what size box.
Can he fit?
When he says to me, I want an 8 by 12 box.
Okay.
How high is that box?
8 by 12 by 8 feet high.
Now typically, I will go to the Heatcraft engineering manuals.
I have found that to be one of the best tools, one of the most accurate.
I have done walk-in boxes by letting other people tell me what I needed.
And I'm sorry, they lived in San Diego and the weather in Las Vegas is not San Diego.
Exactly.
So three months out of the year, that box would not run.
And I have to be performing as well on July 4th at 110 degrees as I do on New Year's Day.
So you have to learn to do your own calculations.
So when you use the Heatcraft manual, there's an average and there's a heavy usage.
Well, I always stick with heavy usage.
And this design work on this is just kind of a generic for restaurant operations.
We have the expectation that there's a certain amount of product that comes in refrigerated
already.
It's not coming from a field, but it's coming from a refrigerator.
And you're going to continue that.
And it could be multiple type things.
It's got lettuce, tomatoes, chicken, maybe beer kegs, whatever.
So you go to the engineering manual, I select the BTUs for heavy usage for that size box.
That's my foundation.
Now I'm looking for extra things.
Is there forklift entry?
Is there glass doors?
For an example, any glass doors like you see in a convenience store merchandiser, if it's
a 35 degree box, those glass doors are going to cost you 1,360 BTUs per door.
You got to add them up because that's part of the total BTU calculation that I'm headed
for.
If it's a freezer, minus 10 degree glass door, 1,730 BTUs per door.
Adding that up, and now you're coming up with your grand total.
And let's say I'm at a grand total of 40,000 BTUs with everything factored in.
My lights, my people, my product, my glass doors.
I have 40,000 BTUs that I need.
I'm going to then step off and look for a compressor.
Not for a compressor that can deliver 40,000 BTUs at 35 degrees.
Not at box temperature.
Right.
That's box temperature.
It has to give me 40,000 BTUs at 25 degrees because I have a 10 degree TD.
A 10 degree TD on that coil.
I need 25 degrees saturated suction temperature.
That step causes most people to miss the mark because when they do that and they miss that
10 degrees, they can't get that box below 40 degrees or 45.
That's the first step mistake that was made.
Now I'm going to have to continue to interview the customer and find out where does he want
that compressor?
Is it going inside the building on top of the box?
Is it conditioned?
Is it in the sun?
Right.
When he says to me, no, I need it to be on the roof of the building.
Well, the other important factor you need to know is I need that 40,000 BTUs no matter
what the temperature is outside.
And I know now that when I go outside, the AHRI manuals are going to dictate that those
BTU calculations are based on 95 degrees.
So first off, the three months in Las Vegas, I am well beyond the 95.
The deregulation factor for that is 6% for every 10 degrees beyond 95.
So now my 40,000 has been dropped by 12%.
This could cause me to select the next size bigger compressor.
Because I still need the 40,000 downstairs is not changed.
Exactly.
The box BTU load is given.
That is not changing.
That's based on size, product, size, product, and other heat load factors, lights, indoors.
That is not going to change.
The weather outside may, but I still need to deliver that 40,000 BTU.
The next thing you want to make sure of is when you have calculated out to your worst
case scenario, let's say it's that 110 degree day is my worst case.
I can't ever let my compressor output become smaller than the evaporator.
In other words, if I let that compressor on 110 degree days slip to 38,000 BTUs, my evaporator
is based at 40,000.
I have just starved my evaporator.
By reducing the capacity of my outdoor unit.
The two things that technician is always looking for in setting superheat, is he flooding or
is he starving the evaporator?
And he has to adjust expansion valves accordingly.
When you have starvation built in, you can't fix it.
You are starving.
So the worst months of the year, your customer is going to be complaining.
My box will not keep temperature.
That technicians up there checking superheat and all he's going to do is overcharge.
Correct.
He's going to try to compensate for something like that that he cannot do.
So now you have a balanced system.
You have a compressor that's going to do it year round.
You have an evaporators that are going to do it year round.
You have the expectation that I don't care how he loads that box.
I'm going to guarantee you.
And that's what I do here.
I guarantee you 35 degrees, 365 days a year.
If I can, in most cases, and this becomes a price factor, I put in what I call poor
man's redundancy.
Now poor man redundancy might be, is let's say I need a five horsepower compressor with
an evaporator.
If I can break that box and divide it with an imaginary line and I can put two, two and
a half horsepower units and two evaporators inside that box, that's poor man redundancy.
Whereas one unit fails.
The panic is not there.
That's right.
The second unit will keep my product refrigerated and it won't keep me at 35, but it won't keep
me at 65 either.
$20,000 worth of beer at 65 is not the same as.
Exactly.
If you have a big freezer full of gelato and ice creams and it goes down and you don't
have some sort of redundancy, the only thing you can get is a mop and a bucket.
Absolutely.
Okay.
So putting the box together, putting boxes together is not real complicated.
I love it because it's like a puzzle.
You get it from the manufacturer, you get a nice blueprint.
You've already designed it or I've designed it.
So I kind of know where it's going to go and its shape and size.
And you begin to look at which corner do I want to begin building so I don't make a trap.
And then the key parts are getting your panels lined up, put into place, and they're usually
locked together with a cam lock.
But one of the most steps that I see missed and I get a lot of calls from owners to say,
what can you do to fix this?
This is happening to me is the step is what we call putting butyl to the warm side of
the box.
So you think of the box, it's four inches thick of foam with a cam together lock.
So the outside panel, the outside edge of the panel is the warm side where you're standing
in the box is the cold side.
So you draw a line of butyl caulking from top to bottom on that panel before you squeeze
it together and lock it.
And that butyl will squeeze in there and fill in all the gaps where air might go.
Now if air can get in past the gasketing, it's going to look like under a microscope,
like a Christmas tree shape, a dart, if you will, as it freezes and it will freeze and
start to separate that panel.
The more it separates it, the more air that gets in and it starts to compound itself to
where it actually will destroy a box.
And I've seen owners all fall out and they'll put silicone over it.
It's not going to fix it.
The air is still going to get in there.
And that's the step that I most often see.
They think you can just lock it together and the gaskets will take care of it.
There's a fine line in the instruction manual that says apply butyl to the warm side.
If you have a floor, you have to think about it.
The warm side is the part that's touching the concrete, not the part you're standing
on.
If it's the ceiling, it's the warm side is the top of the box, not the part you're looking
at when you're in it.
And it's tedious because you got to have one guy I have on my crew, he's got the gun in
the tubes.
And as the panels, we stand them in place, we step back a second, he draws a bead of
caulking and then we lock it together and squeeze it together.
So you now know no air can penetrate from the warm side and get in to the box.
If you tried to do it on the cold side, four inches, that air is going to come in into
that four inch space and be right up against the internal side of the box.
And possibly introduce moisture into the foam area in between the panels.
I've seen that here.
And it does over a period of time.
It separates, it destroys and it ruins the panels.
So key things there, BTU sizing, make sure you know the customer, know the BTU loads,
don't leave anything out.
Calculate for lights, forklifts, people working inside boxes.
There's a lot of manufacturing places that are packaging and doing things.
All of those are heat loads.
Heatcraft engineering manual will give you factors on all of those.
Getting all your BTUs added up right.
Account for your losses.
If you're going to be in high ambient locations with that compressor, think about poor man's
redundancy.
It kind of makes you the savior when you're talking to your customer because you're thinking
about their best interest when you're building the box.
And calculate those BTUs so that you are not starving your evaporator on the hottest months.
And sometimes you have to protect yourself on the coldest months.
I still do that here in Las Vegas.
I like using Headmaster mixing valve.
So when the ambience drop below 60, that's the tough part.
When air conditioners are shutting off, walk-in boxes still have to run.
So we have to keep that head pressure up.
So you're thinking about low ambient as well as I'm thinking about high ambient.
High ambient based on my BTUs that I need.
Low ambient ensuring that I'm pushing that refrigerant down that liquid line with enough
pressure on a cold winter night.
When you do that, you can guarantee that temperature 365 days a year.
What about metering device selection on our boxes?
Well, metering device selections are based again on BTU, based again on the evaporator.
Just because you have a, like the air conditioners, you have a five horsepower compressor unit
on a roof does not dictate that you have a five ton expansion valve in a coil.
It's going to be based on the BTUs of that coil.
I got to tell you today, things are so much, there's so many new controls.
We use a lot of this key to thermostats that have built in defrost capabilities for medium
temp boxes.
Those are fantastic to prevent ice buildups.
And quite frankly, I'm a fan.
If I can get an electronic expansion valve in there, I'm an absolute fan.
Because the electronic expansion valve, number one, it's going to have 256 plus steps in
it.
It's going to do a lot of smart thinking for me and knowing where's that superheat at,
where am I operating the best and how do I get there the fastest?
So that means can I open up and then adjust down so that I can get right to that right
amount of superheat.
And the second thing is, is when it does, the key to thermostats tells it to cycle off
in today's code, it's going to pump down saving me from having to have a solenoid valve and
then allow my fans to switch to a low speed saving energy, meaning the 2020 walk in box
code.
So electronic expansion valves, my favorite.
You can't go wrong there.
And when you communicate that with some smart technology, two speed fans, key to thermostats,
programmable defrost for even medium temp type units, never getting that complaint of
an iced up coil.
Absolutely the way to go.
Expansion valves either way, BTU is based on a coil, not horsepower based on a compressor.
Awesome.
Dennis Hucup, thank you so much for your time.
Once again, we sure appreciate you being here with us.
Awesome.
Happy New Year, Clifton.