Browse Forums General Discussion 1 May 23, 2016 6:06 pm We recently moved into a brand new, super energy efficient single story, 2400sqft home (Ceilings R49, Walls R23, Floors R30) and we noticed the air felt "heavy" as one visitor described it. We purchased a dehumidifier and are AMAZED the we have been extracting about 5 gal per 24 hours every single day to maintain about 42-45% RH. We've been running it a full month and it never changes. The weather has been warm and dry (low humidity) and cool and a bit more humidity, but the water amount extracted doesn't seem to change with outside weather. The house is so "tight" closing an outside door can be felt in your ears, so it's not likely infiltration. Is this normal? We were lead to believe we might get a few quarts a day, but 20L or about FIVE GALLONS? We had a house inspection and they found mold spores in the crawlspace (black spots and some white) and the attic (white powder), yet it's only rained lightly a few times since we moved in, and there's no evidence of leakage. The homebuilder is refusing to investigate saying they built the house right, and since it passed County Inspection and we have a C/O they are not responsible. When the house was being built, before insulation/sheetrock, we paid for a 500,000 BTU heater to run continuously for 4 days ($500 in diesel fuel) to dry the structure, and the building superintendent only allowed work to continue when the wood was down to 18% moisture (if memory serves), so the structure should have been sufficiently dry to complete. How much per day would be reasonable, and how much is TOO much? Re: Exracting 20 liters/24hr water in dehumidifier in oNew H 2May 23, 2016 6:38 pm The downside of modern houses particularly in the US is that to meet stringent insulation codes the houses have become really air-tight meaning not much water vapour can get in but none can escape either. What is your ventilation like from your bathrooms and kitchen ? Everything from those rooms should be extracted to the outside by fans as soon as a shower is run or cooking on the stove. Stewie Re: Exracting 20 liters/24hr water in dehumidifier in oNew H 3May 23, 2016 7:39 pm Well you will get around 0.8L per person living in the house. Then if the house is so airtight I have to ask if you have extraction from Tumble driers. Bathrooms particularly those with Showers. Kitchens. Also dehumidifiers will extract water continously so if you do open windows and doors you will be providing a source of humidity. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Exracting 20 liters/24hr water in dehumidifier in oNew H 4May 24, 2016 3:44 pm Thanks for the replies. We have 2 people in the house (1.6 liters) and we run exhaust fans when showering (2 showers taken per 24hrs) or modest amounts of cooking. We do not open any windows, and the doors are open only long enough to admit or discharge the occupants. Not sure what you mean by "extraction" by the clothes drier, but the drier is piped to the outside by metal piping, and uses the drier's own fan to discharge the vent air to the outside. Maybe 20 liters a day is a reasonable amount of water that needs to be removed from the air in a modern house then? Surprising the building industry doesn't recommend dehumidifiers in these tight houses, then. Bob Re: Exracting 20 liters/24hr water in dehumidifier in oNew H 5May 25, 2016 7:41 am Are the exhaust fans for the showers vented to the outside as well ? Too often homeowners end up with mould inside their houses as the builders just vent the bathroom fans into the ceiling space rather then to the outside ( other reasons for the mould too of course ). Check those vents to the outside when the fans are running just to make sure they are actually doing their job and the builder has done the right thing - showers, dryer, range hood etc. I'd also open your windows for natural ventilation as well ( weather and temperature permitting of course ) as your humidity levels inside may be higher than outside and the moisture will naturally expel. Stewie Re: Exracting 20 liters/24hr water in dehumidifier in oNew H 6May 25, 2016 8:37 am That's a good question about where the exhaust fans expel their air. By CODE outside, but it was common practice elsewhere to vent the to the attic. As far as opening windows to ventilate, we live in Western Washington State, which tends to be damp until summer comes. I'll try to post a humidity chart, but generally, the highest humidity daily (at night) is 90-100% so not sure opening winds is the way to go. [img][img]http://s33.postimg.org/5ycmge26z/Olympia_Humidity.jpg[/img][/img] Re: Exracting 20 liters/24hr water in dehumidifier in oNew H 7May 25, 2016 10:17 am What is the floor - concrete slab on ground or raised timber bearers and joists ? What about soil drainage around the perimeter of the house ?
The moisture in the air has to be coming from somewhere but given that you are experiencing such high humidity it may be just that the dehumidifier is extracting all that water from the air that has made its way inside your house. It is not unusual in places like Northern Australia ( or any other place with relatively high humidity ) for dehumidifiers to remove large amounts of water from moisture soaked air. Stewie Re: Exracting 20 liters/24hr water in dehumidifier in oNew H 8May 25, 2016 1:04 pm Stewie D What is the floor - concrete slab on ground or raised timber bearers and joists ? What about soil drainage around the perimeter of the house ? Wood subfloor over wood floor joists. House is built on a poured concrete perimeter foundation and 4ft crawl space, which is soil with a 6 mil vapor barrier over it. Soil drainage is good (sandy loam) with the ground water at least 8ft below the surface. The moisture in the air has to be coming from somewhere but given that you are experiencing such high humidity it may be just that the dehumidifier is extracting all that water from the air that has made its way inside your house. It is not unusual in places like Northern Australia ( or any other place with relatively high humidity ) for dehumidifiers to remove large amounts of water from moisture soaked air. The floor is extremely tight (as is the whole house). Opening or closing an exterior door causes one's ears to "pop," so I suspect infiltration is very low overall. The floor is insulated with R30 fiberglass bats, but no vapor barrier in the floor. The floor covering is about 50% vinyl and 50% carpet over rubber pad, neither of which is very permeable. It's possible the moisture is coming through the floor (I can't think where else if might be coming from), but we lived in this climate before w/ a crawl spape (and no floor insulation), no dehumidifier and never noticed humid air in the house. I am just amazed that 5gal per day is almost 2000 gallons per year, or enough to fill a 55 gallon drum every 10 days or so, which equates to darn near a quart per hour, which would be a pretty decent flow, or leak if it were dripping from a leaky pipe, yet this moisture is in the air. I have no reference to know what a LOT of water from the air actually IS, so maybe it's normal; maybe it's not. I'd love to know what "normal" is, I guess. Bob Stewie Stewie From what I know about water tanks (I've been working with a client on them for a few years now) is this - The concrete can last a lifetime if they don't crack for some… 2 10619 there was an event. The question is whether the builder had the insurance and whether the event was covered. The workmanship is a separate conversation. 10 23715 We already paid for somfy motors for the blinds. The quote above was purely for “pre-wiring” so the blinds company can install the motors and blinds. That’s why we… 5 16088 |