Treating High Humidity in basement

Hello all,

We have moved into a new house and my system is in a basement with floor heat. I have high humidity in this room, sometimes 68%. What is a good dehumidifier system to use for when I am not in the room? I have ventilated the room for up to six hours which lowered the levels to 59%, what else should I do? Should I turn the floor heat off and turn the room into an iceberg and vent the windows in the evening before I use the room? Thanks.
PS. I am located in Germany
This sounds like a question for a builder

As it says in the link using a dehumidifier may cause more problems as it will accelerate moisture ingress through the basement walls. Fixing a damp basement can be quite involved and expensive.

By the way, living in Boston MA we have 68%+ humidity throughout the house for much of the summer. I haven't noticed it causing premature aging in my hifi, and I actually like more humid air (as opposed to the winters when the air is bone dry). Provided there's reasonable ventilation and that mold is not present I don't see the problem with 68% humidity.
Hi : I live in Massachusetts and have my second system in my basement and have a De-humidifier in the room with the system...I leave it on all the time from May - November...The only time I shut it off during the damp season is when I am down listening..After listening I turn the system back on..I try to keep the room Humidity about 40 % .. Any quality Dehumidifier in the room should work..Just make sure it is large enough to do the whole cellar...It shouldn't be a big deal.......
The floor heat system may be the sticking point. An appropriately sized dehumidifier works fine in our house, but we have forced air heating/cooling. During the cold months, the forced air heat dries the air so that the dehumidifier is not even needed. I am not familiar with your floor heat system (assume it is hot water in pipes, but could be glycol in plastic tubes?), but the temperature differential between the heated room and the surrounding ground will contribute to a migration of water vapor into the room. If there is not an adequate vapor barrier below the slab, you could be bringing significant moisture from the ground into your basement area. Moisture vapor will also migrate through the walls if they are not damp-proofed. I believe the best place to start would be to purchase a good quality, moderately large dehumidifier and let it run for a week or so then see what you think. It sounds like you own a hygrometer, so you can measure the relatively humidity at incremental distances away from the dehumidifier to check the effective radius of treatment. Depending on your basement layout, you may need two dehumidifiers. The next step would be to install some form of forced air ventilation system, but before doing anything like that, I would consult an HVAC contractor. In fact, I would probably call a contractor as soon as I determined one dehumidifier alone was not going to work.
Dehumidifier is very commonly used in Asia, almost every family has more than one in Taiwan. Not popular in US and difficult to get, price is also very high. In Taiwan, you can pick one up for less than US$100.

Leave it on all the time, they don't pump continuously and only turns on when needed. Very effective, doesn't consume much energy, protect your investment with very little spending.
What do you mean a room De-humidifier is not poular and hard to get in U.S.? You can get them at any Home Depot, Lowes, Sears, Hardware stores......I have one in my current house, the house I bought has one and many friends have them, we have a drain hose hooked up to ours so you dont need to drain the pan.
Yhis a popular and easy to get solution, Semi's take on this puzzles me.
Thank you all for your responses. Not having time during the week due to work and a long commute, I have been checking here and other places to see what should be the best way to tackle this issue. First off, I bought a Value Home dehumdifier, 20L/15 hours is the rating. Well after plugging it in for only 70 minutes last night, the room went from 67% to 60%....and the machine is actually quiet. I also turned off the floor heat entirely, and opened the windows this morning to air it out. So I guess I have a process so to speak to exchange air manually, by opening the windows to allow the stale air out and using the dehumidifier once in a while when the levels start getting high. The device draws 450 watts in use. About the same as both of my tube amps in an idle state. I think this will be my solution for a while. Thanks all.

there is a company in new york which makes a product called humidex, look for it online. It's power consumption is less than a night light and you could install it yourself.
Good Luck
If you own your home it's worth cerfing the net for more info. I just redid the entire exterior drainage for my 45 yr old home, not that we ever had the slightest problem, but I've witnessed how moisture problems can lead to horrifying destruction in our damp, coastal environment.
Hi Audioquest4life, I just thought of a question; since you have floor heat, is there any provision for return air. In houses with forced air heat, there are return air vents. When the forced air pressurizes the room, air flows out through the return air vents resulting in a circulation that I would assume lowers the ambient humidity. However, I am not familiar with how exactly the floor heat works, and what provisions are made for air circulation and humidity control. When you say you moved into a "new" house, is that a newly constructed house, or one that is new to you? If newly constructed, I would expect a modern system with some provision for humidity control, so you could contact the builder to discuss the issue. If it is an established house, but new to you, you should consider calling a residential HVAC contractor with a good reputation and see what they say. Let us know how it is going.
Hello Mitch2,

The house we moved into is our own and we had it built to our specs, including the floor heat, outside walls and the whole house plan. The company that built the house, had "Options" when we were planning the house, I decided to get their double wall construction option which is waterproof from the outside and uses pure concrete in three layers, the outer layer is about 1 feet deep, the middle layer about 8 inches and then the inside layer another 1 foot deep. I wanted to have basement walls impervious to outside weather such as rain and also to ensure a soundproof environment for the listening room, fitness room, bar and guest room suite.

The windows are all doublepaned insulated windows with lifetime guarantee...whatever that means. The door to the listening room is a soundproof level 3 door here in Germany and I think that means a 55-60 db protection from outside noise, or the other way around. The floor heat consists of an outside controller with the boiler and elctronics from Viessmann. Each room has its own thermostat. I had the heat guy hear a few days ago to check the boiler for me and he told me to keep the floor heat at least 14celsius and never off, so much for saving money when a room is not used, this is to keep the water circulating in the pvc tubing. The basement slab is also thick, about 16 inches with a moisture barrier added and then another few inches for the floor heat cement. All of this adds up to a pretty sealed up house in the basement.

The only air exchange that is going on is via the ceiling in the main floor as the roof is not entirely sealed, it has several layers of insulation in the roof of the living room on top of drywall over 2x4's. The ceiling is drywall that is sanded and painted. In the attic, the north wind blows by. The attic is called a living breathing attic here as the air is always circulating. The top floor stays at a constant 43-50% humidity, while the basement full of concrete walls stays higher. There are no drafts anywhere in the house. In fact, I open the bedroom window a little bit for fresh air at night to help me sleep because of my sinuses. I know when I open the windows in the basement the levels drop. The heating system is all closed and does not have a means to exchange air, we do not have central air like you do in the states. I heard of this hight heat system that you can rent to blow torched air via a gas blower in the room to heat the air to lower humidity. It would be something like a space heater where a gate guard would use outside to stay warm in the cold. I am not sure if this is something I want to explore. I will have to send some pics of the new house basement and the fogged up glass.

Lat year I worked at construction site of the ROM.That is the Royal Ontario Museum and they expanded the facilities with this enormous addition that went over budget.$$$$
They called the new part "Crystals",because the roof lines look like inverted pyramids or something.Anyway it was the most difficult job that my local union of Glaziers and the local union of Ironworkers had been on,we were overwhelmed(we joined forces to deal with the challenge,110 guys on 60 hour work weeks to finish it),a nightmare of engineering ,over complicated,overkilled ,overdesigned and extremely labor intensive.All material were designed,engineered,manufactured and shipped to us from Germany by a company called "Gardner Glass" the company that did the work here was "Permasteel-isa" the company that did the structural steel erection was "Walter"the general contructor company was "Vanbots".Even down to the last bolt and tiny screw ,everything was shipped from Germany.Funny we HAD to use the German silicone called "Stabalux" and we went through it so fast that we were running out very often ,so our foreman suggested we use the Canadian commercial silicone instead" well, when the German big shots found out,they made us strip all the cured silicone,power brush all the galvanized metal gutter systems and reseal with Stabalux.!!!They wouldn't honor the warranty otherwise!! We had one of our union member by the name of " Kurt"in charge of the supplies and materials because he was a German born and he could read and translate the labels.LOL.I mean the labels were only written in German,no English on them!
I was impressed with the German quality of materials and design.Truly genious design I must say.No corners were cut with anything ,we had visits from German architects to overlook and ensure the project went smooth.
By reading the description of your home I understand that your house is very "tight" and does not "breath" .I renovated my home recently and I got the same problem.Here in Canada we install a vapor barrier on the warm side of the insulation and drywall right over it.Any moisture generated in the house can not penetrate the wall and get in the wall cavity where in time can cause damage to the wood structure.I DID such a perfect job of sealing my home that I get moisture on my glass windows too.An HVAC guy that came to my home said that usually a 10% wall area needs to stay unsealed .I went 100% myself.I use a dihumidifier at the moment set at 50% relative indoor humidity.If the unit is off,my indoor humidity rise to 67-70%.I seen it even higher like 75% last winter.
When I get around to it I will call a specialist to come and in with a better solution to the problem,but dehumidifier seems to work for me at the moment.
Best regards
George (To clarify,I am not Canadian but Greek and live and work in Toronto)
Hi Yioryos,

Thanks for your reply..the company here Luxhaus, is one of bigger companies that offer custom or manufactured homes to people here in Europe. They are always doing some new age technology stuff to increase house efficiencies, hence the double wall construction walls, they advertise the walls with a floating room sitting in a pool of water, and totally dry inside with no moisture seapage at all.

They said that with the house I will never have to worry about water to moisture coming in, ok, but know I need to let some of the indoor humidity escape from the basement. The dehumidifier works great though as does opening the windows for a few hours daily.

I asked the company about the possibility to send us the materials to the United States if we decide to build there someday, they have expanded to the UK and other countries in Asia, but that is not possible, only like how you did it in Canada, order all of the stuff and ship it there and have someone reassemble it there. I am not sure if they are in Canada yet.

I know about the silicon experience, I was doing some of the silicon trim in the basement and the main subcontractor had to leave early because he was sick, I started to do the rest myslef, only about 10 meters of wall, anyway, ran out of the silcion, well, it is some special grey color that only one company makes and it has to be ordered, jeez, I thought gray was gray. Still waiting on the order to come in.

I will have to send some pics as I said earlier of the house and basement shots,
Dehumidifier is very commonly used in Asia, almost every family has more than one in Taiwan. Not popular in US and difficult to get, price is also very high. In Taiwan, you can pick one up for less than US$100.

This has to be the most ridicules statement I have ever heard, finding a Dehumidifier in the USA is HARD? Have you never heard of HD,Lowes,Ace and numorous Hardware chains. I can guess that a neighborhood Cosco/Walmart would even carry one. Geezz pal this is the USA the largest supermarket for goods in the world.