[Dr D]

On my second try, following advice of AC guy and conforming to Honeywell diagram for "4-wire sgl stg HP (jumper intact), I have wired the HP to thermostat as follows: R=R+Rc; O=O; Y=Y+W; G=G; FUEL SWITCH set to E. Nothing works. On my first try I had R=R+Rc; G=G; Y=Y; C (Blue terminal) which should go to Common on tstat I put on B(Changeover in heat). FUEL SWITCH was on F. The fan came on but nothing else.

According to instructions and advice I now have correct connections. The HW book says: do not connect both O & B for sgl stg HP. The C from the HP is a Transformer Common according to HW book.

Could I have fried something on the tstat or the HP? Also I have left the main breaker turned on for the HP. The HP book says that will power Crancase heater to prevent harm at start-up. The AC guy here in sunny Phoenix said not to worry about it. Thanks for any sage advice;this is my first posting.

[labman]

Y and w usually are cooling and heating. In a conventional system you would never connect them both to the same contact. However, in a heat pump, maybe they just wake up the outside compressor that runs either way. O usually is the mode contact, switching the reversing valves. B or C usually is the other contact from the transformer and a blue wire. G is the fan. It is fairly easy to fry a transformer or blow a fuse. Make sure you have 24 volts between R and B. If not, and you have 120 to the transformer, it is gone. A new one should be less than $20 and easy to find.

Not sure what else to say, go through the directions some more, fool around with the fuel switch. Post back what you find, and maybe I will think of something, or somebody else will have a solution. We don't have a great track record here on heat pumps. Sorry.

You don't want to start up the compressor when it is cold enough to condense the Freon. Having it off long enough to do some troubleshooting shouldn't hurt,

[Dr D]

Sure enough I had no voltage to my thermostat. I got on the roof of my new garage addition and put the VOM to the transformer. 240 volts going in and 0 on the 24 volt output. Today I spent the princely sum of $10.50 on a new transformer, installed it, and lo and behold the AC works and the heat works. I'm a happy camper. Perhaps Honeywell and other manufacturers should put labman on their payroll to write their installation manuals.

Thanks again