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HVAC question

1K views 15 replies 8 participants last post by  Techsniffer 
#1 ·
My question is only slightly woodworking related.

My shop is in my basement. Even though my ductwork runs through the basement, there are no ducts in it to serve the basement. I'm considering putting a small supply vent in one end of the basement and a similarly sized return at the opposite end. I would find a way to add a filter on the return vent. The ducts for the first floor run off of the same main using 5" tubes to feed floor vents. If I add a small supply and return, will they end up dumping all the cold air into the basement? I'm not necessarily looking to cool the basement to the same temperature as the first floor, just enough to take the dankness out of it. Any HVAC wizards here?
 
#4 ·
I've used a dehumidifier in past years and put the discharge hose through the rear wall of the basement. Now I've got a nice patio out there and I don't want to have the discharge water making a stain. Emptying regularly is a bit of a hassle. That's why I'm looking for another more automatic solution.
 
#5 ·
That's why I'm looking for another more automatic solution.
I have to calculate and design the HVAC system for the timber frames other architecture I work with. I design typically outside the realm of standard architecture as our projects typically fall within the "natural building" arena of clients, as such, they want natural systems. Nevertheless, there are some things (in the remodel side of it) that you can't really work around. Dank basements are often one of them and the only real way to dry them out is with more heat than folks would not like during certain times of the year...and...dehumidifiers...

So in your case, a dehumidifying unit is really going to be the most cost effective and most likely efficient manner to achieve your goals. The discharge can be hidden in a small natural sump area you dig out with shovel, fill with stone and perhaps place a potted plant on top of this which should deal with your staining challenge...Hope that helps?

j
 
#6 ·
The dehumidifier is good for the dankiness IF that's moisture your talking about.....BUT they put off heat most of the time.

DO NOT tie into your house system DUE TO the dust issue it WILL create!!!!...NOT MAYBE....it WILL. That will introduce dust into the ductwork, HVAC unit, house....it WILL damage the unit. IF you don't think it will just pull your filter out now and see how much regular dust has already bypassed/leaked through already in just the house recirculating.

They make small apartment style room specific units....yes it will require more cleaning due to wooddust BUT it will preserve your house unit. There is several types of fine filters for these units BUT REQUIRE more changing.
 
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#8 ·
What kind of heat do you have? The reason I am asking is if it is gas or oil and has barometric burners, you shouldn't put any return in the basement if the furnace is located there. Because someday somebody will decide to shut off the supply ducts to the basement that you are thinking about installing, then the basement will get in a negative pressure and it could suck the flue gases back into the house

You could tap into the existing pipe or just go straight to the plenum which would be better, that way you could control it better and you probably need to get a dehumidifier on top of that. At high relative humidity you can feel sweaty even in the 60's your sweat doesn't evaporate nearly as fast so your internal T'stat kicks in high gear dumping more sweat

They do make filters that will keep the equipment clean in any environment, I have a 5 ton unit in my shop with 20x25x2 pleated filters Merv 13, and it keeps the coil clean. Don't buy filters in the big box stores, one of the worst is 3M Filtreat filters, they have ruined more compressors than anything, the static pressure drop just across the filter is more than the whole systems static design is. To put it lay mans terms those filters restrict more air than the dirtiest of filters, they should be outlawed. They copied the pleated filter design but it is only 1 inch thick, if they were 4-6 inches thick they would work but you need so much more filter area because of the nature of the filter, and then they get high priced

I retired from HVAC/R, figured about 40 years was enough, have repaired units form 1/8 beer box to 17,500 hp centrifugals chit now I even hate to work on mine
 
#9 ·
Catpower you made some good statements/points. YES I will agree with you IF a system is installed 100% correct then it can be good......UNFORTUNATELY in this area and I'm sure others....the good knowledged installers in HVAC are fair and few while the others, they forget they're also supposed to install correctly......as I also stated the quickest way to see if a system is sealed is remove the filter....sadly most have lots of bypassed dust as most filters don't seal to the metal or the grill hasn't been sealed around correctly.

Thanks for the point on the small pleated filters.....they've damaged numerous units.

I still stand in to do only a dedicated unit for the basement.....save the headaches of future possible problems with a shared system. JMO. Clean house Happy WIFE!!!
 
#10 ·
I actually usually turn the system off when I'm working in the shop for just the reasons you guys pointed out.

I was just looking for an easy way to keep it dried out in the summer and a little warm in the winter.

The barometric thing is a great catch. Mine is oil fired for heat. I know that I wouldn't close the supply without closing the return, but someone else might.

Now to figure out how to get my dehumidifier to drain!
 
#11 ·
As one stated above ....use a condensation pump for HVAC systems. Hose it into it and it pumps it out via hose to designated area...some areas allow this to be in waste line plumbing while others mandatory outside....Remember IF outside it needs to be away from house or it will seep back in.
 
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#12 ·
The discharge for the dehumidifier is just a couple of inches off the floor. The lowest I can get the inlet on the condensation pump is 4-5 inches off the floor. It would be nice if I could find a condensation pump that would fit inside the tank on the dehumidifier.
 
#14 ·
As Steve stated/questioned.....they don't have to sit on the floor.....I have 2 different locations that run 24/7 both mounted on stands above the floor for reasons....one was for direct flow of recieving moving air and the other approx 16" to drain 30' via a hose across a concrete floor and outside.

They make dehumidifiers that have built in pumps...they're getting more poplar for the issue mentioned of no drain to go to.
 
#16 ·
Another potential solution would be to buy a freestanding A/C and Dehumidifier unit, it's like a standard window AC unit but many have built in dehumidifiers that can exhaust out of a window/hole (like your dryer does) this will condition the air and offer a dehumidifier to boot.

I had one in a basement apartment that was often dank/humid (old foundation) and it worked great and I very rarely had to actually drain the water (it usually gets rid of the excess humidity via the vent, but in really humid areas it might need to be drained more often, your mileage may vary. This would also help to make for a more stable and comfortable wood shop, which also has the added benefit of having wood warp less while acclimating to your shop.

This would also keep your current hvac system sealed from the dust you create.

Here is a link to an example (they can vary in price and features quiet widely, so read up on what you want first and make sure what you buy fits your needs)
https://smile.amazon.com/Costway-Po...ds=portable+air+conditioner+with+dehumidifier
 
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