With summer electric bills reaching about $800, a Dallas homeowner looking to replace an aging air conditioner wanted to know whether variable-speed equipment was worth the extra cost.

The homeowner turned to Reddit for advice.

Here's what to know

At nearly double the cost of basic replacement, the homeowner wanted to make sure the cost is worth the savings.

Downstairs has remained comfortable on the existing equipment, while a separate system handles the upper floor. In their Reddit post, the homeowner described the downstairs setup as a 4-ton Goodman air conditioner that's about 20 years old, paired with a gas furnace and serving roughly 2,000 square feet.

A gas furnace and evaporator coil are part of the $15,000 bid, along with a Goodman air conditioner rated at 14.3 SEER2, a 5-ton, single-stage model. The price also covers some replacement ductwork and service to a small back room.

Meanwhile, the contractor put the price of a variable-speed Trane option at about twice the $15,000 quote.

Zoning also interested the homeowner as a possible way to save energy: the household mainly uses three of the six downstairs areas. 

For homeowners comparing HVAC setups, Palmetto helps evaluate efficient HVAC and heat-pump solutions and connect with vetted installers through its Comfort Plan network.

More background

Poor insulation is one of the biggest drawbacks of the roughly 113-year-old home.

"Great house but comes with some flaws," the original poster wrote.

Humidity control could suffer with an oversized air conditioner, cautioned a commenter who said they had spent more than 32 years as an air-conditioning contractor. That warning was part of a discussion questioning the proposed jump from 4 tons to 5.

Inverter technology does not eliminate the need for a Manual J load calculation to size a system, another commenter stressed.

If you're exploring your options but don't want to spend upfront, Palmetto's Comfort Plan offers $0-down options with heating and cooling cost reductions of up to 50%. It also includes 12 years of free maintenance.

What can be done?

A commenter said both the main supply trunk and return would need to be checked for the extra airflow before increasing capacity.

Instead of putting the whole price difference toward variable-speed equipment, one commenter recommended tackling insulation. Other replies seconded the need to upgrade insulation first.

"Do you know what requires almost zero service for the next 50 years? Insulation," one commenter said.

For homeowners considering an efficient electric HVAC system, pairing it with solar can help manage utility spending and make the home more self-reliant. EasyHome offers a solar comparison-shopping tool to help homeowners compare installation offers and make sure they get the best deal.

A look at the house itself should come before an equipment decision, according to the commenter with decades of air-conditioning experience.

"Have you had an energy audit done on your house? Maybe some leaking ductwork is an issue."

Where can I learn more?

Other homeowners have also wrestled with high HVAC quotes and doubts about how well new equipment would work.

• A Texas homeowner's $12,000 AC replacement led to a recommendation to buy a dehumidifier.

• In Dallas, a new $10,000 HVAC system struggled to hold 72 during the hottest afternoon hours.

• A Texas homeowner's $950 winter power bill prompted HVAC pros to flag costly heat-strip use.

• A New Mexico homeowner with $400 summer bills heard a mini-split could run for $0.25 hourly.

• After an AC failed in 105-degree heat, a homeowner faced a $22,000 replacement quote.

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