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Check valves for passive solar hot water system

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Posted by mark.fox on October 25, 2007, 1:01 am
 
Might anyone recommend a check valve for a thermosyphon hot water
system? I've been looking but haven't found anything yet.

Assuming I have to use a pump in my system (and this may be the case),
are there any pumps that come highly recommended for a low energy
system? (I'll admit to not looking much for pumps yet.) If a pump is
used in the closed loop to move heat from the collector to the tank,
is there any need for a check valve or does the pump act as one?
(Certainly, the pumps I'm familiar with (which aren't appropriate for
my solar hot water system) depend on check valves to operate.)

Thanks,

Mark


Posted by sam c on October 25, 2007, 1:21 pm
 
mark.fox@gmail.com wrote:

I have to confess I have no experience with thermo-siphon systems but ,
the use of a flap valve (if you can find one) would probably be better
than a sprung check valve , another idea you could try is to take a
large bore sprung check valve apart and remove the spring . hopefully
someone with thermo-siphon system experience will post .

Posted by mark.fox on October 26, 2007, 2:51 am
 On Oct 25, 7:21 am, sam c

That's a valuable suggestion on the sprung check valve and the flap
valve as well. I'm trying to avoid building my own. (I enjoy building
stuff myself, but it usually makes a lot more sense to just buy
something from off the shelf.)


Thanks,

Mark


Posted by Sundug on October 25, 2007, 2:32 pm
 On Oct 24, 8:01 pm, mark....@gmail.com wrote:

I have built a thermosyphon SHW system, if your collector is below the
HE, as it must be to move heat, than no check valve is necessary,as
cold fluid will stay down in the collector when the sun is not
shining. Doug
DIY Solar Hot Water Articles can be found here:

http://www.solarfacts.net/articles/diy/diy_solar_hot_water_heater_-_doug_kalmer.html

http://www.solarfacts.net/articles/diy/diy_solar_hot_water_heater_two_-_doug_kalmer.html



Posted by mark.fox on October 26, 2007, 3:21 am
 
For the initial configuration (really just for testing), I will be
doing exactly as you suggest. Based on how the system performs, I will
probably reconfigure it at least once. Unfortunately, I find it hard
not to tinker.

Is it really necessary to place the collector below the storage tank
in a thermosypon system? Certainly, its a clever way of avoiding a
check valve. I'm under the impression that as long as the collectors
are configured with the intake lower than the outlet and the opposite
is the case on the heat exchanger, that fluid will flow regardless of
the collector's position relative to the heat exchanger. To be honest,
my question about the valve was because I find it hard to believe that
the fluid flow won't reverse when the collector's temperature is less
than the water in the storage tank. I understand the reasoning for
arranging the tank about the collector though, and home my concerns
have no foundation in reality.


I've read those two articles through several times. They've been very
useful to me. The first inspired me to design and build my own tank.


Thanks for your suggestions and comments,

Mark


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