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  1. #27
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,934
    To stage 10kw, someone would have to redo the controls on the heat kit. Usually it would take 15kw and up to stage.

    Jim, Rheem hasn't replaced demand with time in ages. That was the way they replaced the Ranco DD1 board in the early 90s. Now it is 100% demand and replaced that way. I don't think ICP has been demand in some time either. They used the DDL board Rheem used for a short time. That board was unreliable. They went back to timer, Rheem found a different vendor with a more reliable board. I assume York has a lot of demand boards still. Lennox/Allied in select high end units. Actually Allied in the 16 SEER but not the 18 SEER. I think they needed it to get a HSPF target. Obviously Trane has been demand forever. Oh, and Nordyne on high end too. Still want to replace my time board with the board out of the FT4BF. Looks like it will work!

  2. #28
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,708
    Quote Originally Posted by kangaroogod View Post
    Given his choices of propane or electric and using the rates provided

    balance point is 30 degrees

    all propane below 30

    with the heat pump he will be able to run the unit down to the design temp of 15 degrees with a cop of 2.75 (21200 but output) and supplement the balance of 12800 btus at essentially the same cost of propane.

    The big difference is that he will only need to heat 12800 btus at $3.22 and the 21200 btus at a bonus of $1.17 a therm instead of 34000 Btus at $3.13........If my math is correct......

    $1.09 per hour on propane and $.67 an hour on heatpump with electric backup. No brainier for me. Ass-u-me??? The verdict is still out
    That's what I was thinking! Propane and straight electric basically =. Depending upon common temperatures, that propane might run a lot, and the resistance not much at all.

    And if it's like my mom's 2 stage Infinity, the pump just might just heat the house down to 7f NEVER requiring the backup.

    *She's on NG. The reason we know it heats the house to 7f, they accidentally locked the furnace out at install. She called me on a 7f night wondering if there was a problem because the register air "felt a little cool". She wasn't terribly concerned "because the house was still 70", but thought she better check with me JIC.
    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.

  3. #29
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,778
    Quote Originally Posted by BaldLoonie View Post
    To stage 10kw, someone would have to redo the controls on the heat kit. Usually it would take 15kw and up to stage.

    Jim, Rheem hasn't replaced demand with time in ages. That was the way they replaced the Ranco DD1 board in the early 90s. Now it is 100% demand and replaced that way. I don't think ICP has been demand in some time either. They used the DDL board Rheem used for a short time. That board was unreliable. They went back to timer, Rheem found a different vendor with a more reliable board. I assume York has a lot of demand boards still. Lennox/Allied in select high end units. Actually Allied in the 16 SEER but not the 18 SEER. I think they needed it to get a HSPF target. Obviously Trane has been demand forever. Oh, and Nordyne on high end too. Still want to replace my time board with the board out of the FT4BF. Looks like it will work!
    The local supply house must have had an old T&T in stock then. I did one last winter, and they gave me a T&T instead of on demand.

    Haven't installed a new ICP for a few years now, didn't realize they changed.

    Lower end yorks are still T&T.
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