Cheers Simon.
One last thing cos you said you've used alltecs - do they have something to adjust the pump pressure? And would I be able to change the pump for a bigger one?
Thanks
The Alltec Pro Plus used to have adjustable pressure on the pump, handy for upholstery but I seldom reduced the pressure for carpet cleaning. I upgraded to 135psi but the step up was not massive. The Aqua 50 has an adjustable pump but the 40 does not. There are a lot of twin vac machines on the market that use 200 + psi pumps so an upgrade maybe possible, I would phone Chris at Alltec as the machine uses 2 leads. On mine one lead was for the pump and vacs the other for the heater. I'm not sure what adding a larger pump would do with regards to amperage draw on the same cable as the vacs... My Airflex has 2 cables the pump and 1 vac run of one cable the other vacs on the other. There should be room inside but Pumptec pumps are heavy and expensive, a 225psi from Woodbridge is £412 incl vat and then there will be fitting another £60+. That's getting on for £500 + the purchase price of the machine. In general terms I use between 200 - 250 psi on most jobs which is more than ample. Marks comments regarding pre-spray are not without merit, I cleaned with 100psi for years with no problems using tap hot water and only used the heater to keep water hot whilst doing upholstery. These days I use 25L containers which I fill before I leave and that gives me a start if I have to wait for immersion heaters.
Phone Alltec and see what your options for upgrades are on an older machine, if you're set on more pressure it may be more cost effective to look for a used machine with 200+psi pump as standard. Mytee, powr-flite, Raptor, Ninja etc