What size of a gas furnace do I need?
The size of a gas furnace you need is very different for each home, where you live, and several other important factors. You might be surprised to see two identical homes in the same town that require two completely different sized gas furnace! The only real way to properly size a furnace is with a heat load calculation. Make sure to hire an experienced HVAC contractor who understands how to properly size a gas furnace.
Why is the furnace size important?
Here are some very good reasons to make sure your gas furnace is sized properly.
- f the gas furnace is too small, your home will be cold and the furnace will run 100% of the time. This results in a huge heating bills and maybe even have to supplement the furnace with space heaters.
- If the gas furnace is too large, the furnace will do what is called short-cycling, and you will be cold, then hot, then cold again as the gas furnace turns on and off repeatedly.
- If you buy a furnace that’s too large for you existing duct, it will sound lie a leaf-blower in your home.
- If the blower in your gas furnace is not sized properly, it will have a negative effect on central cooling system also.
What is AFUE?
AFUE is an acronym for Annual Fuel Utilization Efficiency and is a measure of how well a gas furnace or heating system converts fuel into heat. To get a basic understanding of the gas furnace rating you could use a money analogy.
~An 80% Afue furnace convers .80 cents of every dollar spent on fuel to heat.
~A 93% AFUe furnace converts .93 cents of every dollar spent on fuel into heat.
How do I handle repairs of a a gas furnace?
Diagnosing the furnace properly is essential. Proper diagnosis and troubleshooting can take years of experience and training. Make sure to consult with an experienced HVAC contractor.
How often does my gas furnace need to be cleaned?
It is extremely important to schedule an annual maintnenace for your furnace. This yearly exam can help keep you safe and identify small problems before they become big problems. Additionally, the most important thing you can do is change you air filters regularly.
What is the cost of a gas furnace?
Gas furnaces can range in price depending on many factors. The following are considerations:
• Size of furnace
• Gas furnace efficiency
• Market conditions
• Brand of furnace
• Features of the gas furnace
What is an electric heat pump?
An electric heat pump is a single unit that both heats and cools your home. A heat pump is the most efficient heating and cooling system available today because it generates less than one unit of heat for each unit of energy it consumes.
If it cools and heats, why do they call it a heat pump?
It pumps heat. In summer, it moves heat from inside your house to the outside. In winter, it moves heat from the air outside to inside your home. This is done using the refrigerant that is pumped by the compressor through the indoor and outdoor coils.
How does a heat pump work?
A heat pump is essentially an air conditioner that can also run in reverse. Both rely on the fact that a liquid absorbs heat as it is vaporized into a gas and that a gas releases heat as it condenses into a liquid. When in heating mode, a substance called a refrigerant will be compressed by the main component in a heat pump, the compressor. As it is compressed, it will release heat as it is condensed from a gas to a liquid.
The heated liquid will then be sent through a coil inside your home, where it will gradually cool down as it releases its heat into the ductwork or hot water pipes of your home’s heating system. The liquid will then be sent through an expansion valve, where is will be reduced in pressure as it enters a wider pipe. The liquid will then enter the outdoor coil, where it will absorb heat as it boils into a gas.
When in cooling mode in the summer, the cycle is reversed so that heat is transferred from the indoors to the outdoors.
A typical Energy Star-labelled heat pump can produce heat at efficiencies of around 450% at outdoor temperatures of 20C (78F), which gradually drops down to about 250% at freezing.
What does a heat pump’s HSPF efficiency rating mean, and how can it be compared to the AFUE ratings of gas heating systems?
Estimating the difference in energy costs between an electric and a gas heating system involves two steps. First, the watts of heat energy obtained for each watt of energy consumed must be determined. Second, the cost of each watt of electricity to each watt of natural gas must be compared.
The American Refrigeration Institute tests heat pumps and provides them with efficiency ratings which are recognized by Natural Resources Canada’s Office of Energy Efficiency. The heating efficiency rating is called the heating seasonal performance factor (HSPF) which is defined as the "total heat output in Btu of a heat pump over the entire heating season divided by the total energy in watt hours it uses during that time." Different HSPF’s are assigned to different regions, as a heat pump’s heating efficiency decreases as the outdoor temperature falls. The HSPF also factors in the use of supplemental heat.
The HSPF of the heat pumps we install ranges between 7.7 and 9.5. Since 3.413 Btu’s are equivalent to 1 watt hour, this equates to efficiencies of between 226% and 278%. As of June 18, 2008, natural gas from Terasen costs $14.33/GJ (including delivery costs and the $0.50/GJ carbon tax which starts July 1st) and BC Hydro charges 6.55 cents per kWh of electricity. Since 1 GJ = 277.8 kWh, this means that one GJ of electricity from BC Hydro costs $18.20, or 27% more than a GJ of gas from Terasen. This means that, according to the HSPF ratings and converting the different units of energy, heat pumps with HSPF ratings of between 7.7 and 9.5 should cost as much to run as a (theoretical) 178% to 219% efficient furnace. So they should reduce the heating costs of someone with a 60% efficient furnace by 66% to 73%.
Are heat pumps new?
No, they share the same basic technology as refrigerators and air conditioners which were invented over 100 years ago. Heat pumps were first manufactured over 50 years ago and in many regions of the world such as the Southern United States and Italy, heat pumps have been popular and well known for decades. Natural Resources Canada’s 1993 Survey Of Household Energy Use estimated that 2.9% of Canadian households used a heat pump as their primary heat source at that time, while the 2003 survey estimated that over 4% had heat pumps. And it has been in the period between 2003 and the present that the greatest increase in the popularity of heat pumps has occurred.
How often should I change the air filter in my system?
Check it at least every month during peak use, and replace it when it looks dirty enough to impair the air flow through it. Some filters, such as media filters or electronic air cleaners, are washable; others are disposable and must be replaced.
What is the average life-span of a Heat Pump?
It can vary, depending on how much the system is used and how regularly it is checked or serviced. Generally, the average life-span of units built in the 1970s and 1980s is about 15 years, but individual units may vary and last much longer depending on use and how well they are maintained. An ARI survey showed average heat pump life to be about 14 years when recommended maintenance procedures were followed. Newer units are expected to last even longer.
Call Keen Climate Change today for answers to your heating and cooling questions.