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Best HRV for a fire station that gets humid in winter?

mhansenwhc | Posted in General Questions on

I am doing a bid to fix a humidty problem in a fire station. This is in a small town in mid-Missouri. The building is a 2,840 square foot metal building with no ventilation. It is heated with radiant heat. It is 45,000 cubic ft.

In the wintertime the building is trapping all the excess moisture in the building and then it is condensing on the bay doors of the fire station and growing mold.

I am pretty certain that a good HRV will do the job but I’m not completely confident how to size it due to the fact the it is an extreme situation. Any and all help would be greatly appreciated.


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  1. GBA Editor
    Martin Holladay | | #1

    Before proceeding with this job, I would install a few hygrometers to determine the indoor relative humidity (RH) in this building. While a properly sized HRV might help lower the indoor humidity level, you can't be sure that the RH is too high unless you measure it. If the RH is above 30% in the winter, it may be useful to lower it with mechanical ventilation as you propose.

    In cold weather, the fire station doors are likely to be cold, and to be condensing surfaces. It's possible that the fire station just needs new doors with better insulation or weatherstripping.

    Finally, it's useful to know the source of the moisture in the building. Is there a lot of melting snow that drips off of the fire engines when they are parked indoors? Do the firefighters drain their hoses indoors, using a floor drain in the concrete? Did the builders forget to include a layer of polyethylene under the slab? Unless you know the sources of the moisture, it's hard to formulate a plan to address this problem.

  2. mhansenwhc | | #2

    Being spring I cant install hygrometers and get good idea of winter humidity until winter and they would like to get something done before this winter comes. Lets assume that humidity is high and it is because of washing trucks, melting snow, and draining hoses and all the moisture that comes along with a fire station. This is just a small metal building fire house in a small town and is not used or occupied everyday. The doors are somewhat outdated and leaky. If all this is true and they dont replace doors do you think that an HRV would do the job of keeping humidity low?

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