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  1. #1
    Join Date
    Mar 2005
    Location
    Indianapolis, IN
    Posts
    241

    Can this system moded to dual fuel

    Condencer: 591B 3T
    Coil: CK5A048 4T
    Furnace: 311JAV110-048 4T 110K input BTUs ( 89K Output)

    I would like to have 652A or even 656P.

    Manual J for the house:
    Heat loss: 82K BTUH
    gain: 36K BTUH

    Just checking before, so I would not waste dealers & my time.

    I have old ARI sheet:
    633G042 - CK5A048 - 315JAV - Cool 38K - Heat 42K
    633G048 - CK5A048 - 355JAV - Cool 42K - Heat 45K

    Neither comes close....





  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,467
    Size the HP to the cooling needs so the 042 is about perfect.

  3. #3
    Join Date
    Mar 2004
    Posts
    1,042
    Yeah, no problem.

    Except in extreme cold climates, you size a heat pump to cooling load, not heating load. That goes regardless of your backup heat source. As always with dual fuel, the heat pump will be enough to keep up in milder temperatures, and when it can't keep up, the system will switch over to fossil fuel heat. No problem.

    What is your indoor design temp? Manual J tells you how much cooling the structure needs. ARI tells you how much cooling the equipment will do with an indoor temp of 80. Unless you want 80 degrees inside, though, you still need to derate the equipment's cooling capacity to account for wanting a lower indoor temp.

    For four tons and 75 degrees you derate by 6680 BTU, so the 048 is what you'd need if you want 75 degrees. The 042's cooling output of 38k won't quite get you to 78 degrees, which a lot of people would grumble about.

    (835 BTU * (number-of-degrees-below-80) * (system cfm) /1000)



    [Edited by wyounger on 02-02-2006 at 04:17 PM]

  4. #4
    Join Date
    Mar 2005
    Location
    Indianapolis, IN
    Posts
    241
    Thanks,

    Should I be concern that with I have 311JAV and not 315JAV, or 355MAV

    Location:
    Indianapolis IN

    Current 3T A/C unit runs 90 - 95% of the time. It takes 50min to drop house temperature by 1F.

    [Edited by browntigerus on 02-02-2006 at 07:18 PM]

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,467
    No reason your current furnace can't be used. We normally use single stage in our dual fuel applications.

    What temps to drop 1 degree inside? On a 90+ day, dropping 1 degree in 50 minutes is just fine, especially if cool already inside. My stat drops from 70 to 68 for sleeping. Can take HOURS on a steamy day. But if I were dropping 77 to 75 or if it were 70 out, should take a fraction of that.

    Indy is a perfect place for dual fuel. I put mine in 10 years ago not intending to heat with the heat pump but IPL had a huge rebate back then for dual fuel installations. This winter, the furnace was on for 4 days, when we had that 7" snow. Since then, all pump.

  6. #6
    Join Date
    May 2005
    Posts
    44
    Originally posted by BaldLoonie
    No reason your current furnace can't be used. We normally use single stage in our dual fuel applications.

    What temps to drop 1 degree inside? On a 90+ day, dropping 1 degree in 50 minutes is just fine, especially if cool already inside. My stat drops from 70 to 68 for sleeping. Can take HOURS on a steamy day. But if I were dropping 77 to 75 or if it were 70 out, should take a fraction of that.

    Indy is a perfect place for dual fuel. I put mine in 10 years ago not intending to heat with the heat pump but IPL had a huge rebate back then for dual fuel installations. This winter, the furnace was on for 4 days, when we had that 7" snow. Since then, all pump.
    Hey John,

    Can I contact you outside of this forum about this change? I understand there is $200 rebate from Cinergy for Installing 14SEER HP. Don't know if this worth going for.

    I would understand, if you don't want this.

    My house located & 113th street 10 min 96" Meijer.


    Thanks
    Brian

    [Edited by shifrbv on 02-04-2006 at 10:11 AM]

  7. #7
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,467
    My e-mail is in my profile and from my site you can find my employer's site. We'd love to talk to you about it. We don't sell Bryant heat pumps but have other alternatives. 14 SEER is hard to get sometimes without a variable speed furnace. It's also getting hard to get equipment at the moment too as vendors are out of 10s but not getting in 13s. We can get 13 SEER American-Standard units now.

  8. #8
    Join Date
    Dec 2004
    Location
    Derby City
    Posts
    3,964
    It's probably worth pointing out that ANY fossil fuel system, whether oil, natural gas, lp gas, or wood fired, for that matter, (yep wood-fired) can be utilized with ANY heat pump system as a dual fuel system. Back in the '70's when there was a moratorium on natural gas service, virtually everything went to heat pump. Well, in the early '80s when they allowed gas service again (shortage, yeah, right...try market manipulation) every body and their brother clamored to convert the indoor equipment to gas fired. In a lot of the cases, the heat pump was kept and 'locked' into the cooling only mode so it could be used as central air conditioning. Then, when the time came to replace the outdoor unit, the same folks would replace the heat pump with a high-efficiency central air conditioning system. What should have occurred is KEEPING that heat pump from day one and with the new furnace, use it as a dual fuel system. And when the time came to replace the heat pump, then a high efficiency heat pump should have gone in. Dual fuel is not a new concept by any means. It was just as efficient then as it is now. The only difference is the higher efficiency now, and the higher natural gas cost. The combination of the two make dual fuel the best way to go in a forced air application; at least here.

    Equipment does not have to have a minimum efficiency rating to be used in a dual fuel application. For example, years ago, a 60% efficient furnace could have been used with an 8 seer heat pump system and a dual fuel arrangement put in place. Today, we recommend 90%+ efficiency on the furnace and 14+ seer for the heat pump.
    Everyone has a purpose in life..........even if it's to be a bad example.

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