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How Much Will I Save?

The cost of a high-efficiency boiler can be up to twice that of a conventional boiler. On the other hand, high-efficiency models often pay for themselves in less than five years when the high price of fuel and the long boiler life (25 years on average) are factored in.

Table 1 shows how much can be saved by buying a high-efficiency condensing boiler instead of a non-condensing boiler.

Table 1. Simplified Payback Analysis of New Gas-Fired Hot Water Boilers: A Standard Boiler Compared with a Condensing Boiler

  Non-
Condensing
(Mid-efficiency)
Condensing
(High efficiency)
Capacity 2 100 000 Btu/hr 2 100 000 Btu/hr
Rated Thermal Efficiency 83 percent 95 percent
Operating Efficiency*
(see note below)
79 percent 91 percent
Initial Cost $25,000 $50,000
Incremental Cost $25,000
Fuel Price** $9.14/GJ $9.14/GJ
Annual Full-Load Heating Hours*** 2080 hrs 2080 hrs
Annual Cost of Fuel $53,283 $46,256
Annual Savings $7,027
Payback Period 3.6 years

*Thermal Efficiency has been lowered by 4 percent to account for reheating after being off.
**The price is from 2001, Source: Natural Resources Canada, Energy Use Data Handbook, 1990 and 1995 to 2001.
***Assumed: a two-shift cycle, 16 hrs/day, 5 days/week, at 50 percent load factor.
Note: This assumes an installation where condensing can occur most of the time.

This is a highly simplified scenario. Actual savings will depend on incoming water temperature, on-off duty cycle, maintenance, controls and other variables.

Table 2 shows the potential payback period for replacing an older, inefficient boiler with a new, efficient one.

Table 2. Simplified Payback Analysis: An Old Non-Condensing Boiler Compared with a New Condensing Boiler

  Old Non-
Condensing
(Low-efficiency)
Condensing
(High efficiency)
Capacity 2 100 000 Btu/hr 2 100 000 Btu/hr
Rated Thermal Efficiency 74 percent 95 percent
Operating Efficiency* 70 percent 91 percent
Initial Cost NA $50,000
Incremental Cost $50,000
Fuel Price** $9.14/GJ $9.14/GJ
Annual Full-Load Heating Hours*** 2080 hrs 2080 hrs
Annual Cost of Fuel $60,133 $46,256
Annual Savings $13,877
Payback Period 3.6 years

*This considers cyclic, off-cyle and heat air losses.
**The price is from 2001, Source: Natural Resources Canada, Energy Use Data Handbook, 1990 and 1995 to 2001.
***Assumed: a two-shift cycle, 16 hrs/day, 5 days/week, at 50 percent load factor.
Note: This assumes an installation where condensing can occur most of the time.

This is a highly simplified scenario. Actual savings will depend on incoming water temperature, on-off duty cycle, maintenance, controls and other variables.

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