July 12, 2004

WF-HP2 2-Speed Heat Pump WarmFlo Control

This new WarmFlo heat pump “fossil fuel kit” is being promoted for all manufacturers’ 2-speed heat pump equipment and in the future will have capability for all heat pump applications including using standard 4-wire heat/cool thermostat with 2-speed, high efficient, equipment.

Realizing the future these will play with upper Midwest Dual Heat, Electro Industries, Inc. is introducing WF-HP2 WarmFlo interface module. Although this is a universal module, and eventually could replace WF-LGR3 and WF-EZ3, its initial intent is to solve all known wiring and control requirements for all known heat pump manufacturers/brands. The design intent is simplified installation with terminal block points for all wires (as many as 9 for a roomstat, 8 for outdoor unit, 7 for variable furnace). It also has some setup pin jumper features to accomodate different functions relating to different manufacturers/roomstats and in some areas it is actually programmable so the basic unit can be updated for future requirements and future heat pump functions not known today. The front panel has 8 indicator lights plus the traditional Dual Heat override switch.

2 speed cool/2 speed heat vs. 2 speed cool/1 speed heat issue - one of the first functional decisions and somewhat controversial issue is whether or not the Electro-Mate/WarmFlo should be activated with roomstat/heat pump stage 1. The first reaction may be that it should not, stage 1 should be heat pump only to use higher efficient section of the heat pump. However, since the first stage is approximately one-half heat pump capacity there is an almost 100% possibility of heat pump blowing cool air every time the room thermostat is “waiting” for stage 2 to kick in (room temperature will also be reduced). This certainly is not what WarmFlo comfort is all about. On the other side of the coin, if WarmFlo is activated on stage 1, WarmFlo temperature sensing will simply take over and the heat pump may never be used as stage 2 heating. This is not good because the full benefit of the HP heating is not used. Electro Industries now is suggesting the heating be one stage (full heat pump at all times, maximum heat pump comfort heat) and standard manufacturer supplied 2-stage cooling. This seems to be the best of both worlds, the new WFHP2 interface controller has a setup jumper technique for field selection.

Field Service Bulletin 1087 especially addresses Bryant and Carrier new communicating thermostat products. The trade names they are using for this new thermostat are Evolution and Infinity.

We’ve completed considerable research and evaluation on this new communicating thermostat and how it ties into the outdoor unit/gas furnace. Our initial conclusion is that this arrangement is impossible for load control or any type of interrupt or a WarmFlo system. During this research we spoke to local Carrier and Bryant technical representatives, they agree there’s no known method of doing load control on this system and it has been reported to Carrier, they consider it a Carrier national problem.

Our observation is that this communicating thermostat uses an industry standard RS-485 bus arrangement and there are communication standards associated with it. However, within this digital communication there is obviously a software protocol proprietary to Carrier. For the past several years Electro Industries has used RS-485 2-wire communication on several products, we have our own protocol, but have the knowledge to build on someone else’s protocol if that information could be licensed to Electro Industries. We believe we can overcome this load control issue with the Evolution and Infinity series products if there would be a method for Carrier to license the protocol information to Electro Industries.

Electro Industries has no WarmFlo or load control or dual heat solution for Evolution or Infinity control systems as they are configured today. We are advising installing contractors and power companies these systems will probably have to be run on general service electric rate with no load control/Electro-Mate/WarmFlo and probably no rebate from electric utility.

For more information contact sales@electromn.com