You are right to want to avoid aux heat coming on in other than extreme cold or other unusual circumstance.

It is possible heat is moving upstairs faster than lower floors' system can provide it, pushing it into aux mode.

I wonder if there is an option to set up the lower floor thermostat to either wait longer or for a larger deviation from setpoint before it kicks on the aux heat?

Thanks Engineer for your prompt reply. I asked the the contractor/installer about it. He said that the first floor is always called due to lot of windows and as you said that heat rises. I will ask him about if there is a way the thermostat can wait longer before the auxiliary heat kicks in like setting a lower degree. Although upstairs, the heat mode now runs very often than a week ago (40 degrees a week ago) and I hope that's normal too.

This has been installed more than 2 weeks ago. Two weeks ago wasn't this cold so now is the real time and situation to test the efficiency of GHP.

Hi Connie, we need to know what brand and model of thermostat you have.

Hi Geodean, i just got the operating manual. The model is TH5000 Series (with GeoComfort brand) and it says below Non Programmable Digital Thermostat. Does this mean that I have no more option? :-(

I would imagine that it says non-programmable as it won't let you set the heat based on time of day or weekends because that's exactly what you don't want to do with a geo system.

No it shouldn't mean that. But if you put it down several degrees, don't expect to put it back up the same amount without kicking in the heating coils. That's why it's not a good idea to have a geo that you can program to operate at different temperatures at different times of day.
It should be possible to put the temperature down all you want until it the auxillary coils turn off, but ideally, this shouldn't be necessary.

Senecarr, thank you. No I didn't put the thermostat several degrees down. I set it one degree down and as soon as I do that, the auxilliary heat comes off. Now it is set to 66 degrees. As everyone is advising, it has to be set at one setting but I don't want to pay a big utility bill if the auxilliary heat is the one that is working and I would be very dissappointed if I get $500 bill for a month then that really defeat the purpose of installing a GHP.

Connie,

I can't locate an online manual for your tstat. There should be a way for you to have some control over the strip heat.

Two things you could do:

1) Ask the installer to help you program the tstat

2) Scan your manual and post it here so we can help.

Ok dean, i will try to scan that as soon as I can. I appreciate your help a lot!

your problem is your aux heat is controlled by a timer in the thermostat, most are .

There are 3 ways to controll a traditional heat pump ( which all heat pump thermostats are set up for ) you need a fourth option , I have one for you.

Take 2 honeywell pro-8000 with the ots ( out door temp. sensor option ) you will need wires from each thermostat to the outside. These t-stats can be set up to only run your heat pump to a adjustable outdoor temp ( I beleive 10-50 in increments of 5 ) and below this temp only your aux will run. ( I know but where only half done )

What you want is a call for aux to also energize your heat pump and only turn on your aux if both zones are calling at the same time . This requires 2 RIB relays

Show this to your installer

After Pro 8's and ODTS installed

T-stat side of board zone 1 W-1 / E hooked to aux with a jumper to E on t-stat , pigtail off of this connection on zone board and use it to energize a rib relay , repeat with second , to the second relay

On the equip side of zone board jump out E/aux to Y

In the air handler Run R through the end switch side of the relay back to you aux terminal on your air handler board .

Considering most systems can satisfy either zone by itself just about regardless of out door temp

Just remember if you ever NEED aux heat you will have to have both thermostats calling at the same time

your thermostats may say they are calling for aux heat but it wont be on if only 1 thermostat is calling

Any questions?

Geo, that was very technical but i will show it to the installer.

Quoted:Just remember if you ever NEED aux heat you will have to have both thermostats calling at the same time

your thermostats may say they are calling for aux heat but it wont be on if only 1 thermostat is calling

Does this mean even the thermostat on first floor says my auxilliary heat is on, it is really isn't because there is only one thermostat calling?

thank you and to other pro in this board..i'll keep you posted!

Sorry about the technicality , its the only way I could explain it .

If the system is wired this way , Yes a t-stat my be sending a signal for aux heat and not energizing .

The relays act like light switches only turning on when a thermostat is asking for aux heat . the power from 1 switch would feed directly into the next switch , so they would both have to be on for the power to get to the airhandler

You could just disable aux heat at the thermostat by disconnecting the "w" wire. This is what I have done on mine.

Geo, if I disconnect the auxilliary heat by pulling th W wire completely, will there be any consequence once the temperature outside becomes single digits? Will it damage the geo units if its struggle to meet the heat demand because of lack of back up?

Geofan's solution or something like it might be best, but may cost well north of $500 to install and troubleshoot. High end thermostats aren't cheap, then there's the sensors, relays, etc as well as the wiring through outside walls.

I was thinking along Dewayne's lines - lose the W connection. However, Connie's latest concern is valid - no W means no aux heat ever, a problem if system is sized to use aux on very cold days, which many are.

Some thoughts / options:

First of all I'd lose the W (aux heat) on the upstairs stat entirely. That will simplify the problem considerably, and we know from Connie's earlier posts that upstairs should never need aux heat (less area, less glass, warm air rises from below)

So, concentrating on ways to control aux heat calls from downstairs only - four options, with advantages / disadvantages:

1) Add a simple on / off switch at / near downstairs stat - On = allow aux heat Off = disable aux heat. Advantages - very simple to implement, lowest cost. Disadvantages - strange looking, non-standard, inelegant, no automatic control.

2) Add a second simple heat-only thermostat in place of switch above, and set it several degrees below normal heating setpoint. That way if the main stat energizes W for aux heat, 2nd stat would intercept it and only allow aux heat if 1st floor is well below main stat setpoint. Advantages - fairly simple, inexpensive, provides automatic control. Disadvantages - still non-standard, possibly confusing to operate - would have to remember which stat does what.

3) Outdoor temperature sensor / switch separate from thermostat - probably wire from heat pump to nearest convenient point outside. Essentially an outdoor thermostat, it would allow aux heat only if outdoor temp falls below a certain temp. I'd want that to be adjustable, and start at the temperature where design calculations suggest Aux heat will be needed, perhaps 10-20 degrees. Advantages - most 'elegant' sleekest - totally automatic operation, nothing strange for user to look at / deal with. Disadvantages - most expensive (but likely cheaper than Geo Fan's setup), also, making decisions based on outdoor temp ignores what's going on indoors, where we live.

4) Bear in mind we are trying to design and implement a 'band-aid' to fix an apparent design flaw in the downstairs stat - what is really needed is a smarter downstairs stat that knows (and can be adjusted in setup) to call for aux heat. I'd want one calling for aux heat only if main heat has been running for X minutes (30, 60, 90, 120, whatever) AND room temp is Y degrees below (2,3,4,5, whatever). It somewhat irks me that we are having to try to fix what seems to be a pretty basic, common situation. If anyone knows of a stat so configurable, bring it on!

My favorite (assuming 4 is nowhere to be found) is 2, but we engineers are often (sometimes with good reason) accused of overly complicating things for users.

Finally let me reiterate what you seem to  already know / fear - aux heat costs 4-5 times as much to use than the geo, and if it comes on often and inappropriately, then the electricity bill will be very high and savings from geo will not be realized.

Disclaimer - I live in FL, we don't put aux heat in geo - I've never rolled up sleeves and worked through this 'on the ground'.

There is little worry about damage to the geo unit if you disable aux heat.    

I also like engineer's #2 work around.   For the same reasons he stated.

I like the number 4 option , you could use a low voltage Ranco controll , it does simplifiy my solution

I meant number 3 , the only difference/down side between mine and number 3 is the down stairs would get aux. heat by itself , this may never be nessasary , but only a floor by floor manual J calc will tell you this.