Update.
I fitted a Bypass valve to the Heater, see
https://www.talkmorgan.com/ubbthreads.php/topics/795722/gdi-heater-bypass-fitted#Post795722I retested the air temps as before and it does improve things but it's not the result I was hoping for. It's obvious the bypass leaks and there is still heat getting into the Heater Box.
The best result achieved is to get air 10.5 degrees above Ambient into the cabin, this is with the heater bypassed and the flap within the heater set to Cold. This is hardly what you want when waiting to get on a Ferry with the outside temp in the 20's.
When the flap is set to Hot then the air temp going to the cabin is warmed by 17.7 degrees.
Alternatives?
Other bypass valves that may or may not work. I have seen a Brass one but it couldn't be switched remotely.
fit a simple straight through connector in place of the Bypass and have no water going into the heater at all. More chance of working but a pain to switch between bypassed and not.
Stop Valves in an arrangement of T's and Hoses, should stop the hot water getting to the heater but switching between the two states will be manual.
Some more thought me thinks.
