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Prius Heating and Cooling

Discussion in 'Gen 2 Prius Main Forum' started by m4prius, Mar 29, 2004.

  1. m4prius

    m4prius New Member

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    Is the Prius Heating/Cooling system "electric heat pump" based???

    I found this information regarding the Prius system "For the Toyota Prius hybrid car, we developed an ultraefficient air-conditioning system that consumes minimal power. Our new subcool condenser and scroll compressor, equipped with oil separators, allow the air-conditioning system to run on 30% less power than conventional systems. And a two-layer flow heating, ventilating, air conditioning (HVAC) unit saves energy by recirculating heat already in the cabin. "

    I assume that you can get heat during winter start-up without the ICE running...thus, heating must come from a electric heat pump device (i.e., scroll compressor).

    Mike
     
    #1 m4prius, Mar 29, 2004
  2. glscheil1

    glscheil1 New Member

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    "

    I assume that you can get heat during winter start-up without the ICE running...thus, heating must come from a electric heat pump device (i.e., scroll compressor).

    Mike[/quote]

    Nope. The heat comes from the sealed vacuum cannister. It saves hot water for this purpose and also to heat up the ICE.
     
    #2 glscheil1, Mar 29, 2004
  3. m4prius

    m4prius New Member

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    Did another search on Prius heating on the web and found..."Automatic air conditioning
    The automatic air conditioning with electric inverter-compressor is completely powered by the drive battery. As well as allowing heating, cooling and dehumidifying even when the engine is stopped, the highly responsive and effective compressor control, based on temperature and humidity sensors, improves fuel economy during use of the air conditioner and contributes to throat and skin comfort by preventing the cabin from becoming overly dry."

    This implies that the electric compressor which operates from the battery only allows heating, cooling and dehumidifying. I believe the vaccum canister provides pre-heat to the engine for low emmissions during engine start and is not used to heat the vehicle cabin. Please correct me if wrong.

    Mike
     
    #3 m4prius, Mar 29, 2004
  4. stuhillman2004

    stuhillman2004 New Member

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    It does both. On cold days, the vacuum flask with the preheat water keeps startup pollution low (no choke). As a bonus, it provides cabin heating within a few hundred yards of driving away. Remember the Prius phiosophy is to reduce pollution not provide great mileage. The great mileage is just a bonus of the PZEV. I think it's one of the most fascinating parts of the Prius design that attacking the pollution at the source also gives bonuses that convential cars never dreamed of. There is a lesson there somewhere!
     
    #4 stuhillman2004, Mar 29, 2004
  5. Frank Hudon

    Frank Hudon Senior Member

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    the thermous provides a hot flush of coolant to the cylinder head and at the same time there is a rotating valve that blocks the flow of coolant to the heater core so to provide heat in the cabin there are 2 electric heating elements in the heater ducts to provide inital heat to the occupants. The hot coolant to the head helps reduce pollutants and allows the engine to come up to operating temp sooner. I read somewhere the temp that the rotating valve opens but I can't find it right now. I might be wrong but I thought it was 112 deg F. The AC compressor is as I understand a 12 volt unit that get's it power from the converter that charges the 12 volt battery.
     
    #5 Frank Hudon, Mar 30, 2004
  6. daniel

    daniel Cat Lovers Against the Bomb

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    What I've read is that the electric heater only provides some heat at floor level. This is consistent with my experience. My feet don't seem to remain quite as cold for as long as they did in my '89 Civic. But in extremely cold weather it is 4 or 5 minutes before I'm getting a good flow of heat from the dash vents.

    With the heater on, the engine never seems to shut off at stop lights. If I shut the heat off the ICE will stop (if it's warm). If I start the heater, the ICE starts up immediately.

    Clearly, the cabin heat is (mostly) coming from the gas engine, and only after it's warmed up. That said, it warms up faster than my Civic did, and the thermos may contribute to that.
     
    #6 daniel, Mar 31, 2004
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