I have decided to bite the bullet and purchase a GARN 1500. I currently have 1400 sq. ft of radiant in concrete floor and 1000 sq. ft of staple up for second floor (or will when I get around to installing it!) I currently heat primarily with a woodstove and keep the concrete at 66 or so in the winter with an oil boiler (and inslab sensor). House is typically 74 or so with woodstove. I've added a 1032 sq. ft addition with radiant in floor. Woodstove won't get much heat out there. I have also added an attached garage/shop with 2300 sq ft of concrete radiant, in two different zones (garage and shop). Obviously the woodstove won't touch this. So, I could either attach the addition to the oil boiler and burn lots of oil, and have a cold garage, or bite the bullet and install my outdoor gasser to heat everything. Always planned on a wood boiler....might as well do it now. I live out in the woods and once the snow flies, no oil truck will make a delivery up my driveway. I have a 500 gallon tank and a Buderus boiler. Would have to add another tank, or more, and keep paying for oil. No thanks. I'm in NY state, halfway between Ithaca and Binghamton.
I looked at the indoor gassers and decided by the time I added storage I'm fairly close to the price of a GARN. I could go the propane tank refit route and be considerably cheaper, but I think I'd end up buying a refurb tank for $2900 (AHONA) and that puts me within three to four thousand of the GARN. Sounds to me like the GARN, when maintained, will outlast me. I'm 40 today. Perhaps indoor gassers can say the same thing, but the GARN appears to speak for itself. Enough about the decision. I feel poor having made the choice, but I think happy with the choice.
Attached is a JPG showing my system plans. Today I have the two Tekmar controllers, 363 and 362, The 363 does the DHW, controls the primary loop pump P1, and the house concrete floor mixing pump M1, and secondary pump S1. The 362 controls (or will anways) the staple up mixing pump M2 and the staple up secondary loop S2.
My Buderus sits outside the house in its own boiler building, along with the 500 gallon oil tank. I have buried lines that run from the boiler room into the house. 1" insulated pex. I plan to install microflex here for future use, as I know I am losing heat in these initial lines. I slide the "pipe insulation" over the 1" lines and ran the pair through 4" conduit. It works, but not ideal.
The GARN will sit in its own building, an external shed I can empty since I have a garage now. I will run the microflex from the GARN building into the boiler building, through a plate HX, and into the existing pressurized primary loop. When I installed the boiler, I put in the valves in the primary loop to easily accept a HX...as this was always in the plans for the future. There are the three valves between the HX and the Buderus (V1, V2, V3). Currently V2 and V3 are closed and V1 is open. I plan to open V2 and V3 to pass the boiler hot water through the heat exhanger and on its way into the house. V1 will be closed.
I think what I am planning to do is to turn off the power to the Buderus when the GARN is in operation and then connect the GARN pump (G1) to the "call for heat" going to the Buderus. When the call for heat comes, the GARN will heat the HX, bringing the primary loop up to temperature. Is there a controller that will effectively run the GARN pump G1 for a period of time, and if no heat, fire the oil boiler and shut off G1?
I have to sit down and do come calculations on pipe sizing, pump selection, etc. I have performed a heat load calculation. I actually believe the numbers, they agree fairly well with my wood stove consumption, temperatures, etc.
The one concern I have is if I did want to go away and rely on the Buderus to kick in when the GARN became too cool, I suspect the HX would suck away great amounts of heat to heat up the GARN. Presumably I would adjust the valves. I'm considering placing a "tempering" valve that I can partially close between the oil boiler and the HX so I can indeed get some heat out into the GARN to prevent freezing, but also get heat into the building.
I have more work to do, but I'd appreciate comments/suggestions/thoughs. All the pumps are isolated with flanges though not show. I will put full port ball valves in many places for shut offs. Would love to discuss this with those of you who enjoy this stuff as much as me!
Thanks,
Bruce
I looked at the indoor gassers and decided by the time I added storage I'm fairly close to the price of a GARN. I could go the propane tank refit route and be considerably cheaper, but I think I'd end up buying a refurb tank for $2900 (AHONA) and that puts me within three to four thousand of the GARN. Sounds to me like the GARN, when maintained, will outlast me. I'm 40 today. Perhaps indoor gassers can say the same thing, but the GARN appears to speak for itself. Enough about the decision. I feel poor having made the choice, but I think happy with the choice.
Attached is a JPG showing my system plans. Today I have the two Tekmar controllers, 363 and 362, The 363 does the DHW, controls the primary loop pump P1, and the house concrete floor mixing pump M1, and secondary pump S1. The 362 controls (or will anways) the staple up mixing pump M2 and the staple up secondary loop S2.
My Buderus sits outside the house in its own boiler building, along with the 500 gallon oil tank. I have buried lines that run from the boiler room into the house. 1" insulated pex. I plan to install microflex here for future use, as I know I am losing heat in these initial lines. I slide the "pipe insulation" over the 1" lines and ran the pair through 4" conduit. It works, but not ideal.
The GARN will sit in its own building, an external shed I can empty since I have a garage now. I will run the microflex from the GARN building into the boiler building, through a plate HX, and into the existing pressurized primary loop. When I installed the boiler, I put in the valves in the primary loop to easily accept a HX...as this was always in the plans for the future. There are the three valves between the HX and the Buderus (V1, V2, V3). Currently V2 and V3 are closed and V1 is open. I plan to open V2 and V3 to pass the boiler hot water through the heat exhanger and on its way into the house. V1 will be closed.
I think what I am planning to do is to turn off the power to the Buderus when the GARN is in operation and then connect the GARN pump (G1) to the "call for heat" going to the Buderus. When the call for heat comes, the GARN will heat the HX, bringing the primary loop up to temperature. Is there a controller that will effectively run the GARN pump G1 for a period of time, and if no heat, fire the oil boiler and shut off G1?
I have to sit down and do come calculations on pipe sizing, pump selection, etc. I have performed a heat load calculation. I actually believe the numbers, they agree fairly well with my wood stove consumption, temperatures, etc.
The one concern I have is if I did want to go away and rely on the Buderus to kick in when the GARN became too cool, I suspect the HX would suck away great amounts of heat to heat up the GARN. Presumably I would adjust the valves. I'm considering placing a "tempering" valve that I can partially close between the oil boiler and the HX so I can indeed get some heat out into the GARN to prevent freezing, but also get heat into the building.
I have more work to do, but I'd appreciate comments/suggestions/thoughs. All the pumps are isolated with flanges though not show. I will put full port ball valves in many places for shut offs. Would love to discuss this with those of you who enjoy this stuff as much as me!
Thanks,
Bruce
