HVAC

There are many heating systems available to choose from when you build your home, such as forced air, floor heat, wood stove, etc. They all have their advantages and disadvantages, and all have their level of efficiency. In order of efficiency, the most popular systems are:
Masonry heater (for very cold climates), Radiant floor, Heat pump, Solar hot water, Baseboard hot water, Wood stove, Pellet stove, Wall heater, Forced air, Electric baseboard, Wall heater, Fireplace.

Please note that the fireplace is the least efficient heating unit. Although very popular due to the psychological effect it has on us, it is still a big hole in the wall through which heat (and cold air) can escape. It is best to replace the fireplace with a stove, wood, or pellet.
The most efficient systems are the Radiant Floor, Heat Pump and Solar Hot Water. We will concentrate on these systems to expand and explain these systems.

A discussion of heating and cooling (or HVAC) can get complex, but for now we'll keep it simple and conceptual and leave the technical info for later. Eventually, we can add the bells and whistles (as typically the controls, gauges, and safety devices are what make the whole thing look difficult.)

This graph shows that most of the energy we use in a home is used by Heating Ventilating and Cooling (HVAC) and Domestic hot Water Heaters (DWH). We'll start with the Domestic Hot water Heater (DWH). Domestic water heating accounts for between 15% and 25% of the energy consumed in homes.

Types of Water Heaters:
-Storage type water heaters are the most common today.
-Tankless or instantaneous (Demand water heaters) heat water directly without use of a storage tank. (Their advantage is that they use no "stand-by energy," energy used to just keep the water up to temperature when not in use - the reason they are often used in low-demand or remote areas.) There are more, but I won't go into that now.
Storage type water heaters are most common today and are adaptable to the equipment that needs to be added to make the HVAC system more efficient. Conventional storage water heaters remain the most popular type of water heating system for the home.
A single-family storage water heater has a reservoir-from 20 to 80 gallons-of hot water. It releases hot water from the top of the tank when you turn on the hot water tap. To replace the hot water, cold water enters the bottom of the tank.

One way to make the DWH more efficient is to "preheat" the water by letting the water go through a solar water heating system.
Solar Water Heaters - also called solar domestic hot water systems-can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use - sunshine - is free.
Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't.
Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. The DWH provides that backup.

Another way to pre-heat the water in a DWH is letting a Heat Pump do that work. Most homeowners who have heat pumps use them to heat and cool their homes. But a heat pump also can be used to heat water-either as a stand-alone water heating system or as combination water heating and space (room) conditioning system.

How They Work: Heat pump water heaters use electricity to move heat from one place to another instead of generating heat directly. Therefore, they can be two to three times more energy efficient than conventional electric resistance water heaters. To move the heat, heat pumps work like a refrigerator in reverse.

In an AC unit, hot outside air (in summer) tries to "cool" the outside coilů.not very efficient.
In a Heat-Pump, warmth from the cold outside coil (in winter) is drawn in.





The solution: Put the pipes underground where the temp is around 56░F year around.
Called: "Geothermal Heat Pump Systems"
There are 2 kinds of heat pumps:
-Air Source HP: Gets the heat from outdoor air.
-Geothermal HP: Gets the heat from heat stored in the ground.

2 types Geothermal HP
-Ground source HP: collect the heat via a ground coil.
-Water source geothermal: collect heat from ground water.

The Heating Seasonal Performance Factor (HSPF) gives the number in Btus (British Thermal Units) that the heat pump moves for each kilowatt-hour of electricity it uses (very efficient is ~ 10)

The ground just below the surface stays about 56░ year-round. The underground temperature is higher than the outside air temperature in the winter months and lower than the outside air temperature in the summer months, which makes the heat pump more efficient. The excess heat from the ground source heat pump compressor can be used to heat domestic hot water when the heat pump is in use. Ground source heat pumps can be installed in three ways: horizontally, vertically, or in a pond/lake. The type chosen depends on the available land areas and the soil at the installation site. For closed loop systems, water or antifreeze solution is circulated through pipes buried in the ground. The U.S. Department of Energy and the Environmental Protection Agency (EPA) both consider the ground-source heat pump to be the most efficient, environmentally benign, and cost-effective space heating and cooling system on the market.
-Electrical energy use can be reduced 30-60% by replacing standard electrical heating and cooling systems with geothermal (ground source) heat pumps.
-It also will reduce the negative environmental impacts from fossil fuel emissions.
-Ground source heat pumps can be used for heating and cooling, and for domestic hot water.

To reduce Heat Pump (& HVAC in general) energy use:
-Provide good air flow to outdoor cooling equipment by keeping the coils clean and the (fan) equipment clear of tall grass, leaves and other debris. Provide at least 2 feet of clearance on all sides of the equipment and 5 feet of clearance at the top.
-Have the AC equipment checked and cleaned every year, especially in the South)
-Operate the cooling equipment wisely. (A house does not suddenly have to become a freezer in the summer.) A higher setting saves money/energy.
-In the warmer climates, plant shrubbery in front of your South facing window to soak up some heat.
-Clean or replace filters every 1-4 months
-Clean the fan blades
-Continue to use ceiling fans even when you use the AC.
-Do not shut too many doors to save on AC use. It throws the AC unit off balance. You might end up in the same pickle as having an oversize AC unit in where you cannot get rid of the humidity. For privacy, keep the doors open slightly. When building:
-Choose equipment that is properly sized and has a good efficiency rating. Insist that equipment be sized according to the Air Conditioning Contractors Association of America (ACCA) Manual J, or similar procedures. Do not accept simple rule-of-thumb methods for sizing equipment such as so many tons of air conditioning per square foot of living area. A house's heating and cooling needs vary dramatically according to orientation, shade, window area, air leakage, and insulation levels. Proper sizing is particularly important for air conditioning in the Southeast. Units that are too large cycle on and off quickly and do not run long enough to remove moisture from the air. Remember, comfort is a function of both temperature and humidity.
-Install a programmable thermostat, especially when you're away from home all day or more. No use having the AC (or heat) full blast when you're not home.
-Ducts should be wrapped if placed in a crawlspace or in a hot attic; however, lately ducts are placed in the area with conditioned air, such as a conditioned basement or attic space.
-Check the Minimum Efficiency Reporting Value (MERV). It ranges from 1 to 12. The higher the number, the better it filters, but also the more energy it takes to pull the air through. It's a balancing act. Filter better and pay more on electricity, or filter less with less energy.
-Look for a Seasonal Energy Efficiency Ratio (SEER) of 13 or higher.

Taking this a step further, Carrier has developed a system that brings the computer technology into this equations with the following, called the "Hybrid System." A Hybrid System is a highly efficient furnace and a heat pump with a thermostat that is programmed to perform a load calculation on your home, using local electric, propane, or natural gas rates and electrical rates. The Thermostat will automatically choose whether the furnace or heat pump will heat your home at a lower cost. There are 4 primary types of Carrier heating and cooling systems: split systems, hybrid heat split systems, duct-free split systems and packaged systems.

The most typical and traditional heating and cooling systems are split systems. With a Carrier split system, you have products that reside both inside and outside your home.
View Interactive Demo


A Carrier hybrid heat split system is a more energy-efficient variation of the traditional heating and cooling split system. The inclusion of a heat pump allows the option of electricity-fueled heating and cooling, in addition to gas furnace heat.
View Interactive Demo

Carrier duct-free systems can be installed in places where conventional ducted systems cannot go, or are an ideal complement to your ducted system.
View Interactive Demo


Packaged System:
View Interactive Demo


View Rooftop Demo



HYBRID HEAT Savings Examples demonstration to view potential savings based upon a 2,000 sq. ft. house in various locations across the United States. Simply roll your mouse over each city callout to highlight the money you can save.

Since we now have a hot water system (the reason I started with the DWH), we now can use this water to use it in the put plastic pipes in the radiant-floor system. Most hydronic radiant floor systems are installed. in an insulated concrete slab, but can also be installed on wood-frame floors, under either tile or wood, but radiant floor in concrete slabs is the most economical because the installed concrete slab is already factored into construction costs.
Hydronic (liquid) systems are the most popular and cost-effective systems for heating-dominated climates. They have been in extensive use in Europe for decades. Hydronic radiant floor systems pump heated water from a boiler through tubing laid in a pattern underneath the floor. The temperature in each room is controlled by regulating the flow of hot water through each tubing loop. This is done by a system of zoning valves or pumps and thermostats.

Wet installations are the oldest form of modern radiant floor systems. In a "wet" installation, the tubing is embedded in the concrete foundation slab, or in a lightweight concrete slab on top of a subfloor, or over a previously poured slab. If the new floor is not on solid earth, additional floor support may be necessary because of the added weight. You should consult a professional engineer to determine the floor's carrying capacity.

For more info: http://solarhouse.umd.edu/page.php?id=221

For Hot water Heater (DHW) efficiency when building:
-Have a solar collector installed to pre-heat the water you use. These are very efficient and offer immediate payoff.
Consider the following factors when buying a water heater (DHW):
-Fuel availability, including natural gas, electricity, oil, and propane
-Cost-equipment, installation, and expected annual fuel cost
-Capability-system capacity, including first hour rating (FHR)
-Longevity-expected equipment life
-Safety, including possible combustion gas back-drafting concerns

Improving Water Heater Efficiency in general:
-With any DHW system, methods for reducing hot water costs start with lowering the thermostat.
-The greatest inefficiency of an electric hot water heater lies in the heat it loses during the time is sits around waiting for us to turn on the hot water tap. (This is called standby loss). Lower the thermostat on your water heater to 120 degrees F (130 degrees if you have a dishwasher that doesn't have a temperature booster).
-Installing water heater insulating "jackets" of R-11 or higher can be cost effective in reducing standby losses on storage-type units, especially older or poorly insulated ones. Greater benefits are achieved when the hot water tank is installed outside of conditioned space (e.g., garage). For safety, however, never block any controls, valves, or airways for combustion or exhaust.
-If your tank is older than 5 years, check for excessive standby loss by placing the palm of your hand against the side of the tank. If you feel a noticeable warming of your hand, chances are wrapping the tank will help.
-If your hot water tank is older than 12 years, consider replacing it with an energy efficient model. (Look for an Energy Factor of .91 or greater.) The average life for electric water heaters is about 14 years.
-For electric water heaters, install a timer that can automatically turn the hot water off at night and on in the morning. A simple timer can pay for itself in less than a year.
-Install a heat trap above the water heater. (This is a simple piping arrangement that prevents hot water from rising up in the pipes, thereby minimizing standby losses.)

For more information on Geothermal heat pumps go to: Geo.heat pumps or go to:

http://www.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12650