|Heat Pump Primer|
"A heat pump can potentially generate 3 times more heat delivered than it consumes in Electrical power"
A typical small high tech, 1500watt (Electrical power consumption) Inverter Heat Pump can deliver over 3500watts of heat!
ran test where a regular heat pump was replaced by an R410a + Inverter
heat pump with no other differences, in an office environment and the
newer unit used 70% less power than the old unit.
Other interesting facts:
Ground, water (ie rivers, or ocean) and ambient air typically contain an enormous amount of latent heat, however, its low thermal level does not normally enable it to be directly exploited for the heating gains. If we want to utilize low temperature (so called 'low-potential') heat, it must first be converted to that of a higher temperature. This what a heat pump can do.
Operation in the home is generally exceptionally quiet, and thermostat controlled. As a bonus, a heat pump can be reversed in the summer to air-condition the home.
PRINCIPLE OF OPERATION
State of the art inverter heat pumps, use variable loading to reduce cycle times and lower power consumption.
Even though the freezer on your fridge may be at -10c, the amount of heat transferred to the air in the room seems negligible. In an EEH home, this cumulative heat, plus the operational temperature of the compressor, helps heat the home indirectly.
What is special is, depending upon the design and ambient temperatures, you can get up to 3 times more heat per given power consumption over conventional inefficient resistance heater using the latest inverter heat technology..
A cutaway view of a typical outside part of the heat pump, showing the internal compressor and condenser/evaporator unit.
This is an air-to air exchanger, however outside heat exchangers can be had for emersion in the ocean, streams, deep bores or thermal vents. Heat pumps generally have Extremely quiet operation in side.
|Unlike an air-conditioner, a heat pump is
reversible. This means the
evaporator and condenser do double duty, heating in the winter and
cooling in the summer. When in heating mode the condenser is inside,
while the compressor and evaporator are outside. In air-conditioning
mode the condenser becomes the evaporator and the evaporator become
The types of heat pumps on the market are varied with the most typical being air to air. The most commonly encountered other combinations involve the air-to-water, air-to-air, water-to-water, antifreeze-to-water or earth-to-water types. If you live near a (non-freezing) river, ocean, or have a flowing well, the outside unit is highly effect year round, allowing the whole system to operate at peak effectiveness. In geothermal areas, heat pumps can be an excellent way to ecologically exploit the potential.
An outside unit just using air for its exchange, is best operated in temperatures above -10c.
You can now buy hot water cylinders with built in heat pumps to economically heat water. The capital cost remains fairly expensive.
Residential Heat Pumps
A residential heat pump takes low-temperature heat from an outdoor medium (such as air, ground, groundwater or surface water) and mechanically concentrates it to produce high temperature heat suitable for heating the interior of homes. Because most of the heat is moved (pumped) from the outdoor source to the indoor source, the amount of electricity required to deliver it is theoretically much less than using electric resistance heat directly.
Modern heat pump systems are very reliable and have become exceedingly common in Sunbelt areas. By far the most common types are air-to-air heat pumps which use outdoor air as the heat exchange medium.
Want more technical information?:
The theoretical efficiency of heat pumps is greater than 2000%. Thus, the COP, or Coefficient of Performance, would indicate 20 times as much heat delivered as used. However, the practical efficiency of the best air-to-air heat pumps produce COPs of 2.33 to 3.0. Because COP varies with the outdoor temperature, a heating season performance factor (HSPF) is determined which takes into account operation under varying outdoor temperatures as well as part load impacts (effects of running short cycles under mild conditions, coil defrost, etc.). HSPF is rendered as Btu/Watt so that typical values are on the order of 7.2 - 8.4 KJ/W. Older systems may have HSPFs of 6.3 - 7.4 KJ/W.
CapEx & OpEx & Gas vs Electric
When calculating the capital cost of installing a heat pump vs gas be sure to include the installation costs of both including connection to the gas main. (You will have power installed anyway) If you are getting gas installed anyway, this may be mitigated.
Other factors to take into consideration: Gas requires an active flue, also factor in leakage risks. Heat pump compressors are normally located outside, and can generate some noise in their vicinity, so take location of Windows into your consideration for location.
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