Good morning, I am a homeowner but I have done my best to understand as much as I can regarding HVAC requirements in my home. After some back and forth with my HVAC contractor and requesting to see their calculations (which they never gave me), some things changed for the better, but I have a feeling I have an issue with my system.
The situation: Brand new home built in 2021/2022, ~3100 sf total conditioned space, 1800 sf downstairs, 1300 sf upstairs, 1800 sf unfinished basement. Split system, 3 ton Heat pump with 60k BTU propane auxiliary/backup heat for the first floor, 2 ton heat pump with 5kw heat strips auxiliary for the second.
Upstairs is mostly unoccupied so it doesnt run much, I keep it set 2-4 degrees below the first floor. I do get some bleed upstairs, but it averages about 2-4 degrees cooler and the thermostat is near the top of the stairs. I live in Maryland, not near the water but not in the mountains either. We do get some colder weather, lows in the 20s and teens is not uncommon here, sometimes even colder. I am still in the process of moving so I have kept my heat set to 58 at night and 60 during the day and it has primarily been using the heat pump only, not the auxiliary heat. This morning it was around 22 degrees and I turned the thermostat up to 62, which triggered the auxiliary heat to kick on. After 3 hours of auxiliary heat, the house had only raised to 60 and I received an alert from my thermostat due to the excessive run time. We still have some colder weather coming and I am planning to move in soon, so I will likely have the heat set to 66-68, but I am worried the system will not be up to the task in some of the colder weather. Design of the first floor includes the kitchen living room with vaulted ceiling and a gas fireplace (tho that is not used for heating ideally) and master bedroom with a vaulted ceiling. Most ceilings are 9' if not vaulted, open stairwell to the upstairs, 2 entry doors + pedestrian door into the garage and 8x12' glass slider onto the back porch.
From what I could find (and I could be wrong), I believe my furnace is too small for the space. The 60k 96% efficiency furnace covering an 1800sf space in Maryland, from what I could find is too small. I also had an estimate from another HVAC contractor originally planning to put an 80 or 84k backup furnace is (96-97%) efficiency. My contractor would not share their manual J calculations with me and was reluctant to provide any information to me or my builder. The builder also claims that the upstairs and downstairs need to be used in tandem to achieve the correct house temperature. I could turn the upstairs temp up a few degrees to match the downstairs, but I dont see how this would help since they are two completely separate systems. Does anyone have any thoughts on this? Is it normal to take 3 hours to raise the house temperature by 2 degrees on auxiliary heat?
The situation: Brand new home built in 2021/2022, ~3100 sf total conditioned space, 1800 sf downstairs, 1300 sf upstairs, 1800 sf unfinished basement. Split system, 3 ton Heat pump with 60k BTU propane auxiliary/backup heat for the first floor, 2 ton heat pump with 5kw heat strips auxiliary for the second.
Upstairs is mostly unoccupied so it doesnt run much, I keep it set 2-4 degrees below the first floor. I do get some bleed upstairs, but it averages about 2-4 degrees cooler and the thermostat is near the top of the stairs. I live in Maryland, not near the water but not in the mountains either. We do get some colder weather, lows in the 20s and teens is not uncommon here, sometimes even colder. I am still in the process of moving so I have kept my heat set to 58 at night and 60 during the day and it has primarily been using the heat pump only, not the auxiliary heat. This morning it was around 22 degrees and I turned the thermostat up to 62, which triggered the auxiliary heat to kick on. After 3 hours of auxiliary heat, the house had only raised to 60 and I received an alert from my thermostat due to the excessive run time. We still have some colder weather coming and I am planning to move in soon, so I will likely have the heat set to 66-68, but I am worried the system will not be up to the task in some of the colder weather. Design of the first floor includes the kitchen living room with vaulted ceiling and a gas fireplace (tho that is not used for heating ideally) and master bedroom with a vaulted ceiling. Most ceilings are 9' if not vaulted, open stairwell to the upstairs, 2 entry doors + pedestrian door into the garage and 8x12' glass slider onto the back porch.
From what I could find (and I could be wrong), I believe my furnace is too small for the space. The 60k 96% efficiency furnace covering an 1800sf space in Maryland, from what I could find is too small. I also had an estimate from another HVAC contractor originally planning to put an 80 or 84k backup furnace is (96-97%) efficiency. My contractor would not share their manual J calculations with me and was reluctant to provide any information to me or my builder. The builder also claims that the upstairs and downstairs need to be used in tandem to achieve the correct house temperature. I could turn the upstairs temp up a few degrees to match the downstairs, but I dont see how this would help since they are two completely separate systems. Does anyone have any thoughts on this? Is it normal to take 3 hours to raise the house temperature by 2 degrees on auxiliary heat?
source https://hvac-talk.com/vbb/threads/2235446-Auxiliary-Heat-Taking-3-Hours-to-Raise-2-degrees-Fahrenheit?goto=newpost
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