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  1. #14
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,698
    Quote Originally Posted by duckman06 View Post
    I think what George2 is trying to say is in most all cases a (3) ton would be causing you problems with short cycling, increased electic usage and humdity problems. How low do you have to set your thermostat to be comfortable?

    If you are comfortable with the electic bill and how it is working then why would be thinking of replacing the system? Even with rule of thumb you are still oversized with a (2) ton system. Did the contractor preform a load cal to determine the size or say you have roughly a 1000 square foot home and it needs a (2) ton.

    FYI prices are not allowed here. I can say that the price does not sound unreasonable but still depending on the scope of the work I really can't say one way or another if fair. Comfort does have a value for most people so since the addition is not going to be added make sure this time it is sized properly for the home.

    You just have to understand that we see this same thing daily in our line of work. Possiable future additions are just that possiable. When a customer says they are planning on added a addition. I ask how sure? If not 100% sure I suggest to size the home as is and look into other opitons when and if the addition is added. If the customer insists on sizing for the addition I either walk away from the Job or make a note on my estimate that states that going with size that is needed to take are of future addition will be oversized until the addition is added and my company want be at fault if the system does not work properly. The other issue with future addition is this how big will it be, what will the windows, doors and insualtion be etc... To many variables for anyone to size properly without the addition or plans stating all of this!
    Duckman.......well said.................George

  2. #15
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,989
    Quote Originally Posted by bass-o-matic View Post
    Greetings all and thanks in advance for any help.

    Our house is 944 Sq Feet.

    2 years ago when we thought we were going to build a second story and the rebates where good we got a new 3 ton high efficiency Rheem system.

    Now... we are NOT going to do the addition. But a smaller one adding just one 8 x 8 room. 64 sq feet...

    Our house is old. 1937. Leaky. they told us 1 full air replacement every hour.

    We have a bid to replace our 3 ton with a 2 ton for right at $

    Is it worth it?

    We aren't uncomfortable. It doesn't short cycle too bad that we have noticed.

    Update:

    We're in Austin Texas

    Our Summer electrical bill is right at $150... winter $60
    Do what is cost effective to lower the air infiltration, then I'd go with a 1.5-Ton system.

    Also, do everything possible to lower the heat-gain into your home, also make sure the duct system is properly sized, sealed, & insulated if not in a conditioned area; with a 1.5-Ton setup doing all that, - should save money on your utility bills.

    The 2.5% summer design in Austin TX is 98-F dry bulb, 77-F wet bulb, it is very dry there.

    A properly setup 1.5-Ton system with home energy efficiency work performed, should handle 1000-sf home. However, that is for you & the contractor there - to figure out.

  3. #16
    Join Date
    Jul 2010
    Location
    nebraska
    Posts
    1,629
    Sizing is going to be more about comfort and less about energy savings. Does the 3 ton keep the humidity under 50%? If so leave it in until it dies.

  4. #17
    Join Date
    Jul 2009
    Location
    South Carolina
    Posts
    3,224
    Why not get something to measure the humidity in your house & see how high it gets. If it doesn't get any more than 55% RH then I wouldn't change anything. If you're comfortable in the house & the humidity is O.K. where you don't have to worry about mold that's all that counts. It might cost a little more to run do to more stopping & starting but negligible compared to the cost of new equipment.
    Even if short cycling is hard on the equipment you still have nothing to lose by running it as long as it holds out.
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

  5. #18
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,537
    Agree with Marty, just run it till it dies. Why not?

  6. #19
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,989
    Well, my last post agreeing, was lost so I'll do a short form.

    I agree with the last three posts, because Austin TX is a fairly dry area & if the blower is slowed to 350-CFM per-ton or 1050-CFM; I believe the humidity with a reduction in infiltration would be okay.

  7. #20
    Join Date
    Aug 2010
    Location
    West Monroe, LA
    Posts
    1,535
    Quote Originally Posted by udarrell View Post
    Do what is cost effective to lower the air infiltration, then I'd go with a 1.5-Ton system.

    Also, do everything possible to lower the heat-gain into your home, also make sure the duct system is properly sized, sealed, & insulated if not in a conditioned area; with a 1.5-Ton setup doing all that, - should save money on your utility bills.

    The 2.5% summer design in Austin TX is 98-F dry bulb, 77-F wet bulb, it is very dry there.

    A properly setup 1.5-Ton system with home energy efficiency work performed, should handle 1000-sf home. However, that is for you & the contractor there - to figure out.
    Well said! The only real way to see if changing Out the system is a good idea at this point is ask yourself a few questions. 1. Does the system work in removing humdity properly without having to drop the t-stat to 65-68? 2nd does the electric bill bother you? 3rd does making the improvement going to help in paying for itself ROI etc.

    The answer to this questions can only be answered by you as you are the customer and live in your home not us. The electic bill while not horrible can be better but I think you might be having other problems? In other words something has promoted you to consider changing out the system. A proper load cal needs to be preformed to determine what size system is needed to keep your home comfortable. While a (1.5) might be a good idea without a load we are guessing as is your installing company.

    Example of home oversized that we finished up a install on today. House had a (3) ton in it and has 1250 square foot with average windows and insulation that had been replaced within the last few years. While the customers current system maintained temp and somewhat keep them comfortable. While sizing the home out a week ago the customer said that while the system works good it just doesn't feel like it 75 inside all though the t-stat says so. Come to find out the humdity level in the home was very high. After proper load was done the home only required (2.3) tons of cooling. So I sized per manual s a (2.5) ton that meet the full capacity and matched sensible load within 100 btu's of what was needed. Know the system is sized propely and will handle the full load of the home and on 95 plus degree days will run longer by design remove humdity. We installed a variable speed furnace with single stage outdoor unit to achive this. So to recap now the customer has a 16 seer unit that will control humdity and heat and cool the home properly. They will pay less $ to stay comfortable. The upfront cost is one thing but again comfort has value.

    It's not just a plug and play. What good contractors do is as listed above. I can't stress enough to make sure whoever sizes your new system preform a load cal to ensure the amount $ you spent is well spent and will provide comfort while costing you less $ to do so.

  8. #21
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by bass-o-matic View Post
    Our house is old. 1937. Leaky. they told us 1 full air replacement every hour.
    If I had $0.10 for everytime I heard abotu an old house beign accused on being leaky. Whiel thsi can often be the case. ITs' probably more common with stick frame Victorian era turn of the centrury homes. They fcoused on size and flashy exterior over robust build quality (sound familar with 100 year later). By the 1920's craftsmen had returned, and while we wre in a building boom in the 20's quality of materials was very good and real craftsman constructed homes. The boom drove land prices up, so smaller better constructed homes were more common. Being a late depression era home, yours could vary widely. Post WWII, a lot of GI's returned and went to the trades. Combined with many new materials and their lack of expereince in those trades and materials, and a focus again on affordable housing, quality dropped again somewhat.

    1937 is a real mix. It will depend on your area. Hwoever, if its' brick or stucco exterior, it's probably nearly as tight as average modern construction. Without a blower door test, you won't know. You utlity bills will give some clue.

    Finally, older homes often have denser materials. Plaster, brick, hardwood, tile, stucco, all have more mass than many modern mass produced counterparts. That mass will allow you to have a smaller AC system.

    With only moderate insulation, even in Austin, if you have descent shade or deep roof overhangs/eaves, 1.5 tons could be plenty. WHere i live is nearly as hot and humid in mid simmer and a 1500sqft upstairs of older homes can be cooled with 2 tons.

    Thermal Mass + Shade = smaller AC system even with only moderate insulation.

  9. #22
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,989
    Quote Originally Posted by motoguy128 View Post
    If I had $0.10 for every time I heard about an old house being accused on being leaky. While this can often be the case. It's probably more common with stick frame Victorian era turn of the century homes. They focused on size and flashy exterior over robust build quality (sound familiar with 100 years later).

    By the 1920's craftsmen had returned, and while we were in a building boom in the 20's quality of materials was very good and real craftsman constructed homes. The boom drove land prices up, so smaller better constructed homes were more common. Being a late depression era home, yours could vary widely.

    Post WWII, a lot of GIs returned and went to the trades. Combined with many new materials and their lack of experience in those trades and materials, and a focus again on affordable housing, quality dropped again somewhat.

    1937 is a real mix. It will depend on your area. However, if its' brick or stucco exterior, it's probably nearly as tight as average modern construction. Without a blower door test, you won't know. Your utility bills will give some clue.

    Finally, older homes often have denser materials. Plaster, brick, hardwood, tile, stucco, all have more mass than many modern mass produced counterparts. That mass will allow you to have a smaller AC system.

    With only moderate insulation, even in Austin, if you have descent shade or deep roof overhangs/eaves, 1.5 tons could be plenty. Where i live is nearly as hot and humid in mid simmer and a 1500sqft upstairs of older homes can be cooled with 2 tons.

    Thermal Mass + Shade = smaller AC system even with only moderate insulation.
    Thanks for that interesting prospective...my 2-story farm home, with a deep rock wall basement, was built in 1937.

  10. #23
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Moving into my current home comming from a late 60's home was pretty eye opening. I'm probably spoiled in that my home was built by somone with deep pockets, but I think some industry paractices and meterial selection was pretty good overall.

    We focus so, so hard on raw insulation values, when the overall envelope, integrated shading, building orientation and wall material seletcion, from what limited expereince I have, makes a much bigger difference. I think this is what hte guys on the Building Science side of thsi forum are trying so hard ot get people to understand. That an taking the opposite approach to home energy. Rather than size equipment to a heat loss/gain value, you build a home to a target heat loss rate instead. It doesn't have ot be a net zero home either. I think that last step is diminishing returns and forces comprimises, like less window area.

    Farm home however, tend to be DIY and sometimes are more limited in materials available due to logistics. Sometiems they are very well constructed, other times not. They also frequently have additons added. IN 1937 it might not have even had electricity. So it would have good ventilation and possibly shading with nearby shade trees to keep cool and a nice big porch (you don't want to be indoors in late afternoon). Some even had a outbuilding called a "summer kitchen" because its too hot in mid summer to cook indoors. You would set up a table and eat outdoors as well... probably in the shade... then retire indoors at near sunset to a reasonably cool home. Attic werent normally vented... but roof material were more heat tolerant (asbestos shingles, metal shingles or standing seam, wood shakes. Actuually with tile or wood shakes, you want that attic heat to dry them out after a rainstorm.

  11. #24
    Join Date
    Aug 2010
    Location
    West Monroe, LA
    Posts
    1,535
    Quote Originally Posted by motoguy128 View Post
    Moving into my current home comming from a late 60's home was pretty eye opening. I'm probably spoiled in that my home was built by somone with deep pockets, but I think some industry paractices and meterial selection was pretty good overall.

    We focus so, so hard on raw insulation values, when the overall envelope, integrated shading, building orientation and wall material seletcion, from what limited expereince I have, makes a much bigger difference. I think this is what hte guys on the Building Science side of thsi forum are trying so hard ot get people to understand. That an taking the opposite approach to home energy. Rather than size equipment to a heat loss/gain value, you build a home to a target heat loss rate instead. It doesn't have ot be a net zero home either. I think that last step is diminishing returns and forces comprimises, like less window area.

    Farm home however, tend to be DIY and sometimes are more limited in materials available due to logistics. Sometiems they are very well constructed, other times not. They also frequently have additons added. IN 1937 it might not have even had electricity. So it would have good ventilation and possibly shading with nearby shade trees to keep cool and a nice big porch (you don't want to be indoors in late afternoon). Some even had a outbuilding called a "summer kitchen" because its too hot in mid summer to cook indoors. You would set up a table and eat outdoors as well... probably in the shade... then retire indoors at near sunset to a reasonably cool home. Attic werent normally vented... but roof material were more heat tolerant (asbestos shingles, metal shingles or standing seam, wood shakes. Actuually with tile or wood shakes, you want that attic heat to dry them out after a rainstorm.

    Very well put. Build or energy improve your home then have a pro size your heating and cooling system.

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