Boilers - Electric AT AT Electric Boiler Series Absolute Efficiency – Total Comfort! 100% Fuel Efficient Zone Valve Controls AZ4CP/AZ6CP AZ4CP/AZ6CP Zone Valve Controls AZ3/AZ5 AZ3/AZ5 Zone Valve Controls More flexible and convenient than ever before! Hydro Air Zone Controls ARH ARH Hydro Air Zone Control ARGO Hydro-Air Controls provide the easiest way to interface between the thermostat and air handler. These dependable control relays will control from 1 to 20 zones of heating/cooling and provide priority switching for domestic hot water. Boiler and A/C condenser wiring is virtually fool proof. Switching Relays & Accessories ARM2P - ARM6P ARM2P - ARM6P Switching Relays With Priority IR882 IR882 Isolation Relay for up to 3 Zones AD1-AD4 AD1-AD4 Add On Zoning Modules for ARM Control AR822II AR822II Single Zone Relay AR861-2II/AR861-3II AR861-2II/AR861-3II Two and Three Zone Relays with Priority Easy, Economical Zoning with Circulators Modular Boiler Controls AMB4A/AMB8A AMB4A/AMB8A Boiler Control Fuel savings combined with consistent comfort! Outdoor Setback DPM2 DPM2 Outdoor Setback Control Increases hot water boiler efficiency, lowers heating bills, increases comfort. Temperature Guards AR500-1 Temperature Guard Plus AR500-3 Temperature Guard Guard against costly damage caused by temperature fluctuations or power failure while away.