I think it is important to consider, and I am guessing you have, that the Garn inducer motor is only required to run 20% to 25% of the heating season. Of course the coldest days are the biggest concern and the run time required could be anywhere from 8 to 12 hours, but for much of the season it may only run 4 hours or less per day. I think it can sometimes be easy to lose sight of things and being off grid is a lofty goal and a nice dream for many people but in reality it is a necessity for very few. It is important to consider that reducing dependancy and costs by 70% to 80% is a significant contribution and achieving that final 20% can be a very expensive task with a dramtically smaller return. Don't get me wrong, I am not trying to discourage off grid I just think it is important to balnce the debate for anyone struggling with thier investment decisions. If the engineers at Garn can come up with an acceptable option to reduce the electrical requirements for the system you will see it, but not before it is extensively tested.
Forgive my previous empty post which was lost in a posting error. That has happened to me a couple of times and thier is no copy option on this site. Frustrating to write it twice!
DavidT:We could burn year around, less in summer, my solution is to install solar HW, should cover most of our summer needs and make a minor contribution in the winter. So still using the Garn, but not the blower.
David - Not sure what you mean by "still use the GARN, but not the blower". You cannot use the GARN without inducing draft with the blower. The GARN is a horizontal flue design, with almost 60' (in the 2000) of flue piping. You will need to power the fan in order to have any kind of reasonable combustion occur.
The combination of solar thermal, wood heat, and large thermal storage is compelling. Solar thermal will take care of summer loads almost anywhere and even deliver space heat in the shoulder seasons for those of us in milder climates. I'd be interested to hear how it works out for you.
Kenny:As a Garn rep I see and hear a lot of talk about re-engineering the best woodburning equipment in its class. To those who feel a need to do this there is a couple of things that should be considered. Martin Lunde is not only a very competent and well schooled engineer he has made a life study of wood burning technology and how it applies to the Garn product. For 35 years, I doubt a day has gone by, that he has not given thought to how he can improve the Garn and I don't believe that there is anyone on this forum that can out maneuver him in a brain wrestle. (How many waking hours are there in 35 years?) There are a lot of really intelligent people posting to this site (most more intelligent than myself) and I do not in any way mean to disparage anyone. It is often very thought provoking and valuable, but I think it is worth stating that every conversation taking place at the Garn offices includes ideas about how the product could be better without sacrificing safety or efficiency. What we have is really good and it's not easy to come up with improvements, but we will because it is our goal. That was kind of a long preamble to the original point I set out to make, but it is a very important point to remeber. If you modify your Garn product in any way you will void the listing and the warranty. I hope this post does not come off as "preachy" because I really enjoy reading about everyones idea's and you should all know that we are listening.
As a Garn rep I see and hear a lot of talk about re-engineering the best woodburning equipment in its class. To those who feel a need to do this there is a couple of things that should be considered. Martin Lunde is not only a very competent and well schooled engineer he has made a life study of wood burning technology and how it applies to the Garn product. For 35 years, I doubt a day has gone by, that he has not given thought to how he can improve the Garn and I don't believe that there is anyone on this forum that can out maneuver him in a brain wrestle. (How many waking hours are there in 35 years?)
There are a lot of really intelligent people posting to this site (most more intelligent than myself) and I do not in any way mean to disparage anyone. It is often very thought provoking and valuable, but I think it is worth stating that every conversation taking place at the Garn offices includes ideas about how the product could be better without sacrificing safety or efficiency. What we have is really good and it's not easy to come up with improvements, but we will because it is our goal.
That was kind of a long preamble to the original point I set out to make, but it is a very important point to remeber. If you modify your Garn product in any way you will void the listing and the warranty. I hope this post does not come off as "preachy" because I really enjoy reading about everyones idea's and you should all know that we are listening.
mhotel: The combination of solar thermal, wood heat, and large thermal storage is compelling. Solar thermal will take care of summer loads almost anywhere and even deliver space heat in the shoulder seasons for those of us in milder climates. I'd be interested to hear how it works out for you.
Solarwood,
That makes perfect sense to me and I am definatley not an expert at how you get to your goal but it interests me. I have not researched DC pumps, but I might suggest you select a pump for it's GPM and head ratings first and voltage secondary. After all a DC pump that dosen't satisfy the load won't help you. Here's a question. Would it make sense to use a couple of PV panels for trickle charging, install an inverter, keep your blower and pumps and back it all up with a small gas generator?
DavidT:I do not know the specific consumption of the Garn, but sounds like a 1/2 hp motor is in the 8 Amp range, then you have pumps and control systems etc. I am sure it could be done but it sounds like a lot of PV. The Solar DHW uses a lot less electricity, may well be more logical to put your money into more of these than PV to run the blower. Time to get out the calculator.
If I were trying to run "off grid" for an emergency situation I would probably resign myself to the fact that running the Garn combustion blower for 3 hours a day (probably less in your case solarwood) would easily be done with a generator and save the complexity of DC conversion issues. Using DC pumps would not be a big deal if you are going to incoroporate PV panels in you design from the outset. There are lots of DC circulators out there as well as very low amp draw AC mcircs like the Grundfos Alpha.
Steve Ebels: If I were trying to run "off grid" for an emergency situation I would probably resign myself to the fact that running the Garn combustion blower for 3 hours a day (probably less in your case solarwood) would easily be done with a generator and save the complexity of DC conversion issues. Using DC pumps would not be a big deal if you are going to incoroporate PV panels in you design from the outset. There are lots of DC circulators out there as well as very low amp draw AC mcircs like the Grundfos Alpha.