Should I heat unused basement ?

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  #1  
Old 10-29-16, 08:33 AM
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Should I heat unused basement ?

The old question pops up again! I have been the past few years out of paranoia of possible freezing pipes. Basically half my pipes run inside a drywalled ceiling(grrr) in the finished side of the basement and the other half in the unfinished side. This year im finally going to insulate those pipes!

Anyways we never use the finish basement. Its basically a storage room for kids stuff but it has a huge duct going to it. Basically the biggest airflow in the whole house (single story l ranch) and then the rest goes up through the attic and down through the ceiling. If I close the basement damper the rest increases significantly in airflow.

Im really just curious if its worth it though to be closing that damper or should I have it fully open. Obviously I would love to have it warmer in the rooms we actually use but am I risking those pipes? Am I gaining anything by actually heating that finished part since its a drywalled ceiling, and not actually going into the unfinished part? Also considering since warm air rises and my heat comes from the ceiling is it counter productive?

Curious on the thoughts as I live in western MA so we do get some very very cold winters!

Thanks!
 
  #2  
Old 10-29-16, 12:42 PM
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All your basement needs to be is above 32 degrees to keep pipes from freezing. I would close it so enough that you can maintain that temp.
 
  #3  
Old 10-29-16, 01:06 PM
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Not a bad idea. For some reason I read 50 was the threshold for copper piping which didn't really make sense to me. Maybe I misread!
 
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Old 10-29-16, 01:29 PM
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You probably read correctly. 50 degrees F. is considered a good thermostat set point to prevent piping in the walls, floors or basements of an otherwise properly insulated house from freezing under normal circumstances when the house is vacant. This allows for the temperature difference on the unheated side of drywall and flooring. It generally does NOT allow for holes in the siding or into a crawlspace that allows winter winds to blow through. Simply using the water periodically will in most cases prevent the pipes from freezing unless they are exposed to the winter winds.

There IS, however, a good reason not to seal off the airflow from this duct and that has to do with the furnace's required airflow and the temperature rise (difference between inlet air temperature and outlet air temperature) across the heat exchanger. Too high a temperature rise will cause the heat exchanger to overheat and this can lead to cracking which can, in turn, allow carbon monoxide to be circulated into the living areas of the house. There are some other comfort issues as well.
 
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Old 10-29-16, 02:34 PM
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Ahh. So maybe adjusting it so some comes out like previously suggested is the best idea. Find a happy medium so to speak?
 
  #6  
Old 10-29-16, 03:23 PM
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Yes, have at least some airflow through the duct. It would be best to also measure the temperature rise across the furnace heat exchanger as well. The best way would entail using a dual-input digital thermometer but a single probe-type kitchen oven thermometer could be used IF you can find a way to get it into the air stream on each side of the exchanger.

The simplest, and least accurate, method would be to measure the temperature at the return air grille and the closest to the furnace supply air register and calculate the difference.

The furnace rating plate, generally located inside the cabinet, will specify both the minimum and maximum differential temperature allowed.
 
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Old 10-29-16, 05:28 PM
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Ok thanks! I will definitely be looking into that.

Kind of funny but today made me realize I have two unused fireplaces (just for wood burning if I decided not gas) that I installed glass covers over when I bought the house 7 or 8 years ago. Never thought much of it until today when I took my ir thermometer and read the temperature difference. Then opened the glass and the 40 degree air came gushing in (flue is closed)

Guess I could be losing a lot of heating due to that eh? Ill never use the fireplace nor will my wife. Im going to insulate temporarily for the winter (not sure how yet) then in the spring probably have it professionally done. Have one on the main floor and in the basement. Now im really curious if thats why the living room always feels so cold, and why my portable thermometer always reads a bunch colder in that room!
 
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Old 10-31-16, 08:15 AM
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Id heat it! Than warm air is going to go up stairs so you aren't wasting it.
 
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Old 11-01-16, 05:28 AM
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It is closed off (closed door due to toddler) if that makes a difference and has to penetrate a drywalled basement ceiling then a hardwood floor with carpet over it if that also makes any difference!

Thanks!
 
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Old 11-02-16, 07:45 AM
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Its going to heat the floor. Id leave it
 
  #11  
Old 11-22-16, 04:49 AM
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That's been my thought so far. Seems to be making no difference and temp drops off quickly in basement compared to upstairs. Hmmm
 
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Old 11-22-16, 05:54 AM
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It would be helpful to know what part of the world the OP is located in; I can assume somewhere in the Northern US or in Canada . . . . but why guess ?
 
  #13  
Old 11-22-16, 09:36 AM
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He is in western MA.
When oil prices went above $5 a gallon we were trying to help some of the old homes survive the winters. Many wanted to turn off the heat to upstairs and close those doors. The problem that resulted was mold on the drywall. In your case, it isn't just the pipes that you need to protect, but you need to keep all cold surfaces well above the dew point. The dew point is the temperature at which condensation can occur.

A better place to invest your time and effort would be to air seal the house to foundation and then insulate the foundation and rim joist cavity. Then the heat loss down there will be reduced to an affordable level with a 50 room temp, however you create that and no mold or pipe concerns.

Bud
 
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Old 11-22-16, 02:20 PM
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The natural temp of a basement is around 55 due to the ground temp assuming there is no uninsulated walls to the outside (walk out typ of basement). No pipes will freeze, no need to heat! Close the outlets, let it chill and the rest of the house will benifit from the additional air flow!
 
  #15  
Old 11-24-16, 02:36 PM
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I did have it insulated around the foundation on a home energy audit. If I remember correctly from just randomly checking the lowest ive ever seen the unfinished side get is 51 degrees (no heat registers in the unfinished side, finished only)

So ultimately I guess heating the unused finished side is sort of a waste anyways since the unfinished side was never heated to begin with eh?
 
  #16  
Old 11-25-16, 02:03 PM
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Well did I ever find a darn doozy today! I was going to insulate the casement window in basement (unfinished side) and as im on the ladder I realized the guys who did the home energy audit missed insulating the tops. I could see out into my yard. Seriously. I could see grass. Could stick my fingers right through the window case. Cant see it unless you go on a ladder either. Holy crap! I honestly never noticed this as I never thought anything could be done this stupidly. Well I guess im the dumb one.

I double checked everything and everything else is sealed in the basement and very well done, not sure how they missed the tops of all of these 3 windows. Each window is 31" long, so thats a lot of air (explains my mouse issue too)

Yikes...........
 
  #17  
Old 11-25-16, 02:50 PM
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You're not the only one. Mine was essentially the same but they had tried to fill it with fiberglass insulation, which the mice quickly removed. It was my search for entry points that led to my discovery of my view of the back yard. Fill it with something solid and caulk it air tight.

BTW, set a couple of traps at each window to catch the ones living inside as they search for their old entrance.

I find it hard to believe that the rest of the house to foundation was properly air sealed if they overlooked these three windows.

Bud
 
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Old 11-25-16, 06:17 PM
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Well I ended up checking it out and it was good. Only guess would be the stuff I had im the way made it difficult for them to get to it so they took the lazy way out.

Still debating the heating the basement debate though since the biggest return supply vent is in the finished basement. Ugh.
 
  #19  
Old 12-20-16, 01:44 PM
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So I closed the vents. Basement is around 52 (unfinished) 55ish finished with some extremely cold temperatures lately. -10 windchill the other day and extremely cold temperatures to follow. Just paranoid about frozen pipes even though im assuming at that temperature and the sealing ive done I should hopefully be good haha

My other question though is am I potentially causing a major issue because the largest return vent is in the finished basement and its now being unheated? Didn't know if that could cause some major major issues.

If I open the basement vent my finished basement heats up to 70 fairly fast but we don't use it and honestly I don't feel the heat on the floors but the decrease in airflow upstairs stinks and the furnace turns on a lot more. Im just at a lost and don't really have the extra money to have an hvac person come in and check everything out sadly.

Thanks all!
 
  #20  
Old 12-20-16, 03:10 PM
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It won't cause any major issues but the furnace is pulling back 55ish air. This is going to lower the supply temp going to the rest of the house.
 
  #21  
Old 12-20-16, 03:21 PM
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Ahh that explains why when I measured the temperature coming out it dropped about 8 degrees.

Hmm thinking it could be a fair trade off though as it feels so much warmer with the basement closed.
 
  #22  
Old 12-20-16, 04:41 PM
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A couple of points.
1. Your basement is losing a ton of heat, especially the unfinished side. The reason it holds in the 50's is because of heat generated by the ducts and the furnace. If well insulated the temp down there would rise nicely without the need for a register.
2. With no supply ducts and just a return you are depressurizing the basement forcing your furnace to compete for combustion air with that return. That's unless you have a sealed combustion system, PVC exhaust and intake instead of a chimney.

Bud
 
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Old 12-20-16, 05:52 PM
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On number 2 yes I believe sealed pvc as there are two pvc lines that run from the furnace directly outside and nothing goes to a chimney.

So im guessing its ok? Sorry if this is horribly ignorant as im clueless with hvac stuff but attempting to get a little knowledge. Heck im about to seal all the openings on the ducts hopefully after xmas. Lots of them!
 
  #24  
Old 12-20-16, 06:30 PM
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Don't worry about being new to these things, there are topics here where I don't have a clue, but know where to go and ask if needed. And that is the point, don't hesitate to ask.

A sealed combustion system is good, so no risk there of backdrafting. A gas hot water heater can have the same combustion air concerns if naturally drafted. How is your hot water heated?

Bud
 
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Old 12-20-16, 06:34 PM
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Gas power vented so im assuming no backdraft concerns there since its the same theory?
 
  #26  
Old 12-20-16, 08:32 PM
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Heating basement

If the basement is insulated my view is since heat rises then putting some heat in the basement is not being wasted at all, it warms the ceiling which happens to be your first FLOOR. My basement is insulated and I do have some heat going into it from the furnace, as a result my porcellain tile floors are nice and comfortable to walk on even barefoot here in Iowa winters.

If you don't have heat in the basement then the floor above is not being warmed and will be cooler than it would otherwise be.

On the same idea, the claim that pilot lights on water heat somehow "waste" gas is bs, that little flame is heating the bottom of the tank of water, that's not wasted at all- it's preventing the main burner from even coming on at all during "standby", it certainly has been the case with my 30 gal water heater in this house I've lived the last 18 years in, if I don't use more than a gallon of straight hot water the main burner never comes on even in the winter because that little flame keeps the water hot enough.
If I had that pilotless garbage the main burner would be constantly cycling on and off 24/7 and wasting gas not to mention the electronics that run that would go bad and have to be replaced.
 

Last edited by wolff2; 12-20-16 at 08:48 PM.
  #27  
Old 12-20-16, 08:43 PM
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if that makes a difference and has to penetrate a drywalled basement ceiling then a hardwood floor with carpet over it if that also makes any difference!
Very little, drywall has an R value of about 0.45, not even half an R, hardwood flooring 3/4" thick has about 0.91 value, for double flooring plus that sheetrock you can figure on R3, carpet with a rubber pad, about R2, so you might have R5 worth there which is only about twice what double insulated glass windows have, so it would be worth either heating the basement a little, doesn't have to be 70 but more than the 50 mentioned would be good, or insulate between the joists under the floor because R5 is pretty sad.
 
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Old 12-30-16, 07:37 PM
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So ran some tests I guess you could say. The finished side doesn't seem to drop below 58 unheated. But doesn't seem to get above 64 heated. I know im losing a lot of heat, wether it be to it rising to the first floor, poor insulation (which im sure of behind the walls), and into the unfinished side.

Thats where im stuck at though in my cost/comfort level and whats in my head. It seems as though the heat comes on the same amount of cycles but there is definitely a run time difference due to the air flow difference. With the air turned off in the basement it runs around 7 minutes (blower time) and with air turned on in basement around 13 minutes (blower time.) I feel as though its more comfortable without heating the basement but it could just be in my head. Obviously running the furnace longer costs more, but I haven't been home a lot lately to really gauge furnace cycle time. From what I have gathered it seems pretty much the same though.

Now heres what im wondering if its just in my head, floors don't feel warmer and I don't feel the hot air blasting down on me anymore because the air comes out of the ceiling and the air flow is much lower. But I guess in the same theory im just pouring that air into the attic and never actually feeling it. Same theory though I guess applies to basement losing it elsewhere I suppose too.

But here is one thing I did notice. I used to keep the basement damper like a quarter open. A little heat came out but not enough to raise anything. But after closing it about 2 weeks in I noticed the air coming out of the vents smelt like urine almost or stale any time the air came on. Just funky hard to explain (don't forget the biggest return vent is in the basement) kind of smell. That's when I started my fully open the basement vent test. Within a day or two the smell went away. Also noticed my ducts sound much quieter (especially the returns) with the basement open. And yes all my returns are always open and cant be closed haha.

One final question, since I have a whole house humidifier will pumping the moist humid air into the much cooler basement cause those pipe issues im oh so worried about?

Sorry about my wall of text. Figured id blast it out all at once! Thanks and happy new years!!
 
  #29  
Old 12-31-16, 05:45 AM
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I just made notes as I read through so may not have answered everything.

The off cycle is determined by the heat loss in the house that reduces the air temp, thus triggering another on cycle. The run time is determined by the amount of heat delivered to the main living area where that thermostat is located and of course the simultaneous heat loss.

I don't understand this: "I don't feel the hot air blasting down on me anymore because the air comes out of the ceiling and the air flow is much lower. But I guess in the same theory im just pouring that air into the attic and never actually feeling it." You never want air pouring into the attic and any supply or return ducts up there need to be air sealed and super insulated.

Having a return in the basement without an equal amount of supply results in the furnace pulling air from sources, like floor drains, through the concrete, and down any vents when power venting is not on.

You should always be monitoring your humidity levels. Cooler temps will usually result in higher readings. Too high and exterior colder surfaces may drop below the condensation temp.

Bud
 
  #30  
Old 12-31-16, 09:08 AM
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Well with the basement vent closed the air pressure coming through the vents actually comes out very good. You can feel it coming down say if your sitting on the couch, and spread throughout the room. If you have the basement vent open, you cant feel the air coming out the vents hardly at all. The air flow difference is that great. It does take a while to lose the heat in the living area. My main area is the living room, where we spend most of our time. Its the chimney and all the windows thats are the main culprits. Both of which Im currently working to alleviate. I have made big strides in that gain. But do to my own health issues im extremely sensitive to cold.

As for the attic comment, it probably didnt make sense. I was going off the heat rises so I figured it would just find its way into the attic. Which has a lot of new blown in insulation and is actually very well insulated. So I guess that was just a weird comment I probably shouldnt of really made haha.

The thing with the return in the basement is that its the same exact height as the supply in the basement. And about 10 feet away from it perpendicularly as well. Same height, same size. So its almost like hmm, is it blowing out of the heating supply, just to be sucked into return?!

As for the power vent, that im not so sure of to be honest. My furnace has pvc piping running to the outside of my house (out of the siding into the backyard, two pvc pipes, or at least they look like pvc) so im not sure if that applies to my situation?

My humidity levels are around 43% in my house.

Thanks, hopefully that clears up what I was trying to say a little haha.
 
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Old 01-02-17, 09:00 AM
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So hopefully the final question. The original owners of house had cut vent holes in the basement ceiling and living room floor underneath bay window and put vents on them. Two registers to be exact. They don't connect to hvac system but neighbor told me they did it to allow basement fireplace heat to eventually rise up.

I have both of these vents closed upstairs but as we know that doesn't really stop anything. Think insulating them with some 2" foam board cut to size for now would make a dramatic difference? Both are right behind the reclining couch we always sit on! The thermometer I have over here is 4 degrees cooler than if I put in any other part of the room. Starting to think maybe that could really be part of the issue and I just never thought of it until now to be honest.

Also I about half opened the basement damper for the heat. I get decent airflow down there and decent airflow upstairs. As of right now it seems to be a happy medium but I still need to run some more time on it as it's been rather warm the past few days.

Thanks again!
 
 

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