Johnny Rock
Footballguy
To me something's wrong when you need to turn off your air exchanger completely.
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Whole-House Dehumidifier, anyone have one? (1 Viewer)
- Thread starter TxBuckeye
- Start date
I hear you. As I said, Chief's guy says that the system is bringing in the outside air, running it through the filter (good) and across the coils (bad) then venting it through the house. With the house being so air tight, he said the coils are never dry, they are always wet. Therefore, the air is picking up the moisture from the coils and bringing it in the house. Right now, it could be that it is just running to much in fresh air mode because the weather is mild and the AC hardly comes on. If the ventialtion system is trying to bring in air 30 or 40 minutes every hour because of the way it is set, it is just pumping moisture in, and there's not enough AC to dry it out. So, I switched it off until the guy comes out and dials it way back. Then I may try it again and see what happens.
STEADYMOBBIN 22
Footballguy
The last thing I would do us run the system unattended. I'm almost speechless at how criminally dumb that suggestion is.
I'd get yet another opinion.
I'd get yet another opinion.
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Why is that? His point was, when you are home, doors are getting opened and closed, windows, etc. Air is getting in just naturally by your actions. When you leave on vacation, you usually turn the AC up, and it isn't going to run much. So you turn the whole house ventilation system on so it will run occasionally and keep your air a little fresher.
Had the guy dial it down by the way. Now when it runs, it only runs about 4m30s. That is opposed to the other day when it ran for like 45 minutes straight. He told me, I was his second call of the morning on those systems. He said they get at least one per week where people complain it runs to much and they come dial it down. I guess it is set by the builder and the AC company that makes the system and they just set them to run way to much.
Just talked to my neighbor and wow, I don't feel so bad now. His indoor humidity has been running from the 60%s in to the 70%s! I opened my windows again today and got it down to 36% or so. Was loving it. Closed the windows and went to the grocery store. Still sitting under 40%. So making process. But apparently this builder builds really air tight houses!
Johnny Rock
Footballguy
Air tight houses are the reason we need air exchangers. But they have you turning yours off. If the air coming in through the windows brought the humidity down then the air exchanger should do the same.
I have closed cell sprayfoam insulation and my house is very tight. Having a very tight house is not the reason your humidity is high. Something is designed wrong, hooked up wrong, built wrong, programmed wrong or the HVAC is defective.
Did they do a load calculation? http://www.neo.ne.gov/codesconf/pdf/HVACStandards.pdf
As I said earlier, I don't know that you would call this an air exchanger. It's just a ventilation setup. It simply opens a valve to ductwork that pulls air straight in from outside and kicks on the blower fan. The fan pulls the air in, draws it through the filter, then across the coils and in to the house. Every AC person I have talked to has said that the air running across the coils is the issue. The coils are wet. They never dry out. Systems don't work that way. So the process of the air coming acros the coils picks up the moisture from them and brings it in to the house. Hence, rising humidity. Air coming in through the window obviously doesn't run across any wet coils, therefore it comes in dryer.
Edit to add, I'm not saying there is nothing else at play here. There may be. But the ventialtion system bringing moisture in makes perfect sense now that I have seen the system and how it functions. I don't see how it COULDN'T be bringing moisture in.
Edit to add, I'm not saying there is nothing else at play here. There may be. But the ventialtion system bringing moisture in makes perfect sense now that I have seen the system and how it functions. I don't see how it COULDN'T be bringing moisture in.
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ChiefD
Footballguy
Pretty much.
If a fresh air system is set up properly, it's attached to an ERV unit that will treat the air BEFORE it enters your ductwork. It sounds like yours doesn't have the ERV system, so the advice you're getting makes perfect sense to me.
Your guy mentioned the ERV system as an alternative, but didn't feel it would be worth the expense. He was one that basically said "I'd just turn it off." By "your guy", I mean the tech from that company. I didn't actually get the owner of course. I also forgot to give them my Angie's List coupon. Blew $35.
High humidity in tight houses
In Houston, a tight, well insulated house is more likely to have problems with high indoor humidity than an older leaky house. In a tight home, an air conditioner doesn’t run anywhere near as often as in a leaky home, especially during the swing seasons (spring and fall). If the air conditioner is rarely on, there are fewer opportunities for the HVAC equipment to dehumidify the interior air. Of course, adding mechanical ventilation only makes the situation worse.
The solution to this problem is not an ERV. The solution is a stand-alone dehumidifier.
Two researchers from the Lawrence Berkeley National Laboratory, Iain Walker and Max Sherman, wrote a paper, “Humidity Implications for Meeting Residential Ventilation Requirements,”that includes a discussion of the effects of residential ventilation in Houston. They wrote, “The use of an ERV did not change the humidity distribution in a hot, humid climate compared to a continuous exhaust system.”
Elaborating on this finding in an e-mail, Sherman wrote, “It is true our results show little value in ERVs in hot, humid climates, but it is important to understand why. … Almost all hot, humid climates have hours when it is dryer outside than inside and then ERVs actually make the moisture problem worse. The net effect is that ERVs are about a wash for humidity control in those climates. … On the other hand, if there were independent humidity control (such as … a stand-alone dehumidifier) then ERVs pay big dividends in terms of energy savings in hot, humid climates. To say it another way, the whole idea of an ERV is not to change the indoor humidity (and temperature) with ventilation. So if the indoor humidity is good already, the ERV reduces energy costs. If it is bad already, the ERV is not likely to help.”
Here's the whole article. IN a nutshell, it says ventilation of any type will NOT lower humidity, that isn't what it does. Only a dehumidifier will do that.
http://www.greenbuildingadvisor.com/blogs/dept/musings/hrv-or-erv
In Houston, a tight, well insulated house is more likely to have problems with high indoor humidity than an older leaky house. In a tight home, an air conditioner doesn’t run anywhere near as often as in a leaky home, especially during the swing seasons (spring and fall). If the air conditioner is rarely on, there are fewer opportunities for the HVAC equipment to dehumidify the interior air. Of course, adding mechanical ventilation only makes the situation worse.
The solution to this problem is not an ERV. The solution is a stand-alone dehumidifier.
Two researchers from the Lawrence Berkeley National Laboratory, Iain Walker and Max Sherman, wrote a paper, “Humidity Implications for Meeting Residential Ventilation Requirements,”that includes a discussion of the effects of residential ventilation in Houston. They wrote, “The use of an ERV did not change the humidity distribution in a hot, humid climate compared to a continuous exhaust system.”
Elaborating on this finding in an e-mail, Sherman wrote, “It is true our results show little value in ERVs in hot, humid climates, but it is important to understand why. … Almost all hot, humid climates have hours when it is dryer outside than inside and then ERVs actually make the moisture problem worse. The net effect is that ERVs are about a wash for humidity control in those climates. … On the other hand, if there were independent humidity control (such as … a stand-alone dehumidifier) then ERVs pay big dividends in terms of energy savings in hot, humid climates. To say it another way, the whole idea of an ERV is not to change the indoor humidity (and temperature) with ventilation. So if the indoor humidity is good already, the ERV reduces energy costs. If it is bad already, the ERV is not likely to help.”
Here's the whole article. IN a nutshell, it says ventilation of any type will NOT lower humidity, that isn't what it does. Only a dehumidifier will do that.
http://www.greenbuildingadvisor.com/blogs/dept/musings/hrv-or-erv
Johnny Rock
Footballguy
I hear ya. You didn't say what type of wall and ceiling insulation and windows you have.
A Manual J HVAC load calculation will tell you if the system and ducts are sized right. Ask them if they ran the calc and see what they say. I'm betting on blank stares and "You don't need to do that." Many contractors are too lazy, computer deficient or think they're too smart to do it but there are a ton of factors that go into what size unit you need, cold air return sizes, etc. Most experienced guys go by a "ballpark" tonnage figure based on square footage and their experience.
If your house is tight you obviously need less cooling which you know. My guess is they oversized the unit because they didn't do a calc. I'm not trying to be a jerk and I see where you're coming from, but you shouldn't need to open your windows in a new home to keep the humidity bearable, even in Houston.
A Manual J HVAC load calculation will tell you if the system and ducts are sized right. Ask them if they ran the calc and see what they say. I'm betting on blank stares and "You don't need to do that." Many contractors are too lazy, computer deficient or think they're too smart to do it but there are a ton of factors that go into what size unit you need, cold air return sizes, etc. Most experienced guys go by a "ballpark" tonnage figure based on square footage and their experience.
If your house is tight you obviously need less cooling which you know. My guess is they oversized the unit because they didn't do a calc. I'm not trying to be a jerk and I see where you're coming from, but you shouldn't need to open your windows in a new home to keep the humidity bearable, even in Houston.
STEADYMOBBIN 22
Footballguy
So there is a design flaw in your system or it was installed improperly.
I mean , am I reading something wrong here? It sounds like my GB paid good money and contractors went through the process of installing something that doesn't actually work. In fact , he paid to have a system installed that actually poses a threat.
Your neighbor is screwed btw. His humidity has been >70% for what, months now?
ETA- If there is a infant/ child or elderly persons I g on your neighbors home I'd strongly urge then to contact a licensed industrial hygienist to take air samples. Just have them test the lower level first.
I'm not trying to sound overly dramatic here but if this is going on on two homes, Its likely going on throughout the neighborhood. How many houses in your complex?
You just might want to be first in line to get this resolved before the builder goes under cause he's getting back charged for mold remediations and HVAC modifications.
I mean , am I reading something wrong here? It sounds like my GB paid good money and contractors went through the process of installing something that doesn't actually work. In fact , he paid to have a system installed that actually poses a threat.
Your neighbor is screwed btw. His humidity has been >70% for what, months now?
ETA- If there is a infant/ child or elderly persons I g on your neighbors home I'd strongly urge then to contact a licensed industrial hygienist to take air samples. Just have them test the lower level first.
I'm not trying to sound overly dramatic here but if this is going on on two homes, Its likely going on throughout the neighborhood. How many houses in your complex?
You just might want to be first in line to get this resolved before the builder goes under cause he's getting back charged for mold remediations and HVAC modifications.
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Meritage Homes is all over the country I believe. They are a pretty large builder. They are all over San Antonio, that's for sure.
Johnny, I have sprayed insulation everywhere, even in the attic. Double paned windows. Admittedly, the AC doesn't need to run a lot. I come home, and my interior is still only like 72 or 73 downstairs with the AC set at 77 while I am away. So bills will be low. Humidity downstairs today sitting about 47% in the living room, so in the wheelhouse for what they say is comfortable in the summer, 40-50%.
Steady, if you read that article I linked too, you'll see that these newer tight houses, humidity is just going to be an issue. The real answer, I hate to say, is a dehumidifier if I want to ventilate the house. As the article said, there is no ventilation system that will reduce humidity. It will only freshen the air and almost certainly bring in some moisture.
The more I read, the more I realize I am going to have to get used to higher humidity in the home. Oddly enough, I now know, when I move in to my final retirement home, I will NOT want an energy star high efficiency house. I'd rather have it a bit dryer and pay a little higher AC bill.
Johnny, I have sprayed insulation everywhere, even in the attic. Double paned windows. Admittedly, the AC doesn't need to run a lot. I come home, and my interior is still only like 72 or 73 downstairs with the AC set at 77 while I am away. So bills will be low. Humidity downstairs today sitting about 47% in the living room, so in the wheelhouse for what they say is comfortable in the summer, 40-50%.
Steady, if you read that article I linked too, you'll see that these newer tight houses, humidity is just going to be an issue. The real answer, I hate to say, is a dehumidifier if I want to ventilate the house. As the article said, there is no ventilation system that will reduce humidity. It will only freshen the air and almost certainly bring in some moisture.
The more I read, the more I realize I am going to have to get used to higher humidity in the home. Oddly enough, I now know, when I move in to my final retirement home, I will NOT want an energy star high efficiency house. I'd rather have it a bit dryer and pay a little higher AC bill.
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I've pretty much decided against the whole-house dehumidifier. The AC guy Chief put me in touch with said most people use those to get the humidity down to about 48%. Mine is pretty much there now just turning the fresh air ventilation off. Plus, my wife has pretty much refused to have a dehumidifier downstairs, which is where I think we need it. So I think I'll likely be living with what I got for now.
El Floppo
Footballguy
This post is hidden because you have chosen to ignore posts by Otis. View it anyway?El Floppo said:
Please don't circumvent my blockage, mmmkay? I don't need my thread getting Otis'd. If you've seen the Kate Upton thread, his interest, and post count, can reach epidemic proportions.
