On my previous cars. The heater hoses have ran through the bulkhead from the thermostat, then exited in the same place from a pipe underneath. I've tee'd into both the feed and return and never had any issues with overheating or the vapouriser not getting enough heating etc. The Mercedes however has one pipe running into the heater matrix then, running through the right handside of the car into the duo valves and through the auxilary pump and back into the radiator. Is it acceptable to put two tees in the one pipe running from the themostat to the heater matrix or will this cause problems, it'll still be in parallel rather than series. Thanks.