PHE Secondary Piping

[Steve Mackie]

Looking for opinions and/or common practice:

On an NH3 to CaCl2/Glycol PHE, which way do you pump the CaCl2/Glycol? Do you PUMP INTO the PHE, or SUCK OUT OF the PHE?

I would also like to hear reasoning behind which ever way you do it. "It's the way we've always done it" is not a reason.

Steve

[US Iceman]

My belief is it is better to pump through a device. Almost every system I have seen has the exchangers/chiller/etc. on the pump discharge side.

There is probably a very good technical reason for doing this, but I'm not sure what it is. Water piping is to me a different field.

[Josip]

Hi, Steve Mackie

Looking for opinions and/or common practice:

On an NH3 to CaCl2/Glycol PHE, which way do you pump the CaCl2/Glycol? Do you PUMP INTO the PHE, or SUCK OUT OF the PHE?

I would also like to hear reasoning behind which ever way you do it. "It's the way we've always done it" is not a reason.

Steve

Good question, not easy to explain but

If we have gravity feed PHE and we have a CaCl2/Glycol expansion tanks divided in two chambers cold/warm it is not good and less easy to install them enough high to obtain gravity feed CaCl2/Glycol to PHE.

We need some velocity (about o,5-1m/sec) through PHE and for that reason we use primary circuit pumps taking liquid from warm side and pump it through PHE and return to cold side.

If you install pumps after PHE for sure your pump will run in cavitation area due to low inlet pressure caused by dense liquid and construction of PHE.

Is this good reason

But if you like you can try vice versa installation

Of course maybe I miss something due to lack of information about your system

Best regards, Josip

[1torr]

There's a lot more to it,but put simply.If you feed a pump through a restriction you will starve it of water causing cavitation.Better to pump through a restriction to stop the pump running off the bottom of its curve.