Garn question

[ISeeDeadBTUs]

Does anyone here use a Garn for solar storage? If so, how does it work? If not, does it seem possible?

 

[deerhntr]

Does anyone here use a Garn for solar storage? If so, how does it work? If not, does it seem possible?

We just got our Garn wood system up in running, but solar for the shoulder seasons and summer is definitely in our plan. There is a 1/2" bung in the manway for you basic solar "drain back" system. There is no reason solar thermal panels could not be used for DHW, and light heating depending on load and panel gain. My only real question at this point would be related to the standby loss in the garn the panels need to overcome. I don't know as of yet what my stand-by losses are. Just make sure you have good site position for your garn barn, or lean-too when you plan your install.

 

[Jim K in PA]

There some older threads here and over on the forum at GARN.com addressing this. I have been told that the volume of the GARN is too large for most residential solar installs to have much effective input. The Btu output of the panels has to be in the several hundred thousand ballpark to raise the storage temp to any significant degree. As Russ pointed out, if your standby loss is 50% of your solar input, it makes more sense to heat your DHW through a seperate tank and HX. That is what I am going to do.

I suspect that if you lived in a more temperate climate, you could utilize the GARN storage volume more effectively. But if you lived in a more temperate climate, you wouldn't need a GARN!

 

[SE Iowa]

Remind me again what the GARN uses for emergency backup/vacation freeze protection. I wouldn't think antifreeze would be reasonable d/t the cost and volume ($10/gal times 500-700 gallons to make a 50% soln). Is there an electric coil?

 

[ISeeDeadBTUs]

Thanks Jim K. My gut feeling was that it was too much water, even with stratification.

 

[Jim K in PA]

Remind me again what the GARN uses for emergency backup/vacation freeze protection. I wouldn't think antifreeze would be reasonable d/t the cost and volume ($10/gal times 500-700 gallons to make a 50% soln). Is there an electric coil?

There is no backup per se. I installed an electric coil in mine for emergency backup, but you have to order the tank with the electric supplement option so the bungs are there for the coils.

My project for next year is to tie in a propane fired backup system to the primary loop on my GARN. That and a propane fuel Onan genny, and I'll be set.

 

[slowzuki]

If you're Garn is well insulated and in a spot where the waste heat is useful it would be fine for infloor heating. As long as you don't need high temp water for rad's or domestic. If you have infloor in a slab its probably simpler to dump every BTU from your panels into the floor and forget about using the Garn tank. Having it half warm will encourage stuff to grow in the tank.

 

[Gooserider]

The other thing I would expect is that you really shouldn't need much freeze protection - If the Garn is well insulated and the associated plumbing is also well protected, it should take a VERY long time to drop the temp in the boiler down to the point where freezing was a concern - I'd expect at least a week or two before needing to worry...

Gooserider