I have a new gas forced air furnace, Amana. The PVC exhaust
runs about horizontally 30 feet to the outside wall. PVC makes
a slight pitch back toward the furnace for draining. Everything
has worked fine until the temperature outside dropped into the
single digits. (Upstate NY) The furnace will not come on until
I go out and clean out the ice formation on the end of the pipe.
Now there is not a lot of ice, only a ridge around the edge.
What do you suggest I do to stop this? Should I insulate
the pipe so it doesn’t freeze? Or should I change the pitch so
more moisture drains back instead of out? The shape of the
pipes looks like rams horns, 2 pipes up about 3 feet 12 inches
apart. Then to 180 degree fittings on top dump down opposite
each other. Should I change the outside configuration?

Thanks
TP