Knocking from pentair master temp 400.

Flyis4ever

Gold Supporter
Aug 22, 2018
50
Glendora California
Pool Size
19000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
So I have the knock coming from my master temp heater. I changed the bypass as well as the other spring thing. Neither were broken, but since I had it apart. I figured why not. And i continue to have the loud knocking noise. Sounds like it’s coming from inside the heat exchanger. Anyone have an idea of what I should try next?
 
That knocking is caused by the water getting too hot and boiling in the heater which it should not do.

It is usually caused by a low water flow through the heater and the water cannot carry the heat away fast enough.

What speed are you running your IntelliFlo pump?

Post pics of your equipment pad.

Check that no bypass valves are diverting water around the heater.
 
That knocking is caused by the water getting too hot and boiling in the heater which it should not do.

It is usually caused by a low water flow through the heater and the water cannot carry the heat away fast enough.

What speed are you running your IntelliFlo pump?

Post pics of your equipment pad.

Check that no bypass valves are diverting water around the heater.
3250 is the setting. And I don’t think water is diverting around it. Because it’s hot?
 
How old is the heater?

Do you have strong or weak water pressure from the returns?

Post pics of your equipment pad.
 

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Put the system in service mode and check the flow in GPM, the system pressure and the speed in RPM.

Also report the filter pressure.


Check the check valve after the heater.

Check the cell and clean it if necessary, but only if necessary.

Check the stack flue temperature by holding down the “Pool On” or “Spa On” button until the display changes to stack flue temperature. Press whichever mode the heater is on Pool or Spa.

Remove the thermal regulator and see if the flow in GPM goes up or if the stack flue temperature goes down or if the knocking stops.
 
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