Dear all,
I wanted to share my experimentation with heat pump installation.
In my setup, there is a 3 way valve, to connect the underfloor circuit to the heatpump aside the regular radiator circuit.
My samsung gen 7 5kW handles the 3 way valve to regulate the temperature inside the underfloor circuit. However, it does only support proportional valves, which perform a complete open->close or close->open movement within a range of time between 60 and 120 seconds.
From past experience, I know that those valves tend to get clogged quite easily thanks to underfloor oxydation Therefore, spending hundreds in a valve that I know will fail in the same amount of time that a low cost valve was worth the try to reduce the expense.
On amazon, I found a 240VAC operated 3/4" 3 way valve, however, it opens/closes completely with a 10/12 seconds period. Naively, I mounted it, and observed that each 2 minutes (a FSV controls this time) the valve was operated, closing or opening to “regulate” the temperature, but very poorly. But this was expected, as the heatpump expected to for example open by 50%, therefore powering the valve for 30 seconds (when FSV configuring the total time is set to 60 seconds). In 30 seconds, the valve with a 10 seconds full swing was obviously open completely!
I tried regulating the voltage given to the valve by adding a thyristor (gradator circuit), but the valve, was only operating with a minimum voltage which implied running full speed. Wrong path!
Eventually, I designed a NE555 and triac based circuit, to power the valve 0.5s each 3 seconds (1/6 ratio) to convert the 60 seconds full swing into a 10 seconds of effective powering. And this works very smoothly. I went from 2 minutes spikes of temperature curve to a very smooth curve. The only circuit design trick was that I wasn’t willing to have a separate power for the NE555, therefore extracting power from the valve command by the heatpump. The only problem was that the heatpump has 3 wires, 1 neutral, 1 clockwise live, and 1 counterclockwise live. The circuit therefore had to command only a single line at a time.
If anyone is interested, let me know, I’ll post up the circuit.
Cheers