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Hi Daniel,<br><br>
That is good information. Thanks for the link.<br><br>
My take on non vented heaters is that they are a bad idea for general
use. They do have the virtue of allowing off gridders to take winter
vacations without worrying about frozen pipes or dead batteries.
Inverters can be switched off and charge controllers left on, so
batteries will stay charged. They are also a good emergency source of
heat. Windows can be cracked for ventilation if necessary.<br><br>
Best,<br><br>
Drake <br><br>
<br><br>
At 05:56 PM 8/24/2018, you wrote:<br>
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Drake,<br>
<br>
The best thing to minimize blower power draw will be two fold.
<ol>
<li>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)
<li>Minimize head loss in the duct system. Head loss has an exponential
effect on energy use as a whole (blower motor and fuel efficiency)
<ol>
<li>Bigger distribution ducts
<li>metal duct for corners and turns (i.e use good fittings)
<li>little to no flex duct unless for straight runs
</ol>
</ol>
i. flex duct always well supported and
pulled tight, little to no slack allowed in a flex duct job.
<ol>
<ol>
<li>Etc Good read in this article, and the attached presentation
download:
<a href="https://www.energyvanguard.com/blog/secret-moving-air-quietly-through-your-duct-system">
https://www.energyvanguard.com/blog/secret-moving-air-quietly-through-your-duct-system</a>
</ol>
</ol> <br>
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<br>
<br>
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
thats 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.)<br>
<br>
With Regards,<br>
<br>
Daniel Young, <br>
NABCEP Certified PV Installation Professional<sup>TM</sup>: Cert
#031508-90<br>
<br>
<br>
<b>From:</b> RE-wrenches
<re-wrenches-bounces@lists.re-wrenches.org> <b>On Behalf Of
</b>Drake<br>
<b>Sent:</b> Friday, August 24, 2018 4:52 PM<br>
<b>To:</b> RE-wrenches <re-wrenches@lists.re-wrenches.org><br>
<b>Subject:</b> Re: [RE-wrenches] Forced air Furnace<br>
<br>
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. <br><br>
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. <br><br>
Does anyone know how to get accurate data on furnace blower motors?
<br><br>
Thanks,<br><br>
Drake <br><br>
At 01:59 PM 8/24/2018, you wrote:<br><br>
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<dd> boundary="------------914ACDD867C6488AACA07365"<br>
<dd>Content-Language: en-US<br>
<br>
<dd>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......<br><br>
<dd><pre>Ray Walters</pre><font face="Courier New, Courier"></font><br>
<dd><pre>Remote Solar</pre><font face="Courier New, Courier"></font><br>
<dd><pre>303 505-8760</pre><font face="Courier New, Courier"></font>
<dd>On 8/23/18 5:43 PM, Dana wrote:<br><br>
<dl>
<dd>Drake,<br>
<dd>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.<br>
<dd>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.<br>
<dd>The new ECM (electronically commutated motors) pump motors are
basically at DC permanent magnet motor power draws [Taco & Grundfoss]
these days.<br>
<dd> <br>
<dd>Best of luck with this one.<br>
<dd> <br>
<dd>
----------------------------------------------------------------------------<br>
<dd>Dana
Orzel
Great Solar Works, Inc. <br>
<dd>C -
208.721.7003
<a href="mailto:dana@solarwork.com">dana@solarwork.com</a><br>
</b>
<dd>Idaho Contractor - #
028765 Idaho PV #
028374<br>
<dd>NABCEP #
051112-136
<a href="http://www.solarwork.biz">www.solarwork.biz</a><br>
<dd>"Responsible Technologies for Responsible People since
1988" <br>
</u>
<dd>P</b> Please consider the environment before printing this
email.<br>
<dd> <br>
<dd> <br>
<dd>From:</b> RE-wrenches
<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">
<re-wrenches-bounces@lists.re-wrenches.org></a> On Behalf Of
</b>Drake<br>
<dd>Sent:</b> Thursday, August 23, 2018 2:37 PM<br>
<dd>To:</b> RE-wrenches
<a href="mailto:re-wrenches@lists.re-wrenches.org">
<re-wrenches@lists.re-wrenches.org></a><br>
<dd>Subject:</b> [RE-wrenches] Forced air Furnace<br>
<dd> <br>
<dd>Hello Wrenches,<br>
<dd>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.<br>
<dd>Thank you,<br>
<dd>Drake <br>
<dd>Drake Chamberlin<br>
<dd>Athens Electric LLC<br>
<dd>OH License 44810<br>
<dd>CO License 3773<br>
<dd>NABCEP Certified Solar PV <br>
<dd>740-448-7328<br>
<dd><a href="http://athens-electric.com/">http://athens-electric.com/</a>
<br>
<dd> <br><br>
<br><br>
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