Ok, had a look throught the posts but can't find an answer, so here is the question
I have the LPG currently set up in parallel with a T piece to both the feed and return, what I am looking to find out is if I can change this to serial where the feed is taken from the pipe from the engine and then fed back into the pipe that goeing to the heater matrix.
Reason for this is that the heater doesn't heat up correctly, I have flushed the heater matrix and it works for about 5-6 miles then cools down again.
I don't want to put in series if it is going to blow the gaskets on the mixer.
for info its a 1997 4.6 HSE with an Emme gas conversion

I am pretty sure that is how the vap on my Classic (single point system) was piped.....

Have you tried talking to Emme about this config??

Parallel or series is fine. Parallel shouldn't be a problem, and is more "normal", but if it's not working for you I've read about people putting it in series too.

My only concern would be that the heater pipes on the RR are quite big, perhaps 20mm? And most LPG vaps have 10mm fittings. The reduced cross section must restrict flow a bit.

Friends LPG system had problems working at all (winter) so he lagged the heater pipes to stop heat loss and solved his problem. Evap needs to be warm. Think his software flagged the problem