Recirc system add a loop

[frodo]

I have been having a problem with your circ line pump ever since the first day I saw it
Hot water going through the circulation pump is more "active", ... When you push water through pipes, the path of least resistance will get the greatest water flow. When you PULL the water through the pipes, you'll create suction ....

View attachment 20207

I prefer. a simple light switch in the bathroom to energize the 3 way valve when entering the bathroom

 

[Diehard]

Flow is flow, I am not disputing that fact
you are correct...water is flowing

What we are discussing is the manor in which the water is moved [flow created]
heaver water with out air is easier to push
than lighter water with air is to pull

turbulence of moving water causes the air to move to the top of any system, closed or open
air causes impeller cavitation which effects the flow

I am quite familiar with cavitation, NPSH requirements, etc, etc. Part of my job for many years was selecting pumps for various conditions.
Not sure why you're getting into all this stuff to begin with. I'll try to hold my tongue in the future when tempted to correct someones statements.

 

[Diehard]

With multiple loops, you have multiple closed systems, but they combine to form a single, larger, closed system. Reminiscent of Kirchoff's rules for electrical circuits ( I are a EE, not a plumber). In the two-loop system, for example, you might have 3 gpm coming out of the WH, dividing into 2gpm and 1gpm loops, but recombining again at the WH cold side to make up the 3gpm return.

Not according to my friend frodo.

 

[frodo]

Not according to my friend frodo.

I do not understand where you get that wild ass idea.. but run with it

 

[frodo]

http://shop.solardirect.com/pdf/water-heaters/solar-hot-water/active-solar/pumps/grundfos-guide.pdf

 

[hardwite]

Clarification:
In my system today, the pump is pulling water from the circulation loop and pushing it into the water tank. In other words, the pump is the last component in the loop. I believe the one-lines I posted show this clearly.

I have seen this arrangement in other system illustrations, and it makes sense: when a faucet is opened, all pump/valve hardware is not part of the flow circuit. Pump/valve hardware are only part of the circuit when water is returning to the tank. The pump also sees lower temperature water, though this should be <10F lower if designed properly.

I have the following estimates of the existing system and a possible 2-loop system:
per above, working backwards in the loop:

• Existing pump to tank is 4 feet
  
• From pump to manifold with valves would be 12.5 feet.

On the other side of the loop flowing with the water:

• From the tank to the first manifold where the hot water splits to the two loops, would be ~28 feet

The two loops would change to the following:

• Loop#1: 160 feet, 11 T fittings
• Loop#2: 143 feet 4 T fittings and 6 elbows

Again, still rough values. Here is a pictorial. the 3-way arrow is a possible placeholder for a final design.

Recirc_3Way_valve2

• hardwite
• Mar 15, 2019