i have had all sorts of problems over the past 24 hours with my above named boiler. all the heating went off yesterday for no reason and upon checking the boiler it was even though off displaying a very high psi on they system 2.6 bar. Also it would ignite even though it tried i think four times then the error code 'F75' came up. The fault code changed a couple of times through the night but mostly displayed the F75 one but twice displayed 'S97'
i can get the boiler going but this involves bleeding one of the rads and then pressing reset button. i need to get the psi down to about 1.2 bar and then it will run for about an hour before its back at 2.6 or 2.7 at which time it turns off again. HELP

Neil Messent, January 2010

I have the a problem with my system. If i swtich on heating it gives F75 error. But, if I make sure system is working with hot water and burnner is working then switch on heating it works. Reason i cannot jusy use heating and everymorning F75. There is enough water in system. 1.6 bar. No air in system check and double checked.

Ijaz, October 2012

If you replaced the pressure sensor for a black one, made sure the system is debris free with no debris in the vertical pipe to the heat exchanger, and the pump is strong (230V supply, 150-200 ohms (no supply obviously), and cant stop it on the spindle) then you need a F75 Kit (0020023721) which moves the pressure sensor to just above the pump, and fixes the problem.

However, this has a RRP over 200+GBP for a short length of copper pipe and a sensor and some clips. Plenty of room for suppliers to undercut that !

Bert, July 2011

have same boiler same problem. Just been serviced and engineer did not have an answer, checked pressure in expansion tank and fine and no water leaking in from filling pipe.

In the manual it says F75 no pressure rise was detected on turning on the pump - water pressure sensor and or pump defective, air in heating system, quick bleeder defective, too little water in appliance, check adjustable by-pass, connect external expension vessel to return.
No solution as yet. I resst boiler and it works for a week or so before the code comes back.

helpful, January 2010

I am getting the F75 code regular, which appears to be a common fault with Ecotech boilers from what I've read on other sites. One reply spoke of a pressure switch being faulty and a kit 0020023721 being available to repair although Vaillant didn't apear forthcoming on this. Their engineer had suggested cures similar to ones already expressed ie; expansion vessel or pump.

Geoff Rees, January 2010

sounds to me that your expansion vessel may need replacing or your filling loop is still connected and letting bye

steve ipswich heating engineer, January 2010

You have a problem with your expansion vessel, probably needs recharging.

Henry, January 2010