Urgent Tu Derv Bleeding Advice

[Richie-Van-GTi 70 2 Cars]

Ive got a tu derv Im selling, someone is coming to see it in half an hour but the heaters arent working. I fear there is an air lock but I can only find one bleed point. Can anyone point me in the right direction if theres any others?

[djinuk 2]

you should have one on your pipe coming from heater matrix at the back of the engine (has a valve cap on it) and if you look at the thermostat housing you should find a brass screw, this is also to bleed the system.