Zone 5. heat pump generate heat at 5F without using extra electricity. electricity use calculation

LS123

hello all,

i am just wondering how much electricity would be used by a heat pump that works at 5F without using built in heating coil ( this is question #1) please see additional info needed to calculate amount of electricity needed.
* Heating / cooling about 2500 SQ feet.
* Connecticut Zone 5
* There is primary steam radiant heat to prevent over use of HP ( I mean use of built in heat coil that use more electricity)
* I read that now there are heat pumps that use less electricity until temp reach 5F out side
Questions:
1) How much electricity would be used during 24 hours period by a heat pump to keep a 2500 SQ Feet house inside the house temp 68F while out side temp at 5F?

2) I understand ductless heat pumps can be zoned. Is that correct?

3) I read that location of the heat pump out side makes a difference how much electricity would be used. Say if the heat pump located at shady . windy place it would use more electricity during winter, less electricity during summer, as I understand (( please elaborate.)

4) Heat pumps would be needed to be fully replace between 10 to 20 years? Is this general assumption correct?

5) How expensive is general maintenance cost per year?

6) Which brands are the best, lasting Heat?Cooling pumps that would meet my expectations - work at 5F without taking more electricity?

7) How much would it cost to cool the same space (2500 SQ feet) inside temp 78F, outside temp 95F?

Thank you!
\-LS123

LS123

@Erin Holohan Haskell would you please move my post to Heat pumps category?
Thank u!
Best

LS123

Specs of heat pump
Ambient Temperature Range (Cooling)
0 / 118 °F
Ambient Temperature Range (Heating)
-4 / 75 °F
Low Ambient Cooling
Yes
Cooling BTUs
39000 BTU
Cooling Tonnage
3.5 Tons
Total Cooling Capacity BTU
40000 BTU
Total Cooling Capacity
3.5 Ton(s)
Heating Capacity
45000 BTU
Maximum Heating Output BTU
44500 BTU
SEER
21 SEER
Energy Efficiency Ratio
10.4 EER
Coefficient of Performance
3.6 COP
Heating Seasonal Performance Factor
10.2 HSPF
Refrigerant
R-410A
Factory Precharge
131.2 Feet
Minimum Ampacity
29 Amps
Maximum Fuse/Breaker
40 Amps
Maximum Line Length per Zone
82 Feet
Maximum Height Difference
50 Feet
Line Set Connection Type
Flare
Compressor Type
Inverter / Rotary
Zones
5
Liquid Line Size
(5)1/4 Inches
Suction Line Size
(5) 3/8 Inches
Indoor Air Handler Size, W x H x D
Multiple Sizes - See Documentation Inches
Sound Rating, Indoor
26 / 33 / 35 / 36 / 37 / 38 / 40 / 41 / 44 / 46 Decibels
Sound Rating, Outdoor
61 Decibels
Maximum Line Length all Zones
246 Feet
Outdoor Condenser Size, W x H x D
42.8 x 43.42 x 17.32 Inches
Total Weight
389 Lbs
Indoor Air Handler Weight
Multiple Weights - See Documentation Lbs
Outdoor Condenser Weight
198 Lbs
Footprint Mounting Holes, Center to Center
25 Inches
Indoor Air Handler Type(s)
Wall Mounted
Voltage
208 - 230 Volts
Frequency
60 Hz
Voltage Phase
1
Compressor Warranty
7 Years
Parts Warranty
5 Years

Enjoy free shipping on any accessories purchased with the Blueridge BMKH42G321-9W-9W-9W-12W-12W.

Required Components for Installation
Alpine MW4/125
125' 14/4 Stranded Mini-Split Wire - Non-Shielded (600 Volt)
$114.99
Qty:
Alpine MW4/250
250' 14/4 Stranded Mini-Split Wire - Non-Shielded (600 Volt)
$224.99
Qty:
Alpine MW4/050
50' 14/4 Stranded Ductless Mini-Split Wire - Non-Shielded (600 Volt)
$49.99
Qty:
Alpine MW4/025
25' 14/4 Stranded Ductless Mini-Split Wire - Non-Shielded (600 Volt)
$29.99
Qty:
Alpine AG-DCT
Safety Non-Fused Electrical Disconnect
$12.99
Qty:
Alpine AG-WHP8
3/4 x 48 Inches, #8 Gauge Electrical Whip
$17.99
Qty:

Erin Holohan Haskell

LS123 said:

@Erin Holohan Haskell would you please move my post to Heat pumps category?
Thank u!
Best

Yes. I've moved it.

Jamie Hall

Th key figure in electricity use is the COP. The data which you have provided give that figure (3.5) but, unfortunately, do not give the figure at varying temperatures -- and it varies with temperature differential across the system. The amount it varies is different for different designs, but in the absence of any other information it is reasonable to assume that if that figure is measure at a reasonable outside temperature -- say 40 F -- and a reasonable inside temperature -- say ;70 F, it will be somewhere between half that and a third of that at maximum performance conditions.

Now... Your first question (how much electricity would be used) is quite unanswerable, as you don't provide the heat loss of the building. One has to know the heat loss, in BTU, to calculate the energy input, in KW hours.

On location, there is some influence from shading -- but not much, as the heat pump will be moving a lot of air through the evaporator to provide the heat you need.

On longevity -- there really hasn't been enough time, but based on refrigeration systems (which are basically the same) I would say that a design life o 15 years was probably reasonable, given careful maintenance. The maintenance would be about twice that of a straight air conditioner, given that it would run about twice as long.

LS123

thank you @Erin Holohan Haskell
\-LS123

LS123

Br. @Jamie Hall . Thank you!

The heat pump I looked at say it would work at "Ambient Temperature Range (Heating) -4 / 75 °F".

Perhaps I can just use "42,000 BTU (3.5 Ton) 21 SEER Five Zone Ductless Mini-Split Heat Pump System" to just heat up only the space I occupy majority of the days and months.

I am the only occupier in the house, and I have my kids visit me couple of the weekends a month ( when they like to visit me

I will try to find out how to do the heat loss calculation and provide with heat loss number for my home (exclude the new addition planned) and include just the space i use mostly for Zone heat and cooling.

Thank u again!
\-LS123

Jamie Hall

I have no doubt that it will work when it gets as cold as they say. The question is... how well? As I mentioned, the COP drops off significantly as it gets colder, and as soon as the poor thing has to defrost the evaporator coils the performance becomes really problematic.

In terms of Green, in Connecticut you need a COP of at least 2.5 to make the fuel used to make the electricity to run the heat pump equivalent to the fuel used by your boiler to heat your house...

Solid_Fuel_Man

Remember that any heat pump is stealing heat from the outdoor air in heating mode. That outdoor air has various amounts of humidity in it which will freeze onto the outdoor coil. This ice will stop airflow and the unit will go into defrost mode, where it steals some heat from the indoor space to warm up the outdoor coil. Once cleared, it goes back into heating mode and the process repeats. 

This can happen hourly, or several times an hour. So it isnt just the outdoor temps which change the actual operational efficiency, humidity does as well. I tell people who have an air to air heat pump to just turn it off below 20 degrees. This is a generality of course, but it should greatly lengthen the life of the init and the changeover valve. 

LS123

Jamie Hall said:

In terms of Green, in Connecticut you need a COP of at least 2.5 to make the fuel used to make the electricity to run the heat pump equivalent to the fuel used by your boiler to heat your house...

Thank you Br. @Jamie Hall ... good point I looked up eversource rates for electricity for where I am at CT. It is expensive! yes shutting it off when below 20 would save money on electricity. Thank u!
Best!

LS123

sorry about that @Jamie Hall and @Solid_Fuel_Man for getting my quotes mixed up.
typing with one hand... that hand happen to be not my primary hand....