EcoRenovator - View Single Post - Dump the plumbing and use PV to heat water?

Xringer · 04-11-10, 02:52 PM

We're getting good sun on the tracking mount between 10:30AM & 4:30PM
I'm thinking that 6 hours of good PV power will do the trick.

I retested the 250w heating pad on the boiler today and got some good results.
Time: Main: Upper:
13:00 148F 110F
15:00 152F 128F

At these lower boiler temps, It looks like a 2 deg-per-hour increase
on the main gauge and a 9 deg-per-hour under the upper cover.

During a sunny 6 hour day, (if no hot water was used) the main storage could possibly pick up 12 degrees,
if I was using a 250w PV array into a resistive HW heater!

I'm thinking that 240 to 300 watts of PV would be a good match to
my boiler, since it might coast some into the evening hours, before
the oil burner would want to kick in again..

All bets are off, if the dishwasher is used or someone takes a shower..

But, over-all I suspect there will be some reduction in oil use.
Especially during very sunny days when there is minimal hot water use..

If I we had went on a road trip this weekend, (using zero hot water),
that burner is going to keep on running when the loss builds up.
It's going to cycle once or twice a day.

Pay back? Break even? Not a concern with this project..

04-11-10, 02:52 PM	#16
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	We're getting good sun on the tracking mount between 10:30AM & 4:30PM I'm thinking that 6 hours of good PV power will do the trick. I retested the 250w heating pad on the boiler today and got some good results. Time: Main: Upper: 13:00 148F 110F 15:00 152F 128F At these lower boiler temps, It looks like a 2 deg-per-hour increase on the main gauge and a 9 deg-per-hour under the upper cover. During a sunny 6 hour day, (if no hot water was used) the main storage could possibly pick up 12 degrees, if I was using a 250w PV array into a resistive HW heater! I'm thinking that 240 to 300 watts of PV would be a good match to my boiler, since it might coast some into the evening hours, before the oil burner would want to kick in again.. All bets are off, if the dishwasher is used or someone takes a shower.. But, over-all I suspect there will be some reduction in oil use. Especially during very sunny days when there is minimal hot water use.. If I we had went on a road trip this weekend, (using zero hot water), that burner is going to keep on running when the loss builds up. It's going to cycle once or twice a day. Pay back? Break even? Not a concern with this project..