I recently had a 31-year-old packaged rooftop heat pump (unknown size as the serial number was worn off) with a 3-ton single stage Carrier. I live in the extremely hot desert, 1,000 square feet home, but the load calc is 2.5 tons winter and 3 tons summer due to climate, old windows, windows facing the sun, low insulation, etc.
The problems I am having with 3 ton Carrier are discomfort (hot/cold fluctuations) and pressure causing occasional creaking on one of my walls (this is completely resolved by cracking a tiny window the bathroom) and operation is somewhat loud. Installing a Nest thermostat seemed to decrease comfort compared to the old thermostat.
So I want to upgrade to a variable speed Bosch 3 ton inverter packaged heat pump to maximize comfortable with consistent temps and quieter operation. Energy savings would be a bonus.
I understand the Bosch can run between 25-118%.
Questions:
1. If I am just increasing the thermostat temp by 1 or 2 degrees, will it ramp up to 118% and blast air in? I would like to avoid that because I’m not sure if my ductwork could handle it and I don’t want to run into the same problem I’m having with the Carrier (creaking in wall next to a vaulted ceiling toward the end of a heat cycle due to pressure). I’m hoping an increase in thermostat temp of only 1 or 2 degrees isn’t enough to kick it in 118% operation capacity. My guess here is it would only kick up to 118% in the middle of the summer if I cranked the temp way down.
2. Since it will primarily be running at a low capacity for long periods, this should be much less pressure than the single-stage 3 ton Carrier is putting out as it is designed to run at 100% capacity at all times, correct?
3. If it is off for an hour or two due to the house temp maintaining fine all that time, when it does start up, will it start up at 118% or will it start up at just what it needs to get the temp back down/up 1 degree?
The problems I am having with 3 ton Carrier are discomfort (hot/cold fluctuations) and pressure causing occasional creaking on one of my walls (this is completely resolved by cracking a tiny window the bathroom) and operation is somewhat loud. Installing a Nest thermostat seemed to decrease comfort compared to the old thermostat.
So I want to upgrade to a variable speed Bosch 3 ton inverter packaged heat pump to maximize comfortable with consistent temps and quieter operation. Energy savings would be a bonus.
I understand the Bosch can run between 25-118%.
Questions:
1. If I am just increasing the thermostat temp by 1 or 2 degrees, will it ramp up to 118% and blast air in? I would like to avoid that because I’m not sure if my ductwork could handle it and I don’t want to run into the same problem I’m having with the Carrier (creaking in wall next to a vaulted ceiling toward the end of a heat cycle due to pressure). I’m hoping an increase in thermostat temp of only 1 or 2 degrees isn’t enough to kick it in 118% operation capacity. My guess here is it would only kick up to 118% in the middle of the summer if I cranked the temp way down.
2. Since it will primarily be running at a low capacity for long periods, this should be much less pressure than the single-stage 3 ton Carrier is putting out as it is designed to run at 100% capacity at all times, correct?
3. If it is off for an hour or two due to the house temp maintaining fine all that time, when it does start up, will it start up at 118% or will it start up at just what it needs to get the temp back down/up 1 degree?
source https://hvac-talk.com/vbb/showthread.php?2226204-Questions-on-how-a-variable-speed-operates&goto=newpost
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