Our home is ~4 years old and very tight. Heating is by hot water baseboard and we have an HRV but no AC. My problem is that for a period of time in the summer, the house is uncomfortable. At night breezes usually make it tolerable for sleeping, however, in the afternoon it can get quite uncomfortable (humid) particularly on the main floor where my office is located…
I’d like to know if anyone has a suggestion on how to solve this problem installing central air or a window shaker. I’ve tried a portable de-humidifier but it kicks out a lot of heat. Can I de-humidify the incoming HRV air and circulate that?
Thanks
Replies
Telling us where you're located would go a long way towards getting you some useful answers.
Filling out your profile with at least some basic information would also be appreciated.
Well, I took that advice and updated my profile. Thanks for the reply on the split system. Any ideas regarding inline dehumidifiers?
I know less about inline dehumidifiers than I know about women.(-:But hopefully someone will jump in who can help you.BTW - We have several Canadians here..
Got a 3 bedroom split here in Montreal and use two window units to do the whole house.one's a 7000 BTU and the other is a 12000 BTU.
Since you probably don't have the duct work needed to support central AC, you might look into some of the new ductless AC systems made by Mitsubishi and others.
They consist of an outdoor compressor/condenser unit that supplies refrigerant to indoor-mounted "cassettes", which are fan-powered units that mount on the wall or ceiling. The cassettes have the evaporative coil inside, and the fan blows room air across the evap. coil to cool the room.
Some of the ductless systems allow you to mount 2 or 3 cassettes throughout the house. Each one must have the copper lines (supply and return) run to them, plus a drain line to handle the condensation as it takes out humidity. And, of course, power to run the blower.
Edited 4/6/2009 3:57 pm ET by rdesigns
I'm going to inject a different point of view ... a paradigm shift (to some) aka thinking outside the box.
Why is the focus always ... what A/C is going to 'fix' this problem? A pic would be helpfull w/ identifying captions.
I suspect your office is on the west side and you maybe have some west facing and/or otherwise unprotected windows. I'm one that tends to focus first on getting rid of as much thermal load as possible BEFORE you consider A/C options.
Options for e.g. unprotected windows ... mirrored and/or tinted glass with a low low-e value/coating. Landscaping ... yes!. Possibly architectural elements (eaves for south windows (which should be clear, not tinted). Blinds/drapes do little for solar gain as the sun has already passed through the glass ... too late.
In your neck of the woods, I'd focus on non high tech options that don't increase energy use.
Interesting comments. Our windows are top of the line, argon filled and 2 lowE films. We have wooden blinds in place which keeps the place dark if we wanted that. Nevertheless, after a week or so of high temp/high humidity the place is uncomfortable. Any other ideas?
IMO ... just because you have 'top of the line windows' doesn't mean they are doing the best that they could be doing for your situation. You could have double low-e coatings and argon w/ a SHGC of e.g. 0.65 ... They control conductive thermal loads well, but could be poor at solar gain. If they are on the west and aren't tinted and/or mirrored, they aren't doing nearly as well as they could. Your blinds do little ... regardless of the darkness of the room. Once the sun goes through the glass ... the blinds are like closing the gate after the horse is out of the corral. Yeah, no direct solar gain in the room, but the Btus have passed through the glass and converted from UV to IR ... and you don't simply bat them back out through the glass like a ping pong ball. While blinds and shades are better than nothing ... they aren't much better than nothing. Controlling the sun before it goes through the glass is the best way to handle solar loads.
I used two types of Heat Mirror (HM) glass in a house I owned once. HM has a U-value of around 0.25 using a low-e coated mylar film suspended between the double glazed units. On the south side, I did a passive solar sunspace with an eave protecting the glass from the high summer sun and letting in the winter sun. This glass had a relatively high SHGC ... on the west side, however, I used the same HM glass ... except due to the strong western exposure, I ordered the glass tinted and mirrored resulting in a SHGC of down around 0.20. Even though I had relatively little glass on the west, it was a MAJOR problem. The tinting/mirror had a huge positive impact on the comfort. Same high quality glazing, but widely different SHGC.
Edited 4/7/2009 9:29 pm ET by Clewless1
Have you looked into the attic for insulation and adequate ventilation? If the attic is not properly ventilated, it traps a lot of heat. Adding a ridge vent, or even a power vent, might help.
I don't think you'll get the results you want with simply dehumidifying the air. You need to dump heat outside the house, which means some sort of A/C.
Choices are limitless.... window mounted, split systems, heat pumps... etc. depending on what you want to spend.
If the budget is limited, I'd consider a window unit on either the North or East side of the house.
Scott.
I'm like BossHog. At least that part about in line dehumidifiers.
In my part of the world, (Texas) A/C is the means by which the air is cooled and at the same time and same process is dehumidified. It's like you can't have one without the other. Simply stated, they go hand in hand.
By what other means/process can one dehumidify such a large volume of air such as a room or a house?
You're right about the fact that A/C lowers humidity when moisture condenses as it passes through the chiller. But the OP said that he tried a dehumidifier as a means of making the house more comfortable. In my experience this doesn't work; the dehumidifier will lower the humidity somewhat, but it actually causes a net rise in temperature because of the heat generated by the electric motors (one for the fan, one for the compressor).Scott.
I guess you somewhat answered my question. Even the room dehumidifiers that he had placed in his room had a condenser/evaporator/fan that removed the moisture from the air. Same a an A/C unit. Just on a much smaller scale. Is that what you are saying?
As to trying to cool his space by dehumidification, I assume he was working off the theory that by lowering the humidity, his body's natural A/C unit would kick in. Cool humid air does not feel as cool as equally cool dry air. I think there is term for this, but I can't think of it off hand.
I don't think he said what the level of humidity he was dealing with, so it's is hard to know if that was his only problem. What was the actual temperature and what was the actual humidity. If he is listening, maybe he can enlighten everyone.
If he's got the money, I think the advice from a previous post, (Re: split A/C system (single exterior condenser with individual room evaporators) would be good solution if his problem is humidy, heat, or both.
>>>I guess you somewhat answered my question. Even the room dehumidifiers that he had placed in his room had a condenser/evaporator/fan that removed the moisture from the air. Same a an A/C unit. Just on a much smaller scale. Is that what you are saying?The problem with dehumidifiers is that they take heat out of the interior air (to condense airborne moisture), only to dump it right back into the interior air. They do not dump heat outside like an AC unit. Moreover, because the machine has two motors running to do all this work, it actually adds (a small amount) of heat to the interior air.>>>As to trying to cool his space by dehumidification, I assume he was working off the theory that by lowering the humidity, his body's natural A/C unit would kick in. Cool humid air does not feel as cool as equally cool dry air. I think there is term for this, but I can't think of it off hand.Yes, I believe that is what he might have been thinking, but my experience is that dehumidifiers don't make enough of a difference for this to occur.>>>If he's got the money, I think the advice from a previous post, (Re: split A/C system (single exterior condenser with individual room evaporators) would be good solution if his problem is humidy, heat, or both.I agree.Scott.
A "dehumidifier" means a very specific type of equipment in the HVAC world. Unlike an air conditioner whose design is to cool, and dehumidification is a wonderful "side effect", a dehumidifier is intended to remove moisture without cooling. In a great deal of the lower 48, dehumidifers are common, especially in areas that include basements. A self contained refrigeration cycle that first passes the air over the evaporator coil, cooling the air and removing moisture, and then the condesnser coil addin heat back in to the air stream. This is a common unit used almost universally in hotel pool rooms around the country.
More complex systems have the ability to reject heat to the outdoors via a refrigerant condenser, and basically function as an air conditioner or a dehumidifier. Compressor are indoors.
Thanks. That's what if figured, but didn't know for sure. Most of the time you see them around here is when some poor devil is trying to dryout after a flood or something.
If you are looking for cool, you crank the old A/C down some more and sweat it later when you get the electric bill.
As some have pointed out, there are many options.
You need to decide which is more important to you: do want the the most effective/efficient system, the least expensive system of the easiest to install. You can pick one, in a specifc case, you get two.
The most effective system will be a central air handler-based system with a complete distribution system of supply and return duct work. These system also tend to be the most efficient, but not always.
Details such as basement access and number of floors would be important.
The easiest and cheapest (and least effective or efficient) is the thru wall ac (TWAC) or "window" unit.
Given your location, TWACs where necessary and used only when necessary are a reasonable approach. If you need to cool for more than a week or two, I would suggest a permanent system approach. (TWACs in my opinion are temporary equipment to be removed after the cooling season) Some mentally challenged Yankees have chosen this as their permanent solution, not a wise choice.
How often and for how long do need to cool your house? How many people are there and how long (all day, part day, etc)?
You can put a coil in the HRV supply to cool that air. This would be an advanced DIY project beyond your abilities (I am assuming that you cannot size refrigerant components, and have never brazed refrigerant lines) and most contractors would either pass this up or hose it up. Not a good option for you.
Another option is to install PTAC Packaged Terminal Air Conditioner. For under $1,000 you can get a GE 14,000 btu one. They are very common to the motel/hotel industry. They take up a space 16" X 42" so most are located under a window that is 4' wide.
The motel industry is very frugal, I am sure they would find a better option if there was one. Mini-splits are better but can easily cost 4X more. Check into a motel that has then, turn it on and see if its for you. It may cost more if you have someone else install a wall header and a 220 volt circuit. They also come as heat pumps too.
Thanks all for the common sense approaches. I have decided to buy a beer fridge and put it beside my desk...
>>>I have decided to buy a beer fridge and put it beside my desk...Now THAT's the spirit!Scott.
Hi. Don't dismiss the guy who said to try adequate ventilation of youor roof by adding ridge vents and such.
My house was unbearable in the summer (in Philadelphia suburbs) and you could literally feel the heat at each and every rafter behind the drywall ceiling upstairs due to improper insulation between those rafters. The previous owner had stuffed each and every bay with Fiberglass batts effectively blocking the air flow from the soffitt eaves to the ridge vent.
I unfortunately found this out after I had installed central A/C (which works great but unhappy about the electric bill)-one of my stupid blunders. I still hope to someday remedy that air flow situation uip there to help the new AC unit feel less of a need to cool things down but I have yet to figure out how to easily get those batts out of those rafter bays (I live in a Cape Cod style house with kneewalls upstairs and those slanted ceilings above them).
God luck