Indirect Water Heaters

An indirect water heater makes domestic hot water using heat from a boiler. Hot boiler water circulates through a coil inside the tank and heats the potable water around it, so the tank has no burner of its own. Paired with an efficient boiler, an indirect tank can deliver a large supply of hot water.

This collection includes the indirect water heaters we carry from several brands. IBC tanks use 444 stainless steel and come with an aquastat, in sizes from 26.8 to 119 gallons, including the DTI-40, DTI-55, DTI-65 and DTI-80 models. AquaFlow indirect-fired water heaters are made of stainless steel in 30 to 119 gallon sizes. Heat-Flo offers 30 and 40 gallon indirect tanks with top connections, plus a 60 gallon high-output model with an element.

Size the tank to peak hot water demand and to the boiler output available for the domestic hot water zone. Confirm the coil connections and the boiler supply temperature, and decide whether the tank will be piped as a priority zone. Install a T&P relief valve, and a thermostatic mixing valve where required.

Shop boilers, all Heat-Flo products, mixing valves and water heater T&P relief valves.

Frequently asked questions

How does an indirect water heater work?

Hot water from the boiler runs through a coil inside the tank and heats the potable water around it. The tank has no burner or flue of its own.

What size indirect water heater do I need?

Size it to peak hot water demand and to the boiler output available for the hot water zone. Check the first hour rating and the coil connections.

Does an indirect tank need an anode rod?

Stainless steel tanks such as AquaFlow need no sacrificial anode. Check the product details for other brands.