Tricks of the Trade
by Vincent Ciernick, A1 Central Vacuums, Inc.
Finding a place for the CVS unit
What do you do when there is no garage, basement or utility closet to put a unit in an existing home/building? Here is the “Trick of the Trade.” In the past I have used a galvanized metal water heater closet kit from Home Depot or Lowe’s that can be painted. The last time I needed one was about three years ago and it was about $90. These are three sided, one with a door and a top that attach to the side of the house. Note: you will have to buy a water heater vent cap for the top separately.
We have commonly put these on the dark side of the house outside a closet or cabinet so we can bring a pipe through the closet/cabinet from the attic or from under the house. I once used one for a small car rental company that wanted to get away from shop vacs.
As a service and to help get the deal, we will also pull the necessary 14 or 12 gauge romex wire for the outlet with the pipe and then have their electrician do the rest. (Yes, we charge for the romex and time!) If you are in a hot area you may want to cut some extra ventilation on the top and bottom sides so as not to trip the unit’s breaker. Bi-Metal Hole Saws 2-9/16” x 1 3/4” deep can do this; and can cut through metal framing, nails in wood and completely through 2x4’s. It is made by BUL MUL part No. 441; I special order them from a tool supply store.
While on the thought of ventilation, I have commonly had customers and service customers have their units in a cabinet/closet. If they do not want louvers on the top and bottom of the door or do not have them, we will cut five 2-9/16” holes on the top of the cabinet near the front and over the open space of the toe kick at the front of the cabinet. (If this is not plausible, we recommend the door is ajar when vacuuming). This gives almost 15” of ventilation on the top and bottom to create convection. In order for hot air to escape cold air must replace it. This is best achieved if the cold air comes from down low to be pulled up by the escaping hot air, thus, convection. Just be sure to emphasize that they keep these holes clear or their motor life will be shortened and warranty will be void
The question of exhaust length is one that I get asked on a regular basis. The committee has deferred this to, “See manufacturer’s spec.” This is because each motor and unit has it own characteristics. You have to keep in mind that vacuum motors are designed to pull, not push. These are two different physics. If the exhaust run is too long you will create backpressure and excessive heat. The air can only come in as fast as it can escape. This heat can shorten the motor’s life and trip the unit’s breaker.
With that said, my testing in the field has shown that if I use more than 20’ of pipe with 2-3 sweep 90o’s I have had a loss of air flow on the gauge. This is with a clean pure cyclonic unit with no cloth, paper or foam filters. Filtered units when they get dirty will have less thrust, therefore more backpressure/heat build up. I recommend that at this point or sooner, you size up to a 3” exhaust to relieve the backpressure. I know some manufacturers say you can go 30’ with 2” I like to keep the odds in my customer’s favor. We use an ABS plumbing fitting 3” to 2” reducer with white drainpipe, thin wall. It’s lightweight and easy to use and costs about $4 to $5 per 10 feet. You can caulk the different sizes together; when caulk dries it is strong. No need to use schedule 40, there is no pressure just venting air, but you can use Sch. 40.
On a few occasions I have had to go up through a roof. If over 15’ I recommend going to 3” pipe because of gravity and heat build up. When going through a roof make sure you use a large water heater cover vent on a roof jack. Or with pipe through a roof jack, use steel pipe with steel 90o and a 45o to keep water out. Plastic will not stand the test of time and the elements. Turn the 90o with the prevailing wind direction. We use a small self-taping sheet metal screw to hold the vent cover or pipe to the roof jack. Use a tube of roof tar to seal around the jack.
Another problem of exhaust is with double motors. In these photos you can see that the two exhaust lines are going into one line. This is cramming 4” of air into 2” of pipe. The installing company was surprised that this did not work, all I could think of was Duh! The motor coming into the sanitary TY90o caused the reset button to pop due to the backpressure and heat build up. What made this equally bad was that it went up into the mid floor it 90o over and 90o up and then 90o over 10 feet and 90o out the side of the house another 12 feet, approximately 23’ not including 90o’s. As you can see these guys used short 90o’s on the exhaust. How many others did they use in the system?
Because this unit has a paper cartridge filter I simply cut and capped the exhaust to the ceiling and put mufflers on each exhaust turned down (All units should vent out side because of the germs, bacteria, allergens and nasties that all vacuum cleaners breed.) The customer was amazed at how quiet it was. Again for a $5 exhaust muffler, installers are losing thousands of dollars in referral business.
The proper way to run a double exhaust is 1: after installing their mufflers; either run two separate equal bends and length pipes out. 2: wye each pipe into a 3 or 4” pipe. We use Schedule 40 3x2x3 45o wye with a 3-2 reducer on one end into the white drainpipe. We use a common dryer vent cap or the homeowner will have a custom vent made for the out side.
If you have a trick to share, e-mail me at vciernick@sbcglobal.net
Reprinted from Central Vac Professional, February 2007 |
