Posted for Don Skeele <dpske@wvi.com>:

Lorn,
   More heat, wrap the heat muff internally with stainless wire or a stainless matt. Make a "birds nest" inside the muff.   I've got the same RV
filtration system, mine is out of aluminum for induction fire reasons.
Regards.. Don Skeele   235/320..(503) 769-2563