Thread: HVAC standards (2 story home in NC) question

In order to pass HVAC inspection does a home have to have a thermostat up and downstairs on a 1500 sq ft home in NC? Our upstairs is hot as Hades and has no thermostat. The downstairs stays cool as a cucumber. Brand new build fwiw. I heard from a broker that homes over 1 story require a thermostat on each floor in NC. Any truth to that?

Thank you,

-mtnairnc

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No, not required.
It is required to have a system capable of providing heat to all habitable rooms to a certain specification, but air conditioning (cooling) is not required by minimum code.
But remember, CODE is code for the minimum, crappiest house you can legally build.

The simple solution may be to simply adjust your duct registers if you can do so without shutting down air flow across the cooling coil so much that it begins to ice over.
Less cold air downstairs pushes more upstairs (I assume you have already opened the air dampers upstairs) and leaving the fan on to circulate so as to keep the air mixed to a more uniform temperature.
You would have to readjust seasonally since you may need more heat upstairs in the winter.

The next step would be to have a zone dampers and multiple thermostats and controller installed to do this for you automatically.

Bottom line is there is likely no code violation, just either a lack of understanding of system operation or a crappy install/design.
Contact a good HVAC company that does system designs and installations for larger buildings not just a service call.
Ask them to measure air flow and run a load calculation and provide a design for correcting the problems with the system.

The current code in NC is that the top floor and bottom floor has to be with 4 degrees of each. A thermostat is not required if this can be accomplished without one but now you normally see either a single system with zone dampers or two separate systems. Both of these require a thermostat for each floor.

You can read about it here: http://www.nclicensing.org/_fpclass/...Newsletter.pdf

Originally Posted by mtnairnc

In order to pass HVAC inspection does a home have to have a thermostat up and downstairs on a 1500 sq ft home in NC? Our upstairs is hot as Hades and has no thermostat. The downstairs stays cool as a cucumber. Brand new build fwiw. I heard from a broker that homes over 1 story require a thermostat on each floor in NC. Any truth to that?

Thank you,

-mtnairnc

You will need to know the date that the permit was pulled, if it was on January 1 2010 or later the house should have no more than 4 degrees differential between rooms or levels. There is a slight possibilty that this new rule will even affect permits pulled prior to 1-1-10 if the actual install took place after 1-1-10 but they did not make that 100 percent clear in the rule (imagine that).

Agreement with others posts so far.
In terms of fixing the problem there could be many issues. Undersized system or ducts, poor distribution, etc. 2nd floors can obviously run hotter than downstairs. You should consider a full assessment. However, one of the first, most common and relatively easy fixes is return air. Contractors often cheat on pulling return from a 2nd floor. Do you have return air, where is it located etc.
If you don't have return air or only one small one, add sufficient return air.
If you aren't sucking some of the hot air out of the space, it won't matter how much cool air you push in, the space will never get comfortable.
Good luck

Good info James and Bruce, sounds like NC has it's act together. I had never heard of this.

If it is that hot sounds like you may be missing insulation as well.

If the system is not zoned the contractor should have installed a volume damper in each main supply duct, providing there is a supply main for each floor. You may be able to obtain more comfort by adjusting these. If there are seperate ducts, zoning is still possible, and you may have recourse to get the contractor to install this if the install falls within the new code dates.

If we had that requirement here in IL, the majority of giraffe barns would require substantial modification to their HVAC.