What you say about setting water temp to 145 (so you use less) is true for a resistanve hot water heater where every BTU costs the same) but very very counter productive for a heatpump water heater! Heat pump efficiency is inversly proportional to temperature. My water heater setup so that I can pull the air from my attic crawl space where the temps in the summer approach 140 degrees and are often over 90 degrees even in the winter months. However, these temps are typically only available after noon and before 6-9 pm (depending on the season). So my water heater can be controlled by an Arduino to only run when the attic temps are warm enough to make it practical to heat to 145 and then coast for 18 hours or so. When the attic temps don't get that high (overcast days), or the water heater cools below 105, then the Arduino lets it run until it gets to around ~125 degrees. Typically wen the attic is hot I also have a surplus of solar power. FWIW even when pulling in air that is only ~60 degrees and heating water to ~130 my heat pump is only drawing bit over 600 watts. It might not be running a CoP of 3 or more, but it's still better than 1 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200129/833ecee3/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
