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A variable capacity furnace is 100% worth the investment if your home heating priorities include comfort, reduced sound, reliability and energy efficiency.
Variable capacity furnaces have specific advantages over single or two-stage models:
Highest Energy Efficiency
A variable capacity furnace is significantly more efficient than a one or two-stage furnace because it can precisely adjust the heat capacity and airflow to precisely match the heating needs of the home.
A single-stage furnace is either running at full capacity, or not running at all. A two-stage furnace offers two different heating levels, so the furnace doesn’t cycle on and off as much.
A variable capacity furnace can ramp up or down in small increments, so heating system runs longer at much lower output. This is much more efficient than the repeated bursts of energy consumed as a single or two-stage furnace constantly cycles on and off.
Because a variable capacity furnace can operate at a lower setting most of the time, it uses significantly less electricity to power the blower. Variable speed furnaces also consume fuel more efficiently (natural gas or liquid propane).
Even though variable capacity furnaces may cost more up front, monthly energy bill savings typically make up the difference within a few years (faster in regions with long, cold winters).
Maximum Comfort
Variable capacity operation provides more precise temperature and humidity control, for more consistent comfort. Indoor temperature and airflow are optimized, unlike single or two-stage systems that allow repeated temperature fluctuations as the heat cycles on and off.
A variable capacity furnace also provides more efficient zoning because it can better match the output to each zones varying comfort demands.
Paired with an air conditioner or heat pump system in a dual-fuel system, a variable speed blower motor also optimizes cooling efficiency and indoor comfort in warmer months.
Minimum Noise
A variable speed furnace operates more quietly than a single or two-stage furnace because it runs at lower speeds for longer periods, gradually ramping up and down to meet heating needs, rather than switching on and off at full power. This avoids the noise associated with a furnace starting up and running at maximum capacity.
Reliably Long Service Life
A variable capacity furnace has a longer service life because it operates more efficiently at lower speeds, avoiding the strain caused by frequent on/off cycling. This reduces wear and tear on components and results in less frequent breakdowns.
With proper maintenance, a variable capacity furnaces spending most of its time running at reduced capacity has the potential to provide a longer sevice life versus those that frequently cycle on and off at full capacity.
Indoor Air Quality
A variable capacity furnace supports better indoor air quality by running at lower speeds for longer periods, for more consistent air circulation. This means better filtration (because air passes through filters more frequently), reducing airborne contaminants.
If you use a humidifier, consistent air circulation will also give you more balanced humidity levels.
Signs You Should Upgrade to a Variable Capacity Furnace
Still on the fence about making the change to variable capacity? Here’s who stands to benefit the most:
- Your furnace is 10 years old (or older)
- Someone is usually at home
- Your household includes light sleepers
- You want to reduce your carbon footprint
- You live in a region with cold winters
- You plan to stay in your home… or move! If you live in your home for the next few years, the cost difference will be canceled out by lower energy bills. If you’re putting your home on the market, a variable capacity furnace makes it much more attractive to buyers.
Navien NPF high-efficiency hydro-furnaces have industry-leading variable capacity giving homeowners incredible value, consistent comfort and impressive savings:
- 97% AFUE (energy efficiency)
- Low-cost installation with horizontal or vertical configuration & multiple venting options
- Sealed combustion chamber separate from the airstream for ultra-quiet operation
- Compatible with single or two-stage thermostats, as well as smart thermostats
The NPF also meets CEE Tier III criteria, the highest efficiency performance standards set by the Consortium for Energy Efficiency and is eligible for federal tax credits and state rebates.