I need help choosing electric service and heat pump set points with my new Lennox 21
I am not sure of the electric service interruptible or time of day for space conditioning that I need to use for the separate meter. I also need to know what outdoor temp to lockout the heat pump and furnace. I want to save the most money on my utility bills. I live in Sterling Heights Michigan. I use DTE FOR ELECTRIC and consumers energy for natural gas. I would love some help with this. 110000 BTU and 4 ton with a 5 ton indoor coil. 2453 square feet built with 2nd floor in 79 with sealed duct in basement. I also added r30 to ceilings for a total of r45. 2nd floor walls had r4 added for a total of r19 . 1st floor walls have a r 15.New = all Lennox new 98 furnace XP21, heat-pump,indoor cased coil pure air, power humidifier, I-comfort Wi-fi stat. It cost a bunch, now I have to choose electric service and set points.When it was charged they didn't use a weighed calculated charge they just used super heat or gages , they added 19 ounces and the instructions wanted 33 ounces then checked with super cool. Should I be concerned about efficiency with the 14 ounce discrepancy?
Overview of Selecting and Operating new Dual Fuel Heating Equipment
Set points are already established if you are currently living in this 2,453 Sq.Ft. two-floor residence.
Originally Posted by Warlockamized2
I believe Time-of-Day rate could easily at least Double or triple your electric bill.
If you wish to select interruptible electric service on the heat pump,
the heating controls must be set-up for auto switch-over to gas furnace or be prepared to have the house cool at least ~2'F per hour.
IF all that equipment was just replaced, WHERE Is the Load Calculation?
You mention ceiling and wall r-values, however,
the Windows and Infiltration are BY_FAR the MAJOR contributors to Heat Loss.
Actual Area of windows (maybe 320 square feet total ? ) and U-Value ( ~0.5?_, double pane, argon filled?)
along with actual infiltration (? 0.5 Air Change per Hour -A.C.H.).
ARE generally Good STARTING POINTs to determine total Heat Loss ( gain) prior to signing contract for heating ( cooling) equipment replacement.
How did the mechanical contractor determine 110,000 BTU was Actually necessary?
WRONG response here is, that's what the original equipment was.
Is the heat pump set to run now as low as 34'F, _ _'F or 42'F?
Selecting heat pump lock-out set point is dependent on the Heat Loss balance point.
One might make a _wild guess_ that the overall building heat loss would be ~72,000 BTU/hr at ~-2'F design temperature.
.:. Heat loss at 35'F would be in the ball_park of 35,000 BTU/hr.
_ IF _ those guessed values are close, then the heat loss balance point would be estimated as ~36'F for a 4-ton high H.S.P.F heat pump.
Economic balance point _ Later.
Cost comparison$ by energy auditor worthwhile
I'd say time-of-day October-May due to most of your energy use would be with winter and heat pump use given you're in Sterling Heights.
Originally Posted by Warlockamized2
DTE Energy time-of day is not what I anticipated. Much lower rates without any penalty over regular rate.
I can't be sure about specific cases given the various conditions and cost comparisons without doing significant amount of
calcs on sizing, annual heat load and type of equipment/ heat pump vs furnace load share.
However, I'd trust my gut on time-of-day rate being cheaper.
Dan, formerly of Ann Arbor.
I now have to pick low set point for heatpump.
I have ordered an electric meter with schedule D1.7 rate, time of day for space conditioning and water heating. I wont be using it for water heating. Only the heat pump will be using it. Should I cut the heat-pump off at or near the outside temp that it has to have help from the furnace ?