Wilton - Thanks for the great info. I have question. Is thier a magic formula for calculating the amound to return vs. supply? Should it be equal, or shoudl one or the other be larger?
Thanks, Peter On Sat, Mar 14, 2009 at 8:45 PM, Wilton Strickland <wilt...@nc.rr.com>wrote: > 'Sounds like you may have an intake/return leak. I have found several (at > least 3 during the 15 years I inspected domestic systems) with the return > ducts lying COMPLETELY open under houses - ALL the air exiting supply > registers in the house was coming from under the house! I've seen many > others with lesser leaks, of course. We do need to be aware of those > possibilities, understand what happens in the system and try to close those > leaks on BOTH sides of the system. Duct leaks on both sides of the system > do a good job of removing money from our bank accounts and fatten those of > the power companies. > > Most heating/cooling system ducts I've seen are VERY poorly installed and > leak like sieves. Most I've seen are assembled very loosely with worthless > "duct" tape that falls off 'bout the time the check to the installer > clears, > screws or staples with lotsa leaking cracks. Check the ducts thoroughly > and > try to seal them as completely as reasonably possible. Seal leaks with > mastic and/or a VERY good tape (NOT so-called "duct/duck" tape) made > specifically for really sealing ducts - the very sticky, shiny, metallic > tape is usually good for it, and there may be better stuff now. There are > companies who do a pressure (fan door) test of duct systems with aid of > "smoke candles" to find leaks and then work to seal them. 'Been 8 years > since I did an inspection, so I've lost touch with costs, etc. > > Wilton > > ----- Original Message ----- > From: "Archer" <arche...@embarqmail.com> > To: "Mercedes Discussion List" <mercedes@okiebenz.com> > Sent: Saturday, March 14, 2009 3:24 PM > Subject: Re: [MBZ] OT - Stupid > > > Hi Wilton, > Here's another A/C question you or someone else might be able answer. > Because the electric bill seems high, I suspected that there might be a > leak > in the fiberglas ductwork Since this is a "closed" A/C system with no > fresh > air coming in except when the doors or windows are open, I concluded that > if > I opened a window a few inches and taped a kleenex in the opening that I > could tell if a leak in the return ductwork was sucking in air (gaining > air) > which would make the kleenex billow out; or if a leak in the ductwork to > the > cold air registers was blowing cold air out in the attic which would make > the kleenex billow in (losing air). > It turned out that the kleenex billowed out which meant that there was a > leak in the return ductwork in the attic and the house was gaining air from > the attic. Where was this excess air going? I would guess it was going > out > through the usual leaks around the doors and windows or even up through the > range hood vent or other vents. > > When we first built the house about 13 years ago, I did the same "kleenex > test" and found that there was a "big leak", so I called the company that > installed the A/C. He went over it with his gauges and instruments and > said > there was no leak. I tried to explain that since the house was losing or > gaining air there had to be leak, but I was never able to make him > understand that there had to be a leak. After waiting a a couple of weeks > deciding what to do, I did the test a second time and there was no leak. > The Kleenex hung straight down. I guessed that since the ductwork was put > together with staples and duct tape that a loose area of duct tape had > "resealed" itself. > (Note: Using a kleenex, I made sure there was no inside or outside air > movement that might have blown the Kleenex taped in the open window.) > > Since I was only using simple physics for the tests, I'm wondering if the > A/C guy was right and I was wrong since he knew a lot more than I did about > ducted A/C systems? > Thanks, > Gerry > > ------------------------------------------------ > From: Wilton Strickland > Several days ago, somebody was talking about doing something stupid. > "Don't > remember who it was, but be reassured whatever it was probably wasn't so > stupid. Now, let me tell you about stupid; THIS was stupid: > > WHERE IS ALL THE WATER COMING FROM? > By > Wilton Strickland > > During the summer of 2000, while I was working as a private, independent > home inspector and building consultant, I received a call from a woman who > was extremely concerned that her new house had excessive moisture on the > underside and did not have an adequate vapor barrier. (A vapor barrier is > usually formed in the under-floor crawlspace by laying a plastic > sheet/membrane on the ground to keep water vapor from rising out of the > ground and through the floor into the house.) She said she had a wet wall > and lots of water on the floor in a bathroom; she called a plumber who had > been unable to find any leak and had told her that her problem was “no > vapor > barrier under the house.” She had also called a roofer, who could find no > problem with the roof. Because the house was only a few months old, she > wanted a licensed, professional inspector to document the moisture problem > under the house in order to persuade the builder to correct it. > > She had described the house as being a one-story structure of about 1800 > square feet. When I arrived at the house, though, I immediately saw that > it > was a “double-wide” manufactured home on a permanent, full masonry > foundation. From what she had described on the phone, I was expecting to > find a typical “poor drainage” problem around the outside causing water to > accumulate under the house. Ground around the outside of the house, > however, was well-drained, and quick observations of the underside via the > crawlspace access door and foundation vents revealed a reasonably dry > crawlspace and an intact, factory-installed vapor barrier attached to the > underside of the structure. While I was walking around the outside, > looking > through foundation vents, etc., the lady continued to tell me how wet it > was > inside the house, and asking, ”Where is all the water coming from?” > > Shortly, I was ready to see the interior and the water that she was > concerned about. I followed her into the house and into a bathroom, where > the door was standing open against an adjacent wall. As she pulled the > door > away from the wall, I noticed that a large section of wallboard/sheetrock > on > the wall had been removed, and the backside of the door, the remaining > areas > of the wall and the cabinet in front of the door were dripping wet. A > couple of wet towels were on the floor beneath the door. There was a > strong > blast of very cold air coming from the heating/cooling register in the > floor > behind the door. She told me that when they removed the wet wallboard, > they > found a lot of water accumulated inside the wall. I knew immediately that > the water was condensation caused by the blast of cold air flowing in the > confined area between the door, the wall and the cabinet. I laid a > thermometer on top of the cabinet with the probe tip hanging off the edge > so > that the air could flow across it. After a very few minutes, while I began > to explain condensation to the lady, I checked the thermometer and found > the > temperature of the air at the top of the cabinet to be 56F! The wall, the > door and the front of the cabinet were acting as large condensing plates - > water was dripping profusely off the bottom edges of them. > > I tried to explain condensation to the lady, but she could not, or would > not, understand me. First, I tried to get her to understand that the air > all around us contains lots of water as a vapor that we usually don’t see. > Warm air can hold more water than the same air when it is cooler. When air > cools below the dew point, the temperature at which air is saturated or > holds all the water that it can at that temperature, some of the water > vapor > must condense and can be seen as fog, clouds, rain, snow, sleet or hail, > depending on temperature of air that the droplets of water may fall > through. > Dew on grass, condensation on the outside of a cold drink glass and the > water dripping from the surfaces in her bathroom are caused by the air in > contact with the cold surfaces being cooled below the dew point. The > constant blast of very cold air behind the door makes the surfaces cold > enough to cause the condensation to form on them - just like a cold drink > glass and windows inside a car on a cold day. The lady’s eyes had a > constant “glaze” of stupidity with no understanding of my explanation of > simple condensation as she continued to ask, “But where is all the water > coming from?” > > I tried, again, to tell her that the air all around us just naturally > contains lots of water. The amount of water in the air is constantly > changing as temperature changes, as weather changes. The air around us is > saturated, or full of water, when it rains. After a rain, some of the > water > soaks into the ground, much of it evaporates back into the air around us > and > rises away to be seen as clouds or to rain again another day. Inside the > house, water comes from several sources. First, air going into the house > from outside takes with it whatever water it accumulated by evaporation > from > outside. Additionally, we people, just by living, put a lot of water into > the air by breathing, perspiring, constant evaporation from our bodies, > etc. > Cooking, laundry and bathing/showering also put a lot of water into inside > air. We can’t live without putting water vapor into the air around us. > Still, the lady asked, “But where is all the water in the bathroom coming > from?” > > Because I had not seen the heating/cooling system thermostat in the usual > place near the return register in the hall near the bathroom, I stopped > trying to explain the situation for a moment and asked to see the > thermostat. She took me down the hall and through a closed door into a > bedroom, where the thermostat was located. She told me, “We never use this > room - the registers are closed and we keep the door closed.” The > thermostat was set at 67, but because it was isolated from the rest of the > house, it could never shut the system off; it never shut off during my > visit. I told the lady that the thermostat should be moved to a point near > the return register in the hall and should be set no lower than about 76. > When I suggested the more reasonable setting, she exclaimed, “Oh, but we > like to keep the house really cool!” (BTW, outside temperature was about > 95F.) I reminded her that by try to keep the inside of the house so cool, > she has condensation dripping off those surfaces in the bathroom. Back in > the kitchen, she showed me another wall that often gets wet. This wall > also > had a constant blast of 56-degree air on it from a floor register. > > Meanwhile, I stepped outside for a couple of minutes to check the size of > the cooling system. I found it to be a 4½ ton unit! Using a “rule of > thumb” of a ton of cooling for each 600 square feet in a typical house, > the > unit was over-sized by about 1½ tons! As I went back inside the house and > began to try to tell the lady that the cooling system was too big for the > house, that it produces lots of very cold air, but it never shuts off > because of the bad thermostat location, her father-in-law arrived and > asked, > “Where is all the water coming from?” > > With him, I had to start at the beginning, and, again, he evidently could > not, or would not, understand anything I told him about the source of the > water in the bathroom and the associated problems with the cooling system. > As I was beginning to “wind down” with the father-in-law and realizing that > he did not understand me, either, the lady’s husband arrived. Hoping that > he may be able to understand me, I had to start at the beginning, again. > He, too, interrupted occasionally by asking, “But where is all the water in > the bathroom coming from?” > > Several times, I tried to tell them that the thermostat should be in the > hall hear the return register, air flow to the register in the bathroom > should be reduced, the heating/cooling system should be properly sized for > the house, the factory-installed vapor barrier attached to the underside of > the house is sufficient and is in good condition, and there is no excessive > moisture problem under the house. After an hour and a half, or more, of > detailed explanations about basic meteorology, thermodynamics, air flow, > etc., with references to cold tea glasses and cold car windows in winter, I > still was getting the same question, “But where is all the water coming > from?” Because of the blank stares and doubting looks from all three of > them, I finally had to say, “I don’t know how else I can tell you, I just > don’t think I’m smart enough to explain it to you.” In exasperation, I > said, “Please, just let me go. There’ll be no charge. I just need to go.” > The lady then asked, “May we get a written report?” I replied, “Then, I’ll > need a fee. I don’t know how else to explain it to you. Just let me go.” > I just wanted to get out of the situation and have nothing else to do with > them. I just could not get them to understand that the solutions to their > “problems” were VERY simple, and that they, themselves, created a large > part > of those “problems” by keeping the thermostat isolated and by trying to > keep > the inside of the house so cold. > As I drove away, I said aloud to myself, “What a pity. Ignorance can be > cured with knowledge, but stupidity lasts forever.” > Yeah, I guess I was stupid, too, for not writing a report and getting a > fee, > but by then, I just wanted to be FREE of them! > Wilton > > -------------- next part -------------- > > No virus found in this outgoing message. > Checked by AVG - www.avg.com > Version: 8.0.237 / Virus Database: 270.11.13/2001 - Release Date: 03/14/09 > 06:54:00 > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > -------------- next part -------------- An HTML attachment was scrubbed... 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