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  1. #1

    One system or two...

    I've received a few quotes over the last few weeks and need advice on which direction to go.

    I have a 3400 sf ranch that I'm expanding to 3800 sf in Oakland County, Michigan.

    The previous owners put two 135,000 BTU furnaces and two 3 ton A/C units in. I have become very aware that this is overkill and have no idea why they went so big so long ago.

    A few of the quotes recommend 1 80,000 BTU furnace and 1 60,000 BTU furnace along with two new 3-ton A/C units. One is recommending a single 135,000 BTU unit along with one A/C unit. Each quote has options for 2 stage and/or heat pump.

    Understanding that this is a ranch house in SE Michigan, what would you do in my situation? Any other advice?

    Thank you...

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,380
    Ask them what their Manual J comes up with for heat and cool? Are these furnaces twinned meaning they sit side by side and share the same duct system?

  3. #3
    I'll ask them about the Manual J. They sit side by side but have separate duct systems. The house was expanded several times through the last 40 years...

  4. #4
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Yup, manual J load calc using the correct desing temperatures. Its' not as cold or nearly as warm and most people think in SE Michigan when you deisng equipment. Very easy to oversize and AC and furnace. IF your house was very well insulated and fairly tight (well constructed... many new tract homes are not, depsite what homeowners assume), it might only need as little as 100k BTU's for the entire house and with good shade trees, only 2.5-3 tons total for cooling.

    You might be best going with a single systme wiht multiple zones if hte ductwork can be isolated without a lot of zone dampers. FOr what you save with 1 system, you can get premium 2 stage equipment and size for zoning. When zoning, because solar heat gain vaires and occupancy varies at different times of hte day, you can oftne undersize slightly with a zone system at least in AC. You might only need a 4 ton unit on a zone system, if well insulated even as small as 3 tons. DEpending on a load calculation, you might need as little as 80-100k BTU's for the whole house.

    I think winter design is 4F and summer 87F for Pontiac, MI. My family lives in Northville. I give them a hard time because SE Iowa design conditions are 0F and 92F with higher humidity. Yes, it's statistically colder here despite being furhter south. The lakes and resulting cloud cover and precipitation combined with urban sprawl (higher concrete to tree ratio) keep that part of Michigan warmer in winter or at least the coldest days are not as cold or happen less often. Winter is still longer. But hte length of the season and the amount of snow you get is irrelevant to sizing. Atlanta, Georigia has about the same summer design as Des Moines, Iowa.

  5. #5
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,826
    I agree with motoguy128. Full Man 'J' will tell the tale of actual equipment size needed. I'd recommend against considering any company that doesn't insist on doing a full room-by-room Manual 'J', followed by a good assessment of the existing duct systems to be sure they're not too big for the proposed replacement equipment. If zoning, I'd highly recommend 2-stage equipment for both heating and cooling or better yet, modulating furnace with 2-stage AC. Equipment is being pushed, when properly sized, to the limit on efficiency, or at least gas furnaces are. Comfort should therefore be the leading benefit. Looooooooong heat cycles is the goal.
    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!

  6. #6
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,380
    I have a cousin in Northville. Was up there weekend before last. I can give the OP the name of a good contractor that just did his new house if intersted.

  7. #7
    This is all great information. Gives me something to ask intelligent questions. Thanks very much... I'll check back in as this progresses.

    BaldLoonie - please send the contractor info along. I've got a couple that came highly recommended already but am open to a third. Note that this means great customer service/warranty and reasonable pricing to me. It's not always the cheapest price.

  8. #8
    One of the contractors is proposing two different manufacturers for the same type of system. One is York and the other is Lennox Signature. The York is 120,000 BTU Modulating Furnace w/ 17 SEER 2 stage A/C. The Dave Lennox is 135,000 BTU Modulating w XP21 16.7 SEER (9.7) Heat Pump for cooling. Both come with 10 year warranty on parts and labor.

  9. #9
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    So one is proposing dual fuel. Michigan does have lower electric rates I believe, and a long winter, but much of the time it's moderate with temps over 35F. It will hedge you against increases in Natural gas in the future. It might be worth considering. I really liked my dual fuel system at my last house, other than it being oversized.

    You might even consider finding a Carrier dealer and looking at a Carrier Greenspeed hybrid system. If you were to zone your house, it's about the best residential system you can get.

  10. #10
    Does anyone know about the quality of York? I believe they are made by JC but I couldn't find out much about them on the web.

  11. #11
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,380
    I sure don't see super SEER A/Cs up there. Makes the dealer rich but can't fathom a ROI with Michigan summer and good electric rates. I steered my cousin from a 16 SEER to a 14 SEER and he saved a bundle. He never would have gotten said bundle paid back in electric savings over the life of the unit.

    He used: http://www.slasorheating.com/ and they did a nice job.

  12. #12
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    5,658
    Quote Originally Posted by sbarone View Post
    Does anyone know about the quality of York? I believe they are made by JC but I couldn't find out much about them on the web.
    www.york.com. JCI is the parenthttp company. York is my company's "premium" brand. We have been york dealers since 1982. When JCI took over York they brought all manufacturing back to the USA and their quality control is top notch. I like the LX series over the affinity personally, the TM9V furnace is a great furnace.

  13. #13
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    I've been told that the Affinity is nearly as or more expensive and Carrier Infinity, without as many features other than a modulating furnace. LX is definitly the best bargin. That's what I'll rpobably install for my downstairs when it bites the dust.

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