October 4, 2004


This subject generally refers to furnaces or air handler products which have an ECM blower motor or where the internal blower motor control is arranged for the "G" terminal to provide low volume continuous air only. The blower speed needs to be stepped up during auxiliary heating and air conditioning. Depending upon the Electro Industries' heating product, there are two approaches:

Plenum heater with standard DFC or WarmFlo with basic single stage interface modules - during heating and cooling the blower is stepped up to the preset cooling speed by energizing the furnace Y terminal at the correct sequence or system operating mode. This can be taken care of within standard Electro-Mate DFC module, HeatChoice DEC module, WarmFlo interface module, etc. The provisions for this added installation wiring has been part of Electro Industries' products dating back to approximately 1995. It is simply a matter of adding 1 or 2 jumpers and the 5th wire from a "BL" tab terminal to the furnace "Y" screw.

Drawings HD319 and EH001 provide the hookup information for the various products.

Blower speed controlled by WarmFlo temperature sensing - the new WF-HP2 (typically 2-speed heat pump application, but not necessarily) and provisions within the WarmFlo controller provide the ability to activate the various ECM blower motor speeds depending upon warm air delivery temperature and outdoor temperature. This is standard with the new WarmFlo interface module WF-HP2 (1HEAT mode) or hookup drawing HH332 shows installation with the addition of 1 or 2 relays. In other words, the temperature sensing speed is standard with the WF-HP2 but if you desire to do this externally with relays request drawing HH332, page 3.

Please contact us with questions or for more information!