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:ev-boun...@lists.evdl.org] 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" <ev@lists.evdl.org>
To: "Electric Vehicle Discussion List" <ev@lists.evdl.org>
Cc: "Robert Bruninga" <bruni...@usna.edu>
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:ev-boun...@lists.evdl.org] 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 <ev-boun...@lists.evdl.org> on behalf of EVDL Administrator 
>via EV <ev@lists.evdl.org>
>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
>
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