New construction with propane furnaces - second level running way longer than first level for 2f temperature rise

[TurbinetoiZ]

We just moved into a new construction home and I installed 2 ecobee premium thermostats. There are 2 Lennox 93AFUE furnaces in the basement, each sending heat to one level. The main level is an open concept floor plan with the thermostat centrally placed in the living area. The second level thermostat is in the main bedroom by the door.

We noticed that when the upstairs thermostat has to raise the temp by 2f from 68 to 70, it takes about 35-45mins. While the same temperature rise is achieved in about 10 minutes downstairs.

I caught this behavior trend issue using the visualizations in the beestat app.

What might be causing this?

 

[Jeff H Young]

Im not involved in the heating industry other than in the piping end of it. but perhaps the area where the thermostats are located are not equall example being down stairs is in an area where temp rises quickly and upstairs unit in a area it takes a greater volume to heat extreme example one was inside a closet and the other in a huge master suite that was ducted undersize and further from the furnace, smashed flex duct another possibility.

 

[Sponsor]

 

[Fitter30]

Why are you using a 2° dead band and not the .5°? Is the air blowing out the registers about the same? A pocket style thermometer not a ir can measure the temperature rise across each furnace- supply and return.

https://www.amazon.com/Supco-ST02-Stainless-Thermometer-Degrees/dp/B003CL9LMC/ref=mp_s_a_1_12_maf_2?crid=28WOZANP5XCZA&keywords=pocket+thermometer+hvac&qid=1699998374&sprefix=pocket+thermometer%2Caps%2C220&sr=8-12

 

[John Gayewski]

Yes check the temps of the air coming from the registers. But the amount of time it takes to heat a space is dependant on the size of the space and the amount of heat needed to raise the temp. Placement of the thermostat can also be a factor.

If your upstairs area loses more heat than your downstairs then it'll take longer to heat.

 

[Jeff H Young]

I think its comparing apples to oranges many variables nothing jumps out as being the single cause based on the the info provided but there a lot of reasons provided as to why they wouldnt run the exact same amount of time .