Wiring an Indirect Water Heater to One Heating Zone Oil Boiler and Creating A Priority Zone

Are you tired of buying a two-zone control when you have one zone of heat and an indirect water heater? Here is a straight forward way around that problem. Buy a single zone relay like a Taco SR501 and you have a $$$$ cheaper control and will prioritize the indirect. You gain indirect priority and save money in the process.

I have seen many jobs with a single zone of heat, using separate circulators and indirect where they wired in a two-zone control so separate the indirect from the heating thermostat. This wastes money on the control, labor and wire.

I have included two drawings below. One will show the wiring with a Honeywell L4006A Aquastat on the indirect and the second with the Vaughn tanks, Velocity Boiler or US Boiler TPI Control on the indirect. The major difference is the TPI control requires a constant 24v power supply to the control. The TPI control is used on stone lined tanks and will avoid overshooting the tank which the L4006A will not do on the stone lined tanks.

Indirect with L4006A Aquastat.

Indirect with the Vaughn TPI Control

Disclaimer: The information found on this website is for informational purposes only. All preventive maintenance, service, installations should be reviewed on a per job situation. Any work performed on your heating system should be performed by qualified and experienced personnel only. Comfort-Calc or it's personnel accepts no responsibility for improper information, application, damage to property or bodily injury from applied information found on this website as it should be reviewed by a professional.