high pressure water heater

[knighty]

pressure washer at work runs on a mins hot water feed

would be nice to heat it up a bit hotter... 85'C is the max feed in temp. for the pump

I'd rather stay away from a diesel burner (the whole reason I bought a hot feed pump)

gas supply won't provide any extra gas, already at the max with the water heaters we have

happy to go electric (got 3 phase), but it'll have to heat the water after the pump, so runs at 2500psi and peaks at just over 3000psi as you leave go of the trigger

anyone have any experience or ideas of electric water heaters to run at that pressure?

I thought about using some sort of heat exchanger with oil in it, so I could heat the oil electrically and have that heat the water... but I'm worried about the lag between heating the oil then it heating the water, and worried about it holding too much heat and boiling the water when there's no water flow

I thought about running an indication heater with a pipe running through it and a metal core suspended in the middle of the water flow... but couldn't think of a way to do that without heating up the outer pipe too and weakening it?


p.s. 23litres/min

EDIT:

thinking more about this, induction heater heating a pipe could work ok... after all that's how the diesel burners work?  it would have to be really long tho... so it's not red hot/weak in one spot?

[Head Womble]

I used to run a steam boiler at work and had to do a training course to be qualified to do so, this was over 10 years ago so I'm not absolutely certain about figures, however at 2500psi you should be able to take the temp up well above 120°c without turning to steam.
I'm sure you'll find graphs etc on line that will show the pressure/temp curves. 
You will obviously require safety relief vales in the right places (vented outside) just in case you have a runaway on the heater.

So if you can find a way to heat the water at least you know taking it close to 100°c isn't going to boil the water, it will however cause major burns to the operator if not used carefully.

[knighty]

was only really worried about it boiling when it's turned off and the pressure drops... if the heat exchanger is full of oil at 140'C and there's no water flow

I could add a solenoid so as pump is turned off it turns on and dumps water down the drain for 60sec... but I'm trying to keep things super simple

a heating element made for the pressure, turned on and off by a temp sensor and a flow switch would be a piece of cake and (hopefully) super reliable.... I just can't find any for the pressure


I've got freezer evaporators with heating elements (for defrost) in them, they're long straight elements, I've emailed the heating element places I used before but no reply... I thought if I could get some of those with a thicker wall tube I could weld them inside another pipe for a pipe in a pipe style heater... but no reply yet :-(