[james sherwood]

Hi All,

First post, really grateful to all the useful information on here! Learnt a lot for cleaning up generally.

I've built hot washers before, but as a lockdown project I'm looking at building a high temp steam only unit, more for the experience than anything. Got a lot of soft carbon stained red brick on the farm (farmhouse and walls) that I'd like to clean with steam, the lime mortar and the brick itself is too soft for pressure. I'm in southern Ontario (Canada) so renting a unit isn't really possible, rental shops might carry small units for tile cleaning, and if you hunt real hard you can find a 'Hotsy' hot water pressure unit but for the outrageous hire costs here, I'd  recoup building one for 3 days of renting.  I've got plenty of other uses on the farm (some of the machinery would benefit from relatively dry steam over hot water pressure (avoiding damage to bearings seals/belts etc). I'm more than capable of building it (safely too!) it's understanding the boiler sizing that is tickling my noodle.

My question is whether a smaller boiler or a larger boiler is more advantageous? I understand the need for a low-flow (small) pump size, small-bore hose size, as well as what an appropriate unloader valve and the need for high temp rated fittings but I am stuck on whether it makes more sense for a 15L or a 21L boiler for a build. A 15l Lavor will obviously boil faster and be quicker to steam, but if it's a low-flow pump do I really need a 21L boiler? Ideally in 110V (that's our mains power here). I could do it in 220V but it would limit its usefulness around the farm with the need for a large welding cable extension cord.

Any owners of a Doff/Thermatech/Tensid got an idea what size boiler their machines use? Be interested to know.

[Mike Halliday]

Build the biggest you can within reason, if you produce too much heat the hot water/steam can be diverted (after heating) back into the holding tank  (or just allowed to run off). too much heat can be bypassed but nothing can be done about the lack of heat from using a too small heating coil.

A steam machine like a Doff etc has limited uses, a full blown hot system that is adjustable has much more scope