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Mid-Efficiency vs High-Efficiency
The decision to go to either high-efficiency or mid-efficiency
is typically made for many reasons. For example: quieter
operation, government incentives, factory rebates & more
environmentally responsible.
At this point in time, mid-efficiency furnaces are probably
the best replacement value for the money.
A lot of our clients ask what the payback would be when replacing
their old furnace (which is roughly 55% efficient) with a new
mid-efficient (80% efficient).
Here is a quick method to arrive at an approximate payback:
- Take July or August gas bill and multiply by 12. This
is your domestic hot water (DHW) cost.
- Take total gas bills for year less the above DHW to come
to gas spent to heat house now.
- To get approximate new gas cost (mid-efficient):
Take end result from above calculation (A), then multiply by
.55 and divide by .8 to get (B).
- To get payback term:
Replacement cost divided by annual savings (A-B).
Example:
End result from 1 & 2 above is $1,000 (A)
Approximate new gas cost: 1,000 x (.55 / .8) = $687.50 (B)
$1,000 - $687.50 = $312.50
$2,400 (approx. replacement cost) = 7.68 years
$312.50 (A-B)
In this example for mid-efficiency, it would take about 7
3/4 years to save back replacement cost. This is, of
course, based on today's gas prices (last updated April 2004).
Using the same method and example, you can arrive at approximate
annual savings and payback term when going to high-efficiency
furnace except change Item 3 calculation to:
(A) $1,000 x (.55/.92) = $597.83(B)
$4,100 (approx. replacement cost) = 10.19 years
$402.17 (A-B)
Using the same example, it would take a little over 10 years
to save back replacement cost on a high-efficiency furnace. This
is, of course, based on today's gas prices (last updated April
2004).
Alberta Furnace & Heating Services is an authorized
Lennox dealer and, although we service many makes of furnaces,
the only units we install are Lennox at this time.
The following are the furnace systems we install. More
information on features, specifications and energy efficiency
can be found on the Lennox website at http://www.lennox.com.
Mid-Efficiency (80%)
Lennox Elite Series G50 – efficient single-stage operation
Lennox Elite Series G60 – efficient & quiet, 2-stage operation
Lennox Signature Series G60V – efficient & quiet, variable speed operation
High-Efficiency (up to 95%)
Lennox Signature Series G61V – quietest high-efficiency furnace
you can buy with a DC variable speed motor and 2-stage operation
In most applications, the additional expense for a furnace with a DC motor pays for itself within 2½ to 3 years with the electricity savings.
Specialized
Systems (up to 3000 sq. ft.)
If you are considering replacement of at least
two 2) low-efficiency furnaces as well as your water heater,
we recommend the Trinity Ti Boiler with air handling units
and an indirect water heater by Amtrol.
Air handling units come with DC high-efficiency
blower motors which run with less noise and your domestic hot
water is also generated at 95% efficiency.
In order to prolong the life of a system such as
this, a good quality water softener must be installed. We
recommend and install Kinetico Mach 2040 and 4040 units for
within the City.
We highly recommend the installation of a PRV (pressure-reducing
valve) on the incoming water service as well as the installation
of a properly-sized diaphragm style expansion tank to eliminate
water hammer.
Humidifiers and air cleaners are strictly add-on
accessories and can be sized and incorporated easily.
Payback on systems like this is typically in the
11 to 12 year range.
Specialized Systems
(3000 to 6000 sq. ft.)
Multiple heating modules and air
handling units can be utilized to offset heat loss. Since these systems are
meant to be engineered for each application, the consumer should
select a contractor with extensive experience in this area.References
are available upon request.
Specialized Systems (6000+ sq. ft.)
For homes larger that 6000 sq. ft., we recommend
going with a twin boiler system with indirect domestic hot water
tank and Lennox air handling units.
Note: At all times, we would prefer
to see a minimum of two (2) heat sources for homes outside
the City (Calgary) limits.
Ventilation
Air Code Requirements
Only the cheapest (180 cfm and lower) kitchen canopy exhaust
hoods are allowed to be vented to the outdoors without special
make-up air provisions. The maximum amount of unheated
outdoor air allowed to enter a typical furnace is 25%
of supply air. This typically means a 250 to 300 cfm
kitchen exhaust hood is the maximum size allowed without preheating
make-up air.
Many contractors will install an electric heating
coil to preheat make-up air which is very expensive to run
and is strictly an on-off system. We have developed some
alternate ways to deal with make-up air requirements. The
ventilation air systems are all custom design built systems
providing constant discharge air temperatures.
According to the latest Ventilation Code Requirements; if you build
your home with direct vent sealed combustion gas-fired appliances,
make-up air does not have to be provided for kitchen exhaust fan applications.
However, this would result in serious negative air pressures within the home
and we do not support this practice. A properly designed kitchen exhaust/make-up
air system is the only way to go.
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Mid-Efficiency vs High-Efficiency