Electrical Efficiency - Carreir vs. Rheem - Page 2
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  1. #14
    Join Date
    Apr 2004
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    The bonus is the Mod has a lifetime replacement warranty to the original purchaser. If the HX ever fails, they will provide a replacement furnace, not just a HX. If you plan on living there, it could be the last furnace you ever purchase.

  2. #15
    Join Date
    Mar 2004
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    1,042
    *In most cases* I would agree, a modulating furnace would cycle much less than a regular or two stage furnace, and thus do better about achieving the rated efficiency.

    Note that in this case, though, the minimum (40%) output from the Rheem is only 2,500 BTU less than the Carrier's low fire output. This is the case because we are comparing a Rheem with a 60k input and a Carrier with a 40k input. So in this case there will be little difference in how much cycling goes on under low heat loss situations.

    In more moderate conditions, the Carrier will go back and forth from low to high a lot, and the Rheem will modulate smoothly to meet demand. In high heat loss situations, the Carrier will spend most of its time on high, and the Rheem will just keep on modulating.

    I would call the electrical consumption too close to worry about. I would personally pick the Rheem, though. The main reason is that when a big winter storm comes along and knocks out the power, I don't want it to take a week to heat the house up again when the power is finally restored. The Carrier, in this application, would be cutting it so close on capacity that it would be really hard pressed to make up the lost ground.

  3. #16
    Originally posted by tostaos
    more influence on the efficiency of any equipment has the installer, right there is 50% of the efficiency. More important than the different brands is your contractor.
    Going off topic a bit...

    Really? Why?

    To be honest, I've been a bit surprised how 'protective' this industry about it's installers. Heck, this board doesn't even allow people to talk about DIY installs. It seems to me that HVAC is the ONLY trade which is so protective about it's secret knowledge. In looking through this forum, I've seen many posts from 'Pro' members that reinforce this postion, but I've yet to see a single fact which makes me understand this.

    So let's have the facts, not just rhetoric. Why, indeed, does the right contractor make such a huge difference on efficiency of a furnace? How can I, as a lowly, but well researched homeowner, tell the difference between a good or bad contractor?

    Peter Straub

  4. #17
    Join Date
    Nov 2005
    Location
    Kansas
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    1. probably 50% of all installs of “Pro’s” have flaws, so do you think the DIY will do better?
    2. You have to know the code (always somebody got killed before it got to be code).
    3. Experiences of the “Pro’s” with DIY installations tells them that HVAC is not a very good field to do DIY, it’s just plain dangerous.
    4. When you don’t install the equipment correctly, you will reduce the life expectancy of it and possibly your own. Your best equipment will not save you money, when it fails after a short time and you have to replace it. There is the big efficiency difference.
    5. For a furnace install, you have to have the knowledge of combustion, venting, ventilation… for and AC install there is even more involved.
    6. For an AC install you have to have a license to handle refrigerants. You need a lot of know how, you don’t charge the unit correctly, you will loose efficiency, you will have higher cost to run the unit and the shorter life expectancy. You will also need expensive equipment.

    Of course you can DIY, just go and take the college classes necessary at your local community college. And when you like it, why do you not just join our profession, there are not enough qualified tradesman as it is.

    Good or bad contractor is not as easy to figure out. There are some things to look for like: do they have any license, insurance, do they make load calculations, do they look professional, do they take the time to explain to you your options or do they just want the quick sell, do they even know much about what they are doing…

  5. #18
    Join Date
    Oct 2005
    Posts
    88
    1. probably 50% of all installs of “Pro’s” have flaws, so do you think the DIY will do better?
    Interesting question. Double-edged, a bit. Seems to me most of the weird things I've seen done by pros fall in the "I've been doing this so long I don't need to bother with those pesky calculations or tests or looking things up in tables" and "I have to do five more of these this week, not my house, I don't have to live in it, can't afford to take the time" categories.
    You can see things done by pros that would not be done by anyone who simply sat down and read the installation manual that came with the equipment.

    With DIYs there's going to be some shakeout between complete klutzes, and people who will think "hmm, I've never done this before, it is my house and I do have to live in it, and I'm going to be very careful to understand this manual cover to cover, find the codes in the library, and not cut any corners." In those cases, as nice as it would be to just say it's impossible for a DIY to do a better job than a pro, I'm not quite so sure. In any case, the trend is toward equipment and tools being more widely available, so the DIYs aren't going to go away; the pros who want to protect their value are going to have to do so by doing demonstrably better work, not just by trying to lock the barn door--which I think was the earlier poster's point.

  6. #19
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    Originally posted by chapmanf
    1. probably 50% of all installs of “Pro’s” have flaws, so do you think the DIY will do better?
    Interesting question. Double-edged, a bit. Seems to me most of the weird things I've seen done by pros fall in the "I've been doing this so long I don't need to bother with those pesky calculations or tests or looking things up in tables" and "I have to do five more of these this week, not my house, I don't have to live in it, can't afford to take the time" categories.
    You can see things done by pros that would not be done by anyone who simply sat down and read the installation manual that came with the equipment.

    Thats how you tell the difference between a good contractor, and a may be not so good contractor.

    When he's at your house to do the estimate, if he's says things like I don't need to use manual j, or look it up in the manual, BINGO, he's most likely not what your looking for in a contractor.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #20
    OK, Back on Topic... I found some interesting information about electrical efficiency of furnaces... Clearly, this is well known to the pro's out there, but this is posted here as great info for the average home owner.

    Stumbled across this site:
    http://www.aceee.org/consumerguide/topfurn.htm

    And downloaded this document...
    http://www.cee1.org/gas/gs-ht/gas_heat_specs.pdf

    Learned about Air Handling Electrical Use Performance level. basically, they recommend a furnace whose annual electrical use is less than 2% of it's annual heating fuel use. Makes sense. But that was my original question... what's the annual electrical use? Alas, a ling in the above PDF takes you to

    http://www.gamanet.org

    Where you can look up all sorts of stats on efficiency of all sorts of things. I search the carrier, I search the Rheem, and I find this...

    Rheem Ef (annual Fuel Used) = 48 MMBTU/yr
    Eae (annual Electricity used) = 231 kWhr/yr
    PE (I think this is Peak Energy, but not sure) = 138W

    Carrier Ef = 32.4 MMBTU/yr
    Ear = 105 kWhr/yr
    PE = 23W

    Run these numbers through the Air Handling Electrical Use Performance level equations, and the Rheem is 1.6%, well below the 2% recommnedation, but the Carrier is 1.1%, with total electrical use only 45% of the Rheem. That's a significant difference for someone paying CAD$10/watt for solar panels.

    So, it seems I was able to answer my own question! (although, the whole modulating vs. 2 stage remains an outstanding question for me, and my final furnace selection is still undecided) I hope this information is helpful for others in the future.

    Peter Straub

  8. #21
    OK, one last thought...

    I have the last 5 years of gas bills in a spreadsheet. Found this site... http://www.cmhc-schl.gc.ca/en/burema...ose/ce_048.cfm

    Tells you how to calculate heat loss through utility bills. With 5 years of data, I figured I would get a good sampling. Went to Env. Can. web site (www.ec.gc.ca) and looked up Heating Degree Days for the airport 15 mins from my house. Took the average fuel consumed during the 4 coldest months (Nov-Feb), and came up with .33 m^3/HDD gas for my house. That's 16,000 BTU for my home. Adding a 40% over sizing, plus 5% for altitude, and I need a 23,666 BTU Furnace to heat my house on a -35C (53HDD) day.

    The minimum output of the Rheem is 19,200, while the low speed on the Carrier is 22,600BTU. Both would easily be able to heat my home on their lowest settings... and that's BEFORE any of my upgrades, on the coldest day of the year.

    Still doesn't help me choose a furnace, though.

    I was also surprised to see that my energuide evaluation estimated my total energy use at 182GJ/year, with an 'after improvements' estimate of 108GJ/yr. I know for a fact from my 5 years of bills that I am currently at 99 GJ/yr before any upgrades. Hmmm....

    Peter Straub

  9. #22
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    Apr 2004
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    I'm afraid the electrical side of it is a moot point, but if you feel a few pennies make that big of a difference when it comes to the monthly cost of being comfortable then by all means, rack your brains.


  10. #23
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    Apr 2004
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    Your figures are flawed also..

    The amounf gas burned will be the same between the two units with only a small difference because of the different efficiencies, yet you have the Carrier only using 32.4 mmbtuh and the Rheem using 48. Even if the carrier were 3% more efficient, those numbers are much further than that apart. The amount of heat required is the same regardless of the furnace.

    Next 23w Peak energy usage? Someone blew some serious smoke up the chimney there. Both furnaces have the potential to use more than that.

    I'm afraid you out thought yourself. Burn free wood, it costs even less.

  11. #24
    You're right! I didn't apply my freshly calculated Air Handling Electrical Use Performance Level for these two furnaces through the actual heating use for my home!

    OK, assuming 1.1%/1.6% for the Carrier/Rheem, my proven heating load from my 5 years of energy bills, avg. of 1500 Heating Degree Days for my Area from env. Canada, and that both furnaces will run at rated efficiency most of the time...

    The Rheem will use 278 kWhr per season (Oct 1 to April 30), the Carrier 194 kWhr. The savings is 77kg Greenhouse Gases each year. Or, another way, about 80 watts fewer solar panels I need by going to the Carrier, which is about $800 (at CAD$10/watt for panels).

    Thanks Everyone! That's EXACTLY the information I was trying to find!

    Peter Straub

  12. #25
    Join Date
    Mar 2005
    Location
    Fargo, ND
    Posts
    86
    Originally posted by behemoth60
    Wow! Great information.



    I guess all in all, I am leaning towards the Rheem. The modulating technology does seem like a significant move forward in the HVAC world.

    Thanks for all the excellent info. Very good stuff.

    Peter Straub
    If it helps I installed a Ruud, (Rheem), 60K BTU mod furnace in my home this fall. My old furnace was an oversised 80K BTU York 92% that was running fine. My gas usage is 40% less than it was a year ago! No other changes in life style to credit the savings to. With my old furnace I ran the blower anbout 6 hours a day, the Ruud hac been running 24/7 since the install. My electric usage has jumped so I think the blower will be set back to the old running times.

  13. #26
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    Nov 2005
    Location
    Kansas
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    If it helps I installed a Ruud, (Rheem), 60K BTU mod furnace in my home this fall. My old furnace was an oversised 80K BTU York 92% that was running fine. My gas usage is 40% less than it was a year ago! No other changes in life style to credit the savings to. With my old furnace I ran the blower anbout 6 hours a day, the Ruud hac been running 24/7 since the install. My electric usage has jumped so I think the blower will be set back to the old running times. [/B][/QUOTE]

    If you have a 60K BTU or a 120K BTU furnace of the same efficiency, they will both use close to the same amount of gas per 1000 BTU load, the larger one will just heat up the house quicker. Just keep that in mind.

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