A7 AirTap install (ASHP hot water heater)

Xringer · 09-10-12, 01:34 PM

My solar PV back-up system has been supplying 120vac to the A7 a few days now, and seems to be keeping up.
At 2:30 AM this morning it ran off the battery pack for about 50 minutes.
It's partly cloudy today, but the pack's SOC is coming right back up.
http://i46.photobucket.com/albums/f1...Solar/z008.jpg
http://i46.photobucket.com/albums/f1...Solar/z203.jpg
It seems like just a few hours of good sun each day can supply the A7 with all it's power.
(At least during the summer)..

~~~

I've been doing a little experiment to determine if the temperature in the 40 gal tank is dropping down under 115 deg F.
That event should occur when our hot water usage exceeds the heating capacity of the A7.

I set the tank's thermostats to 115F, and plugged in the heating elements
to the grid 120vac, using Kil-a-volt-clone to monitor run time and kWh used.
At 120Vac power use is 1.130 kW. (3856 BTUh).
During the last 4 weeks, we've had two events of hotwater overuse.
In each case, the heating element burned up about 0.5 kWh.
I assume the heating element was running in sync with the A7.

So, this 15 cent test seems to show that a winter time slow-down in recovery time,
could be helped by the additional 3856 BTUh from the heating elements.

09-10-12, 01:34 PM	#11
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	My solar PV back-up system has been supplying 120vac to the A7 a few days now, and seems to be keeping up. At 2:30 AM this morning it ran off the battery pack for about 50 minutes. It's partly cloudy today, but the pack's SOC is coming right back up. http://i46.photobucket.com/albums/f1...Solar/z008.jpg http://i46.photobucket.com/albums/f1...Solar/z203.jpg It seems like just a few hours of good sun each day can supply the A7 with all it's power. (At least during the summer).. ~~~ I've been doing a little experiment to determine if the temperature in the 40 gal tank is dropping down under 115 deg F. That event should occur when our hot water usage exceeds the heating capacity of the A7. I set the tank's thermostats to 115F, and plugged in the heating elements to the grid 120vac, using Kil-a-volt-clone to monitor run time and kWh used. At 120Vac power use is 1.130 kW. (3856 BTUh). During the last 4 weeks, we've had two events of hotwater overuse. In each case, the heating element burned up about 0.5 kWh. I assume the heating element was running in sync with the A7. So, this 15 cent test seems to show that a winter time slow-down in recovery time, could be helped by the additional 3856 BTUh from the heating elements. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..