Consuming 6500 kWh a month is a very large load......it is not a hot water circulatory system. A large load is running and for long periods of time.
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Not solar talk but very General. Need some help.
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Originally posted by bcroe View Post
I decided to take J.P.M.s input and apply it to my system. I actually measured the length and dia of all
the pipes involved. The 3/4" distribution pipes were fully insulated, so I used 1/3 of their actual area.
The return line is much smaller dia (area) and shorter as well, but not insulated. There were also 8
branches of 1/2" pipe to faucets which don't have circulation, but still radiate. These were estimated
at 4' each of which the warm end was insulated; the faucet end is pretty much cooled most of the
time so I took the effective radiating area at 1/3 the actual length. I have my own well.
0.875" dia Tubing area = 0.23 ft.^2/ft.
0.875" dia Tubing length = 68 ft.
full insulation (use 1/3) effective sq feet = 5.21
0.31" dia Tubing area = 0.08 ft.^2/ft.
0.31" dia Tubing length = 32 ft.
no insulation effective area = 2.56
0.624" tap off dia Tubing area = 0.16 ft.^2/ft.
0.624" tap off dia Tubing length = 32 ft.
no flow, insulated at warm end, effective (use 1/3) sq ft = 1.71
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total effective sq ft = 9.48
Tubing surface heat loss = 1 BTU/ft^2 of tubing per hour per deg F
Average pipe temp. = 120 F., air temp. around pipe = 65 F
Heat loss ~ [9.48 sq ft * (1 BTU/hr.ft^2 deg. F.) * (120 F.- 65 F.) * (24 hrs./day) * (365.25 days/yr.)]/(3,412 BTU/kWh) ~ =
1340 kWh/yr. (or 50 gallons propane/year).
Here at $.090/KWH or $1/gallon propane that amounts to $120.60 or $50 A YEAR to keep those pipes warm. Since in
these parts the house requires some heat 6 months a year to be comfortable, half that would be discounted as already
being spent. And since the water in the pipes is being heated up by normal operations perhaps 6 hours a day, I'd take
another 75% multiplier. That puts actual circulator running cost here at around $45 for electric or $19 for propane water
heating A YEAR. Feel free to double these if my estimates are off. Obviously YOUR RESULTS WILL VARY. Bruce RoeComment
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Originally posted by DanS26 View PostConsuming 6500 kWh a month is a very large load......it is not a hot water circulatory system. A large load is running and for long periods of time.Comment
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Actually he put a meter on it after his shower this morning before church. It was perfect. It the hot water heater. I think he said by 2/2 he has already used 500 kw/h. I would flip out.Comment
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I'm far from an electrician but my guess is if he finds whatever is causing those 2 or 3 15kw/h spikes that last 60 minutes during the month, he will find he problem? My question is what in the world is causing them in the first place?Comment
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Originally posted by C_Heath View PostActually he put a meter on it after his shower this morning before church. It was perfect. It the hot water heater. I think he said by 2/2 he has already used 500 kw/h. I would flip out.Comment
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Spikes matter, keep snooping them. But the bottom line is the total energy integrated over time, and ALL continuous
loads add up. A big 60 min spike contributes, but there are 44,000 minutes in a month. Final measurements should
be made with integrating instrumentation. Bruce RoeComment
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Originally posted by C_Heath View Post
the water heating. 20 amps.Last edited by J.P.M.; 02-06-2017, 04:14 PM.Comment
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Ask your friend if those usage spikes correlate in any manner with temperature changes in an automatic set back thermostat? A call for heat (or cooling for that matter) could be setting off the emergency heat.Last edited by DanS26; 02-06-2017, 08:23 PM.Comment
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6500kWh / month is like 40Amps continuous 24/7, which is like having A/C on all the time. Should be easy to find the problem...BSEE, R11, NABCEP, Chevy BoltEV, >3000kW installedComment
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Originally posted by solarix View Post6500kWh / month is like 40Amps continuous 24/7, which is like having A/C on all the time. Should be easy to find the problem...Comment
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Originally posted by C_Heath View PostIt the hot water heater. I think he said by 2/2 he has already used 500 kw/h.
What has he tried so far now that he knows where the power was going?
Just throwing a few ideas out there:
- add flow restrictors to showerheads if showering is a big use of hot water
- put clotheswasher on warm instead of hot
- insulate hot water heater if it's not already well insulated (new ones might be)
- consider a heat pump water heater, depending on the climate and where the water heater is installed
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