DTCW Series Double-Wall Water Tank Heaters

Double-Wall Protection Inside a Potable Storage Tank

A tank heater sits inside the tank, which means a tube failure discharges the heating medium directly into stored contents. Where those contents are potable water, that is exactly the event a code requirement is written to prevent.

Double-wall tubes put a vented path in that route. Two tube walls carry the heat in intimate contact, and any leak through either travels along the vented space to the tube end where it discharges outside the tank rather than into it.

The application is almost always domestic hot water storage. A boiler loop heating a potable storage tank is one of the most common commercial building arrangements there is, and it is precisely the case where a single tube wall between treated and potable water is not acceptable.

Sizing allows for the extra resistance. The double-wall interface is a genuine thermal barrier, so a DTCW needs more surface than a TCW for the same recovery rate. Combined with the low natural-convection coefficient on the tank side, that makes these units long for their duty.

Confirm the local requirement. Double-wall requirements vary by jurisdiction and by the authority having jurisdiction. It is a short conversation before the order and an expensive one at inspection.