Chapter 23 Exercises

Exercise 1: Efficiency Label Research

Find the data plate or model number on your furnace, air conditioner, or heat pump (typically on a metal label inside the unit access panel or on the outdoor unit). Look up your equipment's efficiency rating using the manufacturer's website or AHRI (ahridirectory.org — the Air-Conditioning, Heating, and Refrigeration Institute's certified ratings directory). Record: (a) model number, (b) AFUE (for furnace/boiler), SEER or SEER2 (for AC), and/or HSPF or HSPF2 (for heat pump), (c) year manufactured, and (d) how your efficiency rating compares to current minimum standards. Is your equipment above or below the 2023 federal minimum?

Exercise 2: Annual Fuel Cost Calculation

Using your last 12 months of utility bills, calculate your annual heating or cooling fuel cost. For heating: find your gas bill's therms used per month for October through April; sum them. Multiply by your current per-therm rate. For cooling: estimate cooling months (June–September) and subtract your average non-cooling electricity use to isolate the cooling contribution. Using the AFUE or SEER2 of your equipment (from Exercise 1), calculate the useful heat or cooling delivered per dollar spent. Compare to a high-efficiency alternative at the same fuel price.

Exercise 3: Break-Even Analysis

Using the data from Exercises 1 and 2, complete a break-even analysis for replacing your current system with a high-efficiency alternative. Look up the installed cost of a replacement unit from at least one contractor quote or published price range. Calculate: (a) annual energy savings from the efficiency upgrade, (b) years to payback at that savings rate, and (c) whether the system's remaining useful life (based on its age and typical lifespan of 15–20 years for furnaces, 12–15 for AC) makes the upgrade worthwhile before end of life. Use the Rule of 5000 if you have an actual repair cost to evaluate.

Exercise 4: Gas vs. Heat Pump Cost Comparison

Using the formula in Section 23.7, calculate the cost per BTU of heat for your current heating fuel and compare it to a heat pump alternative. You'll need: (a) your local gas or propane price per therm or per gallon, (b) your current system's AFUE, (c) your local electricity rate ($/kWh), and (d) an assumed seasonal COP for a heat pump (use 2.5 for a standard climate, 2.0 for a very cold climate). Does the heat pump pencil out at your local rates? What would the electricity price need to be for gas to be clearly better?

Exercise 5: Rebate and Incentive Research

Visit your electric and gas utility's websites and identify every available rebate for HVAC equipment in your area. Also check DSIRE (dsireusa.org) for state programs and the IRS website for current Section 25C tax credit details. Create a table listing: (a) program name, (b) qualifying equipment type, (c) minimum efficiency requirement, (d) rebate or credit amount. Calculate the total incentive stack available if you were to replace your system today with a qualifying heat pump. How does this change your payback calculation from Exercise 3?

Exercise 6: Manual J Exercise — Understanding Load Calculation

Request a copy of the Manual J load calculation from a past HVAC installation in your home (your documentation files or the installing contractor may have this). If unavailable, use an online Manual J calculator tool (ACCA offers resources; several contractors use Wrightsoft Online for preliminary calculations). Input your home's approximate characteristics: square footage, ceiling height, insulation levels (from Chapter 4 assessment), window area, and local climate zone. Compare the resulting load to your installed equipment size. Is your equipment appropriately sized, or does the Manual J suggest it's oversized?

Exercise 7: Contractor Quote Evaluation

Request an HVAC quote from at least one local contractor — either for a hypothetical system replacement or for an actual planned upgrade. Using the Red Flags checklist from Section 23.5, evaluate the quote: (a) Did the contractor mention Manual J? (b) Does the quote include specific model numbers and efficiency ratings? (c) Does it include permit costs? (d) Does it specify equipment warranty terms? (e) Does it include commissioning and startup? Write a one-page assessment of what the quote included and what it missed, and what follow-up questions you would ask before proceeding.

Exercise 8: Annual Maintenance Checklist

Using the checklist in Section 23.6, perform a seasonal inspection of your HVAC system appropriate to the current season. For fall: test heating operation, check filter, inspect flue pipe (conventional furnace), test CO detectors, inspect humidifier (if present). For spring: check outdoor unit clearance, test condensate drain, verify refrigerant line insulation, test cooling operation. Document each item: date inspected, condition found, action taken or deferred. Create a recurring calendar reminder for the opposite-season inspection.

Exercise 9: Maintenance Contract Evaluation

If you have an HVAC service contract, find the contract document and evaluate what it includes. If you don't have one, research what a local contractor offers. Compare: (a) annual cost, (b) what tune-up services are included (specific parts cleaned, measured, or tested), (c) what is covered vs. what incurs additional charges, (d) whether it includes parts replacement (capacitors, contactors) or only labor, and (e) whether it provides priority scheduling. Calculate whether the contract cost is a better deal than paying for individual service visits. Include a frank assessment of whether you would actually schedule tune-ups without the contract structure.

Exercise 10: SEER2 Conversion Understanding

Find three air conditioner or heat pump models listed at a manufacturer or AHRI website. For each, record the SEER2 rating. Research whether any of those models have older SEER ratings listed (check older AHRI certification listings or manufacturer archived specs). Calculate the approximate SEER equivalent for comparison (divide SEER2 by approximately 0.95 to get the approximate old SEER equivalent). Write a paragraph explaining how you would communicate the SEER vs. SEER2 issue to a family member shopping for a new AC system who has read that they "need at least SEER 16."

Exercise 11: Energy Bill Seasonality Analysis

Chart your utility bills for the past 24 months — create a bar chart or table showing monthly gas and electricity use. Identify the months where usage clearly represents heating load vs. cooling load vs. base load. Identify your home's apparent baseline electricity use (summer months with AC turned off, or spring/fall months). Use this to isolate heating and cooling contributions from other electric use. Does the pattern match your expectations? Are there months with unexpectedly high usage that might indicate an equipment or building envelope problem?

Exercise 12: Heat Pump Research for Your Climate

Identify the design temperature for your climate zone (the temperature used for heating system sizing — often the 99% design temperature available from ASHRAE climate data or your local weather service). Research two cold-climate heat pump models rated for operation at or below that temperature. For each, find: (a) rated capacity at your design temperature, (b) COP at that temperature, (c) installed cost estimate, and (d) any state or utility incentives available. Based on your local gas and electricity rates from Exercise 4, determine whether either model would produce positive annual savings compared to your current heating system.