[ale] Monitoring Total Household Electricity Consumption

[Byron Jeff]

On Tue, Feb 09, 2016 at 07:28:01PM -0500, Greg Clifton wrote:
>    As an aside, I am very impressed with how well the heat pumps function.
>    They are Goodman units and have been chugging along for a bit over 10
>    years now with very few service calls. When external temps are above
>    about 40 degrees F, you would be hard pressed to tell the difference
>    between a gas furnace and the heat pump by the temperature of the air
>    at the registers. Anything above that and the heat output is way more
>    than adequate. However, below about 37 degrees outside and there isn't
>    much heat to scavenge and below 30 degrees, forget about it! So I set
>    my thermostats to super heat the house while warm out during the day
>    and coast through the night.

I have the same setup and your description of heat pump operation is just
about perfect. The only missing item is that heat pump has a defrost cycle
because the outside coils freeze up when extracting the heat from outside
to bring into the house. The mechanism for defrosting is to temporarily
reverse the heat pump so that it acts as an air conditioner. So it pulls
the heat from the house and puts it back outside. During those periods of
defrosting the registers actually blow cold air. Even though it cycles for
90-120 seconds every 90 minutes, it does impact the house especially when
it is cold out.

I embarked on a project to supply supplemental heat using heated water from
an insulated tank through a hydronic water to air heat exchanger like the
ones listed here:

http://www.outdoorfurnacesupply.com/water-to-air-heat-exchangers.html

Air coming into the house after the heat pump heats it is run through the
exchanger. A circulation pump circulates the hot water through the
exchanger.

I have four reasons for this setup:

1. It supplements the heat pump when the temps drop into the 20s.

2. It heats the air through the defrost cycles. And since the defrost end
time is thermostat controlled, the cycles are shorter.

3. Water can be heated in a variety of ways. Burning wood, oil or propane,
solar, and standard electric are all options. I currently have 275 gallons
and plan to expand to 605 gallons. That much water can can capture up to a half
million BTUS of heat then dole it out as needed.

My current setup uses a DIY electric tankless water heater that I put
together and the circulation pump. Like Greg, I heat the water in the tank
during the day when the heat pump can hold its own. Then at night I route
the heated tank water through the exchanger. The system has no problem
keeping the house in the low 70's even when it's 25 and breezy outside like
its been the past couple of days.

Looking to add a waste oil burner next...

BAJ

-- 
Byron A. Jeff
Associate Professor: Department of Computer Science and Information Technology
College of Information and Mathematical Sciences
Clayton State University
http://faculty.clayton.edu/bjeff