At the risk of boring people to tears, here is how this stuff actually works. It starts with a so-called "Manual J" calculation. This is essentially a heat gain/heat loss calculation for the house that takes into account the dimensions of the home, location and number of windows, the insulating factor for the window, whether the windows have coverings, the orientation of the house (north, south, east,or west), the insulation of the walls, the insulation of the ceiling, the number and insulation of the doors, etc., the climate temperatures and humidity in the summer and winter, and your summer and winter temperature setpoints. From these calculations, you obtain the heat gain (in the summer) and heat loss (in the winter) for each room in the house in BTUs. The total for the house will size the HVAC equipment in terms of tons (12K BTUs is a ton). From this information you can then determine the number of CFM (cubic feet per minute) of airflow needed in each room to maintain the desired setpoints. A so-called "Manual D" calculation is then done to design the duct work to deliver the needed CFM.
By code, this is all done and what they told you is correct about the engineering work and permits. And it is probably correct for the house on average. But, without zoning you are still going to have some issues with temperature uniformity as a centrally located thermostat cannot react to rooms on the periphery that lose heat/gain heat faster than the main living areas.
In my previous house, I did the Manual J calculation myself, designed the 4 zones, and selected the equipment. I hired a local HVAC contractor to do the Manual D and the installation. The results were very good in that there was complete uniformity of temperature and outstanding humidity control because of a variable speed handler. The typical designer home should have 3 zones, in my opinion: the guest bedrooms, the main living area, and the master suite. In the premier homes, they do a little better with 2 zones. Part of that is probably necessary because residential equipment is generally limited to 5 tons and if the Manual J calls for more than that you have to have multiple systems.
Quote:
Originally Posted by HiHoSteveO
More info on this at post #12 and yes, all 3 bedrooms have both a supply as well as a return vent. There is also a large return vent in the main (dining) area away from the supply vents in the living room. Remember, the problem is not receiving enough heat in that room as it will warm up nicely. It just cools down too much between heating cycles, resulting in a cold room. Air conditioning is fine in that room.
Thank you everyone for the input.
I was simply wondering how extensive the cold room problem was and am finding it's more extensive than I thought. Also received some potential partial workarounds here, but the bonus is I've now learned what the actual fix seems to be. Tuccillo is right, a second zone according to a different, large local HVAC company.
Warranty department denies there's any problem at all saying the house was built and engineered according to all building codes and permits were issued by the county. There's nothing more that they will do.
|