I’ll add another choice to the thread which is kerosene The direct vent remote tank kerosene heaters are the most efficient, least costly way to go. Rinnai is one of a few Japanese heaters.
Many people I’ve worked with have gone this way vs propane. Either direct vent or central heaters systems. And all have commented that the cost was significantly less with kerosene than with propane. That said where I live we can get kerosene delivered like diesel, in bulk. I don’t know if everywhere is like that. But either way, with best insulation design practices it greatly changes the metrics of heating design. With that reduction in heating load, central whole house heating is often way more expensive than with zone type heating. It’s back to reduce the load before you have to power it. If I was designing an off grid heating system it would be with kerosene vs propane. My 2 cents Jay Peltz Power. > On Aug 24, 2018, at 2:56 PM, Daniel Young <dyo...@dovetailsolar.com> wrote: > > Drake, > > The best thing to minimize blower power draw will be two fold. > Get the smallest BTU furnace you are allowed to (with and ECM blower). Since > blowers are generally sized at a nominal CFM/BTU of heat output. (Around > 30CFM/ 1000BTU for the usual heat pump or 90+eff furnaces) > Minimize head loss in the duct system. Head loss has an exponential effect on > energy use as a whole (blower motor and fuel efficiency) > Bigger distribution ducts > metal duct for corners and turns (i.e use good fittings) > little to no flex duct unless for straight runs > i. flex > duct always well supported and pulled tight, little to no slack allowed in a > flex duct job. > Etc… Good read in this article, and the attached presentation download: > https://www.energyvanguard.com/blog/secret-moving-air-quietly-through-your-duct-system > > Not knowing the home layout and specs it hard to give specific advise on that > side, but those two items are big drivers on actual power needs for blowers. > But as you said, the furnace is there for insurance costs, not primary > heating… > > Also, the unvented propane heater in a primary dwelling seems like a bad idea > to me. Is the home expected to be well sealed for air leaks? Blower door > tested, relatively well sealed would be a blower door number of less than 2-3 > ACH50 (air changes per hour @ a 50pascal pressure difference to the > outdoors), 1-1.5 is really good, and passive house is 0.6 and lower? Because > both the fireplace and the unvented heater could be bad news if that’s the > case… Something you might want to see if you client is conscious of. (Not > sure how far you are getting involved in the home design Drake.) > > With Regards, > > Daniel Young, > NABCEP Certified PV Installation ProfessionalTM: Cert #031508-90 > > > From: RE-wrenches <re-wrenches-boun...@lists.re-wrenches.org> On Behalf Of > Drake > Sent: Friday, August 24, 2018 4:52 PM > To: RE-wrenches <re-wrenches@lists.re-wrenches.org> > Subject: Re: [RE-wrenches] Forced air Furnace > > A wood stove heats the house, and will be the primary source of heat. An > un-vented propane wall heater is installed and can heat the small, earth > bermed, well insulated structure. A furnace will be a nice supplement, and > will quickly pay for itself in insurance savings. During even a moderately > cloudy day, it will be fine, but will not be used much on batteries. Still, > I'd like as efficient a model as possible. > > If I can find a unit with a 400 W draw, like the one in our on grid house, > that would be adequate. The specifications I've found on the blower motors > are sketchy. I will likely need to order it on line (or take a trip to a > neighboring city), so reading the nameplates might not be so easy. > > Does anyone know how to get accurate data on furnace blower motors? > > Thanks, > > Drake > > At 01:59 PM 8/24/2018, you wrote: > > Content-Type: multipart/alternative; > boundary="------------914ACDD867C6488AACA07365" > Content-Language: en-US > > I always try to talk the client into hydronic heating with ECM drive > circulation pumps. They do make ECM drive blower motors that can be > retrofitted in some furnace systems. Overall, its just a bad combination off > grid: the worse the weather is the less PV production you have, and this > corresponds to the same time that the furnace is operating 12 hours/ night. > They are either running the generator a bunch, or waking up in the morning to > a cold house with the power off, and dead batteries. If its an AC coupled > system, they won't even have any PV production the next morning either. This > is another reason AC coupled is not a great idea, or at least you need to > always have some DC coupled PV as well, but I digress...... > > Ray Walters > Remote Solar > 303 505-8760 > On 8/23/18 5:43 PM, Dana wrote: > > Drake, > All the conventional units I have amp clamped over the years are pushing > 900-900+ watts per hour. I do not recommend them ever & to date I have never > found a lower wattage blower. I would assume that a permanent magnet motor > would fit this suggestion, but I have not found one. > For off grid I recommend: Radiant floor heat first and hot water base board > second long before hot air. Air is a better insulator than a heat transfer > agent. > The new ECM (electronically commutated motors) pump motors are basically at > DC permanent magnet motor power draws [Taco & Grundfoss] these days. > > Best of luck with this one. > > ---------------------------------------------------------------------------- > Dana Orzel Great Solar Works, Inc. > C - 208.721.7003 d...@solarwork.com > Idaho Contractor - # 028765 Idaho PV # 028374 > NABCEP # 051112-136 www.solarwork.biz > "Responsible Technologies for Responsible People since 1988" > P Please consider the environment before printing this email. > > > From: RE-wrenches <re-wrenches-boun...@lists.re-wrenches.org> On Behalf Of > Drake > Sent: Thursday, August 23, 2018 2:37 PM > To: RE-wrenches <re-wrenches@lists.re-wrenches.org> > Subject: [RE-wrenches] Forced air Furnace > > Hello Wrenches, > > What is the best choice for a propane, forced air furnace for an off grid > house? We would prefer one that doesn't have a phantom load, although the > transformer for the thermostat may not be avoidable. Low blower current would > be preferable. The furnace AC will be powered by a Magnum 4448 PAE. > > Thank you, > > Drake > > Drake Chamberlin > Athens Electric LLC > OH License 44810 > CO License 3773 > NABCEP Certified Solar PV > 740-448-7328 > http://athens-electric.com/ > > > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: > RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org >
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