hi my heatline vizo boiler isnt workin. light with BAR is flashin says pressure not working. i have 4 valves underneath the boiler (L-R) red yellow blue and blue there is a flexi hose but connects straight into the boiler and into wat looks like the waste?? but there is defo no valve on it like people r tellin me! wat do i do to get the pressure bk up???
