Frequently asked questions appear below by product (in alphabetical order). If you have a question regarding a product that isn't answered on this page, please contact us - we'd be happy to help!


Products: Eco-Flow-C®  |  FlowVis®  |  M20  |  PSP20

frequently asked questions


Eco-Flow-C® Variable Frequency Drive

Q. In simple terms, how does a VFD work?

A. A VFD converts incoming supply voltage from AC to DC back to AC; In turn controlling the motor speed based on the desired output.

Q. Aside from reducing electrical costs, what other benefits does the Eco-Flow-C® provide?

A. Eco-Flow-C’s patented load curve monitoring protects the motor & pump from voltage irregularities & also eliminate water hammer in pipes by slowly soft starting the system.

Q. How much money will I save in electrical costs using an Eco-Flow-C®?

A. Savings vary, depending on a number of factors. These factors include things like motor and pumps size, flow rate, turnover requirements, and electrical costs in your area. Prior to purchase, an energy audit can be performed to calculate the energy savings & ROI specific to your application.

Q. How do you 'size' a VFD for a motor?

A. It’s based on the supply voltage in conjunction with the motor amperage.

Q. Are energy rebates available for VFD's?

A. In most states, the local utility companies do offer rebates for VFD’s. Check with you local utility provider or www.dsireusa.com

Q. Will installing an Eco-Flow-C® compromise my water quality?

A. No. The Eco-Flow-C's constant flow feature sets the GPM per the design / health department requirements.

Q. What periodic maintenance does the Eco-Flow-C® require?

A. H2flow recommends once a year to check the wiring connections to make sure they’re still secure.

Q. Is technical support available if needed?

A. Yes, either from a local authorized H2flow Distributor or H2flow’s corporate office in Sylvania Ohio.

Q. How long is the Eco-Flow-C® warranty?

A. 3-years.


Want to learn more about the Eco-Flow-C® Variable Frequency Drive? Click here to be re-directed to the Eco-Flow-C® product page.

FlowVis® flow meter

Q. What pipe diameters will FlowVis® work on?

A. The FlowVis® model range includes includes units for 1.5" (FV-C-15), a combined 2" and 2.5" (FV-C), 3" (FV-3), and 4" (FV-4).

Q. Is FlowVis® NSF certified?

A. FlowVis® models FV-C, FV-C-S, FV-C-Saline, FV-C-L, FV-3, FV-4, FV-3-L, and FV-4-L are all NSF 50 certified.

Q. What is the flow range for each model?

A. 1.5" (FV-C-15): 10-90 GPM/38-341 LPM; 2"/2.5" (FV-C): 10-110 GPM/38-416 LPM; 3" (FV-3): 90-220 GPM/341-833 LPM; 4" (FV-4): 160-300 GPM/606-1136 LPM.

Q. Is FlowVis® also a check valve?

A. FlowVis® models FV-C and FV-C-15 function as both a flow meter and a check valve.

Q. Is FlowVis® patented?

A. Yes. FlowVis® is protected by U.S. Patent No. 8,800,473

Q. What is the accuracy of FlowVis®?

A. As verified by NSF, the average accuracy of FlowVis® models FV-C and FV-C-15 is 97.9%, while FlowVis® models FV-3 and FV-4 have an average accuracy of 98.15% and 98.7% respectively.

Q. Is the accuracy of FlowVis® effected by air in the system?

A. No.

Q. Is the accuracy of FlowVis® effected by the direction, location or angle that I install it?

A. No.

Q. Where is FlowVis® most commonly used?

A. Both in commercial pools (where flow meters are mandated) and on systems that are using variable speed pumps.

Q. What are the benefits of using FlowVis® on a variable speed pump?

A. In order to maximize the energy savings that come from these pumps, you need to ‘know the flow’ so that you can set a filtration rate that achieves a well filtered and sanitized pool but at the same time doesn’t consume more electrical energy that is necessary. Without knowing the flow rate, this is a pure guess.

Q. What is the head loss of the unit?

A. The average head loss for FlowVis® is: 0.77 psi at 20 GPM and 2.23 psi at 110 GPM on 2" pipe. 0.71 psi at 21.3 GPM and 2.37 psi at 112.6 GPM on 2.5" pipe. Head loss is not applicable for FlowVis® installations on 3" and 4" pipe.

Q. What length of straight pipe do I need for FlowVis®?

A. Unlike other flow meters, the FlowVis® does not require straight pipe before or after.

Q. Can I install FlowVis® to an existing valve body?

A. Yes, there are retrofit models for Jandy and Praher valve bodies.

Q. Will the retrofit version install into a 90° check valve body?

A. No, the existing check valve body (Jandy or Praher), must be a 180° body.

Q. What is the unit of measurement on the scale?

A. The standard scale is in GPM and there is a no cost option for LPM.

Q. What if I have an SVRS unit where a check valve is not allowed?

A. There is a non check valve version (model FV-C-S).

Q. Does the unit have to be installed horizontally?

A. No. It can be installed in any direction – horizontal, vertical with flow upwards, vertical with flow downwards or even upside-down.

Q. Does FlowVis® need to go on the suction or discharge side of the pump?

A. It can go in either direction.

Q. Is FlowVis® corrosion resistant?

A. Yes. The flapper seal is viton, the spring is 316 SS and the pivot pin is glass filled plastic.

Q. What if I have an in-line chemical feeder?

A. Certain models of these feeders are notorious for leaking extremely high concentrations of chlorine into the piping around where they are installed. It is important to follow the FlowVis® installation instructions relative to these units.

Q. What is the warranty period on FlowVis®?

A. 3-years.

Q. Does FlowVis® provide any additional information, besides the flow rate?

A. Yes, the scale also gives an indication of velocity in feet per second (5, 7 and 9 fps).

Q. Are there any parts that will wear out?

A. The spring may need to be replaced after 7-years.

Q. What are the materials used in FlowVis®?

A. Valve body: CPVC; Lid: Polycarbonate; Indicator Arm: ABS; Flapper and Pivot Pin: PPO with glass fiber; Flapper Seal: Viton; Spring: 316 SS; Lid Screws: 18-8 SS; Lid o-ring: EPDM.


Want to learn more about the FlowVis® flow meter? Click here to be re-directed to the FlowVis® product page.

M20 Shaft Power Monitor

Q. Why is the M20 better than a Current Monitor?

A. Monitoring motor current is very ineffective for underload monitoring. The current profile is none linear and is very flat until the motor has 60-70% load applied to it. A motor running with less load than this level will be very difficult to monitor for an underload, e.g., a run dry condition on a pump.

Q. Why is the M20 better than a motor Input Power Monitor?

A. The M20 goes one step beyond even a Power Monitor inasmuch as it discounts the losses that are consumed by the motor itself. Protection is provided against the ‘working load’ only and the varying losses of the motor are discounted.

Q. What is the largest motor an M20 can monitor?

A. 800 HP at 460V, 400 HP at 230V.

Q. Can the M20 be used on Medium Voltage applications?

A. Yes, but this requires a zero phase shift, 3-phase transformer.

Q. Can the M20 provide both overload and underload protection?

A. Yes, the M20 can be configured to provide protection against either abnormal overload or underload conditions or even both overload and underload.

Q. How fast can the M20 respond to an abnormal load?

A. The M20’s response delay can be set as short as 0.1 sec or as long as 90 sec.

Q. How will the M20 shut down my motor when it detects an abnormal load?

A. The M20 has a relay that can be used in the motor start / stop control circuit to initiate the motor being shut down.

Q. Can the M20 interface with my plant's DCS system?

A. Yes, the M20 has an analog output that is proportional to motor power. The output can be configured to be either 0-20, 20-0, 4-20 or 20-4mA.

Q. Can the M20 monitor single phase applications?

A. Yes, the M20 can be programmed to monitor either single or 3-phase applications.

Q. What is the most common application for an M20?

A. Pumps. More than 300,000 Emotron Monitors have been installed to protect pumps against abnormal operating conditions.

Q. Where is the M20 typically installed?

A. Next to the motor starter.

Q. How is an alarm indicated by the M20?

A. The LCD display will show an alarm message and the trip relays will change state.

Q. How long has the M20 been in production?

A. For 12 years, but its predecessors were in production 34 years ago

Q. Can the M20 be used on motors driven by a VFD (Variable Frequency Drive)?

A. No.

Q. Can an alarm be reset remotely?

A. Yes, the M20 has a ‘digital input’ to which a remote reset pushbutton can be connected.

Q. How much space do I need to install an M20?

A. The M20 is very small – just 3.54” x 1.77” x 4.53” (HxWxD).

Q. How many different models are there?

A. There are just 3 models – motor supply voltage dependent and ranging from 120 to 690V.

Q. Can the M20 be used as an 'electronic shear pin'?

A. Yes, this is another common application. The extremely fast response time makes it ideal for detecting a jam on a conveyor or excessive load on a wastewater clarifier.


Want to learn more about the M20 Shaft Power Monitor? Click here to be re-directed to the M20 product page.

PSP20 Anti-Entrapment Device

Q. What is the basis of operation of the PSP20?

A. The PSP20 uses a unique method of monitoring the motor’s shaft power. This is a very accurate, reliable and practical method of determining an abnormal pump condition such as a blocked suction, dead head or run dry. More than 300,000 Emotron units have been installed on pumps throughout the world.

Q. What makes the PSP20 more reliable than a vacuum-based system?

A. Vacuum systems are difficult to calibrate inasmuch as their alarm level has to be set quite close to the normal day to day operating conditions. These conditions vary due to situations such as pool vacuuming, filter backwashing and blocked skimmers. Vacuum systems will often give false alarms when these conditions occur and recalibration is a frequent requirement. The PSP20’s alarm level is able to be set well beneath these day to day occurrences.

Q. How long does it take to install a PSP20?

A. Typically one hour or less.

Q. Where is the PSP20 installed?

A. Typically on the wall next to the filtration pump.

Q. Is there any plumbing involved?

A. No, the PSP20 is a simple electrical hook up that is connected in the power supply going to the pump.

Q. How long does it take to set up the PSP20?

A. About 2 minutes.

Q. Are there multiple models of the PSP20?

A. Yes, while all systems are fundamentally the same, there are variations that are dependent on the motor supply voltage and size.

Q. Can I use one PSP20 to monitor multiple pumps?

A. No, you must install one PSP20 for each pump.

Q. Can I use the PSP20 if my pump has a VFD on it?

A. No, the PSP20 can only be used with fixed speed pumps.

Q. Can the PSP20 be used with single-phase or three-phase pumps?

A. Yes.

Q. How big is the PSP20?

A. It measures 12” x 10” x 7” (305mm x 254mm x 178mm) – HxWxD.

Q. Can the PSP20 be installed outside?

A. Yes, the NEMA 4X housing is not only watertight, but also chemical resistant.

Q. Are there any periodic maintenance procedures?

A. None to the system. We do however, recommend that a weekly test of the pump shutdown is performed by closing off the main drain and skimmer valves.

Q. How do I know when an alarm has taken place?

A. The pump will shut down and there will be an alarm lamp illuminated on the front of the PSP20.

Q. Can I install a remote audible alarm horn?

A. Yes. The installation instructions show how to connect this and they are available from H2flow Controls via your supplier.

Q. How do I reset an alarm?

A. Simply by pressing the alarm lamp on the front of the PSP20.

Q. What do I need to do if I change any aspect of my system such as the pump?

A. Providing the pump is the same HP and voltage, all you will need to do is press and hold the AutoSet button for 3 seconds after you have installed and started the new pump. This also applies to any changes that could likely effect the power consumed by the pump motor, e.g., a new filter.

Q. How do I test the PSP20?

A. By closing down both the main drain and the skimmer valves. It is important to close both as the suction is not blocked if either one of them is left open.


Want to learn more about the PSP20 Anti-entrapment Device? Click here to be re-directed to the PSP20 product page.