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Robert Jones

Is this a circulator pump?

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Yes. Typically they are hard piped in near the water heater in the dedicated return line. This type is for a system that has no dedicated return line. You would see that one flex line is connected to the cold and one to the hot. It uses the cold water side as the return while pulling hot water through the hot line.

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This is good to know. I have not seen one of these, but did hear a guy discuss running a pump from his hot water heater for just that reason.

Just curious, how do you suppose the pump returns water against the cold water pressure? Certainly you would have to have some pressure differential; i.e. higher circulator pressure than cold water pressure. but, how much higher until you had adequate flow?

Bob Kenney

www.IndependentHomeInspectionMD.com

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When you run into these, it's worthwhile to note the make & model number and download the installation instructions. Some can only be installed with the shaft in a vertical position and some can only be installed with the shaft in a horizontal position.

The one is Rob's picture is made by Laing. It's correctly installed with the shaft oriented vertically -- the only way that Laing allows it.

On the other hand, the Grundfos circulators are only supposed to be installed horizontally.

If they're installed the wrong way, they'll burn up prematurely.

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Just curious, how do you suppose the pump returns water against the cold water pressure? Certainly you would have to have some pressure differential; i.e. higher circulator pressure than cold water pressure. but, how much higher until you had adequate flow?

You are mixing up pressure with flow. In a normal household system, with all faucets closed, the static pressure in the hot lines is equal to the static pressure in the cold. The pump is simply moving water around what is effectively a closed loop. It wouldn't be working against any incoming flow unless you had the cold faucet open.

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I wasn't suggesting that the cold water would flow, only that the static pressure would prevent an impedance to the flow of hot water from the circulator pump. Enough volume (flow) of hot water would need to occur to move the hot water from the heater tank whatever distance to the remote pump, in a short enough time to raise the temperature at the circulator by the desired amount.

You are right though about the static pressure being the same in both lines, and after I read that maybe it doesn't present that much of a difficulty. Just raise the hot water side above the static pressure and return it on the cold water line.

Guess I'll have to buy one and find out....does take a little while to get hot water to my kitchen...

Bob Kenney

www.IndependentHomeInspectionMD.com

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If a loop of piping is pressurized to 100psi static pressure, a pump that is displacing media only within the confines of that loop will not be influenced by the static 100 psi. It's the same way with the air we breathe, it's pressurized to a pressure of approx 14.7 (at sea level) psi but our lungs do not have to act against it to breathe.

Marc

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The deluxe units have timers on them, or you could plug it in to a timer.

It has to get expensive to run those things continuously.

Would it be more correct to call it a circulation pump?

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If a loop of piping is pressurized to 100psi static pressure, a pump that is displacing media only within the confines of that loop will not be influenced by the static 100 psi. It's the same way with the air we breathe, it's pressurized to a pressure of approx 14.7 (at sea level) psi but our lungs do not have to act against it to breathe.

Marc

Point well taken! I was envisioning this system as two independent sources; hot, cold. But of course you are right, it is a loop at the water heater.

Bob Kenney

www.IndependentHomeInspectionMD.com

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The deluxe units have timers on them, or you could plug it in to a timer.

It has to get expensive to run those things continuously.

Would it be more correct to call it a circulation pump?

No, it's not a "pump" - it isn't "pumping" anything. It's circulating water.

OT - OF!!!

M.

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The deluxe units have timers on them, or you could plug it in to a timer.

It has to get expensive to run those things continuously.

Would it be more correct to call it a circulation pump?

No, it's not a "pump" - it isn't "pumping" anything. It's circulating water.

OT - OF!!!

M.

That defines a pump. IMHO

Marc

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The deluxe units have timers on them, or you could plug it in to a timer.

It has to get expensive to run those things continuously.

Would it be more correct to call it a circulation pump?

No, it's not a "pump" - it isn't "pumping" anything. It's circulating water.

OT - OF!!!

M.

That defines a pump. IMHO

Marc

A circulator on a closed-loop system is a wet-rotor centrifugal pump.

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The deluxe units have timers on them, or you could plug it in to a timer.

It has to get expensive to run those things continuously.

Would it be more correct to call it a circulation pump?

As I understand it, these circulators can wear out copper pipes prematurely by "scouring" the pipe with continuously running water, so the timer is also beneficial to the plumbing. Set to be on only during potential use hours.

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The deluxe units have timers on them, or you could plug it in to a timer.

It has to get expensive to run those things continuously.

Would it be more correct to call it a circulation pump?

As I understand it, these circulators can wear out copper pipes prematurely by "scouring" the pipe with continuously running water, so the timer is also beneficial to the plumbing. Set to be on only during potential use hours.

I doubt that these pumps wear out pipes more than others. Could the braded lines wera out faster?... possibly. Typicaly scour occurs when the pipes are not reamed prior to sweating them together.

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Guys, this circulator does not run constantly or you would have hot water in your cold supply. Instead of running the shower for several minutes in the morning until the hot water gets to the shower head from the tank, the user will push a button located in the bath room so the circulator displaces the cold water in the hot lines. By doing this consumes no water at all.

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Guys, this circulator does not run constantly or you would have hot water in your cold supply. Instead of running the shower for several minutes in the morning until the hot water gets to the shower head from the tank, the user will push a button located in the bath room so the circulator displaces the cold water in the hot lines. By doing this consumes no water at all.

Yeah, that's the way some are installed; but the majority of them that I see out here are on a timer and there isn't any button to push. They're often set to come on about once an hour for a few minutes.

ONE TEAM - ONE FIGHT!!!

Mike

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