Partial Valve Positions

[stever]

I may have touches on this before, but I had my equipment put in a little different than they said it would be done. Probably not a big deal, but I must appeal to the guru's of TFP:

If a three-way valve is open to a stop partially -- lets say I want half of the water to go to the pool returns and half to the spa -- is the valve in this position efficient? If the flor is 100% (lets say) full open to pool, is is 50/50 now? Or is it more like 40/40 with 20% loss?

I have a bypass for my spa jets that misses the filter/heater and re-joins after. I had a physical piped bypass on my schematic and they plumbed just a three-way valve. I understand this can be used for this purpose, but I knew the other way I would have at least 100% flow (as the valve would be 100% toward the spa and the other pipe would always be feeding the spa -- adding additional flow).

Just curious....

Thanks,
Steve

 

[JasonLion]

A good quality 3-way valve does have just a little more internal turbulence than a standard T or 90 fitting (depending on where the valve is set) but it is pretty close to ideal.

Only one opening is partially or completely closed at a time. The other two openings are 100% open.

 

[Denali]

Using the Jandy valve as an example, if you put the handle in the half way position, all the ports are open fully. You can close one port partially (such as the spa) and have the pool port fully open. This is how I run mine.

I'm not an expert on flow but if you can consider the flow 100% with one port open, having both pool and spa ports open shouldn't restrict flow in anyway. With the spa port partially open and pool port fully open, you still have what you considered 100% open with additional flow available through the spa.

What was the question again? :-D