Heaters in building entrance area - good or bad?
October 23, 2011 8:40 AM   Subscribe

Will installing a heater of some sort in a building entrance area keep condensation from forming on the front door during the winter, or will heat just rise straight to the top of the stairway with no effect on the entranceway?

I am in a 7-unit condo building. The front entrance area of the building has stairs leading down to one unit, and up to three floors. The front door is glass and wood, and last winter we had lots of condensation problems with the door - and during really cold days the condensation froze over on the inside (this is in Chicago). A suggestion was made to install an outlet in the entrance area and get some sort of heater, thereby keeping the entrance area warmer. The theory is that this will at least keep the condensation from icing over, and that it will be better for the units that are closest to the entrance area since the cold could leak in through front doors.

After some preliminary research on this, it seems like an expensive fix that won't do much other than allow heat to rise in the stairwell. I don't know what type of heater we could purchase that would be safe to have running in a common area, and I don't know how expensive it would be to run.

Should we table this idea, or is there a fix that I'm missing?
posted by bibbit to Home & Garden (6 answers total)
Condensation is caused by moisture cooling. Here are 2 rules you should think about before you start spending money.

1. Stop the cooling and you'll stop the condensation.

2. No moisture, no condensation.

Let's start with the first one. Yes, the heater will likely warm the doorway and slightly reduce condensation. If it is so cold inside that indoor ice is an issue (and you can afford it), then by all means, install a heater.

Now let's move on to "No moisture, no condensation." In addition to heating the doorway, you might consider getting a dehumidifier. Expect to spend around $200 for a unit. A dehumidifier in ensure that all of the water in the air isn't just moving on to the next-coldest thing in your building.

There another long-term alternative is to replace your door with a composite fiberglass door with triple pain windows. The foam insulation inside the door and new weather-stripping will help block cold. Budget $600 to purchase, but you might be able to spend less. Installation cost will vary.

If you don't feel like you are flush enough for the electricity or door replacement, try starting with adding professional weather stripping and just the dehumidifier. Dehumidifiers don't work quite as efficiently at colder temperatures, but it might be all you need.
posted by David-lib at 9:36 AM on October 23, 2011

Why not try spraying rain-X or something similar on the inside of the window? This will help the water to bead and will drip instead of forming a uniform sheet of condensation. It's possible the rain-X will even inhibit the condensation, I'm not sure.

You might need to add something at the bottom of the panes to keep the water from causing any damage to the door, but this might be an easy to test - cost effective solution...

I'm not sure if rain-X is found everywhere, it's basically a synthetic hydrophobic coating applied through a spray that is usually used for car windshields to stop help rain to bead and "flow" off the windshield...I'm sure most auto parts stores will have it...
posted by NoDef at 9:50 AM on October 23, 2011

If your motivation is to keep your apartments warmer or reduce heating costs, the condensation on the door has little or nothing to do with it. Condensation and icing doesn't make your apartment colder. Condensation and icing are just symptoms that indicate that the door is inadequately insulated. Trying to heat the entrance will just run up everyone's total power bill by increasing the rate of heat loss through the poorly insulated door. In other words, heating the entrance will cause your building to lose heat faster, not slower, and cost you more.

Replacing the door with an insulated door with insulated glass will save you money in the long run and make the entrance more comfortable. You likely will reduce draft leakage as well.
posted by JackFlash at 10:40 AM on October 23, 2011

For the price of installation (suitable outlet and heater) by a licensed electrician you could probably have a new door instead.

A short-term fix could be to install a fan (sans heater) to move air in the doorway and help the condensation evaporate. That's going to raise the overall humidity though, possibly bringing you back to square one.

Fan + humidifier?
posted by werkzeuger at 10:51 AM on October 23, 2011

Sticking with the no moisture point, you may want to investigate why you're getting so much in the first place. (The door freezing over makes it sound like a lot.) I would look into how well the door is weather-stripped, for instance, and what sort of doormat you have both outside and in. Is there any means for the pad -- porch, sidewalk -- outside the door to drain? Is the top properly flashed so that water coming down the wall is diverted?

Also, the doors closest to the entrance especially, but all the individual unit doors should be examined to see that they have the proper seal. If they get a blast of cold air whenever someone opens the door, they are probably also leaking heat and humidity back into the lobby area.
posted by dhartung at 1:59 PM on October 23, 2011

The best kind of heating unit to install to mitigate this problem is a heated air curtain. It'll both heat the surface of the door above the freezing point and it'll help prevent the condensation from forming in the first place. And if you've got a lot of traffic coming and going through that door they can actually save more energy than they use.
posted by Mitheral at 8:47 PM on October 23, 2011

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