Reprinted from Florist & Grower newspaper 1999
Build Your Own Floral Cooler by John Hungerford
Because we sell floral display and storage cases, people often call us for advice on building their own coolers. We are happy to give them ideas, and we are pleased to share them with anyone who may plan to build a cooler on their own.
A large walk in can be kept cold with a small coil but the bigger the coil the higher the humidity. More expensive but the coil size is a key difference between beverage and floral coolers.
Types of boxes:
- 2 X 4 studs with plywood walls and ceiling. Insulation is usually fiberglass but may be rigid foam board.
- Factory made foam or fiberglass panels that snap together on site. Usually metal facing.
- "Cheapo" boxes of foam board glued to the walls of an existing room
Do I own the building? When a wooden box is constructed on site, it becomes a part of the building and most leases will not allow it to be torn out later and taken with you. You bought it, you built it, but it's not yours. Factory boxes are movable and snap apart just as they snap together. They are not legally a permanent improvement to the building and may be taken with you.
Is my labor free? Many handy husbands or friends are able to build a box that serves well at no charge. However, if you must pay carpenter's wages of $15 per hour (usually more) for hired help, you come out about even compared to a factory made box.
What kind of insulation do I need? Most houses are made with 3 1/2 inches of fiberglass. That's R-11 value. Most houses are also very drafty and expensive to heat and cool. Fiberglass is rarely put in correctly even by "professionals" and it tends to leak out a great deal of the "coolness" at each joint. Foam board has a lot fewer joints and is therefore better for amateurs to install. Fiberglass also has the disadvantage of being worthless when wet, while foam board will not absorb water even in a high humidity floral environment.
How much insulation do I need? On an 8 X 10 walk-in cooler, you can use a 3/4 horsepower cooling unit if you have R-20 foam board insulation, but you need a 1 horse unit if you stay with R-11 fiberglass. About a $400 difference in the cost of the cooling unit. You will also find that a well insulated box will cost less to keep cold and your cooling unit will last longer because it doesn't have to run as often. I always recommend R-20 or better. Both Oregon and Washington law requires heavy insulation to conserve electricity.
How am I going to pay for this?A bank or other lender will loan against a movable box but a built on-site box is worthless in their eyes for loan purposes.
As you can tell my preference is for factory box’s in most cases.
If you still wish to build your own from scratch, here is some advice.
Fiberglass boxes - Use 4 mil or thicker plastic as a vapor barrier on the inside (not the outside like a house) to keep the moisture inside the box. Cover it carefully so it gets no holes over the years. Be very careful that the batts are snug against the studs so there are no "hot spots". Use caulking or spray foam at all joints and around doors. Make sure that water spilled inside the cooler will not get into the walls and rot them. Don't drive nails or screws into the walls as water will wick through the holes. Use shelf standards instead.
Foam boxes- place the foam as a continuous sheet in its 4 foot X 8 foot size over the studs rather than cut it to fit between the studs. It's less work and gives fewer joints to seal. Put studs on edge to save on wall thickness. Cover the foam with a puncture proof surface such as 1/4" plywood. Better is 1/2 " as you can have 24" centers and it's strong enough to hook shelves on. Most decorative home paneling comes unglued in high humidity, so avoid it.
What size or shape to build?
The most popular size is an 8 X 10 box. Think of your needs this way: Shelf on the left side, aisle in the middle, shelf on the right. Make each shelf 24” deep, the aisle 36” wide, and you have a cooler 7 feet wide. If you go to 8 feet wide you gain a wider aisle down the center. That aisle is important as most of your flowers will be in heavy buckets and you don't want to lift them on and off the shelves repeatedly. You also don't want to be brushing the flowers each time you walk in so a wide aisle is wise.
On walk-ins smaller than 6 X 6, think seriously about a reach-in rather than a walk-in box. There is no empty aisle space in a reach-in. Perhaps a 36” deep case that is 8 foot long will serve you better.
Getting extra space cheap
Since most florists need extra space only at the major holidays, forget about insulation. Even outdoors a plastic structure that isn't drafty can be easily heated to 38 degrees for the three weeks of Christmas and about 10 days for \/alentine’s Day. Mother's Day, however, is different. It's usually too warm outdoors by then and some kind of cooling is required.
Take a spare room and glue or screw rigid foam board to the walls. Add a cooling unit and you are set. Do make sure the door fits well and won't warp from the moisture. An alternative on this is to start in the corner of a larger room and use the two walls already in place for cooler walls. Now build two more walls and a ceiling, then add a door.
Rent a truck with a cooling unit for its cargo area. Make sure the unit is electric so the engine won't have to run. This will give low humidity but its better than nothing.
Don’t try commercial cold storage places -- too much food and other sources of ethylene gas in there
What will it cost?
For a stick built 8 X 10 box, you will need: 10 sheets of 4 X 8 foam (4 ") . 25 studs, 20 sheets of 1/2 inch plywood, a good wide door ($250), caulking and other finish stuff. I figure that to be real close to $1,000 without shelves or labor. Figure two men all day at $15 or 2 days at $8 about $300. You can, of course, cut this cost by using fiberglass and thinner plywood. Figure $1,300 to $2,500 if done right.
A factory box (8 X 10) with 4" foam insulation is right under $2,000 but this includes lights and everything to make it right.
We install a complete factory box (refrigeration and all) of the 8 X 10 size for $4,900. We also have a do-it-yourself pre-wired and pre-charged system for $4,400. For those who want to build their own our do-it-yourself box's are a great way to go. Compared to building your own from scratch, this might be for you.
The SRC company advertises an "easy to receive shipment" which is an entire floral cooler in a box.
Most do-it-yourself folks do not have the knowledge to handle their own refrigeration hook up from start to finish. It's also illegal in the US, since you must be licensed.
You can buy pre-charged systems from companies such as Hungerfords and install them yourself.
You can buy new or used equipment from anywhere and hire a local refrigeration person to hook it up for you.
You can call any refrigeration person and have them do the whole job. However, many of them know less than beans about floral applications, and you might be unhappy when it's done. It's not that these people don't care, it's just that all their training is for the 98% of equipment that is for non-floral use. Florists are not that big compared to the total market .
Figure a 3/4 horsepower unit for 6 X 6 to 8 X 10. This will cost between $2,000 and $2,600 new, installed.
Figure a 1 horse unit for 8 X 12. About $3,000 - $3,500 installed.
Prices can vary a lot depending on equipment quality, but you get what you pay for over the long run. Size of cooling unit needed will vary depending on quality of insulation and whether you have an insulated floor or windows of any type.
Location of compressor on walk-in's is very important. The larger units give off a great deal of heat and are noisy. We always recommend they be placed in another room, on the roof, in the attic, or under the floor.
Word of Warning!When you buy your cooling unit, be sure that you are getting a high humidity, low fan speed floral coil. 98% of what is sold is not suitable for floral use.