For one U.K. homeowner hoping to move off liquefied petroleum gas, shopping for a heat pump quickly turned into a lesson in how widely installer quotes can vary.

For the same property, three separate surveys reportedly landed between 2.9 kilowatts and 6 kW for heat loss, constituting a spread one commenter on r/ukheatpumps argued was far too large to brush aside.

Here's what to know

A homeowner on Reddit laid out competing proposals from Octopus, a Local Heat Geek installer, and British Gas, showing that the differences went beyond cost alone. 

The figures shown were already net of a £10,000 ($13,253) discount, and the homeowner said their mortgage provider would add another £1,000 ($1,325) in cashback. Commenters zeroed in on the conflicting heat-loss numbers. The homeowner said Octopus and Heat Geek had both done full room-by-room calculations.

"Both can't be right at the same time!" one reader exclaimed. "You need to find out which one is accurate before deciding on the options."

The original poster replied, "I think British Gas just work on an estimate and then over-engineer the design so that it'll definitely be up to the job."

For homeowners sorting through similar questions, Palmetto can help people understand their HVAC options and slash their energy bills with new, efficient HVACs and heat pumps. Its Comfort Plan network can help you find heating and cooling solutions for your home and connect you with vetted installers.

More background

Heat-loss calculations shape nearly every part of a heat pump installation, including unit size, whether a buffer tank is needed, whether radiators need to be upgraded, and how efficiently the system will operate.

The replies also showed how broad heat pump recommendations can be from one company to the next. 

One commenter who had reviewed several surveys and ultimately chose British Gas still warned the homeowner: "Do your own calculations and check existing radiators to see if they would be suitable as the variation in your system design and heat losses is drastic."

In a separate comment, another person said their own quotes had ranged from 5 kW to 14 kW.

What can be done?

If you're comparing heat pump bids, the discussion suggests starting with a few basic questions: Was the survey done room by room? What indoor and outdoor design temperatures were used? Are radiator upgrades included? And what level of efficiency is actually being guaranteed?

It can also help to ask installers why they selected a certain heat pump size and whether the system is being designed around comfort, lower upfront costs, or long-term efficiency. If the quotes are drastically different, getting one more independent survey may be worth it.

Palmetto's Comfort Plan is another option for homeowners looking for help navigating those decisions. If you're not ready to spend up front, the Comfort Plan includes $0-down options that can lower your heating and cooling costs by up to 50%, and Palmetto Comfort Plans include 12 years of free maintenance.

Homeowners can also pair solar panels with electric appliances, including efficient HVAC systems, to push utility costs even lower. EnergySage makes it easy to find the best solar system and installer for your home and budget, saving you up to $10,000.

Where can I learn more?

If you're sorting through widely different heat pump quotes, there are a lot of factors to consider. With the right installation, though, major savings are typically the outcome.

• In the U.K., one homeowner chased a 400%-efficient heat pump and ran into installation snags.

• An appliance expert said homeowners often can save $7,000 to $12,000 with heat pumps.

• In colder regions, homeowners learned heat pumps still function in a freeze and save hundreds.

Get TCD's free newsletters for easy tips, smart advice, and a chance to earn $5,000 toward home upgrades. To see more stories like this one, change your Google preferences here.