Bradford White power vent

Used this forum for a while now for info (4 Toto Drakes Later) and now for the water heater for our addition. The tank works great however I have a question about the pvc used for the power vent? The tank is in the garage and the vent goes up the wall through the second floor and then into the attic and finally through the roof. It is 4" PVC with a total length of about 22'. When we did the addition we had extra insulation put in the addition and old house attic area. Last winter and so far this one, we are getting major icicles forming from the over hangs. Everything is fire blocked and with the extra insulation, figured this would not happen. The only different thing now is the vent in the attic. Does the 4" pvc put out enough heat that it needs to be insulated in the attic area? There is negligible condensation that comes from the drip tube. Has anyone in a cold weather climate insulated the vent?
Thanks
Pat

How high above the roof does the thing exhaust? Yes, it will add some heat to the attic. If there is adequate ventilation there, it may not be the problem. If the chase where it goes into the attic is not sealed, that may be a bigger, more constant source of heat into the attic. You'd have to read the manual to see if insulation is allowed. Probably wouldn't hurt, if allowed. Not sure it would help. On a run that long, I'd expect more condensation in your drain.