THE JIM BROWN COMPANY 870-425-5775
Our Family Serving Yours Since 1964
HEAT PUMP QUESTIONS What is a heat pump? A heat pump is a reverse cycle air conditioner. In the summer , when a person feels the air coming from the heat pump it is hot, and the air inside the conditioned space is cold. A heat pump has a switch over valve that allows that to change in the heat mode. When the heat pump is in the heat mode , the cold air that was coming in the house in the summer is now being dumped outdoors , and the hot air that was dumped outdoors in the summer is now delivered to the conditioned space. The reason for a heat pump is economy. Electric furnaces are simple and reliable but are expensive to run. Heat pumps are more complex, almost as reliable and inexpensive to run. The temperature of the outside air determines how much heat can be transferred into the conditioned space. Down to 30 degrees F. outdoor temperature there is nothing that will produce heat any cheaper than a heat pump. As the outdoor temperature drops the heat pump has less and less heat to work with. When the temperature drops below the balance point (the balance point is the place where the unit could run 24 hours a day and the temperature of the conditioned space would neither drop or rise) of the space to be conditioned begins to drop. At this point or some temperature just above the balance point the heat pump will employ auxiliary heat. This can be electric or gas . What is a dual fuel heat pump? A dual fuel heat pump is a heat pump outdoor unit and coil installed on a gas furnace to provide the auxiliary heat. This is a very desirable system because the heat pump delivers cool heat to the space that is delightful in the warmer weather heating periods when the heat pump is in its most economical stage. As the temperature drops the outlet air temperature also drops and as the heat pump begins to need auxiliary heat the compressor no longer is able to deliver enough heat and is told to stop and the gas furnace comes on. This is when the gas heat is the most desirable. When the weather is cold and the heat requirements are the highest the gas heat warmer air is very comfortable. A dual fuel heat pump is a marriage between a gas furnace and a heat pump without auxiliary heat. This system will function without the occupant of the conditioned space having to do anything, it will select the best heat source and change when the outdoor temperature asks it to without any activity from the people in the space. The thermostat and an outdoor temperature controller will do all the work. but are expensive to run. Heat pumps are more complex, almost as reliable and inexpensive to run. The temperature of the outside air determines how much heat can be transferred into the conditioned space. Down to 30 degrees F. outdoor temperature there is nothing that will produce heat any cheaper than a heat pump. As the outdoor temperature drops the heat pump has less and less heat to work with. When the temperature drops below the balance point (the balance point is the place where the unit could run 24 hours a day and the temperature of the conditioned space would neither drop or rise) of the space to be conditioned begins to drop. At this point or some temperature just above the balance point the heat pump will employ auxiliary heat. This can be electric or gas. What is a geothermal heat pump? A geothermal heat pump is a normal heat pump that uses water as the source for the heat in winter and the dump for heat in the summer. Instead of needing outside air the water source or geothermal heat pump uses water. The summer time cool water from below the earth comes to the unit and the heat from the inside space is transferred to the water and sent back to be dissipated in the earth, in the winter the warm water from the earth is brought to the heat pump and the heat is extracted from the water to heat the space and the cooler water is sent back to the earth. Geothermal heat pumps never see a big variation of water temperatures since they get their water from the earth below the surface where the temperature never changes very much. This means that they are very economical to run. They will need little or no auxiliary heat. How does a geothermal heat pump get water from the earth to make it work? In three ways. The first way is to employ a well with a water pump in it just like the well that furnishes water to your home or office. Water is pumped from the well and sent to the heat pump used then returned to the earth via a companion well, or simply dumped into a pond, stock tank or just put directly on the ground. This is called a pump and dump system. The second system does not have a well to pump water. In areas where trenching is possible trenches that are approximately 200 feet per ton are dug below the frost line to insure that the ground temperature is constant and pipe is laid in these trenches. The pipe then becomes the heat transfer device and the ground around the trenches becomes the heat sink. The water travels through these pipes in the trenches and either receives the heat to bring it to the temperature of the earth or gives up heat to get down to the temperature of the earth depending on whether the system is heating or cooling. In areas where trenching is not possible due to rocky terrain shallow wells are dug and serve the same purpose as the trenches. This ground loop system allows the heat pump to see a constant temperature of water and makes it just as efficient as the pump and dump. The ground loop is more efficient than the pump and dump in fact due to the fact a circulating pump will run cheaper than a well water pump. The third way the geothermal heat pump gets water is to circulate the piping in a pond or lake. This pond or lake must be at least 10 feet deep and have enough surface area to keep the water temperature at a constant at that depth year round. Can a geothermal heat pump heat domestic hot water? Yes a geothermal heat pump can employ a device called a desuperheater that can be installed and will strip the hot water leaving the condenser and put that heat in a water heater. In the summer time the temperature of this water can get very hot since heat is a throw away item in the cooling mode. In the winter the heat pump puts hot water in the tank at the same low cost as it heats the air so in the summer it is more efficient to have a desuperheater than not to have one and in the winter it gives hot water at the same low price as the heat pump heats air. Why does my air source heat pump shoot steam out of it and make a hissing sound in the winter time ? Because a heat pump takes heat from the air it will drop the temperature of the outside air below the dew point and this will create condensation to form on the outdoor coil. Since a heat pump will take 20 degrees F. of heat from the air or more when the outdoor temperature is 52 degrees F. outdoors the temperature at the outdoor coil can be freezing. The condensate that is formed from the heat being removed from the air frost will form on the outdoor coil. When the temperature drops and the heat pump runs a long time and the air from the outdoors is not warm enough to melt away the frost formed on the outdoor coil ice will begin to build up. The heat pump has a system in it called the defrost system that will sense this and periodically go through a defrost cycle to get rid of this ice. When it does the outdoor fan stops, the switch over valve switches to the air conditioning mode, the auxiliary heating system comes on to overcome the cool air produced by the air conditioned air and hot gas heats up the coil. When it does this steam forms and at the end of this process the switch over valve switches back to heat and the excess pressure developed by the melting process is let to escape and a loud hissing sound is heard. All of this is normal. Why is there a puddle of water around the base of my heat pump in the winter time? Because a heat pump takes heat from the air it will drop the temperature of the outside air below the dew point and this will create condensation to form on the outdoor coil. Since a heat pump will take 20 degrees F. of heat from the air or more when the outdoor temperature is 52 degrees F. outdoors the temperature at the outdoor coil can be freezing. The condensate that is formed from the heat being removed from the air frost will form on the outdoor coil. When the temperature drops and the heat pump runs a long time and the air from the outdoors is not warm enough to melt away the frost formed on the outdoor coil ice will begin to build up. The heat pump has a system in it called the defrost system that will sense this and periodically go through a defrost cycle to get rid of this ice. When it does the outdoor fan stops, the switch over valve switches to the air conditioning mode, the auxiliary heating system comes on to overcome the cool air produced by the air conditioned air and hot gas heats up the coil. When it does this steam forms and at the end of this process the switch over valve switches back to heat and the excess pressure developed by the melting process is let to escape and a loud hissing sound is heard. All of this is normal. Why does my heat pump make a burning smell every fall making me think it is too hot? The heat pump will function without the need of auxiliary heaters until the house gets near the balance point. At that time the electric heaters come on or the gas furnace comes on for the first time. Since the heating system has been working for some time, the smell of the dust burning off the auxiliary heat source. When the weather is cold , my heat pump runs a lot -- why does it do that? Because the cheap heat comes from the air and air source heat pump reaches out to get as much of this cheap heat as possible. Because the balance point may be below the outdoor temperature auxiliary heat may be required but the modern microprocessor thermostats are smart they limit the use of auxiliary heat to the minimum with out sacrificing comfort. This means that your heat pump may run a lot in the cold weather periods. Does SEER mean anything to a heat pump? Yes it does. A heat pump is an air conditioner first and a heating system second so SEER means just as much to a heat pump as an air conditioner. For a definition of SEER go to Air conditioners and look for SEER . Does a heat pump have a rating for the heating performance? Yes it does. It is called HSPF which means heating seasonal performance factor. This is the “miles per gallon” performance rating for a heat pump. Because the performance is determined by the outdoor temperature and this is a variable that can not be controlled the HSPF is harder to understand but still gives a good rating for heating performance. Like SEER the higher the HSPF the better heater it is. Does a heat pump cost more than a conventional gas furnace and air conditioner? An electric heat pump is about the same price as a gas and electric system. Dual fuel is higher because it has many more controls and needs more attention than an all electric heat pump or a standard gas furnace with air conditioning.
My heat pump puts out cool air in the winter when the weather is cold -- is this normal? Yes a heat pump delivers heat in the range of 110 degrees F. on the high side during warm weather when heat is abundant outdoors to 90 degrees F. in the cooler weather. This means that register placement is more important with a heat pump than a gas furnace or electric furnace. Cooler air will heat the space but may not feel as good on the feet as warmer air is and should be delivered to the conditioned space in places where people are not exposed to the direct air flow. What is the difference between R-410A or Puron and R-22 that has been around forever? The new generation refrigerants are designed to be environment friendly and not damage the ozone layer. They also use a different oil to lubricate the components of the refrigeration system. R-22 boils at 32 degrees F. below zero and R-410A boils at 56 degrees F. below zero. This means that R-410 A is a more aggressive refrigerant and will be able to extract greater amounts of heat than R-22 at the same temperatures. Other than the boiling points and oils with environmental concerns addressed they all work the same way and do the same things. My heat pump has ice on it all the time in the winter -- is this normal? Yes it can be. The heat pump pulls heat out of the air and this creates a condition that allows ice to form on the unit even when the temperature is above freezing. A healthy heat pump could have ice or frost on it anytime the outdoor temperature is in the 30’s F. or below. This is caused by the unit taking 20 degrees of heat from the air passing over the heat pump outdoor unit. This will make the air drop moisture on the coil because the air has been brought below the dew point and at 40 degrees outdoor temperature the air will be 20 degrees at the coil after the heat has been removed so it will be both wet and cold which will make the unit gather frost and ice. This is a healthy condition. A quick check to see if the unit is working properly will be to look at the frosty coil and see if there is any water or ice under the unit where it could have melted and collected directly under the coil. If there is water or ice directly under the coil that means that it is working as it should. The reason for this is the water or ice will be proof that the unit has run through the defrost cycle and all is normal. If there is large quantities of ice on the unit and it has no water under the coil this will indicate the defrost mechanism is not functioning properly. This will require service. You will need to call the Jim Brown Company at 425-5775 and select extension 2 to reach the service department. If it will be some time before the service man can come fix the unit or you want the unit to return to normal you can turn the mode selector to off for 5 minutes and then turn it to cooling and set the thermostat down to bring the air conditioner on and let it run until the unit thaws out. Turn the unit back off for 5 minutes then resume the heating mode. What does the emergency heat switch on the thermostat do? If the outdoor unit fails the emergency heat switch can be used to provide heat until it can be brought back on line and return to normal. If the house is cool and the heat pump is not bringing the temperature up as fast as it was wanted the emergency heat is the hottest fastest warm up possible. If your system is dual fuel and gas is the low cost fuel you can make a standard gas furnace out of your system by switching the emergency heat switch. Why would you want to use the emergency heat feature on the thermostat? If the outdoor unit fails the emergency heat switch can be used to provide heat until it can be brought back on line and return to normal. If the house is cool and the heat pump is not bringing the temperature up as fast as it was wanted the emergency heat is the hottest fastest warm up possible. If your system is dual fuel and gas is the low cost fuel you can make a standard gas furnace out of your system by switching the emergency heat switch. What is the most economical way to run a heat pump? The most economical way to run a heat pump is to set it at the desired temperature and leave it there. Does a programmable thermostat save money with a heat pump? Yes it will. The summer settings can save the most. If the house is unoccupied during the day the temperature can be set to 3 or 4 degrees warmer than what is desired during the occupied times. If the temperature is set more than 3 or 4 degrees difference the economy disappears and the level of comfort also goes down. When the setting is changed 3 or 4 degrees it will shorten the run time considerably and not create a heat sink in the house making the set back save money. In the winter the heat pump delivers cooler heat so it will not come back as fast as in the air conditioning mode. It is not recommended to change the temperature during the day more than a degree or two but if it is desired the night time temperature can be set back as much as 5 degrees for cooler sleeping. The occupied setting must be given time to recover so a longer ramp up time is required. Example: The normal temperature for a home is 72 degrees. The desired night time temperature is 67 degrees. The occupants arise for the day at 6:00 AM routinely. The set back time is scheduled to start at 10:00 PM and to get the house up to temperature in the morning the return to the desired temperature will start at 5:00 AM. This hour will allow the system to gradually come to temperature and use the cheapest heat source, which is the compressor, to bring the temperature up. Quicker recovery times will require the use of auxiliary heat which is more expensive. More expensive thermostats have logic boards in them that will limit the use of auxiliary heat to be the minimum. This logic sequence will keep the compressor as the main source of heat unless the temperature in the conditioned space starts to drop or runs too long at one setting. Lesser cost units use the temperature differential as the determination factor to start the emergency heat cycle. A more sophisticated logic thermostat will be the most economical for a heat pump. |
