How many thermostats are required?

[justsam]

I have a home built in 2005 by a custom home general contractor who occupied it until I bought it in late 2010. The home is in Sonoma county of Northern California.

The home has only one FAU, located in the garage, and the home is a large single story, about 3700 sq ft., with a loft type game room.

When I purchased the home I noted there were three thermostats, and when I asked the owner builder about it he laughed and said, yes there are three. It seems that in order to get his COO the inspector felt a house of this size needed more than one thermostat.

I dismissed it as buracracy running amuck. I thought perhaps the stats were used to control a remote dampener or such but no, not so. They do have wires connected to them, but the wires go to the FAU location and are not terminated. The one active thermostat is of course wired to the FAU. One of the unused stats had only a two conductor cable, really making me think a simple dampener type device.

The HVAC works fine, I did just install a NEST thermostat, but thought I would post this to see if the story makes any sense. I am about to just pull the unused stats and spackle over the area. Anyone see why not?

In my garage I use a 5K btu, 220VAC heater which knocks the chill down pretty well.

 

[Full Throttle]

are you sure it is not a zoned system? meaning each stat controls certain area's. IE master bed, living area etc. each zone has a damper and control logic that brings on the HVAC system as needed. A house that size with 1 system for sure thats the case. I do HVAC for a living and would have done a house this way for the size.

they have remote sensors as well, they do not all have wires

 

[justsam]

Thanks to you both for your professional advice. I was hoping a real pro would respond. The furnance is a Bryant Legacy model 350AAV. It is a 91.4 AFUE and is mounted in the attached garage in a downflow configuration.

The house is prepped for AC, but no condensor installed. The furnance sits on the evaporator coil (Bryant CK5BXT060024AAAA). Lines are run, a pad is in place and 220V is there with a disconnect. Control wire is in place at the pad. In asking the previous owner/builder about the AC, he stated that the weather is so mild, he never put it in, but did prep for it.

The two unused thermostats are Braburn Model 1000, just simple non programmable stats.

The builder did not like exposed large return grills, so there is only one large return air, hidden in the loft area with a Maxxair permanent filter.

All seems to work fine, perhaps the unused stats were somehow required for future AC but I do not understand why. The one working and connected stat was a programmable Honeywell, before I changed to a NEST.

I should also add that the house has a charged sprinkler system, but I have seen no HVAC connection to it, and I believe by code it is totally independent. I mention it because I know there are automation systems that shut down FAU in case of fire. There is no fire detection other than the temperature sensitive heads, and of course smoke detectors.

AS stated all works well, I too have felt no need for AC, but I am just curious what the plan was and it bugs me to have unused stats on the wall. I am very pleased with the house, the quality of the work and materials, but I do not think HVAC was the builders area of strength.

 

[Full Throttle]

Thanks to you both for your professional advice. I was hoping a real pro would respond. The furnance is a Bryant Legacy model 350AAV. It is a 91.4 AFUE and is mounted in the attached garage in a downflow configuration.

The house is prepped for AC, but no condensor installed. The furnance sits on the evaporator coil (Bryant CK5BXT060024AAAA). Lines are run, a pad is in place and 220V is there with a disconnect. Control wire is in place at the pad. In asking the previous owner/builder about the AC, he stated that the weather is so mild, he never put it in, but did prep for it.

The two unused thermostats are Braburn Model 1000, just simple non programmable stats.

The builder did not like exposed large return grills, so there is only one large return air, hidden in the loft area with a Maxxair permanent filter.

All seems to work fine, perhaps the unused stats were somehow required for future AC but I do not understand why. The one working and connected stat was a programmable Honeywell, before I changed to a NEST.

I should also add that the house has a charged sprinkler system, but I have seen no HVAC connection to it, and I believe by code it is totally independent. I mention it because I know there are automation systems that shut down FAU in case of fire. There is no fire detection other than the temperature sensitive heads, and of course smoke detectors.

AS stated all works well, I too have felt no need for AC, but I am just curious what the plan was and it bugs me to have unused stats on the wall. I am very pleased with the house, the quality of the work and materials, but I do not think HVAC was the builders area of strength.

Hope a real pro would respond, preciate it bud, only been doing this for 15yrs, Licensed NC HVAC contractor #28488, and have been working at Norfolk Trane for the last 6 yrs as a Chiller tech

 

[justsam]

I hope I did not word that wrong. I meant I had hoped for and felt I did indeed receive advice from professionals.

 

[Steevo]

Hope a real pro would respond, preciate it bud, only been doing this for 15yrs, Licensed NC HVAC contractor #28488, and have been working at Norfolk Trane for the last 6 yrs as a Chiller tech

I read that as him thanking a pro for responding. He was glad you (a pro) had responded.

 

[Full Throttle]

I mis read

and I don't know about Cali, but in NC there is no fire shut down required on systems under 2K CFM of air, which is 5 ton system and smaller.