[Greenbuilding] Alternatives to Solarhart Thermosyphon Tanks

[Antonioli Dan]

I've seen quite a few horizontal tank thermosyphon systems over the years, and they make perfect sense to me. Granted, they're big and ugly on the roof, but they have no pumps and last a very long time. 

For my application, I'm currently using an open loop Solarhart tank for an outdoor solar shower on my rural property. It's solar only, no electricity, gas, or back-up and works like a charm. 

 Two weeks ago when the weather was grand and the warm sunny days of late Fall just didn't seem like they would even end....the nighttime temperature dropped to 29 degrees and one of the panels burst. When I'm on the land and I know there's a good chance of freezing/frost, I isolate the tank and manually drain the panels. But the latest frost caught me by surprise, and I've decided the time has come to invest in a closed loop system. I was seriously bummed out when the sun shined on the panels last week and the temperatures were close to 80 and I couldn't take a solar shower!!!

There are plenty of closed-loop solar storage tanks on the market, but I've yet to see a horizontal one. Solarhart tanks run about $2,100 and they all have the back-up heaters in them. I don't need a back-up heater for the outdoor solar shower. I'd like to think that there's a horizontal closed loop solar tank out there. If not, I'll make one!

Dan Antonioli



On Nov 4, 2011, at 4:59 PM, Nick Pyner wrote:

> Damn right.
> 
> Indeed, it is fair to say that the Solarhart system is a triumph of
> salesmanship over the laws of physics.
> 
> Solahart do have some patented hocus-pocus to promote horizontal
> thermosyphon but they are really all about is a simple package that is fairy
> easily retrofitted by spreading the tank load over several rafters.
> 
> Solarhart do make split systems but I believe they all use vertical tanks on
> the ground and, somewhat ironically, I have never seen or heard of one of
> their horizonal tanks in the roof.
> 
> Further to this, I think it is becoming apparent that a little bit of
> thermosyphon is not necessarily better than none, and you don't see so many
> horizontal tanks being installed these days. I understand they don't attract
> as much rebate as tanks on the ground and, as plumbers now routinely work
> with solar, their installation advantage isn't as attractive as it used to
> be.
> 
> Nick Pyner
> 
> Dee Why   NSW
> 
> -----Original Message-----
> From: greenbuilding-bounces at lists.bioenergylists.org
> [mailto:greenbuilding-bounces at lists.bioenergylists.org]On Behalf Of
> Frank Tettemer
> 
> It seems the horizontal tank idea would be a great physical fit
> into a elevated space, under a roof slope.  It doesn't take up much vertical
> space, which is usually good under a sloped roof. .
> 
> But isn't the shape of a fairly wide, and not-too-tall of a tank, going to
> be a challenging shape,
> to use for thermosyphon systems?
> I've never tried it, so I know little about that sort of shape. And I'm
> curious about how it works out.
> 
> I'm not a plumber, but I've built a few dozen DHW systems over the decades.
> These various experiences have used a vertical tank,
> from 40" to 75" tall.
> I'm not an engineer or a boiler technician, so the 'Ass'umption is all mine,
> that the height of the tank, as well as the height of the stack of coils in
> the heat exchanger partially accounted for the efficiency of the system.  In
> this case, more height would be a good thing.
> 
> 
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