3-way or diverter (bypass) valve?

[whitedog4]

Howdy - any advice would be appreciated as I can't find the particular answers within the site (which ROCKS).

Background: I will be re-installing a 12' round Intex metal frame AGP (for the 2nd season) and integrating a new pump, solar panel and blanket (specs below). My goal is to raise/maintain the temperature while maximizing potential and preserving my investment.

I have further leveled my pad and anticipate better setting compared to previous years, as there is a slight pitch in the lawn (approx. 3" per 12'). I will have 35% of pool surface represented with one panel, may add another next year if configuration/budget allows. Space dictates I place the panel on ground level adjacent to the pool (I may configure a rack to angle it). The panel header would be about 6' away from the pool and the tubes would run 'downhill'. Questions:

1. Given that the panel is below the water level and ever-so-slightly 'downhill' (even if there's a rack involved), am I better off with a 3-way valve vs. a diverter (bypass) valve? It seems to me that with a diverter open (solar off), gravity will push some H2O through it. Or do I not get the hydrodynamics and despite the 'downhill' placement, I need to close the diverter to force the panel to engage? I don't anticipate ever closing a diverter all the way as I've gone a bit overkill on the pump flow vs. pool size and I don't want to over-pressurize the panel (it's an Ebay special).
2. Do I need a vacuum break? I'm thinking no, as it's not above water level.

Thanks,

 

[jblizzle]

The water will take the path of least resistance. If you just have a ball valve on the solar supply, then you may not get enough flow through the panel. Solar heating is most efficient at higher flow rates. So, you would be better off using a 3-way valve that would allow your divert all or some of the water through the solar panel.

A vacuum break will not do you any good.

 

[Isaac-1]

Either a 3 way valve going into a T with a check valve on the solar return or 3 individual ball valves, I would be inclined to use 3 individual ball valves in this case (a cut off for solar output and on solar return, plus a valve used for variable restriction on solar bypass loop) this would give the advantage of quickly being able to isolate the solar panels if they spring a leak.

 

[whitedog4]

Thanks for the responses. I found a picture of the configuration I will likely use and am wondering: is a check valve really necessary given that the panel will be lower than the filter (another potential leak point) and if it is, where on this diagram should it go? Between panel outlet and PVC tee?

 

[jblizzle]

The check valve would go above the PVC Tee on the Outlet pipe ... yes you should have it as the point is to prevent the water trying to enter the solar panels backward and pressurizing the panels when the solar is turned off.

 

[whitedog4]

Thank you. I picked up a Pentair 3-way valve today and was asked if I want a spring-loaded or flapper style check valve. I said flapper (it's on order). Is that OK w/ this configuration? I was advised to hang the flapper: operating top-to-bottom, not side-to-side.
I again want to express thanks (esp. to jblizzle/Jason as he's responded the most to my questions). I'm a small-time guy who is learning the ropes and truly appreciate the support. I plan on contributing to support this site. There should be a warning on how obsessive this can become. I had trouble getting to sleep last night thinking about how to configure/plumb/fit my new setup this weekend.

 

[jblizzle]

I am not sure I understand the comment on the orientation of the flapper (good choice, BTW). It can be horizontal or vertical ... although maybe they mean if you are mounting horizontal to have the clear part on the top so the flap moves up and down (which I agree with).

Note that I think Mark (mas985) mentioned you can actually remove the spring to reduce head less if you want. I still have not removed the 2 in my system to see if it helps anything.

 

[whitedog4]

The comment from the supplier was that the manufacturer doesn't recommend installing the valve so that the flapper operates side to side (left/right), that it should hang and operate like, say, a pet door would. I plan on installing it horizontally. And yes, you can expect pics when I'm done this weekend!