dolphin
New Member
Posts:37
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| 05 Feb 2010 05:47 PM |
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I am wondering if anyone can recommend a size generator for a home that will have a 6 ton geothermal unit for the main and basement floors and a 4 ton unit for the second floor. I would expect that during a power outage I would only care if the 6 ton unit was powered. Obviously I understand that other appliances/conveniences would affect the unit's size, but I am trying to understand what a good starting point would be. It seems that the electricians have a good idea how to size a unit based on appliances and other conveniences, but the introduction of geothermal causes them to ... hesitate. Thanks for any advice. |
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geome
Advanced Member
Posts:555
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| 05 Feb 2010 05:53 PM |
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If your unit is a Water Furnace, check out their IntelliStart (soft start). It may help keep the size of the generator you need smaller instead of larger. |
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| WF Envision NDV038 (packaged) & NDZ026 (split), one 3000' 4 pipe closed horizontal ground loop, Prestige thermostats, desuperheaters, 85 gal. Marathon. |
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jonr
Veteran Member
Posts:1042
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| 05 Feb 2010 06:02 PM |
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I agree. Starting current is the big problem. An electric motor can require 6x as much current to start as to run. But having a generator 6x larger than needed is expensive and not good for generator efficiency.
Perhaps a small propane boiler for electric outages would be easier.
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geotek
Basic Member
Posts:139
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| 05 Feb 2010 06:16 PM |
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Locked rotor amps an a six ton unit is about 150. Intellistart would cut that over 60%.
You don't have to own a WF to use it as long as the compressor is a scroll.
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engineer
Veteran Member
Posts:1734
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| 05 Feb 2010 06:32 PM |
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Intellistart sounds like a good move. Unfortunately I can't vouch for it first hand.
I start an 038 Envision easily with a 25 KW Generac 1800 rpm Guardian, but that's a big pricey generator. They have an 18 KW 1800 rpm model that probably would have sufficed for me.
Intellistart might allow an 18 kw to handle 6 ton, but I can't say for sure.
I will say that the difference between 1800 rpm gensets and the cheaper 3600 rpm models is like night and day.
There have been occasions where we did not observe the transition to generator and were unaware of being on generator power until realizing that the neighbors' houses were dark |
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Curt Kinder
Absent data, you have only an opinion.
No thing done well is as simple as it seems
www.hoviscustombuilders.com
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jonr
Veteran Member
Posts:1042
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| 05 Feb 2010 07:02 PM |
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I am going to guess that the Intellistart is a solid state reduced voltage starter. Perhaps like a Square D LH4N125LU7.
Soft start might even make your motor last longer.
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geotek
Basic Member
Posts:139
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| 06 Feb 2010 07:13 AM |
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I am going to guess that the Intellistart is a solid state reduced voltage starter. Perhaps like a Square D LH4N125LU7.
It is a soft start device built for single phase compressors up to six ton, that's as big as they get in single phase. It is solid state device containing a relay and start capacitor unlike the Square D.
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Geothermalman
New Member
Posts:56
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| 06 Feb 2010 11:42 AM |
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Anyone using this Intellistart?? |
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G.O. Joe
New Member
Posts:60
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| 07 Feb 2010 03:50 AM |
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Yes.
I don't have the instruments to verify amp draw at start up and I don't know how it works.
But when it starts-
-you hear the contactor close
-a fraction of a second passes
-you hear the compressor cranking slowly for a fraction of a second
-then normal run
All the while with no dimming lights and no loud bang at startup.
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