We have a GE hybrid heat pump water heater in our basement. We select the resistance coil in the winter, because the heat pump cools the room too much. We use the heat pump mode in the winter, and route the condensate.down to one of our sumps.
Len M. > On July 18, 2019 at 5:03 PM Peri Hartman via EV <[email protected] > mailto:[email protected] > wrote: > > > (Really off topic, here) I'm curious about the overall efficiency of > heat pump HW heaters. If it's in your garage (or basement), and it's > drawing heat from the garage, that's going to create a very cold garage, > right ? Further, if adjoining spaces or spaces above aren't fully > insulated from the garage, you'll also be increasing the heat load in > those spaces. All this would seem to reduce the efficiency of the HW > heater dramatically. > > So, shouldn't the heat pump be vented to the outdoors ? If so, then its > efficiency would be determined by the climate where you live. In winter > it may rely solely on resistance heating. Though it should do quite well > in summer in most parts of the US. > > Peri > > ------ Original Message ------ > From: "Robert Bruninga via EV" <[email protected] > mailto:[email protected] > > To: "Electric Vehicle Discussion List" <[email protected] > mailto:[email protected] > > Cc: "Robert Bruninga" <[email protected] mailto:[email protected] > > Sent: 18-Jul-19 1:23:02 PM > Subject: Re: [EVDL] Solar off grid with an EV? (DC AC/heatpumps and > waterheating) > > >> *-Because a heat pump system is using energy to "move" existing heat, > >> it gives you 400% (or more!) efficiencies. [i.e. you use 800 watts to > >> drive a compressor and fans, but get 3,200 watts of heat into the > >> tank, while cooling the area around the water heater.] > > > >I think it is more like 3 to one. The higher temp you want the water, the > >lower the efficiency and can range between 2 to 1 or 4 to 1. > > > >> I haven't shopped for heat pump water heaters. It looks like I should. > >> I have recently resolved to stop using my propane water heater... > > > >Here is my summary. They are often called HYBRID water heaters with the > >heatpump heating the incoming water at the bottom of the tank and then > (if > >enabled) a resistance element at the top to provide rapid response and > >higher temperatures. Remember the heatpump is the most efficient when it > >is throwing energy at the incoming 60F water with a greater delta-T > > > >The efficiency goes down as the temperature rises. SO I have mine set to > >heat the bottom of the tank to only 105F (where it is still pretty > >efficient) and then the top coil heats the rest to 115F. > > > >IN fact, I really have the Heatpump one in series with the old pure > >electric one and both have an added 4" insulation around them. So I let > >the heatpump one heat its entire tank to 105F, from there it goes into > the > >old heater which has the bottom element turned off and the top element > set > >to 115F. SO the bulk of the heating (55 to 105F (50 degrees) is done at > >3:1 electric effdiciency, and the final 105-115 (10 degrees) is straight > >electric at 1:1 (but saves wear and tear on the heatpump, working much > >harder j ust to get the final 10 degrees). > > > >Remember you can drastically change the "capacity" of a water heater > >simply by the temperature setting. If you set it to 140F, then when you > >take a shower, you only use a little bit of hot water mixed with more > cold > >water to get to final temp. This gives you a lot of "hot" water capacity. > > > >If you don't use that much hot water, then set the temperature to 110F, > >but now then your shower will be using mostly hot water from the tank and > >only using a little bit of cold water. Now your capacity is much less but > >you save energy by not throwing a higher temperature away mixing it all > >with cold water. > > > >Your wife may vary. > > > >Bob > >http://aprs.org/Energy-Choices.html > >_______________________________________________ > >UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > >http://lists.evdl.org/listinfo.cgi/ev-evdl.org > >Please discuss EV drag racing at NEDRA > (http://groups.yahoo.com/group/NEDRA) > > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA > (http://groups.yahoo.com/group/NEDRA) > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20190718/59ca322f/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
