We recommend NEST Thermostats. Check them out at www.nest.com Nests unique new connector can accept any one of four wires (W3, E, HUM or DEHUM), which means Nest now works with almost all heating and cooling systems in the US and Canada. Nest's Heat Pump Balance is a Nest exclusive that optimizes how often you use expensive auxiliary heat. Just choose whether you want more comfort or more savings, and Heat Pump Balance will automatically adjust when AUX comes on.
Nest will automatically activate Heat Pump Balance in the Max Comfort setting if you have a heat pump with auxiliary heat. The Nest Learning Thermostat automatically activates Heat Pump Balance for homeowners who have a heat pump with auxiliary (AUX) heat and are connected to Wi-Fi (otherwise, you can use Early-On).
When you switch to cooling, Heat Pump Balance will no longer apply and you ll have the option to use Early-On.
What is auxiliary (AUX) heat?
Heat pumps are super efficient compared to most other heating systems, but they take longer to heat your home the colder it gets outside. So heat pumps are sometimes paired with powerful AUX heat, which is much less efficient but turns on when the heat pump alone isn t working fast enough.
Unfortunately, auxiliary heat costs two to five times as much as your normal heat pump and often comes on even when your heat pump could have gotten you efficiently to your target temp without auxiliary heat.
Other thermostats have one way to control auxiliary heat: the AUX lockout temperature. If your AUX lockout temp is 40 F/4.4 C, then auxiliary heat will come on when the outdoor air temperature drops below 40 F/4.4 C.
With Heat Pump Balance, you don t have to worry about the AUX lockout temp. Just choose whether you want more comfort or more savings, and the Nest Thermostat will adjust your lockout temp as needed.
How does Heat Pump Balance work?
Heat Pump Balance monitors how well your heat pump is working, the current weather, and the weather forecast. It uses this info to minimize how often expensive auxiliary heat is used and predicts how to best use it in the future.
For example, Heat Pump Balance automatically turns the heat on early to give the heat pump enough time to get there without using AUX. So if your schedule says 70 F/20 C at 7 pm, Heat Pump Balance will use Early-On technology to start heating at, say, 6 pm. Because auxiliary heat is so expensive, running the heat pump longer is still cheaper than using AUX.
There are Four 4 Operating modes of the Sweetwater Solar Assisted Geothermal Heat Pump System.
The ability of the SSAGHPS system to respond to hour by hour changes in both outdoor and indoor ambient conditions and system performance while maintaining maximum efficiency performance depend on close adherence to the control system logic. The description of the control sequence for the 4 different operations covers all of the major control logic.
Operating Mode One
1. Radiant Solar Energy Available No Demand for Solar Space Heating. Heat collected by solar panels and stored.
When the collector differential control senses that the temperature of the water glycol in the collector is 18 degrees F higher then the solar storage tank temperature collector pump turns on and moves coldest water from the bottom of the solar storage tank into the collector array where it absorbs radiant solar energy and delivers it to the middle of the storage tank. This action continues until the temperature differential between the collector and storage tank is reduced to 3 degrees F when the collector pump turns off or the solar collector temperature exceeds manufactures specification see section 9 . This system functions independently of all other controls collection radiant energy whenever it is available.
Operating Mode Two
2. Space Heating in Demand Solar Radiant Energy Available Thermal Energy Tank Temperature Below Level Required by Ambient Conditions, All Systems Operational.
Solar collector differential and collector pump function as in operation mode 1. Room thermostat turn on terminal pump and blower in air handler if used. Reset thermostat, sensing that terminal tank temperature is below level required by outdoor ambient turn on the DX Geothermal Heat Pump and the heat pump operates in the water to water mode. Water is circulated to the terminal heating equipment is returned to the warmer of the solar storage tank or terminal energy tank by use of a diverting valve. Action continues until room temperature rises to level required by outdoor ambient condition.
Operating Mode Three
3. Space Heating in Demand No Solar Radiant Energy Available Terminal Energy Tank Temperature Below Level Required by Ambient condition Solar Storage Tank Temperature above 53 degrees F Energy with drawn form Solar Storage Tank.
System functions as in operating mode 2 except that control differential control does not activate collector pump. Energy is drawn from solar storage tank by evaporator pump and is not being replenished causing drop in solar storage tank temperature.
Operating Mode Four
4. Space Heating in Demand No Solar Radiant Energy Available Terminal Energy Tank Temperature Below Level Required by Ambient condition Solar Storage Tank Temperature above 53 degrees F Energy with drawn form Solar Storage Tank. System converts to DX geothermal heat pump operation.
When the solar storage tank fall below 53 degrees F system converts to geothermal heat pump mode and condenser gas heat air handler delivering required heat to living space.
The Solar Energy Factor (SEF)is a performance rating for solar domestic water heating systems. We use F Chart to calculate solar loads. The SEF is defined as the energy delivered by the system divided by the electrical or gas energy put into the system. The SEF is presented as a number similar to the Energy Factor (EF) given to conventional water heaters by the Gas Appliance Manufacturers Association (GAMA)1, but with the exceptions noted in the Rating Parameters Section.
SEF Formula 1
QDEL = Energy delivered to the hot water load: Using the SRCC rating conditions, this value is 43,302 kJ/day (41,045 Btu/day).
QAUX = Daily amount of energy used by the auxiliary water heater or backup element with a solar system operating, kJ/day (Btu/day). To convert to kWh, divide this value by 3,600 (3,412). To convert to therms, divide this value by 105,000 (100,000).
QPAR = Parasitic energy: Daily amounts of AC electrical energy used to power pumps, controllers, shutters, trackers, or any other item needed to operate the SDHW system, kJ/day (Btu/day). To convert to kWh, divide this value by 3,600 (3,412).
The Solar Energy Factor can be converted to an equivalent Solar Fraction (SF) as follows:
SEF Formula 2
The EF for the SRCC standard electric auxiliary tank is 0.9 and for the gas tank is 0.6.
In this context, the Solar Fraction is the portion of the total conventional hot water heating load (delivered energy and tank standby losses) provided by solar energy. Note that an alternate definition for Solar Fraction is often used. In this alternate definition, solar fraction is the portion of the total water heating load (losses are NOT included) provided by solar energy. The alternate method of calculating solar fraction will yield higher solar fractions. Therefore, use caution when comparing the solar fraction for specific systems, inputs into energy codes (such as California's Title 24), or outputs from software (such as F-Chart) to ensure that the same calculation procedure for solar fraction has been used.
The Solar Energy Factor can be converted to an equivalent Solar Savings (QSOLAR) as follows:
SEF Formula 3
QCONV = Daily amount of energy used by the auxiliary water heater or backup element without a solar system. The SRCC standard electric auxiliary tank has an energy usage of 47,865 kJ/day (45,369 Btu/day). The SRCC standard gas auxiliary tank has an energy usage of 72203 kJ/day (68,439 Btu/day).
EF = The Energy Factor is the ratio of delivered energy to input energy for the reference electric auxiliary tank without a solar contribution. The balance of the energy is lost to the surroundings due to standby losses and conversion efficiency.
QSOLAR = The Solar Savings is the amount of the total conventional water heating load (delivered energy and tank standby losses) provided by solar energy minus any parasitic energy use. To convert to kWh, divide this value by 3,600 (3,412).
In this context, the Solar Savings is the amount of the total conventional hot water heating load (delivered energy and tank standby losses) provided by solar energy minus any parasitic energy use.
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