Backup for the coldest hours
A handful of hours each winter are colder than the design temperature. The boiler covers them without oversizing the heat pumps.
Heat pumps alongside your boiler or furnace.
You do not have to rip out a working boiler to go electric. Many owners let heat pumps carry most of the winter and keep the existing system for the coldest hours. Done properly, the two work as one system instead of fighting each other.
Why owners keep the existing system
Hot water
Where the boiler also heats the household water, it can keep doing that job while the heat pumps take over the rooms.
Hard-to-reach rooms
A bathroom or back hall that no indoor unit reaches well can stay on radiator heat.
Spreading the cost
Heat pumps can go in now, with the boiler retired later when it reaches the end of its life.
How the handoff works
Integrated controls decide which system runs, so nobody has to remember to switch anything.
Setting the switchover
The switchover temperature is not a factory default. We set it from two numbers: the heat pumps’ published capacity at low temperatures, and the house’s calculated heat loss at those same temperatures. Below the point where the heat pumps can no longer keep up, the boiler is allowed to help.
A lower setting means more of the season on heat pumps. We record the setting and the reasoning behind it in the job file, and revisit it at the follow-up visit after the first real cold stretch.
Without integrated controls, a thermostat on the old system will often run the boiler first out of habit, and the heat pumps sit idle. That is the most common reason a hybrid system disappoints.
When to retire the boiler
There is no single right answer. These are the things we look at with you.
- Age and condition
- A boiler near the end of its life, or one needing an expensive repair, is a natural point to let the heat pumps take over completely.
- Whether heat pumps can carry the load
- If the load calculation shows the heat pumps meet the whole house at your town’s design temperature, the backup has little left to do.
- Hot water
- If the boiler also makes the hot water, retiring it means a separate water heater first.
Will both systems ever run at once?
Only when the controls call for it: on the coldest days, or when a room falls behind. The rest of the time one system runs.
Can I remove the boiler later?
Yes. If the heat pumps are sized to the whole load from the start, retiring the boiler later needs no change to them. If they were sized to work alongside it, some rooms may need more capacity first.
Do I need a new thermostat?
Sometimes. The two systems have to be coordinated by integrated controls, and whether the existing thermostat can stay depends on the equipment. The quote names the controls and says whether anything on the wall changes.
Keep it, or retire it?
At the assessment we look at the boiler, the house and the numbers, and tell you plainly which makes more sense for you.