Frozen sewer vent pipe. Can I safely...

[tidal9]

I live in MN, it's cold. This year has been especially bad and my sewer vent is freezing up every 2-3 days. So far, I have climbed the roof and used a broom handle to punch through the frost dome that has formed. I do believe I have a cleanout in my basement directly below, can I safely re-route my (electric) dryer vent up the pipe to thaw it out? If not, how about a 2-3 foot section of heat tape dropped into the sewer vent from the roof? Is that a fire hazard, or s there a low wattage version that is safer? Any help would be greatly appreciated!

 

[johnjh2o]

What size vent pipe do you have. In cold climates the vent line should be increased to at least 3" one foot above and below the roof.
some frost partials will till appear in the vent but when a fixture is used the heat from the sewer gas should melt it.

 

[tidal9]

What size vent pipe do you have. In cold climates the vent line should be increased to at least 3" one foot above and below the roof.
some frost partials will till appear in the vent but when a fixture is used the heat from the sewer gas should melt it.

It is 3" and yeah, maybe a foot above the roof. The problem is, for a week we have had sub zero HIGH temps. The vent doesn't freeze unless we have 2-3 straight days of constant subzero temps. Well, here we are into the second week of December with a few more months to go. I'm just tired of climbing a sloped roof with 3" of snow on it.