[tuccillo]

I have essentially the same issue. I did check the Manual J heat loss for our front bedroom (which can be colder) and found what I suspected; the heat loss is much larger than the other spare bedroom. I suspected this because of 3 outside walls and a lot of windows. The insulation values of the walls in the concrete block houses is only R-5. I find this a surprisingly low value. The insulation value of the windows is also low (typical unless you go with triple pane). The aluminum frames on the windows doesn't help as they conduct heat. I noticed the new homes have vinyl windows. The best insulation is in the ceiling at R-30. Apparently these insulation values are to code.

I don't think anyone is really to blame. These are not custom built homes where you can design your own systems. It is just not possible to maintain uniform temperatures with a single zone system under these conditions with relatively short heatpump run times. During the summer, temperatures are much more uniform but there are also longer heatpump run times. Unless you can find something in the building code about a required maximum temperature variation across the house I believe we are out of luck. I am not happy about it but it is only an issue on a handful of days. I can fix it but it won't be inexpensive. A small portable electric heater with a thermostat is probably the lowest cost solution.

Originally Posted by HiHoSteveO

I'm the OP and very much appreciate the feedback and ideas.

Please keep in mind that the room warms up fine from the heat pump. The problem is that it cools too much/too quickly between heating cycles. Could be an hour or several hours between cycles. The rest of the house is fine but when you walk into that one room, it's cold.

Data loggers were placed in the house to monitor for a couple of days and is easy to see what's going on in that room compared to the main living area.
Early on, the main feeder trunk in attic was enlarged to that area and registers adjusted to maximize air flow into that room. Insulation was checked and increased. Fans operated, door open/closed. Air flow re-balanced. Nothing really changed. No trouble with the A/C during the summer, just cold during cool or cold days.

I have been asked by the builder and I think that the cause is either cold air infiltration into the ducts in the cold attic which then slowly drops into the room below via the vent, (remember warm air rises and cold air drops), or air leakage from those big windows or a combination of the two. No air leakage testing has been performed.

Over the past two years many of the ideas suggested above have been tried (have to look into the paint idea) This has been a continuing warranty item since day one. Warranty department will do no more to find out why. Let alone who pays for the fix.

It looks like I'll have to have a permanent supplemental heater installed as some have suggested. Not the end of the world, but I really shouldn't have to.

To those who have seen the heating and cooling engineering that goes into each individual house, you have to wonder how this could happen. If you haven't, you can look up your address here. The "MAND" and "MANJ" are the calculations that Tuccillo was talking about earlier.

https://etrakit.sumtercountyfl.gov/e...ch/permit.aspx

Permit Search> Site Address> Contains> (your address)

Click the "Attachments" at the bottom of the first tab.

[gardeniagirl]

A Duraflame small heater that looks like an old fireplace does well in cooler areas, and surprising how much heat (has a flame and blower) it can give. It has been cheap to operate, safe, durable, and lightweight to move. Lowe's has them

[Chi-Town]

Solved my cold room and need for an entertainment center problems with a Dimplex electric firebox console. Looks good and provides the right amount of heat. Got it at Babette's.

[DangeloInspections]

No wonder it's cold in there...you have "Ice Age" playing....!

Frank

[TNLAKEPANDA]

We have a Designer home built in 2013 and the problem exists in our front BR and the same is true with our neighbors. We complained under warranty but nothing was done.
There are several problems:
Distance from the HP unit
Return is in the ceiling very close to the supply vent. Hot air rises so it stays up high
and it gets sucked out before it can heat the room.
Vaulted ceiling probably has far less insulation. Who knows if there is any insulation?

The Fix:
You could try closing off the return vent which will help keep more heat in the room.
What we did is put a small quartz heater in the room. It heats up real quick. Our heater
is wood and tall with a very small food print. It looks very nice and can be moved into
another room is needed.