Garn placement feasibility

I know nothing about the Garn, but off-hand using it as a radiator should work well. I heat my 20 x 40 shop with a Tarm gasser installed in the shop, along with 1000 gal LP tank pressurized storage. The LP tank acts as a radiator and is the only heat source I need for the shop: no fans, pumps, etc., just the circ when the boiler is firing. I wrapped the tank with 6" of regular kraft-faced fiberglass, leaving about 4' exposed, and setup so I can remove another 2' of insulation as needed. The tank is 19' long. Works very well.

SolarAndWood said:

I have a lower level walkout that I am considering sliding a 1500 into. I will be able to back the trailer right up to the outside wall. A few issues:

1. The header height I will have to slide under is 78". I can take one of the 2x8s off the plate to buy an inch and a half. Is this enough?

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I was able to squeeze mine in an even shorter space, so as long as you are able to go in nearly level, you should be fine. Check out the pics on my site.

2. The horizontal vent will go under the floor of the porch. The floor is 10' above grade. This a problem?

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It may be. The GARN flue is about 4' above floor level, so it would only be 6' below the porch floor. I would add horizontal piping to get it to discharge out past the porch. How far is the edge of the porch from where the GARN flue exits the building?

3. The ceiling in the lower level is only 7' 2". Is this enough or will I have to cut a hole in the floor above to access the hatch? Not the end of the world but not real desirable.

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You will have to have some sort of access hatch. The GARN lid has the low water cutoff switch mounted to the center of it, so if you stay with the OEM configuration, you will need about 18" of clear height to get it on/off with the switch attached. Check out my pics to see how my hatch is configured.

It would be placed in one end of a 40x22 room. I am wondering if I can use the Garn as a radiator for this space? I am thinking that I would insulate on all sides/top except the one facing the room. Then, have a removable spray foam panel that would be in place when I don't want heat in the space. Has anyone tried this?

Thanks for the feedback.

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I think you will find the room TOO warm with an entire side exposed. I am sure you can find a reasonable configuration that will keep the space comfortable. Perhaps a couple of chases with convection from a floor level intake and upper level discharge, or add a fan and move the air to where you want it.

Keep us posted!

If the Garn will be in a 40x22 ft room, is there any possibility of turning it 90 degrees so that the vent need not exit under the porch? I guess that will depend on whether either of the other walls around the corner from the porch have any above-grade area. I don't have a Garn, and any of these varying technologies have their pros and cons, but a Garn in the basement would be an excellent arrangement, for the precise reasons you mention.

Can you put in a 90 under the porch and let it discharge to the side of the porch and roof overhang?

SolarAndWood said:

What is exiting the vent that I need to be concerned with under the porch floor? Is it a fire risk you are concerned with?

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Flue gases from the GARN exit at anywhere from 250-350 degrees F. At start up and toward the end of the burn you can and will get some smoke/soot. During the burn you will get incandescent embers exiting the flue from time to time. Depending on moisture content, you will also get a fair amount of steam. Heat, sparks, CO, and soot would be my concerns.

Given that the flue is only 6" wide, I would still run it out past the end of the porch, and if need be, build a snow deflector. However, whether discharging under or at the edge of the porch, make sure the snow pile does not block flow and trap CO in a well near the house. You have a lot of windows there.


Cute little garden gnome you have there. She'll be able to load the GARN as soon as she is tall enough to reach the handle.

cycloptic pendulum said:

water condensation may freeze in extended pipe resulting in blockage?

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Unlikely with a run under 20', as the flow rate in the GARN is very high, and the vapor phase is in the early to middle part of the burn.

Sounds like you found your solution. Call Jim S at GARN and bounce your idea off of him. You can add a 90 in the discharge run, just keep the run shorter. Sounds like you can do that.

Plumbing simplicity really has nothing to do with proximity to the manifold. Since you are referring to manifold(s), I am taking that to mean you are not going P/S?

SolarAndWood said:

Is a 90 legit?

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I had the same question last Fall, and I wound up talking to Martin Lunde about it. His answer is "yes" (but maybe not for you - read on), you can execute a 90 with a Class A tee, but he had a few rules:

· The local inspector has final say on any project.
· You must have complete and continuous access to the tee for periodic cleaning - ie it cannot be buried in insulation, etc.
· The clean out cover of the tee is sealed, and resealed after each cleaning.
· The unit is not in a building where people are located.
· There is a 1' section of class A flue between the GARN unit and the tee.
· The tee and flue are full structurally supported utilizing metal (not wood or other combustible materials). A tee used in this configuration is not strong enough to support the flue connected to it.

Class A tees are made for non-pressurized outdoor installation as they will leak flue gas, including CO2 when used in pressurized flue applications. The GARN is a pressurized flue application.

If I understand your setup correctly, your install is inside a building where people are located, and given the concern about leaking flue gas, Martin would rule out the use of a tee ...

For what it is worth, I installed a tee on my unit, and despite sealing it well with silicone, I do think it still leaks a bit ...

Tom