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  1. #14
    Join Date
    Jul 2002
    Location
    Yuma, AZ
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    2,361
    Quote Originally Posted by tedkidd View Post
    ...Besides some wonderful features for comfort and control, communicating takes the emergency brake off the furnace. Most furnaces have emergency brakes pulled up 1/2 way, making them much less efficient than their ratings. Some due to gross oversizing, other improper design issues, or bad installation...
    Tell me more about the "emergency brake" idea. I never heard this metaphor before.
    "I have never let my schooling interfere with my education."
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  2. #15
    Join Date
    Feb 2009
    Location
    Portland OR
    Posts
    1,951
    Quote Originally Posted by lynn comstock View Post
    Tell me more about the "emergency brake" idea. I never heard this metaphor before.
    Maybe he is referring to outdoor temperature sensors instead of communicating EEVs. The emergency brake could be a gas furnace kicking in for backup at 35 degrees when the heat pump can actually run down to 25 degrees. Just a thought until he chimes in.
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  3. #16
    Join Date
    Aug 2011
    Posts
    11
    Quote Originally Posted by SkyHeating View Post
    There are two reasons I don't install many XC80 furnaces... First my distributor in Portland sucks and has to factory order them because I am the only company in my 4 state area it seems that installs an XC80 and XL20i communicating system. The videos I showed were of the XC95M simply because at that time the rebate was not on the XC80 furnace so it was not cost effective. I just finished an XL20i and XV80 with XL950 stat this week and am putting in another XC80 and XL20i with a 950 next week. The customer with the XC80 didn't mind waiting a month for the furnace.

    Can we do an install in TN next week... Yes just pay the airfare for my employees I assure you they are smarter than I am ;-)
    I would prefer the XC95M myself for the better efficiency but the company I'm talking to now refuses to put one in attic. Is that a sign of a good installer? I've heard about the condensation and freezing issues with the higher efficiency furnaces, but I have no idea if that's a legitimate concern or not. Thanks!

  4. #17
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by jkberry View Post
    I would prefer the XC95M myself for the better efficiency but the company I'm talking to now refuses to put one in attic. Is that a sign of a good installer? I've heard about the condensation and freezing issues with the higher efficiency furnaces, but I have no idea if that's a legitimate concern or not. Thanks!

    There can be issues with installing any condensing furnace in an attic. The condensate created by extracting the last 17% of the energy from the gas fire, creates condensation. This water can freeze in an a cold vented attic.

    I think sometimes you can insulated and heat trace some of the condensate lines and drains to keep them from freezing.

    I know my HVAC contractor was suprised to find one in my attic on the new house I bought. It was however unvented and likely stayed above freezing most of the winter. I've since spray foamed the roof deck so it will be nice and warm all winter long thsi year.


    I'll let some pros elaborate further.

  5. #18
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,702
    Quote Originally Posted by lynn comstock View Post
    Tell me more about the "emergency brake" idea. I never heard this metaphor before.
    When you drive your car with the e brake on you don't get the rated or expected efficiency from the vehicle.

    The first few minutes of operation of equipment is tremendously inefficient. You get incomplete combustion, you arent condensing, everything is getting to design temperatures. Just like cold start on your car, the first few miles get terrible mileage. Like driving with the brakes on.

    Heating up or cooling down ductwork is inefficient, until the duct work temperature reaches steady temperature, energy delivery to rooms is not optimal. If you don't deliver even comfort to rooms, for a lot of reasons (including occupant thermostat interaction) it is like driving with the brakes on.

    When equipment shuts off, energy in ductwork is lost rather than delivered to rooms being conditioned, like driving with the brakes on.

    Oversized equipment shuts off A LOT

    Two guys are driving across country (or across the heating season). One guy gets off at every exit, the other guy never exits. "Mr exits a lot" has to drive hard to match "mr never exits" leisurly pace. They've got the same distance to run, but who uses more fuel?

    People report to me; "I installed this high efficiency furnace a few years ago and my energy bill didn't go down at all." I can only conclude it is not running at high efficiency if they aren't saving, must be running with an emergency brake on somewhere.

    Installing load matching equipment that gently delivers energy replenishment to meet losses, and runs as near to continuously as possible has netted me really surprising energy savings. It's counter intuitive, but I want equipment to RUN, never shutting off. Anything else is like driving with the brakes on.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  6. #19
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    It also worth noting that a 95% furnace is still only going to extract 15% more energy than a 80% furnace. Its' not like going from a AC unit with a COP of 2.5 to 3.5.

    So if you normally use 400 Therms in a winter with a 80% furnace, you'll need 336 Therms with a 95% unit. That's only $75 all season or probably only $30 on a $200 bill for Jan.

    Also consider that if they are going to 2 stage, they might be getting more even heating throughout their home. Rooms that get underconditioned, save you money (but at the expense of comfort).

    My electric bill in August only declined a very small amount form July. One of hte reasons I beleive is that I made ductwork corrections and 2 rooms are now 2-3 dergees cooler than before. That means I'm ultimately using more cooling capacity.

  7. #20
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,702
    Quote Originally Posted by motoguy128 View Post
    It also worth noting that a 95% furnace is still only going to extract 15% more energy than a 80% furnace.
    This is not true! This is really bad information that we need to stop perpetuating!!

    Again, I've gone to homes, seen the energy bills, and can CONFIRM that what people say about the crappy 95% install they got last year not impacting their bill ONE WHIT.

    I've replaced 80%ers with 95% and see the TOTAL energy consumption go down 28%. Total, not just hvac. NO ENVELOPE MEASURES, JUST EQUIPMENT!

    While energy efficiency is math, it's not first grade math. You don't look at efficiency ratings and calculate your savings. You need software to do it, and even that isn't dead nuts.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  8. #21
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    I didn't say there weren't other factors when replacing any furnace that will impact actual savings. But if installed correctly, and wiht all other vairable isolated, one furance converts approx 80% of the available energy to heat, the other 95%. If there are other factors... well then it's all out the window. If you save more, its' because of other indirect factors. maybe the old furance was less than 80% or more than 80%. Maybe the new furnace heat a home more evenly so now you use mor energy than before.

    But hwne you throw crappy installs or equipment that's not working properly or do other things like fix air leaks and correct ductwork. Well Duh... of coruse you won;t see exaclty 15%.

    My point was that someone might easily spend $$$$ more for a condensing furnace over a new 80% furnace and apples to apples (lets assume you fix those "other" things irregardless of whichever furnace you choose) you are only going to save that incremental 15%. Not the 20, 30 or 40% maybe some folks are magically expecting.

    Now if your'e also talking electrical consumption of the blower motor and inducer as well... now thats something different entirely. I believe we were just talking gas bills.

  9. #22
    Join Date
    Jul 2008
    Location
    Rochester NY
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    4,702
    Quote Originally Posted by motoguy128 View Post
    But hwne you throw crappy installs or equipment that's not working properly or do other things like fix air leaks and correct ductwork. Well Duh... of coruse you won;t see exaclty 15%.

    My point was that someone might easily spend $$$$ more for a condensing furnace over a new 80% furnace and apples to apples (lets assume you fix those "other" things irregardless of whichever furnace you choose) you are only going to save that incremental 15%. Not the 20, 30 or 40% maybe some folks are magically expecting.

    Now if your'e also talking electrical consumption of the blower motor and inducer as well... now thats something different entirely. I believe we were just talking gas bills.
    Everything is interconnected, you can't parse out the furnace from the rest of the house.

    What I'm saying is, without a lot of diagnostics you don't know whether you have a crappy install now, or at replacement, so using "in laboratory conditions you will save X" as a decision assisting piece of information is pointless.

    The only way to KNOW these things is measure and design, not plop in. If you GUESS it's like playing roulette. We call that the Poke-N-Hope method of disease treatment. The way to start building a basis for KNOWING is to have an energy audit. Existing conditions need to be measured, defined, and understood.

    Assuming any existing furnace IS properly installed, or that the replacement WILL BE, without following this critical path is a crap shoot. Telling people what they can expect to save N% if they replace furnace efficiency x with furnace efficiency y is a huge oversimplification and public disservice. That leads people to believe equipment replacement is a plug n play product rather than an engineered solution.

    If it were plug n play, there wouldn't be so many unhappy homeowners here reporting nightmare results from plug n play installs.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  10. #23
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,058
    Don't stop now. The more customers become aware of our industry and what they should expect the better our industry will get.

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