Scala1 3-45 with pressure tank?

[TJanak]

Plan to boost from an atmospheric tank up to ~50psi. Customer is asking about Scala pumps. I know the Scala1 is NOT variable speed. It will cycle more than I prefer, demand is about 4 gpm constant. Can I run it coupled to a standard pressure tank?

Scala1 3-45 specs

Grundfos makes no mention of this, but a pressure tank is not their intent.

I know I can use a J5 or J7 with Pside-Kick. I might

Thank you

 

[Valveman]

Had to do some research. I thought all Scala pumps were variable speed. The Scala2 looks like it is variable speed but the Scala1 is not. They must be using the flow switch control like in the MQ they have videos of how to replace. I don't think a larger tank will help as the flow switch will turn the pump on as soon as there is more than about 0.5 GPM flow. How these pumps work must be a closely guarded secret, as I can't find any info. But I assume they also come on at a set low pressure like 27 PSI, even when the flow is less than 0.5 GPM like the MQ pumps did. The flow switch also means the pump should not cycle when using more than 0.5 GPM, regardless of tank size, which is why they basically don't have one.

I think you will have the same problem as they do with the MQ. You would need to get into the circuitry before the flow switch control to be able to use a regular pressure switch and a larger pressure tank. With all the controls closed up like that you get what you get. From the curve it looks like it will operate at 62 PSI when using 4 GPM constant. When using 20 GPM it will operate at 25 PSI.

The real problem with pumps like this is the "Fully Integrated, communicating, Blue Tooth, remote app, and customization options". The more electronics you add, the less likely water is to come out of the faucet. Keeping it simple means dependable water supply. It doesn't get any simpler than a standard diaphragm tank and pressure switch. Adding a Cycle Stop Valve, which is also very simple, solves the age old cycling problem and delivers strong constant pressure better than any so called high tech devices.

 

[Sponsor]

 

[Fitter30]

Need a bladder type expansion tank on discharge of pump and the.pressure switch like for a well.

 

[TJanak]

Thanks guys. It makes sense it would work if I added a tank and separate pressure switch to control the pump, but then I might as well use a plain jet/booster pump.

Cary, what do you mean by "I think you will have the same problem as they do with the MQ"?

Also, what makes you say "The flow switch also means the pump should not cycle when using more than 0.5 GPM, regardless of tank size,"? First hand experience with these types of pumps? Looks like at 0.5 GPM it would be 65 psi.

 

[Valveman]

You really can't use a regular pressure switch with a Scala or MQ unless you disconnect the internal flow switch. Otherwise the flow switch will stop the pump when flow is less than 0.5 GPM, regardless of the pressure switch. They don't have a high pressure off setting. Only the flow switch stops the pump, which is why it will still run and not cycle at 0.6 GPM or more, no matter the pressure. You would need a pressure switch set to work at 50/70 to make that work, and it would never reach 70 because of the flow switch.

Flow switch control has always caused problems, which is why pump manufacturers use them. Problem pumps make lots of money for the manufacturers. They could easily make pumps that would last, but that would not be profitable. Just adding a Cycle Stop Valve will make pumps last longer, which is why pump companies hate CSV's.

The MQ has always been a problem. I see dumpsters full of them at the supply houses all the time. I understand they were going to replace the MQ with the Scala, but had so many problems with the Scala they have not discontinued the MQ.