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  1. #14
    Join Date
    Jul 2004
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    Massachusetts
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    6,829
    Quote Originally Posted by jerrod6 View Post
    Thanks Mark
    Any thoughts about the other part of my question regarding leaving the fan circulating while no one is home?
    Yeah. Unless you have exceptionally high ceilings with returns at the highest levels, leaving the fan on when no one is at home is a waste for heating purposes. If you've got IAQ equipment (EAC, UVL, HUM, HEPA) then operating the fan is a distinct plus because those things can't work if the fan is not on. Operating the VS blower in "On" wastes a small amount of money during the dwell cycles but since you asked, it gains you nothing and loses you a small amount in electrical costs. Generally the 'On' selection is made for either IAQ or for personal comfort, where you feel more comfortable when the air is constantly mixed than you feel when it isn't. As for Btu savings, I don't see any advantage at all. Again, Btu's out (house heat loss) needs the Btu's in (furnace is running) to maintain set-point. Lower the set-point for several hours, you save money.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  2. #15
    Join Date
    Jul 2003
    Location
    Philadelphia Pa.
    Posts
    461
    Quote Originally Posted by beenthere View Post
    Did you op to pay early for the rate hikes? So you don't see a sudden increase in 2010.
    We can't do that with gas and electric - it is not like we are under any contract. The utilities will increase the rate and we will pay for it monthly when the bill comes.

  3. #16
    Join Date
    Jul 2003
    Location
    Philadelphia Pa.
    Posts
    461
    Quote Originally Posted by skippedover View Post
    Yeah. Unless you have exceptionally high ceilings with returns at the highest levels, leaving the fan on when no one is at home is a waste for heating purposes. If you've got IAQ equipment (EAC, UVL, HUM, HEPA) then operating the fan is a distinct plus because those things can't work if the fan is not on. Operating the VS blower in "On" wastes a small amount of money during the dwell cycles but since you asked, it gains you nothing and loses you a small amount in electrical costs. Generally the 'On' selection is made for either IAQ or for personal comfort, where you feel more comfortable when the air is constantly mixed than you feel when it isn't. As for Btu savings, I don't see any advantage at all. Again, Btu's out (house heat loss) needs the Btu's in (furnace is running) to maintain set-point. Lower the set-point for several hours, you save money.

    I have 13ft ceilings on the 1st floor and 11ft on the 2nd and 3rd. Returns near the ceilings in all rooms except kitchen and bathrooms, and hall ways have returns near floor. Have an air cleaner, so that is why I was running the fan all the time when home.

  4. #17
    Join Date
    Apr 2008
    Location
    Princeton, NJ
    Posts
    581
    Quote Originally Posted by allan38 View Post
    .......
    Any lower and it will result in not enough air, at a low enough speed the heat exchanger overheating and cracking.

    .
    A quick question.....
    Since some of the newer units have lifetime guarantees on the heat exchangers.......would there not be a built in safety feature to prevent damage?

    Key1
    In the land of the blind.....the man with one eye is king....

  5. #18
    Join Date
    Jun 2008
    Location
    Lancaster Pennsylvania
    Posts
    60
    All new furnaces have high limit switches which will keep them from getting dangerously hot. It is the constant heating and cooling (Expanding/ contracting) that will weaken the metal of the heat exchanger. And make it crack or make gromits and other fastners pop.

    _J_

  6. #19
    Join Date
    Apr 2008
    Location
    Princeton, NJ
    Posts
    581
    Quote Originally Posted by cororumrex View Post
    All new furnaces have high limit switches which will keep them from getting dangerously hot. It is the constant heating and cooling (Expanding/ contracting) that will weaken the metal of the heat exchanger. And make it crack or make gromits and other fastners pop.

    _J_
    Understood.
    But since there are "Lifetime" gaurantees in place. I would think the manufacturer would make the heat exchangers extra durable so they wont have to replace it down the road.........and even if one failed, it is gauranteed.
    Key1



    Key1
    In the land of the blind.....the man with one eye is king....

  7. #20
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,770
    Quote Originally Posted by jerrod6 View Post
    We can't do that with gas and electric - it is not like we are under any contract. The utilities will increase the rate and we will pay for it monthly when the bill comes.
    PPL, is offering to allow you to pay the increase spread over time.
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  8. #21
    Join Date
    Dec 2007
    Location
    Southern, CA
    Posts
    520
    The furnace was built to get the best efficiency for its level and it's settings checked at the factory. Nothing you can do will make it better, and you could void your warranty if there's evidence of repeated overheating because of improper operation (fooling with it). Leave that sleeping dog alone.

  9. #22
    Join Date
    Jul 2008
    Location
    Poestenkill, NY
    Posts
    769
    Quote Originally Posted by Coolmaniac View Post
    The furnace was built to get the best efficiency for its level and it's settings checked at the factory. Nothing you can do will make it better, and you could void your warranty if there's evidence of repeated overheating because of improper operation (fooling with it). Leave that sleeping dog alone.
    Many of you are missing the fact that the Trane VS furnaces have adjustable airflow: Low, Medium Low, Normal, and High. The VS motor will "self adjust" to pre-determined cfm levels with varying static pressure up to 0.5 esp., according to the dip switch setting(s).

    While lowering the fan speed will not save any gas, I contest that the settings provided by Trane are not going to violate any warranties if you use them! Each fan speed has a corresponding temp rise across the heat exchanger - it must be assumed that if you can set the fan to low speed - Trane has already determined that the higher temp rise is something they are comfortable with, so to speak.

    I do agree that the higher fan speed (and therefor lower temp rise) is easier on the heat exchanger as far as longevity. I also agree that a higher fan speed will likely have a slight - very slight - advantage in actually delivering the heat you are producing as apposed to sending it up the chimney. But, like I said, Trane provides the settings, they are there to be used if you want.

    All this being said - I see no advantage to lowering the speed if the house is comfortable now. It won't save you any gas.

    With the tall ceilings, you might be wise to run the fan during the day like you are. I doubt it will save any money per-say, but it will help de-stratify the spaces. Although this would happen quickly when you come home and turn the fan on. I suggest experimenting.
    Last edited by larobj63; 09-21-2008 at 07:25 PM.

  10. #23
    Join Date
    Jun 2008
    Location
    Lancaster Pennsylvania
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    60
    Quote Originally Posted by key1cc View Post
    Understood.
    But since there are "Lifetime" gaurantees in place. I would think the manufacturer would make the heat exchangers extra durable so they wont have to replace it down the road.........and even if one failed, it is gauranteed.
    Key1



    Key1
    True, they are also built better then they were even 10 years ago. Most of the lifetime warranties I have seen are limited though to. So they are only good for the purchasing home owner. And I am sure the manufactures know that the average person in America moves every 7 years. I am sure one company started doing it so everyone else had to follow suit.


    Another note to the main topic...

    If you were to perform static pressure tests, it would be more efficient to lower your blower speed if your static was too high... making your overall system more efficient.

    _J_

  11. #24
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    If your ducts are in unconditioned space, lowering your blower speed will make your system less efficient. You'll lose more heat to the unconditioned space.
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  12. #25
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    Jul 2008
    Location
    Poestenkill, NY
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    769
    Quote Originally Posted by beenthere View Post
    If your ducts are in unconditioned space, lowering your blower speed will make your system less efficient. You'll lose more heat to the unconditioned space.
    That's a risky statement. I assume you are considering that the temp of the ductwork will be higher. But, you must also consider that higher airflow will yield more leakage (often considered a percentage of total airflow), therefor less airflow would yield less leakage.

    I'll bet it comes out a wash in practice...

  13. #26
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    Jan 2004
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    Quote Originally Posted by larobj63 View Post
    That's a risky statement. I assume you are considering that the temp of the ductwork will be higher. But, you must also consider that higher airflow will yield more leakage (often considered a percentage of total airflow), therefor less airflow would yield less leakage.

    I'll bet it comes out a wash in practice...
    That would be an indication that more attention should have been given to the duct work, then the blower speed.

    If you have that much leakage at 50° rise. Then sealing the ducts will do far more then just slowing the blower down to a 60° rise.
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