Switching from Ecobee to Honeywell

TheStressMachine

Hi, I have a high velocity AC & Heat Pump Spacepak system, and on the advice of my property manager, I'm removing the ecobee thermostat and replacing with a "dumb" honeywell because he says supporting smart thermostats is often a pain for him.

The heat pump system has two stage cooling and single stage heat.

The new thermostat is a honeywell RTH7600D.

Despite me trying to do my compatibility homework, in trying to wire the new stat and set the new system type, it seems there isn't a setting for "Two Stage Cool & Single Stage Heat Pump". The closest options are "Heat Pump without backup heat" and "1 Heat Stage & 2 Cooling Stages"

When setup as "1 Heat Stage & 2 Cooling Stages", the Cooling setting blows heat, I assume because it's not operating the O/B changeover valve.

When setup as "Heat Pump without backup Heat" the cooling works, but it doesn't appear to run two stage, the Y2 wire on the conventional side is shared with "E" on the heat pump side, so I assume the stat will never energize the Y2 wire.

Sounds like this thermostat can't do two stage cooling and and single stage heat on a heat pump, but wanted to confirm, because I'm not very smart.

My tenants are moving in soon, and I live far away now, so I'm up against the clock and probably don't have time to get another T-Stat. The high velocity system ran on stage 2 most of the time anyway, so can I just combine the Y1 and Y2 to always run it on stage 2? Or should I go through the hassle of getting a new stat (and paying a pro to do it since I'll be far away in a few days). Trying not to hemorrhage too much more money getting this place ready to rent so if there is a way to run this thing with what I have, that's ideal. If it helps, the heat pump is never used (long story), so if I can do 2 stage cool without any heat, that's also perfect.

Attached are previous and current wiring, apologies for the mess on the current.

EdTheHeaterMan

I think we need to see if @pecmsg wants to let you know that you should have selected NEST

All joking aside, I have never heard of a heat pump that has two stages of cooling and only one stage of heat. There is no logic in that. if the compressor has the ability toi have two stages of cooling then that same compressor MUST have two stages of heating when the cycle is reversed. Can you double check the Ecobee you removed to see that there is actually a 2 cool 1 heat setting... I believe you will find there is no such setting.

What is the model number of the Ecobee?

ALSO: you do not have the same wiring terminals on the old Ecobee and the new Honeywell. All seem the same however you must read the Heat Pump wire designation on the Honeywell when connecting a heat pump to that thermostat. The conventional terminal labeled Y2 is not Y2 when connected to a heat pump. It is actually labeled E which is quite different from Y2
E will act a the all stages of electric heat when the thermostat is set for emergency heat. This eliminates any compressor function for heat mode and will only operate the electric resistance heater if properly wired.

It appears that the brown wire was connected to operate the second stage of the compressor. When you select emergency heat, that brown wire will get power and cause the compressor to operate on second stage. I don't believe that is what you want. The Honeywell thermostat you selected does not have the capacity to operate a Y2 terminal on a heat pump.

The thermostat you need will have a 3 heat 2 cool designation and a connection terminal set up like this

TheStressMachine

Thanks @EdTheHeaterMan, it's very possible the heat also has two stage, but I don't see the W2 wired on it. Either way this Honeywell doesn't seem to support it, it seems to only support heat pump with aux and without aux.  And I'd be perfectly happy if the heat wasn't working at all, long story.

To your point about Y2/E I realize that Y2 is actually wired to E, since I setup the Honeywell to heat pump without aux/emergency, that wire will just sit idle I assume.

Unfortunately I'm not smart enough to get into wiring diagrams and wouldn't know where to find them.  I'm hoping there is a way to wire two stage cooling without heat at all.  I wonder if there is a way to rig it as conventional and have the O/B setting the changeover to always to cool or something like that.  I set the system to say I connected the "O" wire to the O/B port, does that mean the O/B is energized when in cooling mode?  Could I connect O and Y1 together so it always energizes the O to force the changeover into always cooling?  

EdTheHeaterMan

I have edited my original post with more info. Referesh and re-read

EdTheHeaterMan

So let me be clear. If I understand you, you are using a heat pump as a cooling only appliance. You are not using the reverse cycle during the winter. And you have no intention of using the reverse or heating cycle ever. Is that correct?

You can make that happen with the thermostat you have.

EdTheHeaterMan

What is the brand and model number of the heat pump? ...of the air handler? ...of the thermostat? ...and what are you using for heat?

Is the heater on the same thermostat?

TheStressMachine

@EdTheHeaterMan correct.  I was sold the heat as a "cool weather" option to use my solar energy instead of my steam when it's not cold enough yet, but the way high velocity is installed there are more air outlets on the higher levels of the house because when cooling you want more airflow upstairs where heat rises.  Because of this the heat pump is useless, it blasts heat upstairs and not as much downstairs which is the opposite of what you want, so we never use it.  That's the long story.

Looks like my reversing valve is "O", so can I connect that to Y1 so that it's energized when calling for cooling?  Could I then set it as conventional so it'll operate Y1 and Y2 for two stage?  

TheStressMachine

@EdTheHeaterMan sorry for not keeping up on your questions.  The air handler model is a spacepak esp-2430j.  Heat pump is a carrier 25hnb636a310.

Heat is steam on a separate thermostat.

EdTheHeaterMan

Yes you can set the thermostat for conventional and use the Y2 for second stage cooling. as far as the reversing valve is concerned, I would just wire it to R and leave it on all the time. If I know the model number of the heat pump, I can tell if the reversing valve is powered for heat or powered for cooling. O usually means powered for cooling. The companies that sell in the south usually have reversing fail in the cooling mode so you would use B to operate the reversing valve. Companies the sell in the northern climates prefer reversing valves that fail in the heating mode requiring the O to activate the reversing valve for cooling.

EdTheHeaterMan

Carrier uses O and you can wire the reversing valve direct to R and leave it powered all the time. This will make the valve stay in one position all the time and reduce the chance of failure.

EdTheHeaterMan

With that carrier model number you have a two stage compressor. For cooling only operation you can wire as follows.

Hope this answers your query

Mr.Ed

TheStressMachine

Thanks @EdTheHeaterMan, the thermostat doesn't have a 2 stage cool only, but it has 2 stage cool 1 stage heat and that'll be solved by a sticky note for the tenants ("No heat, use the other thermostat").  You helped me out of a time sensitive bind late at night, you're the best.  Send me your Venmo or favorite charity!

ratio

If you aren't going to use the heat pump heat, you can safely leave the white wire off. That will eliminate the possibility of turning on the heat strips in the air handler

TheStressMachine

@ratio yep, white was nipped and tucked, stat still has the mode enabled because of its design but it effectively does nothing.