Peri, What you describe is essentially the indoor unit of a split heatpump, you just supply the heat from a different source.
-----Original Message----- From: EV [mailto:[email protected]] On Behalf Of Peri Hartman via EV Sent: Thursday, November 30, 2017 7:35 AM To: Electric Vehicle Discussion List Cc: Peri Hartman Subject: Re: [EVDL] Heat pump vs resistive Heater (with radiators) Robert, your method of putting fans near a radiator is something I had wanted to try. Really getting OT, here, so if people prefer, reply privately. A couple years ago I had to replace my gas furnace. I looked into getting a heat pump system but it was not possible with the various constraints and payback period so I bought a new gas furnace :( Anyway, one of the options I studied was to put in radiators instead of forced air. I would have run pex through the ducts to each register. One of the advantages of this kind of unit would have been space - no blowers, and I could have reclaimed return air duct space. I didn't want surface mount radiators because of the space they take. It might have been possible, but not easy. Instead I wanted to find some recessed radiators with a small fan to waft the air over the fins and into the room - gently, not with a breeze. Couldn't find any such product. Also, the fans would have to be very high quality in order to last and operate extremely quietly. Has anyone considered this? Peri ------ Original Message ------ From: "Robert Bruninga via EV" <[email protected]> To: "Electric Vehicle Discussion List" <[email protected]> Cc: "Robert Bruninga" <[email protected]> Sent: 30-Nov-17 4:54:49 AM Subject: Re: [EVDL] Heat pump vs resistive Heater (with radiators) >Yep, 90F is just fine for heating since it is continuous and low >velocity. >Sure, people love to stand over a blast of 140F furnace air, for the >few minutes the furnace is on, because they get so cold with no warm >air when it cycles off. I prefer the consistent warming of my heatpump >and cast-iron radiators. > >PLUS it reduced our $3000/yr oil costs down to only $1000 electric >which was easily made up with another solar array to keep us 100% >carbon and oil free. See http://aprs.org/geothermal.html > >The water in the heatpump and old cast iron radiators rarely gets above >about 105F and yet heats the house in Maryland just fine*. Of course, >being a hacker, I keep the hot water that low (higher efficiency for >the >heatpump) by having some convenient fans by some of the radiators where >we can hide the fans. This doubles convection and heat flow while >keeping the water temp lower. The heatpump can go to 126F, but the >efficiency is >-much- lower than when it is running at only 105F. > >PLUS it is free "zone" heat in every room, simply by which fans are on. > >I even wired an outlet on the floor near every radiator where we can >hide a fan, so that the fans only come on while the compressor is >running. > >Our church went from $4000/yr for Propane down to $1100 added electric >with an air-source heatpump. And again, we are reducing that to zero >with another solar array. > >* When temps get below about 20F, then the radiator water temp does get >to about 115F and the house can barely maintain 65F. At lower temps, I >finally turn on the AUX heat. > >The three HVAC companies all wanted to design an 8 TON heatpump and all >were leery that the water temp would not be high enough for COMFORT >because "radiators are designed for 140F". I argued, that the house >was built with no insulation and with blown in insulation a few decades >ago, that the radiators are now oversized, AND that if I needed more >heat, I'd do the fan thing. > >Two of the three companies refused to do the job because they clearly >had rarely done a heatpump-to-hot water system and only were following >"typical" guidelines without any actual "engineering" to match my >needs. >The winning contractor, agreed to do it MY way and his was the lowest >price too. He got $28k, the others wanted $38k and $48k. Half of that >was the HEATPUMP cost. The other half was for the Geothermal wells. A >lot, but reducing my family's $6000/yr energy costs down to only about >$300/yr very qickly has made it up. > >If we had gone for air-source instead of ground-source, the cost would >have been half but not quite as efficient. Besides, the wife wanted a >new driveway, and since that is where the wells had to go, then she got >a new driveway (costing more than the entire HVAC system in the first >place) yet that was all part of the job which also qualified for the >30% energy tax credits. > > >Bob > >-----Original Message----- >From: EV [mailto:[email protected]] On Behalf Of ROBERT via EV >Sent: Thursday, November 30, 2017 12:22 AM >To: Electric Vehicle Discussion List >Cc: ROBERT >Subject: Re: [EVDL] Heat pump vs resistive Heater (never buy another AC >unit) > >Anyone who has a home heat pump can check the register temperature with >a thermometer. You will find if the heat strips are not energized the >maximum temperature is about 90 F with an outside air temperature of >about >68 F. Give it a try. Then tell me I am incorrect. In addition, the >current building codes require a 15% fresh air intake to the return >air. >The old codes allowed a closed recirculating system. This does not >help the efficiency but improves the air quality in the structure. > > >________________________________ >From: EV <[email protected]> on behalf of EVDL Administrator >via EV <[email protected]> >Sent: Wednesday, November 29, 2017 10:13 PM >To: Electric Vehicle Discussion List >Cc: EVDL Administrator >Subject: Re: [EVDL] Heat pump vs resistive Heater (never buy another AC >unit) > >On 29 Nov 2017 at 18:14, ROBERT via EV wrote: > >>A heat pump outputs a register temperature of approximately 90 F. >>This low a temperature blowing across your skin is not comfortable to >>a lot a people. > >I think this is less true of recent heat pumps. > >I'd like to hear from someone who owns an EV with a heat pump -- how >warm does the air from the vents feel in the winter? > >I think that many or most older heat pumps did have this annoyance. >It's >not an EV, but I knew someone who had a late-1990s GSHP (Waterfurnace >brand) at home. The heating air from the vents always felt cool to me, >meaning that it was below body temperature. Ninety deg F would be quite >believeable. > >That's definitely not the case with my Mitsubishi mini-split from 2013. >Although I haven't measured its outlet temperature in heating mode, >most of the heating seasons it feels quite warm, almost hot. So it has >to be well above body temperature. As the outdoor temperature falls, >its outlet temperature declines too. However, it stays noticeably >above body temperature down to an outdoor temperature of around -15 deg >C. > >Thus I see no reason that an EV heat pump would have to produce air >that feels cool under most conditions. For the times that it did, I'd >expect it to have auxiliary resistive heat. > >David Roden - Akron, Ohio, USA >EVDL Administrator > >= = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL >Information: http://www.evdl.org/help/ >[http://www.evdl.org/images/evdl.jpg]<http://www.evdl.org/help/> > >EVDL Subscription Information and Help<http://www.evdl.org/help/> >www.evdl.org About the EVDL: The Electric Vehicle Discussion List, >founded in 1991 by EV enthusiast Clyde Visser, is an active and vital >source of information and help for people ... > > >= = = = = = = = = = = = = = = = = = = = = = = = = = = = = >Note: mail sent to "evpost" and "etpost" addresses will not reach me. >To >send a private message, please obtain my email address from the webpage >http://www.evdl.org/help/ . >[http://www.evdl.org/images/evdl.jpg]<http://www.evdl.org/help/> > >EVDL Subscription Information and Help<http://www.evdl.org/help/> >www.evdl.org About the EVDL: The Electric Vehicle Discussion List, >founded in 1991 by EV enthusiast Clyde Visser, is an active and vital >source of information and help for people ... > > >= = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > >_______________________________________________ >UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >[http://www.evdl.org/images/evdl.jpg]<http://www.evdl.org/help/index.ht >ml# >usub> > >EVDL Subscription Information and >Help<http://www.evdl.org/help/index.html#usub> >www.evdl.org >About the EVDL: The Electric Vehicle Discussion List, founded in 1991 >by EV enthusiast Clyde Visser, is an active and vital source of >information and help for people ... > > >http://lists.evdl.org/listinfo.cgi/ev-evdl.org >EV -- Electric Vehicle Discussion List - lists.evdl.org >...<http://lists.evdl.org/listinfo.cgi/ev-evdl.org> >lists.evdl.org >The Electric Vehicle Discussion List is a forum for discussing the >current >state of the art and future direction of electric vehicles (EVs). 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