If your home or building is heated by a boiler, there's a good chance it can do more than keep the radiators or floors warm. With an indirect water heater, that same boiler can also make your household hot water. For a lot of Western Montana homes, it's one of the most practical upgrades you can make to a hot-water heating system.
I'm Jeremy, owner of ProCare Climate. I've spent more than ten years doing hands-on HVAC work around Missoula and Western Montana, and indirect water heaters come up a lot when I'm working on boilers and radiant systems. Here's a plain-language look at how they work and whether one makes sense for you.
What Is an Indirect Water Heater?
A regular tank water heater has its own burner or electric elements that heat the water inside it. An indirect water heater doesn't. Instead, it's an insulated storage tank with a heat exchanger coil inside. When you need hot water, your boiler sends heated water through that coil, and the coil warms the water in the tank. The boiler water and your drinking water never mix.
The tank is basically treated as one more zone on your boiler, with its own thermostat and a pump or valve that calls for heat when the tank cools down.
Why Boiler Owners Like Them
One heat source instead of two. You're not running and maintaining a separate burner just for hot water.
Plenty of hot water. A boiler can usually reheat an indirect tank quickly, which helps when the whole household is showering in the morning.
Fewer things to vent. A gas or propane tank-style water heater needs its own venting. An indirect tank doesn't, because the boiler is doing the heating.
A natural fit with radiant heat. If you have radiant floors or baseboard heat, the hot-water system is already there. Adding an indirect tank uses equipment you already own.
Is It a Good Fit for Your Place?
Indirect water heaters make the most sense when:
You already have a boiler, whether it runs on natural gas, propane, or another fuel, or you're planning to put one in.
Your boiler is in good shape and sized well. The boiler now has two jobs, so it needs to handle hot water without leaving the house short on heat during a cold snap. Many systems give hot water priority for short periods, which works well when the setup is designed right.
You're replacing an old water heater anyway. That's often the easiest time to make the switch.
You're building new. In new construction around Missoula, Lolo, Stevensville, Hamilton, or Polson, it's simple to plan the boiler, radiant heat, and indirect tank together from the start.
If your home is heated by a forced-air furnace and has no boiler, an indirect tank usually isn't the right choice. A standard water heater or a different setup will make more sense, and I'm happy to talk through options.
Heat Pumps and Hot-Water Heat
More homeowners are asking about heat pumps that tie into hot-water heat. Some of these setups can also work with an indirect tank, often with the boiler still on hand for backup during the coldest stretches of a Montana winter. Whether that works well depends on the equipment and the house, so it's something I'd want to look at in person. You can read more on our heat pump installation page.
Multi-Unit and Commercial Buildings
Apartment buildings and commercial spaces with central boilers can use indirect tanks too, sometimes larger tanks or more than one. ProCare Climate works on multi-unit building boilers and commercial systems, including new construction, and I work on all brands, major or not.
Keeping an Indirect Water Heater Running Well
Indirect tanks are generally low-maintenance, but they aren't no-maintenance. A few things worth knowing:
Have it checked with your boiler. A yearly boiler service is a good time to look over the tank, the controls, and the pump or zone valve feeding it.
Watch the relief valve. Every water heater has a temperature and pressure relief valve. If it's dripping or discharging, call a pro.
Notice changes in hot water. If hot water runs out faster than it used to, or takes longer to recover, it could be a control, pump, valve, or coil issue.
Look for leaks around the tank fittings and the piping to the boiler.
If your boiler needs attention before winter really sets in, see our boiler service in Missoula page.
Permits and Inspections
Installing a water heater or changing a boiler system typically involves a permit. I pull permits and schedule inspections, so you don't have to chase down that paperwork yourself.
Thinking About an Indirect Water Heater?
Whether your old water heater is on its last legs, you're planning a new build, or you just want to get more out of the boiler you already have, I'm glad to take a look. Call ProCare Climate at 406-546-1289, any time, 24/7, or request a free install estimate on our website. We serve Missoula, Lolo, Frenchtown, Stevensville, Hamilton, Polson, and communities across Western Montana.