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 > Need help with a SF 30 Suburban Furnace

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enblethen

Moses Lake, WA

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Joined: 01/05/2005

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Posted: 11/14/20 12:06pm Link  |  Quote  |  Print  |  Notify Moderator

What extra switch?


Bud
USAF Retired
Pace Arrow

2003 Chev Ice Road Tracker


mikestock

Vestavia Hills, AL, USA

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Posted: 11/14/20 06:15pm Link  |  Quote  |  Print  |  Notify Moderator

Maybe I'm not understanding the location of the switch on p. 20. I thought it was a separate switch, not part of the thermostat.

I admit that I have not spent a lot of time studying the manual since, at this point, I have committed to an exact replacement for the OEM thermostat.

enblethen

Moses Lake, WA

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Posted: 11/14/20 06:21pm Link  |  Quote  |  Print  |  Notify Moderator

The switch is located in the thermostat just below the battery back-up.
Very easy to switch out wiring. Use the included stick on labels to mark each wire as to their location on terminal strip which labels function. then install in new thermostat per instructions.

mikestock

Vestavia Hills, AL, USA

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Posted: 11/15/20 06:51pm Link  |  Quote  |  Print  |  Notify Moderator

I'm looking at the touch pad menu and don't see anything that allows selecting gas/heat pump. The nature of the beast says that a heat pump will only work down to about 40 degrees. If I tell my wife she has to take the cover off the thermostat to do anything, she would look at me like I'm crazy. She has enough trouble with the settings right in front of her.

enblethen

Moses Lake, WA

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Posted: 11/15/20 07:18pm Link  |  Quote  |  Print  |  Notify Moderator

If you are talking about the Lux, Switch is a mechanical one on the back of thermostat body. Your existing thermostat is for heat pump only.

mikestock

Vestavia Hills, AL, USA

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Posted: 11/16/20 07:26pm Link  |  Quote  |  Print  |  Notify Moderator

emblethen wrote:

Your existing thermostat is for heat pump only.


Wrong. It has ac, off, gas heat, heat pump.

enblethen

Moses Lake, WA

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Posted: 11/16/20 07:47pm Link  |  Quote  |  Print  |  Notify Moderator

Your model is for an A/C and heat pump. That is what HP on model number means. It does not have internal mechanism to run a standard propane or electric furnace.
You might what to get some professional assistance!

dougrainer

Carrolton, Texas

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Posted: 11/17/20 07:50am Link  |  Quote  |  Print  |  Notify Moderator

https://www.airxcel.com/rv/coleman-mach/thermostats/digital-thermostats

This should be your Tstat. 6536A3351
2-Stage Heat Pump & Gas Furnace - White

It controls both Furnace and HP function. Plus AC. The color control at the Tstat will NOT be the same at the furnace to those 2 BLUE Furnace wires. AT the furnace, ONE of the 2 blue wires should be 12 volt positive. This goes back up to the wall tstat. When you select FURNACE, the second blue wire is then 12 volt positive from the wall tstat. This runs the furnace like your bench test. It makes NO difference which blue wire is used. IF one of the blue wires is 12 volt positive and when you select furnace the 2nd blue wire is NOT 12 volt pos, then you have a problem in the circuit from the tstat to the furnace and replacing a different brand/model tstat will not fix the problem. You should have 2 wall tstats, unless you have the single ZC wall tstat. If 2 just look at the wall tstat wiring of the other tstat to verify color code and how the other furnace is connected. I assume you have 2 furnaces. Doug

dougrainer

Carrolton, Texas

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Posted: 11/17/20 07:53am Link  |  Quote  |  Print  |  Notify Moderator

In case you did not know, this is the RVP parameters for a HP system. Electric heat refers to HP. Doug
Why does my furnace come on when I am calling for heat pump?
When your thermostat is in the “Electric Heat” mode, if the set temperature is five or more degrees above what it shows as the room temperature; the thermostat will consider this too much of a load for an electric heat source and bring in the furnace to assist. The furnace will continue to run in this case, until the thermostat is satisfied. When the room temperature starts to drop again, the thermostat will try to proceed as normal, with just the electric heat (unless the difference between set point and room temperature reaches five degrees again).
PLEASE NOTE: Some of our thermostats will not run your electric heat and gas heat simultaneously. They will shut down the electric heat in order to bring in the gas heat.
Multiple consecutive calls for the furnace in the “Electric Heat” mode, can cause the thermostat to lock out the electric heat function for approximately two hours, triggering the furnace only when it needs heat. For more information on the Lockout function of the thermostat,

dougrainer

Carrolton, Texas

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Posted: 11/17/20 07:55am Link  |  Quote  |  Print  |  Notify Moderator

How does the Heat Pump Thermostat Work
The RvComfort.HP, the RvComfort.PHP, the Coleman True-Air, and the RvComfort.ZC
thermostats by RvProducts Inc. are all capable of running not only an Air Conditioning unit, but
also an Electric Heat Pump. Frequently we receive calls from customers who do not
understand the functions of the Heat Pump Thermostats. This guide is a quick run through of
the information already provided in the Thermostat Operation Manual, included with each
thermostat.
The Heat Pump is an electric source for heat. It will supply and maintain heat assuming the
outside (ambient) temperature is above 40 degrees. This number of course can be slightly
higher or lower depending on the humidity. Higher humidity can cause a heat pump to lose
efficiency at a slightly higher ambient temperature, while lower humidity can cause a heat
pump to lose efficiency at a lower ambient temperature.
Since no one wants to wake up to find that the outside temperature dropped below forty
degrees and it is now 50 degrees inside the coach, the Heat Pump thermostats are programmed
internally to recognize when the temperature drops five degrees or more from the set
temperature to the actual inside room temperature. When the temperature exceeds five
degrees or more between the two, the thermostat will default to the next available heat
source.
The thermostat, upon sensing a temperature split of five degrees or more in the electric heat
mode will bring the gas heat on to assist the electric heat. This is the first strike. A strike is
created by the thermostat having to change modes (or run dual modes to sustain a
temperature split). The electric heat and the gas heat will continue to run together until the
thermostat reaches the set temperature and satisfies. When the electric heat comes back on, it
will be in electric heat only at that point. If the temperature again drops five degrees or more
from the set point, the thermostat will again bring the gas heat on to assist. This is strike two.
The system will then go through the above stated procedures. If the temp should drop five
degrees from set point for a third time, the thermostat will give up on the electric heat, lock the
electric heat out for two hours (showing either DIFF on the display or FLASHING GAS HEAT on
the display) and default to Gas heat only. You WILL NOT be able to run any Electric heat
during this two hour lockout.

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