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LBrad2 · Nov 8, 2009, 03:04 PM

I have been having problems for sometime with heat pump system & thermostat. I am trying to replace a Honeywell RTH7500 with a LUX TX500.

The old Honeywell had this "Wait" feature that kicked in all the time and we could not get any heat.

The new Lux thermostat only has five terminals:
I attached the wires as follows:

G - Green wire (Fan)
Y - Yellow wire (Cooling Relay)
W - White Wire (Heat control)
RH - Red Wire (Heat Transformer)
RC - Jumper to RH Terminal

I have a BL (Black) wire and a O/B (Orange) wire that are not hooked up. But were used on the old Honeywell.

My problem is I get heat now but the compressor does not come on. I fear that I am just using the electric backup and by electric bill will be outrageous.

PLEASE HELP!

Joshdta · Nov 8, 2009, 03:07 PM

You can not use this stat with a heat pump, you must have a stat that says 2 heat 1 cool

LBrad2 · Nov 8, 2009, 03:12 PM

Any suggestions? I know the old Honeywell is supposed to work but it just doesn't. I can't understand why?

Joshdta · Nov 8, 2009, 03:15 PM

Most honeywells have a installer setup, where you can take the time delay from 5 minutes to 0, do you still have the books on it?

KC13 · Nov 8, 2009, 03:16 PM

The "wait" feature is typically activated after lost power is restored, or immediately after a cycle ends. I would be compelled to check the control wire connections at the indoor unit before condemning the original thermostat.

LBrad2 · Nov 8, 2009, 03:18 PM

I do still have the book. The thermostate worked for 18 months. Then when I tried to use heat this season, I kept getting "wait" soI tried to get another thermostat to see if I could rule out a thermostat vs. a control unit problem. I could try to put the Honeywell back to see if it will work but I don't think it will.

KC13 · Nov 8, 2009, 03:20 PM

Look in the book for a setup option that allows you to select recycle delay. See where it is set currently, then try turning it off.

Joshdta · Nov 8, 2009, 03:21 PM

You are saying the old stat would never go off the wait mode?

KC13 · Nov 8, 2009, 03:22 PM

Sorry J, didn't see where you had already suggested that 'til it was too late..

LBrad2 · Nov 8, 2009, 03:23 PM

"Wait" mode did go away however no heat ever came on. As soon as I tried to change the temp the wait would come back on

Joshdta · Nov 8, 2009, 03:26 PM

When the wait went off, did the indoor fan or anything start to run?

KC13 · Nov 8, 2009, 03:26 PM

Perhaps a call to Honeywell Technical Support is in order. Is the # anywhere on the stat or in the book?

LBrad2 · Nov 8, 2009, 03:28 PM

After wait mode ended no fan no compressor. No heat

Joshdta · Nov 8, 2009, 03:29 PM

You can try jumping the wires at the stat, but sounds to me like you are going to need anouther stat, once the wait goes off, there should not be anouther wait just because you changed temp, the wait should be if you go from heat to cool, or from off to heat or cool.

KC13 · Nov 8, 2009, 03:30 PM

Does this thermostat use batteries, or is the "C" terminal connected?

LBrad2 · Nov 8, 2009, 03:31 PM

I think I will try to put the Honeywell back to see if it will work. However, the Lux at least gave me Aux heat & fan but no compressor. The Honeywell gave no heat at all.

Joshdta · Nov 8, 2009, 03:37 PM

Turn the power off at the indoor unit, and put the r the y and the o wires together up at the stat. Turn the power back on. The heatpump should start after the 5 min delay outside goes off. Then if that works and you put the stat back on and it does not work then you know the stat is bad.

Kc asked a good question, is the c terminal hooked up?

LBrad2 · Nov 8, 2009, 03:40 PM

On the old Honeywell C was connected. On the new Lux it is not. Both thermostats use batteries. I will try to reconnect the honeywell & make sure that C is connected