A U.K. homeowner facing a full renovation wanted to modernize and future-proof their building. They wanted a heat pump, but the renovation team was "anti-heat pump."

Not fully bought into the builders' advice, the homeowner turned to Reddit to ask whether a combi boiler or an air-source heat pump makes more sense. 

Because the project already includes major plumbing and insulation work, it's important to make the right call now.

Here's what to know

The homeowner said they plan to stay in the home for 15-30 years. For that reason, they said they wanted to settle the heating question during this renovation. In a Reddit post, they described a renovation that would replace the windows and doors, redo the plumbing throughout, and add insulation "where necessary," then asked, "How bad is retrofitting ASHP if I choose combi today?"

The thread quickly addressed timing. Most commenters said this is the point to choose an ASHP rather than leave the switch for later.

As one commenter wrote, "If it's a full renovation with a full replumb and insulation, a heat pump is a no brainer." Another argued that sticking with gas carries longer-term risk, saying, "Homes built around gas heating today are a future liability."

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That was the theme that came up repeatedly in the thread. Commenters said the homeowner should rely on certified heat-pump specialists instead of a general building team that is "anti-heat pump."

More background

The house is a 1930s cavity-wall semi already headed for a full renovation, and the homeowner said the budget was tight enough that underfloor heating was off the table, though larger radiators were still possible.

One commenter pushed back on the build team's advice: "Their aversion is likely because they don't understand how to do it properly."

Commenters said radiator sizing, pipework changes, and hot water setup are far less disruptive when walls and floors are already open. One commenter also warned against a combi because it removes the hot water cylinder, which "at minimum greatly benefits" electric heating systems.

One commenter said their heat pump was "already costing half as much to heat the house," while another said that after switching in September 2024, they had "already saved £280 this year versus gas" (around $371 USD) and expected that to rise to "nearer £400" ($531 USD) by year's end.

What can be done?

Deciding based on a general builder's preference can come at a cost. In this case, the homeowner could be locked into gas prices for decades. Commenters said the next step should be a heat-pump-specific survey before locking in a boiler. 

Commenters said the minimum move is to make the home heat-pump-ready during the replumb by using upsized radiators and larger pipework. If upfront cost is the sticking point, the Comfort Plan includes $0-down options that can lower heating and cooling costs by up to 50%, and Palmetto Comfort Plans include 12 years of free maintenance.

Commenters still encouraged planning around batteries and solar. They said battery storage, off-peak charging, and a hybrid inverter can all improve the economics of an electric heating system later.

Homeowners can also pair solar panels with electric appliances, including efficient HVACs, to drive their utility costs even lower. EnergySage makes it easy to compare solar options and find the best solar system and installer for your home and budget, and it can help homeowners save up to $10,000 on solar installations.

The original poster was receptive to the comments, writing, "I think based on today's comments it'd be worth getting the surveys done and go from there."

Where can I learn more?

These articles dig into heat pump questions about timing, cost, and finding the right installer. 

• In the U.K., one homeowner found the switch gets messy once retrofit complications stack up.

• After hearing conflicting advice, homeowners said it's a comfort issue as much as savings.

• On Reddit, skeptical homeowners kept asking whether they actually save you money.

• Heat pumps can be 5 times more efficient than older systems in many homes.

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