Fridge Guy's Cold Room Project
The following piece is put together from a series of posts to the Home Brew Digest by Forrest Duddles (FridgeGuy), a home brewer from Kalamazoo, Michigan. Forrest is a refrigeration technician by profession, and he often posts to the HBD to answer fridge related questions. As most of you know, Wayne Smith is building a cold room of his own. He's already got design done, and the bulk of the construction is also finished. However, I thought he might be like to look at Forrest's posts anyhow. I sent him Part 1, and he was interested so I sent him the remaining portion.
I'm using it here in our newsletter for several reasons. One is that I can't write the whole thing myself (blatant plea for articles from you, hint hint). Another is that I thought some of you might find this interesting; I know I've thought of putting a cold room out in my brewery. And the last, and perhaps most important, is to show you why I keep mentioning the HBD. I would like to see more of you become part of the HBD.
You can use the HBD in a number of ways. Perhaps the easiest is just to go to the web site at http://hbd.org/ and look around. There are instructions for signing up to receive the digest daily. To SUBSCRIBE to the Home Brew Digest, send an email note to req@hbd.org with ONLY the word subscribe in the body. This note MUST come from the address you wish subscribed. You will then receive the digest in your email most mornings. Or you can access past digests through the HTMLized archives. You can also search the archives for information on a particular topic. The HBD site also hosts many homebrew club web sites (including our own Hogtown Brewers site).
Anyhow, I hope you take a look at the HBD site. As I've said before; it's the most valuable brewing resource I've found. It's also like a big, extended homebrew club. It really gives you a sense of community with brewer's all over the country, actually all over the world. Anyway, on to Forrest's article.
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * FridgeGuy's Cold Room Project By Forrest Duddles Greetings folks, In HBD#3381, Jeremy Bergsman posted several questions regarding cold room construction. As luck would have it, I recently built my own cold room and will describe my design considerations and construction techniques. I'll have to post in multiple sections over the next few days. Building a cold room is a major undertaking for most people. A project of this magnitude will require considerable planning, patience, time and money. The result will often become a permanent part of the home. Long-term usage factors such as construction integrity, energy consumption, humidity control and ease of use need to considered at this stage, before materials are purchased and before starting construction. The first and most important area of consideration is how the cold room will be used and where it is to be located. These two factors will determine the size of the room, the amount and type of insulation that will be required, and the size and type of refrigeration system that will be needed to hold it at the desired temperature. In my case I wanted to replace the chest freezer I'd used for serving with something that would hold all of my kegs, bottles and any brewing supplies that need refrigerating. I also wanted to provide a cooled/heated fermentation chamber I could use across a wide temperature range. I expected to keep one chest freezer for cold- temperature lagering since it is something I don't need to do on a regular basis or on a large scale. I wanted to do away with multiple refrigeration systems where I could and decided to use cold air from the main room to cool the ferm chamber as needed. This would also allow for good moisture control since I could rely upon the main cooling system, which will have a low enough evaporator temperature to properly dehumidify the air. I could have designed the cold room with a partition between the ferm chamber and main area but I wanted to have easy access to carboys during fermentation without having to open the main cold room door. I found a dead side-by-side fridge which has a low lift-over height for the half-barrel I usually ferment ales in, and has plenty of room above for carboys or corny kegs on shelves. The fridge was free and already had good insulation and tight door gasketing. I gutted the system and plan to use the original evaporator fan along with a Ranco controller to draw air from the cold room through a pair of insluted ducts (supply and return). For fermenting ales in winter, the Ranco can be switched to heating mode. I use a carafe heater from a dead coffeemaker as a heat source and limit its output via a lamp dimmer. I serve and store my beers in my basement, which stays between 60 and 70 degF year-round. The relatively low ambient temperature and reasonable humidity (I use central a/c in summer) mean a relatively small temperature difference between the cold room temp (about 40 degF) and the basement ambient. This allowed me to get by with less insulation and saves on operating costs. Stay tuned for part two: Hope this helps! ************************************************************* Subject: COld rooms - part2 Greetings folks, In the first installment, I wrote about issues to consider when planning to build a cold room. In this installment(and probably the third), I'd like to discuss materials and construction techniques. Now that I knew how I wanted to use my cold room and where it would be located, I had to decide upon the room layout and what elements I needed. This includes taps, CO2 manifold, lighting, shelving, and anything else the room needed as a feature. I wanted the room to be economical to run so the size had to be kept small. By this time I had decided to use only materials with easy-to-clean surfaces inside the room. Moisture resistance is important. I chose to use melamine-faced 3/16"hardboard for the interior wall and ceiling surfaces. The melamine face is reasonably moisture resistant (it's made for use as bathtub surround). I reasoned that I could later paint the interior if moisture eventually deteriorated the surface. The floor is 3/4" melamine double-faced particle board. These materials come in 4'x8' panels so I initially planned to build a 4'x8' room (outside dimension). I wanted to be able to disassemble and move the cold room if I later wanted to relocate it. I can just barely get a 5'x8'x1' panel up my basement stairs and outside, so I had to be sure not only that the room could be disassembled, but that no panel was too large to haul out of the basement. I laid a sheet of plywood on the floor where I wanted the room to be and tried to visualize the finished space. It didn't take long for me to realize I needed a bigger room if I wanted shelves on both sides and still have room to walk down the center (I needed the door to be on a narrow side). I finally arrived at an inside dimension of 5'x8', with a ceiling height of 7'6". This decision made the room much more expensive to build since each ceiling, roof, floor and end panel now took two sheets of each material (with a lot of waste) instead of one. Expanding the room to 8'x8' wouldn't have cost much more but would have required a much larger refrigeration unit and would cost a lot more to run. I also didn't need the extra space. I next needed to know how much insulation to use. I did heat-load calculations for various construction and insulation materials and room sizes. In HBD#3383, N.P.(Del) Lansing posted how to do a heat-load calculation. For an on-line calculator, try: http://www.glacierbay.com/Heatcalc.htm and for R values for common materials try: http://www.its-canada.com/reed/insul/in-insul.htm After pricing insulation materials, I decided to use expanded poystyrene (bead board). Its R value is less than extruded polystyrene, but it's MUCH less expensive. I could use a 2" layer and a 1-1/2" layer to fill a standard 2x4 stud cavity and end up with an R-factor of 11. Since I had only 30 degrees maximum difference between my basement ambient and my desired 40 DegF cold room temperature, and there is no radiant heat load, this is enough. Stay tuned for part 3: Hope this helps! ************************************************************* Subject: Cold rooms - part 3 Greetings folks, I ended the last installment with a description of what I used for cold room insulation. In this installment I'll describe how I built and insulated the cold room panels. I wanted to minimize heat paths through the insulated cold room panels so I didn't use conventional house framing techniques. I instead built each panel with a perimeter 2x4 frame and used the rigid insulation board and wall coverings as structural members. After assembling the panel frames, I cut 2" thick rigid insulation board to tightly fit each frame. This became the outer layer of insulation. I applied styrene-safe construction adhesive in a zig-zag pattern across the outer face of each half-insulated panel and applied a heavy poly vapor barrier to the insulation. I stapled the poly to the perimeter frame as well. Note that I applied the vapor barrier to the WARM side(outside) of the panels. My reasoning is this: Warm air can hold more moisture than cold air. With a perfect vapor barrier on the cold side of the wall, warm, moist outside air will penetrate the insulation and the moisture will condense as it nears the colder inner wall and remain there. This can cause rot and diminishes the insulation's R-factor. With the vapor barrier on the warm side, any moisture that finds its way around the vapor barrier and into the insulation will be removed by the refrigeration system as it dehumidifies the cold room. I applied the same adhesive to the outer face of the vapor barrier and attached the outer wall coverings. I used the same melamine-faced hard board for inner and outer wall coverings for all but one wall and the roof. I used 5/8" wafer board for the roof and I used T-111 plywood for the outer wall covering where I planned to run my taps through. In addition to the adhesive, I nailed the wall covering to the perimeter frames. Next I added a 2x2 stiffener across the inside of each panel, midway between top and bottom. This was to help stiffen the panel and provide a place to screw into for any hardware or shelving inside the room. These were glued to the foam insulation as well as nailed to the perimeter frame. I cut 1-1/2" insulation to fill the panels and glued inner and out insulation panels together with construction adhesive. To complete the panels, I glued the inner wall covering to the inner insulation panels and nailed around the perimeter. I needed the door to be on the end of my cold room so I prepared one end panel to accept a pre-hung, insulated steel entrance door. I found it was cheaper to buy the door ready-made than it would have been to buy the parts to build one. I squared the door to the end panel and installed it like any other household door. I insulated around the door frame and under the threshold with expanding foam-in-a-can to make it air-tight. I decided to insulate my floor as well as walls and ceiling, but wanted to avoid a big step up into the cold room, since I wanted easy hand truck access. I used 3/4" bead board and 3/4"x2" sleepers to insulate and support the floor panel around the perimeter and where hand truck traffic would stress the floor and compress the insulation. Stay tuned for part 4: Hope this helps! ************************************************************* Subject: Cold rooms - part 4 Greetings folks, In the previous installment I described panel construction for the cold room. Now it's assembly time! I prepared my basement floor by painting it with porch & floor enamel. When it was fully cured, I put down a heavy poly vapor barrier and laid out the sleepers and floor insulation. I laid the floor panels on the insulation and sleepers and caulked the joint between the two floor panels with mildew-resistant silicone caulk. I set the rear end panel in place and screwed the side wall panels to it. I placed the roof panel on top and then attached the outer end panel with the door. All panels are assembled together with caulk to make air-tight joints. With all of the panels assembled, I caulked every joint in the interior of the cold room with mildew-resistant silicone caulk. I had framed one wall panel to leave an 18" x 18" square opening near the top to allow easy installation and service access for whatever refrigeration unit I decided to use. Now it was time to install the refrigeration system. I have several different refrigeration units in my collection of junk. I thought I'd first try a dehumidifier that happened to have about the right capacity. I built an 18" square 2x4 frame to fit the wall opening. I removed the case from the dehumidifier and carefully rotated the evaporator coil 270 degrees from its original position until it was perpendicular to the condenser coil. The refrigerant lines were long enough to allow about 6" between the two coils. I slipped the 2x4 frame between the two coils so the dehumidifier was on one side and the evaporator on the other. At this point only the refrigerant lines passed through the frame. I cut insulation to fill the frame, added the vapor barrier and wall covering to both sides of the frame. I attached brackets to the outside of the frame to support the dehumidifier and tightened everything into place. I fabbed some brackets to hold the evaporator coil parallel to and about 1" away from the inside wall of the frame. It is necessary to draw air across the evaporator in order to properly cool the room so I built a box around the coil, with an opening for a large muffin fan on the side that would face the interior of the room. The back of the box is left open so air can be drawn from behind the coil, through it and out the fan opening into the cold room. The bottom of the box is open to accept a drip tray. I installed the fan and ran its wiring through the panel to the ouside. I fabbed a drip tray out of an old aluminum ice cube tray and installed it, with a drain line to the ouside of the room. With the fridge unit assembled, I installed it through the opening in the wall and sealed the joints with caulk. Stay tuned for part 5: Hope this helps! ************************************************************* Subject: Cold rooms - part 5 Greetings folks, I ended the last installment by installing the refrigeration unit. This time I'll cover refrigeration accessories and operation. After I installed the refrigeration unit, I wired up an interior light, installed a CO2 manifold and fittings for Corny kegs, put taps through the wall and installed shelving for bottles, etc. I also installed a small control panel, consisting of a Ranco digital temperature controller, 24 hour timer and a 2-pole relay. The refrigeration unit and evaporator fan are wired so they run together. When the room reaches setpoint, both the fan and compressor shut off. The 24 hour timer and relay are used to provide a defrost cycle. At noon and midnight, the timer energizes the relay, which prevents the compressor from running and starts the evaporator fan. I use a 1 hour duration for each defrost cycle. I've run the room for about 6 weeks now and am very happy with my results. This is, however, a work in progress and I intend to make changes as I go. First is my refrigeration unit. I knew when I decided to use it that it was on the borderline of being too small. It is good to undersize a bit in order to get good dehumidification performance but this little guy has to run abot 75% of the time. The room is as dry as a bone inside and I've seen it remove a quart of condensate each day when I've put something damp in the room or I'm in and out of it a lot. I have a larger dehumidifier I plan to install. I should easily be able to get the duty cycle down to 50% with it and still expect to have good moisture control. I would like to experiment with an off time-delay for the evaporator fan. The refrigerant continues to flow through a refrigeration system for a period of time after the compressor shuts off. The evaporator fan could continue to run during this period, which would provide a little extra cooling and reduce coil icing. If the evaporator fan runs continuously, however, the air flow tends to re-evaporate any condensate still in the drip tray and since the fan itself rejects its heat into the refrigerated space it too becomes part of the heat load. In my case, that's 40 watts. If I were in and out of the room a lot, or the room was located in a very warm ambient I'd want the fan running continuously and use a bigger refrigeration unit to maintain even temperature throughout the room. I haven't yet set up the ferm chamber and want to install the larger dehumidifier before I do so. Lastly, I want to add a 2" layer of insulation to the inside of the door. The steel door seals tightly but only has an R-value of 4. I really hadn't planned to document my cold room project and I wish I'd taken photos as I built it to better illustrate the construction details. I do hope this series of posts is helpful to those of you interested in building a cold room. I'll post updates from time to time as I use the cold room and make changes to it. I welcome questions and comments from those who have built cold rooms or are interested in doing so. Hope this helps! Forrest Duddles - FridgeGuy in Kalamazoo fridgeguy@voyager.net