Plate heat exchnager noise problem

[remp]

I have a brazed plate heat exchanger with hot water on the primary side 130/115 Deg C and 80/70 Deg C water on the secondard side.

When both sides are pumping there is a constant noise from the unit as if there is a nut or piece of metal in the Heat exchanger trying to get thro. We have checked the hot side for debris but nothing in there.

When the cold side pump is siwtched off and the hot side running the noise goes away immediatly. So we thought it must be debris in the cold side. However if the cold side is running and the hot side is turned off the noise also goes away also.

The noise must be something to do with heat and water flow on both side. No flow on either side and the noises goes away... anyone knows what is going on?>????

 

[Latexman]

What are the pressures in and out on the primary and secondary sides?

Good luck,
Latexman

 

[remp]

Primary side 6 bar, secondary side 2 bar.

 

[rmw]

We need in AND out for each side please. At least for the primary side, that is.

rmw

 

[Latexman]

And, is that bar absolute or bar guage?

Good luck,
Latexman

 

[remp]

In/out on the primary side 130/115 deg C - 6 bar gauge
In/out on the secondard side 80/70 deg C - 2 bar gauge

This is a new heat exchanger that replaced another reasonable new one that used to leak ( it was not brased) when the primary hot water was turned off at night. It used to leak thro the seals.... there was no noise problem with this.

 

[Latexman]

What's the pressure drop across the primary and secondary sides?

Good luck,
Latexman

 

[StoneCold]

remp
Basically what Latexman is trying to figure out is if you have conditions that would allow flashing and recondensing inside the heat exchanger. That is probably what the noise is. But without all the pressures we are just guessing.

If you just slow down the flow on the hot side does it go away?
Can you increase the flow on the cold side?
Did the old heat exchanger leak at night because you closed the inlet and outlet of the exchanger and it had no where for the liquid to expand?

Regards
StoneCold