Vertical vs horizontal storage tank...piping

[vti-chris]

Hi to all,
I would like to ask a Q regarding the position of the hot water storage tank which is placed above the flat panels.

I noticed that the houses that use vertical tanks have hot water faster and manage to keep it hot even after cold water is going through because of use...when the horizontal ones seem to lose their energy faster and require more time to get the water at the same temp(obviously it will have more volume of hot water but can't be used if it only reaches 25C(77F).
I know it's simple physics but the manufacturers here insist that there is no difference..

I also would like to ask in the case i use a horizontal tank just because my wife doesn't want it to be seen at the roof!! Is there a difference whether the inlet piping of the hot water from the panels gets in the tank in the middle or at the top?
I've seen a few on the internet where the exit of the tank for the DHW was coming from the same pipe where the inlet from the panels was.

Middle inlet
2012101620252734_2.jpg


Top inlet

http://greennav.files.wordpress.com/2008/03/solar-panel.gif?w=450

[J.P.M.]

Hi to all,
I would like to ask a Q regarding the position of the hot water storage tank which is placed above the flat panels.

I noticed that the houses that use vertical tanks have hot water faster and manage to keep it hot even after cold water is going through because of use...when the horizontal ones seem to lose their energy faster and require more time to get the water at the same temp(obviously it will have more volume of hot water but can't be used if it only reaches 25C(77F).
I know it's simple physics but the manufacturers here insist that there is no difference..

I also would like to ask in the case i use a horizontal tank just because my wife doesn't want it to be seen at the roof!! Is there a difference whether the inlet piping of the hot water from the panels gets in the tank in the middle or at the top?
I've seen a few on the internet where the exit of the tank for the DHW was coming from the same pipe where the inlet from the panels was.

Middle inlet
[ATTACH=CONFIG]3616[/ATTACH]


Top inlet
http://greennav.files.wordpress.com/...anel.gif?w=450

I'd be interested to know how you discovered vertical tanks "get" hot H2O faster and keep it warmer ?

As for vertical vs. horizontal, assuming this is a thermosiphon type heater, a tank in vertical orientation will, in theory move water a bit faster than the same tank in horizontal, but only because of an assumed increase in the height available for the thermosiphon effect, and not fast enough to improve the collector tube to water heat transfer coefficient which will almost always be that of laminar flow in setups like this. Raise the horiz. tank to the height of top of the vertical tank and that advantage pretty much disappears. From the sound of it, I'm not sure your wife would approve however.
In practice, I doubt if a difference in performance between vertical and horiz. tank systems could be measured much less noticed. Just make sure the system has a high point and a low point and everything runs uphill or downhill with no level fluid paths in between.
The bottom outlet from the tank is probably the better arrangement of the two shown as it will tend to get the coldest tank water to the collector, improving efficiency some by reducing the collector heat loss coefficient due to a lower operating temp. The other arrangement will have the same effect as reducing the tank size - probably not desireable unless the tank is oversized to start with.
Don't forget about safety and serviceability. Think about relief valves, valves in general, especially check valves, piping layout including consideration and allowance for expansion/contraction, consideration of how to handle water volume changes - expansion tanks/bleed valves. And a very big deal - freeze protection. Unless you live somewhere that NEVER freezes allow for it. It will happen.

[russ]

Right - vertical or horizontal the water temp should be about the same.

This is something you want to build or to buy?

If you live in a freeze area a drain back system should be considered.

[vti-chris]

The reason i'm asking is because of the stratification effect of the hot and cold water.
More height=more space for the hot and cold water to seperate.

Can i use the hot water outlet for both DHW and pannel hot water input?

[inetdog]

The reason i'm asking is because of the stratification effect of the hot and cold water.
More height=more space for the hot and cold water to seperate.

Can i use the hot water outlet for both DHW and pannel hot water input?

Now you are getting into the real questions.

If you have a primary or auxiliary heat source in the tank, instead of a preheat tank or solar only system, then it does make a difference where you connect all of the plumbing.

You always want to take your water to use from the top of the tank and feed your cold makeup water into the bottom.
But ideally you also want to run the loop to the thermal panel or heat exchanger from the bottom to the middle so that you are not cooling off the expensively heated water near the top of the tank.

You can make this happen easily with a tank that has four connections, or you can follow the directions given, I believe, by Naptown in another thread and use just the bottom drain connection (normally not used for circulation), the original cold water inlet with the dip tube cut short, and the original hot water outlet.

With a horizontal tank, stratification will be reduced and you will only be able to draw of water at close to the average temperature rather than the hottest temperature the panel produces.