I have connected my oscillator (to the Brown(Sig) and blue(Ref)) wires and discovered that my elderly motors do not indicate that they are working in PWM mode!
No RED LED lights up , no 12 HZ green LED it just works!
I have used my second , Radiator circuit motor, for this test with measurements of flow rate from my DANFLOSS ( Sharky) Power meter.
Grundfoss have obviously changed the PWM indicators several times since my pumps were produced.
I will now return to the mystery of the dying PWM signal fed to the First Grundfos motor!
The PWM signal was overloaded when previously connected to the primary loop motor.
My respect for Grundfos and SAMSUNG has just disappeared ..................
@iantelescope as per previous, my pump , UPMM type, has no LED's.
the obvious indicator of "is PWM working or not" is that with PWM heating profile, the pump will be stopped by PWM if the heating system demand is zero. but if the PWM is not working or not connected then the pump will run at max (by design, as per PWM profile A spec, to allow for failed PWM cable)
so on my system, I have permanent live and neutral to the pump. If I set the heating demand to zero, and I have a correctly wired PWM, the pump does not run. If I was to disconnect the PWM cable , the pump runs at max, as per the expected fallback behaviour. thus proving that PWM is telling the pump not to run.
I do not understand what you mean by " the grundfos motor is overloading / killing the pwm" .
I notice you've said you have two pumps a primary and a secondary. I only have one (single loop). I've no idea how this behaves with two pumps. Perhaps you should simplify your testing to just one pump, probably the primary side as the ASHP will have the direct control relationship with that one?
the flow rate will indeed tell you if PWM is modulating, thats what I look at as well. pump noise level is a rough and ready proxy.
PWM was developed to vary the amount of power being supplied to a device in a more efficient manner. It operates using DC, and as the name states, varies the pulse width rather than the frequency. If the output signal is connected to a Resistor - Capacitor (R-C) network, the DC voltage developed across the capacitor would vary as the width of the pulse is increased or reduced.
I don't know exactly what happens inside the PWM controller built into a water pump, but since the main power source is the AC supply, the PWM signal must be used to vary this in some way. Whether the PWM signal varies the phase angle, the number of on - off cycles only the manufacturer will know.
One possible way to test the Samsung PCB would be to connect an R-C Network to the Sig. and Ref. and see if the DC voltage across the capacitor can be varied by making changes to the heat pump controller.
A possible way to test the water pump, would be to connect a DC voltage source to the Sig. and Ref.via a suitable resistor, and vary the voltage to see if the motor speed can be varied.
@iantelescope ok, I think I follow, but I'm not sure of the accuracy of a simple voltmeter in tracing the detailed behaviour. as it is a pulsed signal.
do you have anything else that can generate a PWM signal to prove whether the pump is capable of responding correctly to PWM, to prove whether the fault lies with the pump or the controller? my system is indeed extremely new - its been in a month - so if yours is older there may be potential issues there? have you contacted samsung tech?
@derek-m its all in the grundfos documentation and there's a standard for it as well VDMA Einheitsblatt 24244. page 17 of the relevant grundfos pump manual snipped below for ease of reference:
@derek-m its all in the grundfos documentation and there's a standard for it as well VDMA Einheitsblatt 24244. page 17 of the relevant grundfos pump manual snipped below for ease of reference:
Thanks for finding the information.
If my electronics knowledge serves me well, the lower of the two circuits on page 17 is a variable frequency oscillator, which operates in the following manner.
The PWM signal coming in on terminal 4 charges the upper of the two capacitors, and supplies power to the circuit. The voltage at the Base of the right-hand transistor increases via the 68k resistor, until the transistors starts to conduct. As current flows through the transistor from Collector to Emitter, voltage is developed across the 2k7 resistor, the photo diode within IC TLP2704 and the 110R resistor at the Emitter. The photo diode initiates the circuitry inside TLP2704.
As the voltage increases across the 100p capacitor, which is in parallel with the 110R resistor, it will reach the level where the left-hand transistor starts to conduct, and in doing so stops the right-hand transistor from conducting. As the 100p capacitor is discharged, the left-hand transistor is switched off, and the right-hand transistor is once more switched on.
The above will continue switching each transistor on and off, until the PWM signal drops to 0v and the upper capacitor discharges.
The number of oscillator pulses sent via IC TLP2704 will therefore be dependent upon the width of the PWM pulse and the value of the upper capacitor.
I assume that the internal circuitry of the pump controller will interpret the required speed from the number of oscillator pulses received during a given time period, and will be inversely proportional to the width of the PWM pulse.
If the pump controller circuitry is functioning correctly, then applying a DC voltage from 0v to 12v across terminals 4 (+ve) and 3 (-ve), via a limiting resistor, should cause the pump to go from maximum speed to minimum speed.
I assume that the internal circuitry of the pump controller will interpret the required speed from the number of pulses received during a given time period, and will be inversely proportional to the length of the PWM pulse.
The speed should be based ONLY on the duty cycle, which is independent of the number of pulses, but is dependent on the pulse width.
I assume that the internal circuitry of the pump controller will interpret the required speed from the number of pulses received during a given time period, and will be inversely proportional to the length of the PWM pulse.
The speed should be based ONLY on the duty cycle, which is independent of the number of pulses, but is dependent on the pulse width.
I suggest that you read the rest of my post, which should then make the content of my statement clear. If you prefer I will change length to width.
So my PWM is not working and not indicating that it is not working!
I suspect this is your measuring equipment not having enough resolution/bandwidth. The minimum pwm frequency for the grundfos is 100hz, so you should see at least 10 pulses, assuming the Samsung is generating those pulses. If the PWM is near 100%, at 100Hz [the minimum] the low part of the pulse will be around 10ms I put a scope on mine a while ago and was seeing what was expected, but [the pwm out] was plugged in at the time.
You can force the Samsung to send max 70% PWM signal, I suggest doing that, then check the output, with it plugged in. The expected characteristics of the PWM into the grundfos are as below.
If I get a chance I will put my scope onto the output and send you a screenshot.
Thinking about installing a heat pump but unsure where to start? Already have one but it’s not performing as expected? Or are you locked in a frustrating dispute with an installer or manufacturer? We’re here to help.
