How can I tell if Stage 1 and Stage 2 heating are connected correctly?

[McD2024]

I installed a new Nest Learning Thermostat using the same wiring layout as my previous thermostat.  In stage 1 the fan came on but no heat.  When I tested stage 2 the heat came on.  

After looking at the layout of the wires in the unit, I think my previous thermostat was wired incorrectly, so I switched the W1 and W2 wires in the Nest, and now I get heat in both stages 1 & 2!  Woohoo!  But how can I make sure I'm only running stage 2 heat during stage 2, and not running up a huge heating bill?

Thank you!

[kenheitland]

I have the same issue. Please reply, Google!

[CoolingWizard]

@McD2024 , what kind of heating system do you have? With a 2-Stage gas furnace, the gas valve has two flow rates, this increase in gas flow produces more heat and the blower speed increases.  In a gas furnace it is usually the furnace control board that turns on and controls the blower fan.

AC Cooling Wizard

[McD2024]

@CoolingWizard It's a Rheem electric/forced air unit, model RH1T2417STANJA

[CoolingWizard]

That model number you provided me is not a gas furnace.  That is a 2-ton air conditioning coil with the option to upgrade it with a heating kit that include circuit breaker and up to 15kW of electric heat strips. 

AC Cooling Wizard

[McD2024]

@CoolingWizard Correct, it's electric, and has two heat wires W1 and Waux.  When it comes to testing if the Nest is installed correctly it shows both stage one and stage 2 heat.  When I had the Nest wired like my previous thermostat, only stage 2 worked, so I switched the W1 and Waux now both produce heat.  

From what you're telling me it sounds like there is no stage 2 on an electric unit?  Thanks!

[CoolingWizard · Accepted solution]

@McD2024 , when it comes to electric heat strips, there are kits that give you different sizes, and for the larger sizes, you cannot turn them all on at the same time. For this reason for say a 15 KW heating system you would have what they call a sequencer that would turn on 5K at a time. Once the energy draws for the first 5K stabilizes, it was start the 2nd 5K and then after that stabilizes the 3rd 5K. So in all reality, there is no first stage or second stage heating when it comes to electric heat strips. And in the case of yours, the control board and sequence are handle all the heat. So all you should have hooked up is W1.  Having stated all this, there is a situation with your model that can cause you to have two stages of electric heat. This occurs when there are two separate heat relays built into the air handler. And your particular case I would have to know how many heat strips modules and relays did the contractor install into your unit. It’s not likely considering that your unit is only a 2 ton capacity and so therefore you wouldn’t likely have, the need for two stages of electric heat such as a 5 ton system.  

AC Cooling Wizard

AC Cooling Wizard