The mention of aux heat perked my interest. At -7C (20F) outside with set point 70F.  When the furnace reaches 71F it disengages. As the thermostat drops to 68F Stage 2 kicks in.  Then a few minutes later aux heat comes on runs for approx 10 minutes to get to 69F stage2. It then runs for about 15 minutes to reach 70F stage 1.   I have a 6ton Waterfurnace and a Waterfurnace thermostat. I have 3700 ft of piping. Is this normal that the aux heat comes on when the temperature is two degrees less than the set point? I an using 90K of electricity per day. (outside temperature ranges from 10F to 32 F)

That could be normal. Activating aux is done by the thermostat or zone board, and configurations vary. Some are changeable.

By 90k I assume you mean 90 kWhr. Is that just heating or whole house?

Michael, this is your third thread in 4 days all related to staging (1st, 2nd, and aux). You have unanswered questions in the other 2 threads. We'd be happy to help, but you need to help us help you by answering relevant questions and by keeping your related questions in one thread.

What is your thermostat brand and full model number? Is your Water Furnace an Envision, or another model?

While this is the way your thermostat is currently set up to function, that doesn't mean that some settings can't be changed for the better. To me, it is senseless for a thermostat to call for second stage and then shortly call for aux without giving the system time to try to catch up with the extra 1/3 capacity it enabled by engaging 2nd stage.

As the thermostat drops to 68F Stage 2 kicks in

Michael, I think you are being confused by the use of the word "stage". It is applied to both thermostats and compressors and unfortunately does not mean exactly the same thing for each one. Moreover, the terms do have some loose connection making the whole picture even harder to discuss or sort out.

For example, as it applies to compressors; almost none of the compressors discussed here are true two-stage units, even though they are referred to as "two-stage". Technically, a stage is a separate engineering process. In these scroll compressors, Stage 2 is just a further continuation of the same Stage 1 process. I'm not saying this description should be used, but maybe another way to think of it is "low power" (more efficient) or "high power" (a little less efficient, but more output).

Your thermostat also has "stages" during which it sends signals to the heat pump. In (thermostat) Stage 1, it says to the heat pump "Hey, I've got a temperature setting we need to try to get to, so start up and get to work." That engages (compressor) "Stage 1". That is the most efficient output stage for the compressor.

After a while, the thermostat sees that it isn't at the desired setpoint (or it isn't getting there fast enough) and decides to enter (thermostat) Stage 2. Now, it tells the heat pump "We aren't doing well enough, better work harder." At that point, the heat pump compressor goes to (compressor) "Stage 2" - full output.

After a while longer, the thermostat sees that it still isn't where it wants to be and decides to enter (thermostat) Stage 3. It tells the compressor "Keep giving me full output" (compressor) "Stage 2", but it also sends a signal to the resistance coils (AUX) to start up and start heating as well. What's even more confusing is that the aux heat resistance coils have their own "stages" in which 1 coil, then the next and the next and so on start up in order to supply enough heat to meet whatever the demand is.

Normally, all of these operations are time sequenced, giving each piece of machinery a reasonable amount of time to do its job before the next "Stage" is entered. Depending on your thermostat and other options, you can probably override and cause these things to occur in different ways.

Finally, depending on inputs, it is possible for the thermostat to enter "emergency" stage in which it decides something might be wrong, so it shuts down the heat pump compressor and the loop pump and goes just to distributing AUX (resistance) heat.

Hope this helps you in describing what is happening.

I have a Waterfurnace Envision and a Waterfurnace thermostat non programmable TP32U03. And I use 90kw heating and electricity included.

Michel, I'll PM you recommendations tomorrow. :-)

Posted By ICFHybrid on 06 Feb 2011 03:29 PM
Michael, I think you are being confused by the use of the word "stage".
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I didn't know the stage thing was so complicated, but it's clear as mud now with this rosetta stone!

Posted By ICFHybrid on 06 Feb 2011 03:29 PM
Michael, I think you are being confused by the use of the word "stage".
Hope this helps you in describing what is happening.

I didn't think Michael was confused.
I think Michael described the situation well.

A "D" for ICF Hybrid's explanation.  (I suppose that would be a 1.0 GPA in 4-year chemical engineering school lingo!)
An "A+" for ICF Hybrid's ability to conceal the fact that he has no geothermal experience.

Posted By ICFHybrid on 06 Feb 2011 03:29 PM

...the terms do have some loose connection making the
whole picture even harder to discuss or sort out.

Yes! ...if "loose connection" means that each wire has two ends.
Three signals controlling three stages ...a veritable brain-buster.

...possibly that's not the only "loose connection" here?

Looby

Michael, I'll just post my suggestions here. You should check with your installer before making any thermostat changes to the Installer Settings to make sure this is ok with them.

Here is a link to the TP32U03 manual from Water Furnace:

http://www.waterfurnace.com/thermostats/TP32U03-5.pdf

1) It appears that this thermostat can be set up to be either programmable or non-programmable in the Installer Settings. If you maintain a fixed thermostat set point 24 /7, I would leave the thermostat as non-programmable.

If you vary the temperature at consistent times, I would change the thermostat mode to programmable, and use the programming capability of the thermostat, but don’t vary the programmed temperature by more than 2f. Also, do your best to avoid manual temperature changes to the thermostat. This can bring on higher stages faster than using programmed temperature changes with Smart Recovery (see #2.) During very cold spells, it may help avoid aux if you don’t set back at all.

2) If using the programmable mode, make sure Smart Recovery is enabled. This will help avoid use of higher stages with programmed temperature increases, but may not eliminate them.

3) Smart Heat Staging – I would only try this if aux is still engaging after you have tried everything above. This setting will enable you to delay aux heat for up to 120 minutes, but if the thermostat is still not satisfied (i.e. the geothermal system is still running) by the end of the delay time you set, aux will come on at that point, even if there is only 0.1f left to satisfy the thermostat.

4) If you have an outdoor temperature sensor installed (you will see the outdoor temperature displayed on your thermostat if you have the outdoor sensor installed), you can use the Electric Heat Lockout feature. This setting will prevent aux heat from engaging if the outdoor temperature is above the lockout temperature you select. I list this last since you should disable this feature if you go away (to make sure aux and emergency heat engages if needed when you are away to prevent the house from freezing.)

If you know the system design temperature, (the outdoor temperature at which the geothermal system can’t maintain the thermostat set point on its own) you can try setting the Electric Heat Lockout maybe two settings higher than this temperature (originally suggested by Joe many moons ago.) For example, if your system design temperature is 12f, the next higher setting is 15f, then 20f. I would start with 20f. If you set this too low, aux heat will not engage when needed, and your indoor temperature will drop.

You can handle the F. to C. conversion. I hope this helps. :-)

A technician resolved the problem. Hopefully. He reconfigured the differential , the cycles per hour and the smart heating staging on my Waterfurnace thermostat. He aslo set the heat at manual instead of automatic. It is 4F and the setpoint is 70F and the system is maintaining that temperature at Stage 1 so far. Last the time the temperature was 4F the system although set at 70F ran at 69F stage2 for over a day.

Great news. :-) Keep us posted.