By the way, I’m going to try the original hydrovac before buying a replacement. We’ll see if it is any good. The bolts holding it are rusted and I couldn’t get the vacuum line off so I figure I’ll give it a try. Does the vacuum line need to be steel and that big?
You can use thick-wall, fiber-reenforced hose no problem, as long as it won't collapse on itself while under vacuum. For longer stretches of hose, it might be worth finding hose that is wire-wound so it has some rigidity - perhaps even hydraulic hose?
Try to at least match your hose inner diameter with the pipe inlets of the hydrovac. Larger hoses mean better flow from the air leaving the vacuum chambers, and your hydrovac will respond faster.
Another mod to consider is attaching a reservoir to the circuit so you have the maximum amount of vacuum available to operate the hydrovac in an emergency. A ten or twenty pound propane tank would work nicely.
