Basement dehumidifiers.

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Old 08-06-17, 05:03 AM
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Basement dehumidifiers.

I currently have two 70-pint home depot type dehumidifiers in my large basement. I think one is frigidaire, can't remember the other brand. The type that cost around $200. I was recently told my an HVAC installer that I would be better off with an APRILAIRE 1850F. that it would be more energy efficient than using two of the other units, and would work better. These are fairly expensive, especially the quoted install price(not sure it really needs to be installed, it's not going to be part of the system, just for basement). The main question, do these work better than having two of the cheaper units? I don't think the increase in efficiency would make up for the cost, but if it would work better, it might be worth it. thanks
 
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Old 08-06-17, 05:10 AM
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IMHO...No! Are your current humidifiers doing the job? If so then spending more money to gain a small amount of efficiency is not worth it. If the contractor can make a guaranty that you will save X amount of dollars over X amount of time, then perhaps. But I'm betting he can't and won't do that. Keep in mind that a dehumidifier is like running an open refrigerator. Seems like a waste, but it's one of those "cost of doing what's necessary to gain an objective" type thing. In this case your thing is to keep the basement dry in the summer.
 
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Old 08-06-17, 05:19 AM
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Are they doing the job? Not sure. As far as I can tell they are constantly running. They are definitely keeping the humidity down, but would one of these industrial units do a better job? Do they do anything differently or is it the same technology? They are much larger, is that all just a larger fan, might that make a difference in the ability to dehumidify? thanks
 
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Old 08-06-17, 05:29 AM
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Hi ez, let's talk about where that moisture is coming from. In most cases it is a combination of moisture coming through the concrete walls and floors plus outside air that infiltrates through the many leaks all homes have. The least obvious is that air leakage and all homes suffer much more than they need. Example, the target for indoor air quality is to exchange all inside air every 3 hours (on average). That's a lot of outside air to dry out and in the winter to heat. To reduce the load on those dehumidifiers consider some air sealing, at least the typical big leaks which are often easy to find. I would need to know more about your home, style, size, and age to get more specific, but as a retired energy auditor I have helped resolve many air leak issues. I'll add a reference link for tracking down the leaks.

There are other sources of moisture like "people" or known moisture issues and they all add to the humidity in the basement. Basements will register higher because they are colder, I.E. relative humidity. The same moisture content at a lower temperature reads higher on a humidity gauge. You should also have one of those if you don't.

https://www.energystar.gov/ia/partne...ide_062507.pdf

Bud
 
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Old 08-06-17, 05:35 AM
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Bud makes some goods points of why you're getting moisture. If you can't resolve those issues then to answer your question to my 1st reply, I'd say that if the current units are not doing the job, then yes an "industrial" or "commercial" unit will be necessary. Again it's like asking a typical refrigerator to do the job of an industrial freezer, just not big enough.
 
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Old 08-06-17, 05:44 AM
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Thanks Bud, we did have an energy audit and they didn't say anything about leaks. House is only about 20 years old. Large house, about 5000 sq ft. Kind of a non-traditional colonial. We live near a pond and have a fairly high water table. Have a sump in basement floor, only runs if there's an excessive amount of rain, but there's water under the house for sure. Seems previous owners "sealed" the basement. Only a couple spots where I've ever seen dampness in the floor. So, I assume most of the moisture is coming through the walls/floor which is just going to be a never ending battle and the cost of living where we live. So, the dehumidifiers are essential. Wasn't sure if we should upgrade to one of these more industrial units or not. Do they do a better job of dehumidifying than the cheaper ones or is the pint rating the only thing that matters?
 
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Old 08-06-17, 05:47 AM
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thanks Norm, yes I don't know that there is much more we can do do prevent moisture from getting in at this point.
 
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Old 08-06-17, 05:57 AM
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You could try using a free standing unit as opposed to an installed system, but not from the HD or Lowes type of store. Try Googling "high capacity free standing dehumidifiers". Lots of choices. You'll be looking at $500 plus for a unit that will do the job. Just think you will have an unlimited supply of distilled water.
 
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Old 08-06-17, 10:27 AM
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That APRILAIRE 1850F is 95 pints/day so you would get significantly less dehumidification than your two 70 pint/day units. Could have at least quoted the 1870F as it is 130 pints. Those bigger units are more energy efficient. If truly running 24x7 you could save $30/month on your electric bills.

Two units in different parts of a large basement will work a bit better than one unless you have an open floor plan with some air circulation.

You also need to consider noise and space. If a finished basement a built in dehumidifier could be in the furnace room ducted to the living area.
 
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Old 08-08-17, 09:49 AM
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Santa Fe Classic - Santa Fe - Basement and Crawl Space Dehumidifiers

Most of the good dehumidifiers do a much better job at removing moisture at lower temps that your standard off the shelf units.

Remember that 70 pint dehumidifier is sized at 80 degrees not 65ish (temp of most basements). So your 70 pint dehumidifier is now like a 55 pint. So of the better units have hot gas bypass which will help with defrost on the better units.
 
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Old 08-08-17, 01:29 PM
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Airman's advice is good.
Sorry I missed your reply. "we did have an energy audit and they didn't say anything about leaks." The energy code target for air leakage is a complete air change every 3 hours. They either let the house leak randomly or they install some form of air exchange unit like an HRV (heat recovery unit). Homes that leak less then the 1/3 house volume per day (that's an average number) will have other problems. So your 5,000 ft² home with an estimated volume of 40,000 ft³ is getting 13,300 ft³ per day of fresh (humid) air just from leakage. If that energy audit included a blower door test that result would estimate the leakage. 20 years ago they weren't aiming for this leakage target so I suspect yours is higher.

Point being, there are most likely some easy places to seal that can reduce the amount of outside air you are having to process.

Are your basement walls covered/finished or exposed concrete?
Do you have any form of fresh air system operating?
Do you have a Radon mitigation system or have you tested for Radon?
Do you have exhaust fans in all bathrooms and kitchen and do you use them? Bath exhaust fans can be controlled by a delayed off switch to help dry the room after showers.
A related question, do you have 3 teenage daughters, a known source of huge amounts of moisture (multiple long showers per day)?
Are all showers equipped with low flow shower heads?

The list of moisture sources goes on, but the idea is to reduce the amount the occupants contribute.

Pick up several moisture meters (inexpensive) and monitor moisture and temperature readings in different areas of the house and the basement.

Bud
 
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