4/11/2024 0 Comments Grundfos scala 2 manual pdf![]() I guess that is one way to handle one of many very technical problems with VFD controls, but it doesn't go along with what they say the pump will do. If the pressure drops, the pump knows you are still using water and comes back on. So, they just bump the pressure and turn off the pump every few seconds. Long explanation but it has to do with the pump not knowing how slow it can go and when to shut off. That is also the way the Pentair PID system works. I cannot believe the distributor told you that is the way they are supposed to work. I have a video of this happening and will try to post it. It is also very common for the pressure transducer or VFD itself to malfunction, which will also cause the pressure to spike above 100 PSI. Expansion would also only cause spike pressure sometime after the pump shut off. If expansion was what caused the pressure to spike above 100 PSI, it would show you the tank in the pump is so small it is useless. The little tank built into the pump is after the check valve that is also built into the pump. You are correct that a variable speed pump should slow down to supply the demand and never shut off as long as there is a demand. This video shows what I am experiencing, but I have longer cycles: I went with a larger Amtrol ST-12 thinking it would help maintain a bigger buffer of pressure and smooth out the pump engagement, but maybe it is taking a little too much work off the pump slowing the feedback loop that the pump depends on. I might give a smaller pressure tank a try. I imagine if I had much higher flow, or a lower set pressure, it might stay on longer or continuously. My theory is now that there is more "elasticity" in the system that allows pressure to be maintained within the 10psi target band of the pump for longer so it takes breaks. It seemed to cycle a lot less before I introduced the external pressure tank. I just spoke with their distributor and he told me that this seems normal, but my understanding was that the pump should "slow down" to maintain a constant pressure. It clearly has speeds, as the pressure settings on the pump create audibly different frequencies. I thought the speed was supposed to be variable and expected it to hold a steady pressure at whatever speed was needed. Maybe it's unnecessarily stressing me out, but I don't like the sound of the pump turning on and off. My measured pressure seems to ping-pong from 60-70psi as the pump goes on and off. With 2 taps open wide, the pump clicks on for a mere 5-10 seconds, and then stays off for around 30, before cycling back on. ![]() Internal pressure tank, and external pressure tanks set to 70% of that = 50.75psi. Pump outlet pressure set and measured 72.5psi. ![]() When you’ve found the product, tap ‘Documents’ and select ‘Installation and operations manuals’.I had a chance today to drain and triple-check my pre-charges were set to exactly the recommended pressure. Open the Grundfos GO Remote app and find the product for which you’d like to troubleshoot, either by catalogue or by a quick search. Simply fill out the form and your download will start automatically. Then, select the Engineering Manual for the pump you need, and you will be presented with a webform for download. Once you’re in the Search Engine, choose ‘Engineering Manuals’ under ‘Type of content’. Go to the Grundfos for Engineers Search Engine or click the ‘Search Engine’ banner at the bottom of this page. You will find the pump troubleshooting guide at the end of the Installation & Operating manual. Then go to the ‘Documents’ tab and download the Installation & Operating Instructions. Choose your product from the list of options. Option 1: Use Grundfos Product CenterĮnter the product for which you want to troubleshoot in the search bar at the top. Whichever situation you’re in, you can find the pump troubleshooting guide you’re looking for in 3 possible places: Grundfos Product Center the Grundfos for Engineers Search Engine and the Grundfos GO Remote app. Troubleshooting can be done both proactively before pump failure occurs and once the issue has already set in. 3 sources for pump troubleshooting guides
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