Bathroom fans

Published on May 6th, 2018 | by Henri


Installing bathroom fans

Q.  Do you have a bathroom fan that you like? I’ve got a late 1950s ranch. Two full baths back up to one another – both 8×8. We have not yet remodeled yet, but plan to this year.

I hoped to get the old one replaced now, though, as during cold weather, cold air from the attic is POURING into the house because of how poor the existing fan is. It is NOT ducted anywhere and just exhausts to the attic, currently. Thanks.

A. Do both bathrooms have fans? You mention only one fan. If both are discharging into the attic, they should be individually ducted to the outside.
The cold pouring in is due to the lack of adequate venting of the fan, not the fan itself.

Unless you feel that you can do it yourself, you should have a contractor install proper ducting to a gable wall, and I suggest that you use these instructions:

  1.  Do not vent through a gable vent, a ridge vent, a soffit vent or through the roof in a cold climate;
  2.  Install a 4-inch 90-degree PVC hub or an adjustable metal connector to the fan exhaust (if you use the PVC hub, you’ll have to cut a short section of the recommended Schedule 10 or 20 PVC pipe to fit both into the hub and the bell-end of the pipe);
  3.  Use Schedule 10 or 20 PVC drain pipe (4-inch diameter, 10-foot long with a bell-end);
  4.  Connect the first section of pipe — bell-end facing the fan – to the short piece of pipe attached to the hub and, if needed, additional sections of pipe to a gable wall;
  5.  Cut a 4-inch hole in the gable as low as possible in order to keep the pipe run as flat as possible and preferably with a slight slope to the outside by placing small wood blocks of decreasing thickness under each section of pipe;
  6.  Connect the pipe to a hooded wall jack (avoid plastic louvered jacks as they have a tendency to break in the cold);
  7. Snug 4-inch thick fiberglass insulation to each side of the pipe and place another layer of insulation over the pipe to keep it as warm as possible for the length of the run.

That should do it without having to replace the fan if it is satisfactory otherwise. But if you feel that you need to replace it, get a whisper-quiet one in a bath specialty shop.

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