First off: I HAVE read the FAQ section on plumbing in VS. letting the natural vacuum of the pump suck water from a reservoir. I only have one question concerning the whole thing that I could not find anywhere.

My machine's inlet tube branches off into the pump then into the boiler fill line. The pump runs through the boiler to the group heads. How does the boiler fill when its hot and full of pressure? Based on the picture of my machine the pump is not feeding the boiler, the pressure of the outside line is doing that. Im pretty confused on this whole thing so if someone can explain it...that would be amazing.


note: I have attached a picture of my machine so you can see what im talking about (im sure all HX machines are similar)

gungabin wrote:(im sure all HX machines are similar)

The ones that I'm familiar with feed the boiler via the pump output. Typically the pump output line tees off in two paths - one to the solenoid and boiler, and the other to the HX (typically with a check valve and expansion valve in that line.)

Here's a diagram of one of those

I'm not sure how common your arrangement is, but should do the job because the water line pressure is in the 2-3 bar neighborhood (maybe more if you don't have a pressure regulator on the water line) and the boiler pressure is well under that, so when the valve opens water will flow into a pressurized boiler.

homeburrero wrote:when the valve opens water will flow into a pressurized boiler.

Huh, this makes sense...I checked the over pressure valve to see its max pressure and it said 30psi which is approx 2 bars...so as long as my water line in is more than 2 bars im good! (technically speaking)

does that all sound correct?

gungabin wrote:does that all sound correct?

Yes. Also, even though you have a 30 psi safety valve, your pressure stat will be keeping the boiler pressure down in the 15 - 20 psi range (1.0 - 1.4 bar) so you have a bit of leeway in case your line pressure is on the low side.