One of the big issues with BMH seems to be mold. Well, not so much the mold as the odor that it produces. This year, the BOS has decided that it wants to put in “commercial dehumidification”. I’m not sure what that is but I got the estimate and know what equipment they are proposing.
First lets talk about what mold is. Here’s a good paper on the subject. I may be over simplifying but mold is a type of fungus that infects organic substances when conditions are relatively damp and warm. Read the article.
Now let’s talk about humidity. When people talk about humidity, they usually mean relative humidity, which is the amount of moisture contained in the air as a percent of the maximum that could exist at the present temperature. Warm air can hold more moisture than cold air so as the temperature is increased, the relative humidity goes down. That is to say that at the increased temperature, the air can now hold more moisture. The inverse is that as temperature goes down, the relative humidity goes up.
So everybody thinks that basements are damp because a lot of moisture comes through the walls and floor. And sometimes that’s true. But a lot of basements are damp in the summer because the 80 degree outside air that’s at 50%-60% relative humidity will become near 100% when it enters a 65 degree basement. Most of the time in the summer, you’re better off reducing the moisture in the air that you already have and preventing outside air from coming in.
Last summer the town had an Indoor Air Quality firm do mold testing. One of their recommendations was to reduce the relative humidity in the basement. So the Town Planner asked CCI to recommend something and his HVAC guy recommended an air conditioning system with ductwork and outside air ventilators. He used a fancy word for it – DX coil.
The CCI guy recommended a 1½ ton DX coil to dehumidify the basement. One and a half tons of refrigeration can remove 18,000 BTUs (units of heat) per hour. You have to remove about 1000 BTUs to condense one pint of water, so the system would have the capacity to remove 18 pints of water per hour or 432 pints per day. The total cost of the proposed system is about $20,000.
You can get an 80 pint/day dehumidifier at Bradleys Hardware for $250. Six of them would remove 480 pints/day for a total cost of $1,500, and it could be working tomorrow.
In the air quality report it was noted that there already was a dehumidifier in the basement, but it wasn’t working because it was full. That’s a fair point: Who’s going to empty all those dehumidifiers? The answer is that you can get an automatic condensate pump kit for about $50 each that will pump the water up to a drain.
So for 10% of the expense, about $2,000, we could get the same result. I’d put six of them in and if that didn’t do it I’d add more till the problem is solved. It’s called scalability. We can add capacity at about $350 per 80 pint unit.
The rest of the money should be spent on sealing and insulating the walls with spray foam. It goes without saying that if the broken windows and outright holes that have been ignored for years are fixed it will not only help with the moisture laden air infiltration problem, but will slow down the rodents a little as well.
Makes you wonder how much more money is going to be wasted because we ask somebody that gets a percentage of the cost of the solution to come up with the solution.