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Posted By cpmken,
Nov 21, 2013 at 11:28 AM
sorry, I didn't see that in there.
Trust me, we are. In addition to the usual household of computers and half dozen television sets, we have four AC systems (15 - 16 tons combined), three dehumidifiers, more than 200 incandescent lights (most of which my wife leaves on continuously), two electric water heaters (in addition to the one on the boiler), five refrigerators, one freezer chest, and a shop full of machines lugging 3 - 5 HP motors (16" radial saw, 14" table saw, 18" & 32" band saw, 6" and 16" jointers, 3hp heavy duty planer, etc.). Every time one of the AC units kicks on, every light on the property dims to 1/2 intensity. With 6 sub-panels, panel space is actually not one of my issues.
I do think we have a main feed problem, but haven't had time to deal with it. I don't think the inrush of a 5 ton AC unit should be sufficient to cause a significant drop in mains voltage, but that's a separate issue from net capacity.
that's a lot of a/c. I am not a tree hugger and don't drive a prius but good god man. that's nuts. lol
Yea with all those refrigerators and the two HW tanks you may be close. Heating and Cooling load are not added together in a load calculation. Presumably you do not run both at the same time.
I paid circa $900 for a Geyser HPWH from Tom in Maine (http://www.americansolartechnics.com)
There is a thread showing pictures of my installation: https://www.hearth.com/talk/threads/ducting-and-geyser.108580
The Geyser uses a 15 amp supply. My KillAWatt meter shows that it rarely draws above 12 amps.
We still have our original 80 gall oil HWH and keep it operational for those weeks in Jan/Feb when the Geyser struggles. Our Geyser is in a fully "in bedrock" basement and this stays above 50 degF year round so we can use a HPWH for 10+ month/year.
Our house is 1800's Federal, National Historic Register, so we have some limits on what we can do. The insulation & sealing process took place over 3 years. Did a lot of infra red work to set the job list for the year. Repeated at annual intervals until we started reaching diminishing returns.
We basically reduced our overall energy consumption and replaced our oil heating with pellets and chord wood.
We have kept the oil systems fully functional for use during vacations etc. but they are not used on a daily basis.
Didn't really mean to derail the OP's thread, but heating is wood + oil, for 96% of the house. We have a heat pump (mini-split) which heats only 260 sq.ft., and electric resistive in three of the bathrooms, but that's pretty minimal compared to the summer AC load. The AC tonnage is based on cooling 6660 sq.ft. of house plus 1200 sq.ft. of shop, so 7860 sq.ft. total. In fact, the shop is not even up and running yet, but I have it planned into our service loading, nonetheless.
Thanks for the info! At 10 months usage per year, and with the need to keep secondary options, I don't see the HPWH working out for me. The issue is as much about time, effort, and space, as cost. We're in the thick of so many projects, expansion, renovation... but it's an interesting option to consider.
We could use the HPWH for 12 months of the year but when its cold outside, the efficiency drops off and its recovery time increases to where cold water showers sometimes happen. It is out of convenience rather than necessity that we use the HPWH as our primary DHW for 10+ month/year.
The hidden benefit of a HPWH is that it takes a BIG bite out of the AC load during the summer. We use ours to cool a 2000 sq ft section of the house. With your AC loads, this must be worth considering. The snag is you need to time the use of DHW to get the AC benefit. So my wife carefully spaces out laundry loads during the day to maximize the AC effect.
The point that is often missed with an oil powered DWH is that the excess heat from burning oil to create hot water is in the air conditioned space in the house.
So the AC has to cool the house plus shift the excess heat from burning oil for DHW.
A HPWH starts by pulling heat out of the air conditioned space and eliminating the excess oil heat.
The AC savings are significant.
In winter, the HPWH has to feed off excess heat from burning wood and pellets. But this is still cheaper than burning oil.
You've got all those tons of A/C going. Plus three dehumidifiers. Plus two electric water heaters.
Sounds like the perfect situation to utilize heat pump water heaters to me - they can condition and dehumidify the air that passes through them, and put the heat that they take out of that air where it will be used, hot water tanks. Efficiently.
Your electric bill must be off the charts.
Electric bill is surprisingly low, given our peak draw when we're home. With judicious use of electronic timed thermostats, I think we're at only 20,000 - 21,000 kWh per year. Worst month ever was $450, when a guest turned up the electric resistive baseboard heater in the third floor bathroom, and then turned down the oil thermostat for the rest of the third floor when they left. That poor little heater cranked its heart out for a few weeks, until we got the bill, had a chit, and went hunting for what racked up an extra $150 in electric that month.
I will definitely check out HPWH's, when we get to that point in our reno work. Right now, we're knees deep in more immediate needs!