Turbo diesels and heat exchangers, does it get hot enough

I have this problem with the Discos cooling system TD5, it's to bloody efficiant, to the point that it won't sustain enough heat in the coolent due to controlling flow of the coolent to heat the fresh water pumped into the heat exchanger for a hot shower.

I have plumbed it in where it would normally go, before the heater (hot coolent into exchanger) and after heater (coolent) out of exchanger, this is how i had it in my last vehicle and it worked brilliant.

I have been speaking to Helton, who have been very helpfull i must say, thanks guys and there suggestion is to plumb into the top radiator hose directly, where the coolent flow never stops (coolent flow before and after heater only happens when heater is on and the engine is reving at over 1500rpm) and is controlled by the ECU so can't do anything about it.

Is the Landy alone in this or are all the new electronicly controled Turbo diesels like this (ie)3.0ltr Patrol, 3.0ltr Jack.

Baz.