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I’m building a 3500 sq.ft. house in Long Island N.Y. The problem is the HVAC contractors I have 4 different estimates with 4 different systems. All quoting different Tonage for the A/C theyare ranging between 7 to 12 tons I know Manual J has a formula But I want to zone the Heat and A/C upstairs into 2 or 3 Zones. I am new to this site and am kind of confused . Any help would be Appreciated.
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Unless you plan to have a very large amount of south glass and/or little or no insulation, 7 tons is on the high side and 12 is way off the mark. A contractor that would recommend 12 tons in a 3500 sf house warrants no further consideration.
Zoning or not, the heat gain of your house will remain the same. Did you run the calculation? The first item to be resolved is unit capacity. What has been proposed in terms of boilers for the heating?
Design conditions for Central Islip 88/73 deg F dry bulb/wet bulb summer (0.4%) and -6 in the winter. What the db and wb number mean is that the higherst temp you will see, 99.6% of the time is 88. The wet bulb temp indicate humidity and in the case listed is about 47% relative humidity. That's a fairly mild environment. Best to have and undersized AC, personally 5 tons would be as large as I would recommend.
*Thanks Tim. One Contractor is recommending two 31/2 Ton units One for each floor.Both are Lennox 13 or 14 seer Model HS27-042. Downstairs has a 5 ton Blower also Lennox CB31V-65 variable speed.Upstairs a 4 ton Blower Variable speed Mdl.CB31V-51. Each has a hot water coil a White rodgers Prog.Themostat and a(Skuttle Filter)system.and 1 Humidifier Lennox Model 560 with an option for an additional upstairs humidifier Mdl Aprilair 350 fo $600 more.Upstairs is Zoned with a Lennox Harmony Zoning Control System for three zones.I've read a little about this but not much to make an Informed decision.They call it the (Cadillac) System. The boiler the Plumber is supplying is a Slant Fin Gas Fired and I believe is between 225 or 275,000 Btu.The house is Tyvex wraped with 1/2 inch Tuff board foam with R-13 in the walls and R-30 in the attic. The house has Southern Exposure to the Back with one large Window Bay type a 6' slider and Double Casement Kitchen Window. All ceilings on the first floor are 9' an window height is set at 8' Windows are Marvin Integrity Double pane Argon, low E. Now you now as much as I do I also plan on Insulating the Basement with R 30 also 9' ceiling(I'm Tall) Any other advise would be Greatly appreciated. ie. How is Lennox What Price Might be Reasonable etc.Thanks Again. Any one else also please weigh in, George
*A follow up isnt the Heat and A/C theory that Hot air Rises and CVold Drops. With this system almost all installers want to put the registers on the first floor in the floor and the second floor in the ceiling. Is there a way to balance this so you get the proper mix.Also should there be returns in every room or just those Huge ones that the always put in each floor. I'msure I'll have more Questions. Tim are you from the New York area. Thanks George
*George,It is not a theory, hot air is less dense and rises in relation to cooler air and vice versa. If the system(s) are installed with the proper provisions you can control it somewhat but you can't change physics.The reason that the contractors want to layout the system as you described is accessibilty. It is practical to install floor supply registers in the first floor over a basement or crawlspace and ceiling supply registers in the second floor because of the attic. That is the way it is done, nothing wrong with it.Returns are a different issue. You need a return in most rooms except kitchens and bathroom (those need exhaust), not just one in the hallway. Common areas (like achallway, stairwell, foyer/entry) can be served by a single return. Best to have returns opposite of supplies, i.e. in the first floor they would have to pan (or use wall stacks if the local code doesn't allow panning) the wall studs to take high returns and on the second floor do the same to take low returns. Request (or demand) that the installers provide branch dampers in all supply AND return ducts and have them install registers, not grills (supply and return). This will give you more control over where the air goes and the flexibility to balance the system to your needs/preferences.Lennox is as good as anyone else, however because of the very short cooling season in your area (I am not from New York, but from Dallas and now live in northern IL) I would recommend that you go with a 10 or 12 SEER max. The additional cost to go from a 10 to 12 SEER, 4 ton condenseing unit is about $1000, to get 14, $2000-2500. You'll never see a payback in your area. I just bought one, a 4 ton 10 SEER for my 4000 sf house. Crunched the numbers for me, my usage and my normal (not design conditions) and the extra 20% efficiency (from SEER 10 to 12) would have cost $950, and would have taken me about 12 years to save that money. My AC runs around 200 hours a season. I don't expect the equipment to last longer than that.Reasonable costs for a forced air with AC system is around $3000 to 3500/ton, installed. More with the boiler and hyronics. If you are going to use hot water to heat air, as opposed to infloor tubes, radiators or panels, consider gas fired furnaces and do away with the boiler, piping and coils.
*Minor point if calculating payback...don't forget the Energy Star rebates. I don;t have the paperwork, but it varies (SEER dependent) from around $45 per tom to $90 per ton. The higher the SEER, the higher the rebate per ton.It's better than nothing...
*I think with 12 tons of AC the penguins would freeze to death. The local AC guy told me last year that he didn't think 5 tons was enough to cool a 1500 Sq ft commercial space. I put in a 1.5 ton (18,000 BTU) window unit and it cooled it fine.Remember that if you oversize you aren't going to get the dehumidification you need. I'm going to replace a 5 ton with a 3 ton in a building I own because after we insulated the hell out of the building the AC only runs for a little while and is clammy as anything.
*Thanks Jeff I have a meting with HVAC on Saturday and Hope I can work out all this stuff.I think one of my main problems is trying to Zone the second Floor George
*I've had a nagging question since we installed A/C in our house last year.The contractor used what seems to be pressed fiberglass boards that are cut and taped together to form the main trunk lines from which the flexible foil wrapped supply tubes branch out to different registers.I asked several times if there would be any danger with loose fibers, etc. from the fiberglass and was told not to worry.We are very pleased with the quality of installation and amazed at how quiet it is but the question still remains....should I have insisted on insulated metal trunk lines that would have cost more money ?It seems like removing the "fiberglass" trunk lines would be an easy job if it came down to that because I saw how they were put together.Thanks for shedding any light on this stuff.Alan
*Allen,Ductboard is designed for the installation as you described and very suitable for that. No need to worry.
*Thanks, Tim -Lo and behold, after posting my question, I did my usual random grabbing of a copy of FH from my collection and in Issue #110 (July '97) there is an article on "Choosing Ductwork" and it speaks very unfavorably about the pressed board ductwork and that it is very prone to leaks....Our trunk line sections were cut and assembled in the carport and taken into the attic for final assembly.Alan
*It wouldn't be my first choice, but as in all things, attention to detail and craftsmanship counts.
*Tim, I finally found someone That I think is on the ball. He sized the House to 6 tons and was adamant about using 12 seer Repeating what you previously stated. We are putting the upstairs Master bedroom on a separate Zone so that is adding 1 1/2 tons to the system, He felt it was a little High but it's the smallest unit available. The Condensing unit is a RUUD.Any Idea of its Quality? By the way the Saturday Meeting was cancelled as He increased me to 8 tons... Thanks for your help and good luck Alan.Keep us Posted George
*My HVAC Contractor has installed Ruud in all of our jobs and I am impressed by the consistent quality of their product... he has been doing A/C for over 45 years and he feels it is comparable or better than other manufacturers like Trane and Carrier.
*George,I don't have any direct experience with RUUD. The features (not just SEER), warranty, and the quality of the local rep/installer are as/more important than the name on the side. If you asked about any manufacturer you will find those who love them and those who hate them. The market is pretty competitive and RUUD is surviving, so they must be doing something right.So what are the features that are available on a condensing unit? High and low pressure cutouts, 10 year compressor warranty, compressor crankcase heater, forced compressor lubrication, multiple stages and/or hot gas bypass, oil sightglass, suction accumulator, inline filter/dryer and anti-cycle timer. Some of these are not applicable to small (i.e. I hope that everything works out to your satisfaction. I would also, as a matter of professional curiosity, like to know when your all done, what exactly you got, how much it cost and how it all works, if you don't mind sharing that info.
*Tim, I wills be more than happy to give you a final tally and how it all works. Start date should be 1/28 sooner if I can get it. The quoted estimate was 10,000. Pay nothing until totally installed and I am happy with the system.Company name is P&B heating and Air . They have been a family business for 20 + years. Bob the boss likes Baseboard heating the best or Radiant floor but the latter is prohibitively expensive here. Anyway I'll keep you posted and Thanks again. George
*One more question? I may be interested in putting some sort of heat under a black Top driveway which is about 75 feet long is there a Inexpensive way to do this . A friend told me he knew someone who also heated his pool with the return somehow. I read the thread posted but really didn't get much out of it. dont want it to run through my furnace the plumber said it would be Way expensive to run... Thanks
*Check out "Heat exchanger plate and snowmelt combo" several threads below this one.Stainless steel heat exchanger plate is a nifty device along with a tempering valve (for heating back up the boiler return water from the driveway loop) that coule be easily retrofitted into an existing boiler setup. Better yet if it's new construction.This would be on its own loop for seasonal use.The another heat exchanger plate could be used for indirect domestic hotwater heating. (Or the same plate could serve both purposes.)
*George,It is fairly easy to put heat in a poured pavement (polyethylene tubes, with a water/glycol mix and a heat source), but since blacktop is placed and then compressed, I don't know if it is or can be done. There are folks that post on this forum that can help you more than I.Inexpensive is a relative term. I would love a snow melt system for my drive/lane, at least the sloped portion, but it won't happen. I have about 1000' of driveway, 400' is at a decent slope that is heavily shaded even when there are no leaves. Its gravel, so no matter how smooth, I can't scrape it "clean". Always get ice, sooner or later.
*I'm back with a glitch... My HVAC guy does not want too and won't install the humidifiers for the 2 Zones upstairs in the attic for obvious reasons frozen pipes etc. The system he originally was going to use was the Aprilaire Model 550 or 560 but they won't fit on any returns without going into the attic. His Solution is to put a self-contained humidifier Aprilaire model 350 in a hall closet return on the second floor,which blows? into the hallway and use that as the sole humidifier for the whole house. It has a separate Humidistat and has a hot water feed,it provides moisture in Vapor form. My Question to him and you guys is how does it Work on the whole house . If the bedroom doors are closed can this reach these rooms? He says the house acts like a sponge and with doors about 3/4 " open on the bottom the Humidity will penetrate. Question If there are rugs and the door is free but close how will ties work. Will there be too much humidity in that hallway area and not enough in the rest of the house. Can it get so Humid in the Hall as to create Mildew or Mold. Again I know Hot Air can be brutal and I just want to lessen that possibility. Aprilaire has a web site http://www.aprilaire.com. I've checked tics guys references and business record . His customers love his work and system but like most home owners don't really know what type of Humidifiers etc. he uses. So any help you can give me I appreciate. He started and doesn't come back until Monday. So I'm only slightly pressed for time... (Construction don't you love it) George
*Adding moisture to modern tight homes...is iffy... YOU should be fine as long as you keep the system set to very low. All the problems I have seen are from people over wetting their homes. You cannot raise the humidity past a certain point as you will never get their before the inside of your walls are bathtubs of moisture and with in a short time you will have enormous amounts of rot. Does your wife boil water with the lids off like most women? Do the females run the bath fans always when showering? Mine do not... Most do not. Just these vapors alone can be more moisture than should be allowed.near the stream,ajIf you want to sleep in vapors...get a vaporizer and aim it at the bed.
*George,I will look into the models you referenced when I get back into the office Monday am. One unit on the first floor furnace should suffice.AJ, adding moisture into homes in a controlled manner is in some opinions, an option, though not "iffy". The range of reletaive humidity that a properly functioning humidifier will provide in a home during winter, i.e. 20 -40%, will never cause moisture problems as you describe.
*Added moisture... can always cause problems.... Always.Not that it definitely will.... but... it can.near the stream having found enormous hidden lakes in walls,aj
*The best houses built today, with specific measures taken to reduce air infiltration, as well as superb insulation and construction, still leak at the rate of 0.2 air changes per hour. a 2500 sf home with 8 ceilings (20,000 cu ft) would leak about 70 cfm. If outside air is @ 20degF and inside air is at 70 degF and 30% rh (the minimum recommended level) the difference is 4.7 lbs of water per hour. The humidifier that George's contractor is proposing has a capacity of 0.5 gal/hour or about 4.2 lbs. As long as the unit is controlled with a humidistat in the return at the unit, a residential humidifier will barely maintain 30% rh and will not cause any thing to mold or "hidden lakes in walls". If you have found such things, they are indicative of a serious problem, but would exist independent of controlled humidification. The idea that a house or building can be sealed up so tight that all moisture inside will remain so is "iffy". If it were possible to build such a "tight" house, the air quality inside would be so poor, the occupants would experience adverse health effects constantly, if they didn't suffocate or die from carbon dioxide poisoning. In my part of the world, such a house would also be in violation of applicable codes that govern ventilation requirements.
*OK JIM was that an answer or a retort to (0ne...) Still trying. George
*Tim... we will have to agree to disagree... Tight homes concetrate air loss through cold condensing wall leaks. So..in concentrated areas... there may or may not be huge damage happening. I have seen huge damage. I have seen no damage. I have seen 3 pots on a stove boiling gallons of water off 7 days a week. I have seen bath vent lines in attics plugged with ponds of water that condensed.Near the stream with no humidifier,aj
*George,You asked how will it work. First, humidifiers are installed on supply plenums, not returns except for bypass types which take some supply through the humidifier and dump it back into the return. I prefer "powered" humidifiers such as the AprilAire 760/768 because you loose no unit efficiency bypassing part of the system flow constantly.Ever hear of Boyle's law. It has to do with gases and partial pressures (I think I have the right law here, school was a few years ago) and the fact that a gas will expand to fill its container and not remain segregated. Water vapor is a gas and will expand to fill you entire house, so long as it stays as a vapor and does not condense on a cold surface or leak out. Since hot air tends to rise, and air flow will affect to some degree how much the moisture gets around the house, I would recommend, if at all possible to put the humidifier on the unit that serves the lower floor.You asked "If the bedroom doors are closed, can this reach those rooms?" Yes, the moisture in one part of the house get everywhere, if not by simple physics, then the air handler that serves the various ares will help by taking it into the return and distributing it through the supplies. "He says the house acts like a sponge...." That is true to an extent. Most of the materials in your house; wood, concrete, plaster, drywall, and people all are hygroscopic (people aren't really) which means that the moisture content of these materials is directly related to the moisture content of the environment, i.e. the air, around them.It can get so humid that mold and mildew can form in your house. Not discounting AJ's experience with a concentrated leak points, inside the space, the duct system will disperse the moisture evenly through out and large area and unless the controls fail, will limit the amount of moisture produced based on feedback from the space, the humidistat in the return.The short version is: one will work for the whole house, placing one in the attic is a bad idea.
*AJ,I don't think we have to disagree, but see two parts of a large problem from different perspectives. You bring up a point that I failed to consider, and that is with most of the leaks reduced or eliminated, tight houses create concentrated problem areas.Also, I would expect that even a well designed residential ventilation system cannot handle 3 pots boiling continuously. (I would never think of accommodating that in a residential kitchen).Let me ask you, in the house that you saw concentrated leak points, was there outside air provided to the house by way of gravity vents or an energy recovery ventilator? Did they also have trouble with gas burning appliances drafting properly?I could understand a bathroom vent line being run by an idiot in such a way as it might hold condensate in a low point. But that wouldn't deter me from humidifying. I believe that we have a lot to learn about building houses that are not only tight, but are also well ventilated. I seldom, if ever see anyone addressing ventilation when it comes to vapor intrusion and control. I remember one poster on another thread, was going to make a presentation to his building association about this very issue, yet seemed clueless concerning air and water as a mixture and how to control it.So is the solution to not humidify? I don't think so. The health consequences of low RH levels are well documented. Obviously the answer is not to build "leaky" houses. I would prefer to provide controlled and predetermined "leakage".
*Tim... tight homes have naturally higher RH levels. My home is late 80s tight and is fine. RH as I type is 39% on my Radio shack temp/RH meter. I have no humidifier. We have 2 taking showers... and we vent shower moisture to the home. We boil with lids mostly but not totally. We as 99% of America do not have an air exchanger...We open doors and rely on the home being leaky enough.This home is not my design nor did I build it. Someday I may play the build and sell per 2 years game. Then I will have to choose insulation methods and all. As to running vent lines correctly, 99% of all vent lines are run by some rookie laborer and just pulled from point a to point b with no regard to water trapping. I Know of not one person other than myself and the homeowner that understand what happened.near the stream,aj
*Tim and one... Today the Contractor finished running his ducts. The Conversation about Humidifiers went along the lines of one main humidifier on the first floor supply. The one on the second floor that he plans to install would be mounted in a closet facing into the upstairs hallway, near hi might add the upstairs return. He never wanted to nor would he install one in the attic. I have two Zones upstairs. I need the humidity on the second floor for some health reasons. I've had Bells Palsy 4 times and while sleeping my left eye apparently stays open slightly. So with dry air I have a problem of drying out too much. His feeling of the upstairs Humidifier is that it probably would not cycle much because of the one on thew main trunk. It has an Independent Humidistat that I would control. The only problem I see is cosmetic in leaving more vents exposed than I would like to see. The other in that it does not interface with the blowers so it would truly be an independent unit. Again I appreciate your help and reading opposing views is nothing if not a great learning tool. AJ thanks for coming input I have lived with a Hot air furnace for toooo many years though Hydronics is not as severe it is as Tim pointed out many posts ago it still is HOT AIR. This drys your skin eyes and Mucus Membranes as to cause many a bloody nose for my Kids. Ihave used portable humidifiers and they helped but in building a new Home why not try and do it right. I being Italian Boil lots of Pasta water and believe me it's not enough to keep it moist. And Yes my wife won't use the shower vent and there is some mildew, but it is contained in the bathroom. And the 50 + year old house I live in no does indeed leak. End result is that the Main system gets a device. And the second floor is on hold until I get enough Information to convince me one way or the other. There is no real urgency at this point as it doesn't need to be installed until sheet rock. Which is still a few weeks away. Please keep up your comments and anyone else who has a thought would be helpful.. Finally as I've said in the past you guys are technically way over my head but the more I read you the more it makes sense(somewhat)Mabey Humans are sponges Tim . Some humor food for thought Thanks George
*George,Unless I misunderstand what you said, a humidifier may be placed somewhere prior to drywall being installed? And be inaccessible thereafter? One installation "must" is that the humidifer be accessible for cleaning. Another item you mentioned, "...more vents exposed"? I guess I don't fully understand the installation.
*AJ,Your house is a prime example of my point. In the post energy crisis America, we looked and found ways to make buildings more efficient in terms of retaining heat, reducing leakage, etc. What was and still (amazingly to me) ignored especially in houses is that the leakage was good for the quality of the air. You live in upstate NY, I believe. Probably don't spend a lot of time with your doors or windows open in Dec, Jan & Feb. Also the time of the year that you and your family spend more time indoors. In a residence with 2 or 4 or so people, the problems are minimal. However, the situation can aggravate and in some cases cause, various respiratory problems. I see the same problem on a large scale in commercial buildings, schools and churches. With many more people concentrated in a space, the problems that affect air quality are amplified and have to be addressed. Humidity is one of many components of air that determine quality.Something to consider, this is somewhat related to the great vapor barrier debate, is why houses leak. Simple explanation is there is a path (construction joint, door or window) and a driving force (pressure). You can't eliminate either. A building with no or inadequate ventilation (by ventilation I mean outside, fresh air, intentionally introduced) will be at a negative pressure. Bathroom vents, water heaters, kitchen exhausts, clothes dryers, etc., all expel gases from the house forcing it to "inleak". Until building "scientists" and building "professionals" realize and account for this simple concept, the problem only get worse.Do you accept code minimums as good enough? My experience is that the codes are legal means to prevent morons from causing harm to unsuspecting people. The International Mechanical Code and the American Society of Heating, Refrigeration and Air conditioning Engineers (ASHRAE) recommend a minimum of 0.35 air changes per hour. Good practice exceeds that several times over.
*Air changes.... In my area... no one is involved in it that builds new homes. Well maybe one contractor.near the stream opening doors often as I have pets!ajps... except for the fish... But someone said fish aren't pets... Is that because we don't pet them?
*Tim:"The International Mechanical Code and the American Society of Heating, Refrigeration and Air conditioning Engineers (ASHRAE) recommend a minimum of 0.35 air changes per hour. Good practice exceeds that several times over."Is a blower door the only way to reliably measure this?
*Bob,To be honest, I do not know how air infiltration is measured in the numbers that I referenced a few posts earlier. I read them in the 2001 ASHRAE Fundamentals book, Ch 26 "Ventilation and Infiltration". The blower door seems to be the most obvious way. I can think of no other.When designing, I count on 0 and provide all required via ducts sized to accomodate the air. Depending on the system details with or without an energy recovery unit/ventilator.AJ, do you know what,if any code applies to ventilation in your area? No one does it around here, either, but that just makes it common, not right.
*Many of us are living to ripe old age... so...near the stream,ajThere is no inspector asking for forced ventilation. Bathrooms must have a window or fan, that's it.near the stream,aj
*Tim The unit is the Aprilaire 350 or 360. It is installed in between a stud wall and has a grill cover.I assume not having seen the unit (hands on)that the grill cover is remvoved if it maintenance is necessary. It has a flow rate of 6 gallons per use hour with a drain connected sot here is no standing water.
*George,Sounds to me like your contractor knows what he's doing. As long as he is willing to stand behind the work and as you said, has good references, do what he recommends. If it works well, tell him (or her?). If it doesn't, tell him. That model is not one that I am very familiar with, in general, I like the products that Research Products (the maker of Aprilaire) sells. One further recommendation, get the best filter you can find. The Aprilaire High Efficiency (2200) is an excellent filter.Tim
*Tim, As far as I know right they are installing Filters right on the returns so that no dirt gets into the ducts. They are calling them Electrostatic. I'll let you know. George
*George,They done yet?
*Not yet Jim still waiting for gas and electric hookup. Soon I hope.
*Sorry Tim Typo
*Hey Tim No news yet Still waiting for Gas..
*George,I looked through the thread, and unless I missed it, we never talked about fuel. You getting natural gas or propane? What does it cost you there? For that matter what does electricity cost on Long Island?Still interested, when your done.Tim
*Hi Tim, Fuel will be Natural Gas. I never liked Propane. And electric on Long Island is one of the Highest in the Country. I don't have the numbers right now but it is always a source of contravercy.We had the Shoram Nuclear Plant that never opened,but continues to cost the Taxpayers. What a business make a billion dollar mistake build a plant that is totally unsafe,Lose mega bucks, and Charge the consumer. Don't you wish you could do that in your business. They (the utilities) have it better than Weathermen. Anyway the Gas meter should be installed this week and by Friday we (hopefully can take the System out for a spin. I'll keep in touch. George