I have an oil fired hot water pressure washer, 3.5gpm, 3000psi. I was thinking I could use the pressure washer for a hot water source and maybe attach an upholstery tool to it or something. So here is what I did: I plumbed a low pressure unloader valve before the boiler to bring the pressure down for the upholstery tool. But when I tried to use the tool the boiler wouldn’t turn on. It turns it's out the pressure switch for the boiler fuel pump wasn't activating because of low pressure. The switch needs 250 psi. If I turn the pressure up the upholstery tool puts out way too much water. I'm I missing something? I thought this would be an easy thing to do, but I can't get it to work. Any help would be greatly appreciated.