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post #31 of 57 Old 07-19-2004, 05:29 PM
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Quote:
Originally posted by uxbridge
Bob:

<snip>HRVs and ERVs only remove moisture in the winter. They tend to bring it in, in our summer climate. By the way whats the humidity like in the rest of the house. Is the floor sealed?

Bill
I think uxbridge is on the right track here. I'm not an hvac technician but I've contracted a few large projects and learned a few things (ie don't put trane economizers in a library, doh!)

If you have a heat exchanger I'm assuming you have a relatively new home, which means the living space should [should!] have an effective vapor barrier (ie foil or paper faced insulation, or even better sheet plastic over unfaced insul). If you ever cut a hole if your drywall or had reason to remove it you probably have noticed one of these. Of course it's easy to cut corners on this type of thing, but the quality of the rest of your home should be indicative of how well insulated it is.

The reasoning behind the heat exchanger is your living space is so well sealed that all the building materials (plywood, osb, carpet, etc) that are off-gassing into the home cannot dissipate via the drafts common in older construction. Thus the heat exchanger pulls fresh air into the home and removes the "contaminated" air.

As far as your living space goes, there are only two ways humidity can be introduced 1) your vapor barrier is inadequate and humidity is coming in through the builiding envelop (walls, ceilings, etc) or 2) the heat exchanger is drawing moist air into your hvac system, which is then pumped throughout your house. Aside from an open window or the occasional open door, there really is no other way humid air can enter (well, fireplace is another one- brick and mortar that is).

My bet is your heat exchanger is introducing humidity. I'm not sure of the mechanics (do these things have motorized dampers?)-- would unplugging it actually disconnect the outside air, or would it merely cause the air exchange to be passive?

Next is your basement itself. I know you did the "foil test", but I would wager you are getting at least some moisture in through the walls and floor. My suggestion would be to lay down some plastic over the floor before you do the floor covering (heavy plastic- HD carries it in boxes like 20x100 and other sizes). For the cost, it's well worth the benefit.

For the walls you could go with a drylok type sealer, but that would be my least favored stand-alone option. However it is a great compliment to any of the others I will mention.

In my own home I would drylok, stud out (metal studs), insulate with r13 and cover the studded walls with plastic and whatever covering you are using. Another option would be applying a foil-faced rigid insulation directly to the walls (homosote makes a product "ultra-r" in various r values)-- make sure to tape the seams. Last would be good old plastic sheeting over the walls.

Next is the ceiling, or the bottom of the first floor. Is the floor insulated? If it's not insulated with foil or paper faced insulation, I would bet money there is no vapor barrier between the basement and first floor.

The question is, do you want to isolate the basement from the rest of the home with a vapor barrier. That is going to depend on how you solve your humidity problem.

It would be nice to zone your basement, in which case I would install that vapor barrier. If you don't ever intend on doing that, then I probably would not. Another solution would be an air conditioner for the basement (mitsubishi makes some nice units) with it's own supplies/returns (thus a completely independent system- no exhange of air between the living space and basement). Impractical, I know, but it is an option.

Lastly, where is the condensate from the coil going? Do you have a condensate pump to pump it outside?

Again, I'm not an hvac guru, but I hope this information is helpful.

Tim

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post #32 of 57 Old 07-19-2004, 07:06 PM - Thread Starter
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Tim

I won't build unless I get the basement humidity under 50%. So it's not a question of how to build, but if to build. (actually how to build is a whole series of questions...)

The end townhouse was built in Dec 1993.

Assuming I'm successful, the current plan is
- Remove existing yellow insulation to where double wall stops near existing washer dryer
- Drylock paint the wall, including bricked window
- Mount 1" R7 foil based polyisocyanurate rigid insulation on upper portion of foundation wall ($40)
- Mount 1" semi-permeable EPS or XPS rigid insulation on lower portion of foundation wall, leaving 6" gap at bottom
Famous Mold PDF
Existing wall with yellow fiberglass under vapor barier
Edited picture showing what the wall might look like without yellow fiberglass
Relevant wall diagram from Famous Mold PDF
Lots of other Basement pictures

I'm not planning on doing anything vapor barierish with the ceiling, but acoustimat on the floor.

BTW, people put out a fair bit of humidity by breathing etc. Although I have my doubts if it's 28 liters per day. I'm fairly sure I don't drink that much.

Although I'm not zoning my basement, the current hvac plan includes motorized dampers to triple the airflow when the HT is in operation.

Quote:
where is the condensate from the coil going?
It feeds striaght down a 5' pipe into the sump/sewer/drain under the concrete slab. It flows very well. No pump is needed.


Here's the current status.

No change in humidity.

The evaporator coil was in fact tilted the wrong way and pooling water in its tray. This has been changed, and it now has a 1" slope towards the corner drain in two axis.

The new thermostat/humidistat was installed. It disables the furnace motherboard timed 7.5 minutes at stage 1 (68%cfm) then stage 2 (100cfm), and instead controls the fan speed itself. If the house temperature is more than 1 degree different then it runs the fan at 68%, and if it's more than 2 degrees different then it runs the fan at 100%. It does 'call for cooling' and 'call for dehumidification'. Call for dehumidification only works if the temperature is within 3 degrees of the preferred temperature setting. The lowest dehumidification setting it allows it to be set to is 45%.

The new thermostat/humidistat has a digital humidity guage which has values much lower than my portable steel humidity guages (3 of which match). I set the portable on top of the thermostat, and the thermostat said it was 45% RH, and the portable said 60% RH. As a test I wrapped the portable in a damp towel for 40 minutes, and when I took the towel off the portable said 98%.

Saturday, over 27 hours, it removed 28 liters of water, into a large plastic garbage bin. The basement was fairly constant at 65% at 23C. Outside started at 51% at 26C, then 61% at 25C, then 73% at 22C. The HRV was running at the time. The portable dehumidifier was off.

The HRV has been off the past day or so, and it's not made an obvious difference in humidity.

I went to two Home Depot's today looking for that 65pint portable, but now they say it'll be available on Wednesday morning (trucks arrive at night). This is returnable. Next thing up is a whole house dehumidifier, like the one Dennis described.

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post #33 of 57 Old 07-20-2004, 05:59 AM
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Those pictures helped.

I am still working on the premise of how to prevent the humidity from entering the home rather than how to remove it.

Looks like whoever built the home did a quality job, the unfaced insulation with the plastic is great.

I looked at the PDF image you attached. Looks like a well thought out system-- but remember, it is a _system_. I am not sure how well it will work if you don't have all the components. I guess what concerns me the most is the "drying to interior" portion at the bottom of the wall. Seems counter-intuitive.

Also notice the vapor barrier under the floor. I doubt you have this-- few peole do (the plastic makes the concrete take forever to cure, thus the concrete finishers are there forever trying to polish the slab). I've seen concrete companies actually remove plastic.

Given how well the basement walls are already insulated I would say that your heat exchanger is the culprit. I'm thinking it's introducing moist air into the home.

Maybe you could unplug it and somehow block the outside air intake/exhausts and see if that makes a difference.

Tim

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post #34 of 57 Old 07-20-2004, 01:59 PM
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BB I'm also thinking that the Air Exchanger is the source of your problem.

I know you did a test and turned it off but I think now that you have had your AC fine tuned you should turn it off, block the intake outside and give your system SEVERAL DAYS to see if it dries out the basement.


I think drilocking the walls is another low cost immediate thing I would try. When I did my basement I perceived an improvement.


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post #35 of 57 Old 07-20-2004, 04:04 PM - Thread Starter
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The HRV has been off since Saturday or so, and the humidity is still up there.

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post #36 of 57 Old 07-20-2004, 05:12 PM
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Quote:
Originally posted by BasementBob
The HRV has been off since Saturday or so, and the humidity is still up there.
Again, I'm not sure of the mechanics behind the HRV, but could air still be moving passively through the unit?

I would try blocking the exterior inlet/outlets. Cheaper than the other solutions :D

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post #37 of 57 Old 07-20-2004, 08:41 PM
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BB have you checked with your shared wall neighbors? Do they have the same levels of humidity? Are they using the basement as a swimming pool?

I don't own any meters to measure my humidity any recommendations?


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post #38 of 57 Old 07-21-2004, 04:35 AM
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I have a combination Digital Thermometer/Humidity guage that I got a Radio Shack.

http://www.radioshack.com/product.as...5Fid=63%2D1032

Seems to work ok...

Dwight
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post #39 of 57 Old 07-21-2004, 09:16 AM - Thread Starter
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BIGmouthinDC:
I have one neighbour, and he doesn't talk or come out much. For the first year he was here he didn't mow the grass (ever) or shovel the snow (ever) or pick up the assorted junk mail on his porch more than once a month. He now has a girlfriend who made him landscape the back yard (i.e. sod over the 4' tall weeds). He wasn't happy about it. The landscaping may have been coincident with a letter from the condominium property manager saying something like "This is your last notice. Pursuant to the condominum agreement you signed, if it's not done in a week we will hire professionals and bill you."
I don't think he ever goes into his basement. Also I believe his AC is broken (the next neighbour down said so).
It's a little ironic that I hear his stereo every other day, and it's me who's bonkers on soundproofing to keep from offending the neighbours.
The previous owner was much more affable.

The next neighbour down leaves their windows open all summer long, except when it rains.

Across the way (not attached to my building group, but only 20' away) there is a woman who's sick all the time (poisoned working in a chemical factory) and she keeps the AC set to 18C/64F or she goes to the hospital for a month. She has no humidity complaints and seemed to think her main floor is ok.


dwightrahl:
I'll see if I can find one at my local radio shack.


Right now, I'm off to another Home Depot in search of that portable dehumidifier I wanted to try.

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post #40 of 57 Old 07-21-2004, 12:50 PM
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By the way,
I noticed early several people mentioned a dehumidifier needing to drain into a sump or else dump the bucket.

Another option if you cannot or don't want to have the dehumidifier near a drain or don't have one is to get a condensate pump.

I got one from Lowes for around $40. You attach the pipe or hose from the dehumidifier to drain into a hole on the pump. The pump then is attached to small diameter clear plastic hose that you can run great lengths to either a drain or build in a drain to your existing plumbing (be sure to have a trap to avoid sewer gases in the old HT). The pump I have is only as loud as the dehumidifier and I used it to transport the drainage a good 20 feet to my drain, running the hose up the wall, through the ceiling and back down again. It will give you much more flexibility in placement of your dehumidifier, and just attaches to 110 vac. If I can install it, anyone can....
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post #41 of 57 Old 07-21-2004, 01:27 PM
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Bob:

What is the temperature and humidity on all of the floors, usually an unfinished basement is freezing in the summer? If the first floor has the following conditions 75F dry bulb and 50% RH it is holding 64 grains of moisture per pound of air. The basement could be at 70F dry bulb and 60 % RH and still be holding the same 64 grains of moisture per pound. If this is the case you will have to add heat to the basement to bring it back up to 75Fdb/50%.

What kind of metering device is on the A/C a Tx valve or a piston orifice? A Tx valve is the best as it ensures the evaporator is fully flooded with refrigerant at all times and conditions.

Here in the GTA the HRV will bring in moisture during the summer. Today the dry bulb temp is about 85F and the humidity is 66%, that corresponds to a dew point of 72F, this would mean the HRV would have to be exhausting air colder than 72F for it to be pulling any condensation out of the fresh air that it is bringing into your home. I doubt that you will be running the A/C that cold unplug and cap the HRV for now. I don't think I have ever seen an HRV remove moisture in the summer, come to think of it I have never seen the windows of my house sweat on the outside.

Bill
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post #42 of 57 Old 07-21-2004, 02:06 PM - Thread Starter
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empirebuilder:

I have conveniently located sump floor drain access. I don't think I'll need a condensate pump for it.

Home Depot received dehumidifiers last night, but not the one I wanted, just a bunch of small ones. None of the Home Depots in my area have it. Tomorrow I'll phone the guy who orders for Home Depot. The service desk said they couldn't order one (1) for me, but the professional desk could order a skid full of them if I wanted 48 of them in my basement.
Today I called a store called "The Maytag Store" which interestingly doesn't carry them. So I called Maytag's customer service, who routed me to Maytag's AC/Dehumidifier customer service, who didn't know either.

I'm beginning to feel incompetent. The relatively simple task of picking up a dehumidifier that is well known to work, bringing it back to my home, plugging it in and turning it on, seems to be beyond me.

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post #43 of 57 Old 07-21-2004, 02:32 PM - Thread Starter
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uxbridge

The basement is currently 22C at 62%.
The first floor is currently 23C at 59%
The top floor is currently 23C at 58%
Outside temperature is 32C in the shade, and 37C in the sun, at 70%.
The HRV has been unplugged for several days now.

The metering device is a LB-85663L, and the AC is a new Lennox HS29-024-3P. I believe that's a TXV, but I'm guessing based on the documentation (it's in the TXV section). I was told that it compares the refrigerant going in to the evaporator coil against the refrigerant coming out and adjusts the flow based on that (both by pressure and temperature?).

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post #44 of 57 Old 07-22-2004, 07:36 AM
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If I were in your shoes (a little soggy maybe) I'd do some on-line shopping and have UPS drop it off.


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post #45 of 57 Old 07-22-2004, 05:31 PM
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Bob:

Wow, thats fantastic air balancing for a house, I dont think I have ever seen such even air temperatures.

Yes it is a tx valve it should have a green sticker on top of the power element that says R-22.

My neighbour has a basement dehumidifier that has an exhaust vent to the outside. I beleive it is a Humidex unit.Humidex

I read the web page and it sounds like an exhaust fan that pulls from the basement floor and the air is made up from the leaking windows on the first and second floors. So try this, plugging in the HRV and remove the stale air duct from its connection on the furnace, and drop it too the floor (so the HRV pulls the stale air from the basement floor). Then seal off the return duct connection. Only do this if the furnace room is not partitioned from the rest of the basement, you don't want to cause a down draft in the water heater or the furnace.

Bill
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post #46 of 57 Old 07-22-2004, 06:01 PM - Thread Starter
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BIGmouthinDC

Oh this is just getting silly.

Quote:
If I were in your shoes (a little soggy maybe) I'd do some on-line shopping and have UPS drop it off
I did a google search and found a couple of internet dealers -- and the first three were SOLDOUT. (I only tried three.)

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post #47 of 57 Old 07-22-2004, 06:08 PM - Thread Starter
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uxbridge:
Quote:
Wow, thats fantastic air balancing for a house
All the vents on the top floor are wide open (both the floor and in the ducts).
Half of the vents in the main floor are closed.
All of the vents in the basement are closed -- so the cooling comes from convection from the steel main duct and the furnace plenum.
The furnace has plenty of CFM.
The computers are in the basement -- so there's very little upstairs that generates heat right now.

The old thermostat always said 23C (two integer digits, no decimal). The new one keeps fluctuating because it has a decimal digit -- from 22.1C to 23.9C. It's kind of neat to watch it rise a tenth of a degree every few seconds when the AC shuts off. You can actually predict when the AC will start.

The metering device has a green sticker that says R22, and a brown one that says R407C.

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post #48 of 57 Old 07-23-2004, 07:11 PM - Thread Starter
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A man with one watch knows precisely what time it is.
But a man with two watches never knows the correct time.

Well I went out and bought three digital humidity guages.

Radio Shack Indoor/Outdoor Thermometer with Hygrometer (the one that dwightrahl mentioned above, so we can compare)

Indoor Outdoor Thermometer by La Crosse Technology

Bionaire Humidity And Temperature Monitor (Bt400)

I've been doing some internet reading, and while one can buy humidity guages accurate to 0.3%, the digitals seem to be good to accuracy 5% to 7%, and the steel spring ones are occasionally as bad as 20% or even 30% depending on what you are reading. (Note 'resolution' does not equal 'accuracy'.)

Side by side I have 3 identical steel spring ones by Accu-Temp that I've been using up to this point all read 60%.
The Bionare says 45%
The RadioShack says 41%
The La Crosse says 40% (note the above link says it's good to 3%)
The Lennox SignatureStat says 39%.

I'm beginning to suspect I've been pursuing a untamed ornithoid without cause.

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post #49 of 57 Old 07-23-2004, 07:19 PM
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I bought a radio shack meter today and I'm at 49 percent in the basement and it's comfortable.


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post #50 of 57 Old 07-24-2004, 08:18 PM
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Same thing just happened to me. Cheap spring-based analog meter reads 62%, while the Radio Shack digital meter reads 38%. And in case anyone is looking for a digital hygrometer, the Radio Shack model is currently available in-store for 50% off for a final cost of $9.99 (print the coupon using the link on the product page ).
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post #51 of 57 Old 08-11-2004, 08:33 PM
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Great thread on basement humidity. I also had a cheap analog device that was showing humidity levels of 60-65%. Just went out today and got the radio shack digital one and it reads 53%. Unfortunately I have to run my dehumidifier 24/7 which really drives up the electric bill!

MBK
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post #52 of 57 Old 08-11-2004, 09:19 PM - Thread Starter
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I still haven't gotten a new dehumidifier. HD is perpetually sold out.

Instead of a digital or a spring based humidity meter, I
made a Psychrometer. The results were:
Dry 21.5C, Wet 15C, difference is 6C and a bit, so, according to
Relative Humidity Table that's 53%.
(102.44 kPa)

I used warm water to dampen the gauze, so the initial wet temperature was over 30C.

Picture of DIY Psychrometer after half an hour
Picture of dry thermeters after half an hour

RadioShack digital says 42%
La Cross digital says 42%
Bionaire digital says 46%
AccuTemp spring says 62%

So my current rule of thumb is to take whatever the Bionaire digital says, and add 5% for the 'true' humidity.

Note that when I run the dehumidifier, the digitals pick up the change in humidity fairly quickly (within an hour), but the spring based one's don't seem to notice it. Similarly when I stop the dehumidifier.
The digitals also notice a change in humidity when I run the air-to-air-exchanger.

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post #53 of 57 Old 06-23-2005, 11:44 PM - Thread Starter
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I bought a couple Maytag dehumidifiers. They seem to work well.
http://www.bobgolds.com/dehumidifier/home.htm

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post #54 of 57 Old 06-24-2005, 09:45 AM
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My radioshack digital has been 50 - 55% this week and I'm comfortable but have been thinking about plugging in my dehumidifier for the next few months.

What is your target zone?


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post #55 of 57 Old 06-24-2005, 11:24 AM
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I just bought a small dehumidifier online, the surround air 510. Rated sound level is 39dB. It keeps my basement room (12x18) to ~45% RH (right now the RH in the rest of the basement is almost 80%)

Its fairly quiet - too loud to be completely unnoticable in a room, but quiet enough to be almost unnoticable. I'm going to try to make a 'hush-box' like box around it, I think it'll do the job nicely.

Still considering whole-basement dehumification but it really depends for me if cutting holes in the ceiling for the vents is going to make a significant difference in sound isolation, after double drywalling plus green gluing it all.

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post #56 of 57 Old 06-24-2005, 01:36 PM - Thread Starter
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BIGmouthinDC:
Quote:
What is your target zone?
35% to 45% on those meters -- preferably 38% to 42% in the basement, and 35% to 38% in the upper floors.

kromkamp:
My two portables are effectively doing the whole house. I keep the upstairs door to the basement open, and the furnace/AC draws air from the basement too.

Quote:
Rated sound level is 39dB.
Yea right. Published sound ratings. :) Use a sound level meter. My projector is rated at 35dB according to it's manual, but it's something like 65dB(c-slow) at 1m according to my meter.

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post #57 of 57 Old 06-24-2005, 02:51 PM
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I'm going to have to deal with humidity soon myself as I build my home theatre. Something tells me I'm going to have some serious issues.

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