Brewery hot water pump control

[Beerman]

Our hot water system is a pumped rather than a pressure system. The 130 gpm pump is currently manually controlled, and tends to run continuously during operating hours. I would like to switch it to on-demand, and the CSV sound like just what I'm looking for.

Our problems stem from the high temperature of the water, 195F, and the extremely high carbonate hardness of our water. Valves do not last long in our hot water system, especially check valves (we've tried all styles, and none last more than a few weeks). The culprits are heavy deposits of calcium carbonate and corrosive CO2 gas.

Will a CSV survive in these conditions?

[Cary Austin]

We have an all SS valve that will handle most anything.  But with water that hot, your pump won’t survive if you restrict the flow as with a CSV.

Cold water is a very good lubricant and coolant.  So a pump can be restricted to a very small flow rate without any damage.

But hot water has no lubricity (not a good lubricant) and is already hot, so it is not a good coolant.  Most pumps have a minimum recirculation rate, depending on the temp of the water and design of the pump.  It is not uncommon to need to dump excess water to keep the minimum flow required.

You might be able to use a smaller pump with a pressure tank and pressure switch.  This way you would have hot water on demand.  Then if the pressure dropped to a lower point you could have the large pump come on, the small pump shut off, and continue dumping the excess as you do now.

But if check valves, pressure switches, or other things needed won’t survive, you may already be doing the best you can.