Feed Pump using Pressure Washer
I finally found a feed pump solution I mostly like. It's much heavier than I wanted, but It's capable of much more pressure (400 Bar, 5800 psi) and higher flow rate than my boiler needs, but since the output is controllable from 0 to 3000 psi, in this case, over-capacity is not necessarily bad.
Using an adapter plate and spindle attachment, I was able to mount the pump section from the pressure washer shown below, onto a 36 VDC motor rated at 1 kW. As a test, (and to make my wife happy), I spent about an hour pressure washing a concrete patio using the 36 VDC motor powering the 3-plunger pump to 20 MPa (2900 psi). The motor is powered by a PWM speed control board and a 36 VDC switching power supply. Now that my pressure washer cleaning duties are complete, I have replaced the 60 MPa gauge shown in the pics, with a 0 to 700 psi gauge, which is the pressure range I expect to see on the boiler. My next choir will be attaching the needed high pressure tubes and fittings between pump and boiler.
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