Help with hot/cold, upstairs/downstairs issue.

[jmlcolorado]

I know this isn't garage related, but I know of no other forum then GJ with the expertise I'm looking for.

Heres the rundown. I live in a 1700 sq ft split level home with gas forced air and AC.
I've been in the house for a year now and am really having a hard time keeping the temps equal (or even remotely close to equal) between the upstairs and downstairs.
Both areas are of equal size, only difference is the basement in 1/2 embedded in soils.
If I keep the AC on during the summer at 75*, it is usually 10* cooler in the lower level. I've closed the vents in the ceiling of the lower level with no noticeable change in temps.
The AC struggles to keep the upstairs cool if we have it off for a day. It will run all night to get it back down to temp, which makes the lower level even cooler.

Heating is the same way. The lower level is always cooler. I know some of that is natural for the style of home but I gotta get it to at least be reasonable.

I don't want to keep the vents closed in the basement as that restricts required air flow for the coils. I've had them freeze up a couple times this summer.

I'm a very hands on person and I'm thinking of building some "deflectors" to install inside the supply dusts in the basement. This would allow me to fully open the lower level vents but allow the air to skip over the tops of the registers. I would keep the deflectors "closed" during cooling so the air passes over the top of the registers in the summer, then I could turn the deflector to catch some of the warm air for hearing during the winters. The deflector would be fully adjustable so if the basement (god forbid) was getting too warm during heating, I cold close it a bit more at each register to block a little more air.

The basement ceiling registers are all 10x6" in size. All the upstairs registers are baseboard style. I also think the baseboard registers are restricting the air too much allowing back pressure to be relieved in the lower level. I'd like to change the upstairs registers to 10x6 floor registers too eventually to hopefully help balance the air movement.

Attic insulation is also another problem, which would likely help solve most of this I'm sure, as the insulation is only 3" thick and original to the 1970 build. The exterior of the house has vinyl siding, soffit and fascia installed as well and I'm also thinking the vinyl over the soffit vents is restricting the attic venting. Each of these items will also be inspected and corrected within the next few months.

Attached are a couple photos. One id a crude drawing of what im thinking. The second is my house to show grade. The back yard is the same as the front.

So am I on the right track of thinking here? You think these deflectors would aid me at all?

 

[JimL]

So am I on the right track of thinking here? You think these deflectors would aid me at all?

No.


A house like that to heat and cool properly and evenly needs zoned ductwork. In other words, separate supply trunk for the upstairs, and one for the down stairs. Thermostat upstairs and one down stairs. Electric dampers in the trunk line to open close each level. Probably be about impossible to do now but without seeing the duct system I can't be sure.

Best thing you can probably do now is run the fan in the furnace continuously even when it isn't heating or cooling. Help keep the air circulated and mixed.

insulate the attic will help as well.

 

[jmlcolorado]

No.


A house like that to heat and cool properly and evenly needs zoned ductwork. In other words, separate supply trunk for the upstairs, and one for the down stairs. Thermostat upstairs and one down stairs. Electric dampers in the trunk line to open close each level. Probably be about impossible to do now but without seeing the duct system I can't be sure.

Best thing you can probably do now is run the fan in the furnace continuously even when it isn't heating or cooling. Help keep the air circulated and mixed.

insulate the attic will help as well.

This would be similar to an electronic damper system except I would be doing it manualy.

The trunks are as easy as they can get. 1 supply and 1 return trunk both running the entire legnth of the house. The lower level registers have the least resistance to dump air, since they come directly out of the main supply trunk, so I feel like most of the air goes out them before ever reaching the main floor registers (which are legged off the main trunk with 6" duct.
By closing all the lower level registers and leaving the main floor ones wide open, wouldn't that effectively act as a 2 zone system where the lower level gets minimal air and the main floor get the majority?

 

[Big-Foot]

Subscribing because I have the same darned problem...

I also have an air exchanger system that I have not got a clue how it operates.. My house might be a bit bigger at 2800 SF, but that includes the almost fully finished basement..

 

[philjafo]

If you only have three inchs of insulation in the attic I would bet thats your biggest problem, easiest fix too, just blow in more just be sure you don't block the soffit vents when you do. After the insulation problem is fixed then look into zone systems, arzel is a company that makes vacuum operated dampers to go in each 6 inch pipe, that way you don't have to replace or add trunk lines. Something else you might look into is the size of your furnace and ac, although it sounds more like not enough insulation upstairs. Running the fan continually can help, but if the duct work isn't correct, as in proper amount of supply and return air it won't help much. Oh and air filter, if you have the 1inch thick ones pleated expensive filters are restrictive, either get the super cheap hog hair ones or a 4 or 5 inch thick media air cleaner. Hope this helps good luck this sort of problem can be difficult and expensive to fix, mostly because something wasn't done right the first time.

 

[JimL]

If you only have three inchs of insulation in the attic I would bet thats your biggest problem, easiest fix too, just blow in more just be sure you don't block the soffit vents when you do. After the insulation problem is fixed then look into zone systems, arzel is a company that makes vacuum operated dampers to go in each 6 inch pipe, that way you don't have to replace or add trunk lines. Something else you might look into is the size of your furnace and ac, although it sounds more like not enough insulation upstairs. Running the fan continually can help, but if the duct work isn't correct, as in proper amount of supply and return air it won't help much. Oh and air filter, if you have the 1inch thick ones pleated expensive filters are restrictive, either get the super cheap hog hair ones or a 4 or 5 inch thick media air cleaner. Hope this helps good luck this sort of problem can be difficult and expensive to fix, mostly because something wasn't done right the first time.

Cheap pleated 1" filters are best if you don't have a media filter. The 3M filtrete filters are way too restrictive.


If you can close off the downstairs registers, give it a go. How many registers do you have on the main level and how big is the a/c? Model # will work. My house is zoned and the basement on certain days is still a degree cooler than the main level. Nature of the beast...

 

[pseudorealityx]

By closing all the lower level registers and leaving the main floor ones wide open, wouldn't that effectively act as a 2 zone system where the lower level gets minimal air and the main floor get the majority?

Yes.

If you fix the insulation in the attic, it'll help to equalize the temperatures between, as well as quicken that response time to cool the house back down if you leave it off while out of town or whatnot.

Also change the filter per what the other guys are saying. 1" cheap pleated, every 3 months, or sooner if you've got pets. That should help solve the freezing coil issue as well.

There are some 'averaging' thermostats out there where you can mount a remote sensor upstairs. Unit will run based on an average temperature between up and down, and you'll reduce the difference between the two a bit more. Also, as stated, keep the unit turned on to keep air circulating.

 

[BD1]

Do you have returns in each room ? That makes a huge difference. A lot of two stories have only a single common return for upstairs for cost reasons.
As stated, keep fan running all the time.

 

[jmlcolorado]

If you only have three inchs of insulation in the attic I would bet thats your biggest problem, easiest fix too, just blow in more just be sure you don't block the soffit vents when you do. After the insulation problem is fixed then look into zone systems, arzel is a company that makes vacuum operated dampers to go in each 6 inch pipe, that way you don't have to replace or add trunk lines. Something else you might look into is the size of your furnace and ac, although it sounds more like not enough insulation upstairs. Running the fan continually can help, but if the duct work isn't correct, as in proper amount of supply and return air it won't help much. Oh and air filter, if you have the 1inch thick ones pleated expensive filters are restrictive, either get the super cheap hog hair ones or a 4 or 5 inch thick media air cleaner. Hope this helps good luck this sort of problem can be difficult and expensive to fix, mostly because something wasn't done right the first time.

It sure would be nice to retrofit dampers in each register and let the system do its own thing.

I will try the fan on thing for sure. Will the AC condenser cycle on/off normally with the fan in operation at all times?

Cheap pleated 1" filters are best if you don't have a media filter. The 3M filtrete filters are way too restrictive.


If you can close off the downstairs registers, give it a go. How many registers do you have on the main level and how big is the a/c? Model # will work. My house is zoned and the basement on certain days is still a degree cooler than the main level. Nature of the beast...

I have all the basement registers cloced currently. There are 6 registers downstairs. 90% of them are directly installed in the trunk line. Im not sure of the AC or furnace model but ill check into that tonight. I think its a 1.5 ton condenser.

Ill take a degree or two......or three or four difference between levels all day long! That would be a TON difference then what it is now. Right now, i cant even get the lady or the kids to clean their mess down there cause "its too cold!"

Yes.

If you fix the insulation in the attic, it'll help to equalize the temperatures between, as well as quicken that response time to cool the house back down if you leave it off while out of town or whatnot.

Also change the filter per what the other guys are saying. 1" cheap pleated, every 3 months, or sooner if you've got pets. That should help solve the freezing coil issue as well.

There are some 'averaging' thermostats out there where you can mount a remote sensor upstairs. Unit will run based on an average temperature between up and down, and you'll reduce the difference between the two a bit more. Also, as stated, keep the unit turned on to keep air circulating.

I will definitely try running the fan at all times.

Do you have returns in each room ? That makes a huge difference. A lot of two stories have only a single common return for upstairs for cost reasons.
As stated, keep fan running all the time.

I have 2 returns on the main floor and only 1 return in the lower level. The lower level return is installed right on the trunk line next to the furnace so i imagine that it has quite a bit of suction.

 

[LouG]

FWIW, we have a traditional two-story with non-zoned HVAC. Not a very smart way to design the home but we bought it this way and I'm not in the position to drop $4k-$6 on a redesign. What I did do was have a attic-fan installed and it now lets me keep the thermostat at 76, whereas before it was constantly set at 70-72. YMMV, but I would definitely say that it was some of the best money I've ever spent. I also keep the fan at the ON setting vs. AUTO whenever the outside temp is at or above 90, I finf this helps a lot as well.

 

[jmlcolorado]

FWIW, we have a traditional two-story with non-zoned HVAC. Not a very smart way to design the home but we bought it this way and I'm not in the position to drop $4k-$6 on a redesign. What I did do was have a attic-fan installed and it now lets me keep the thermostat at 76, whereas before it was constantly set at 70-72. YMMV, but I would definitely say that it was some of the best money I've ever spent. I also keep the fan at the ON setting vs. AUTO whenever the outside temp is at or above 90, I finf this helps a lot as well.

Thanks for the input!
Im pretty sure i have a lack of proper attic venting as well. Im waiting for a solid day that has an extreme temp so i can break out the thermo camera and see what has leaks and whats hot. Plus its a fun toy to play with

 

[pseudorealityx]

I will try the fan on thing for sure. Will the AC condenser cycle on/off normally with the fan in operation at all times?

Yes. The condenser will only cycle with a call for heat/cool from the thermostat.

 

[Jackfre]

You can mess with the ductwork but what you need to do is read the static pressure in each duct. Check you static from supply to return. YOu can use a digital or U-tube manometer. I used to use a Dwyer 100-5 for this as it read in .01 levels. that was a long time ago and I now use digital manometers for these type things. Put the probe into a 1/4" hole you drill at the boot, perpendicular to the air flow. As well, check it at each take-off from the main. It sounds like a duct problem but numbers will help you see where that problem is. Most furnaces are designed with a design external static of .5". that means if you put the probe into the air stream on the S/R plenum just off the unit the nega and pos pressures shouldn't exceed the .5" total. Find the restriction working backwards from the unit.

Also, understand that the DOE has published reports that indicate older duct systems can loose as much as 18-42% of their air flow through duct leakage. Duct seal and metal tape can help on those ducts that you can get to. You are a Diy guy, so perhaps you can repair your own duct system, but having an understanding of precisely what is going on will be a big help. Airnor, I think it is make hoods to actually measure your air flow at your individual registers.

 

[6t7gto]

http://www.energyvanguard.com/blog-...Set-Your-Air-Conditioner-Thermostat-Like-This

 

[pseudorealityx]

http://www.energyvanguard.com/blog-...Set-Your-Air-Conditioner-Thermostat-Like-This

I have to admire his logic...Don't run the fan continuously because:

1) you PROBABLY have a poorly designed air conditioning system.

2) you PROBABLY have poorly designed duct work.

 

[wornoutoldman]

FWIW, we have a traditional two-story with non-zoned HVAC. Not a very smart way to design the home but we bought it this way and I'm not in the position to drop $4k-$6 on a redesign. What I did do was have a attic-fan installed and it now lets me keep the thermostat at 76, whereas before it was constantly set at 70-72. YMMV, but I would definitely say that it was some of the best money I've ever spent. I also keep the fan at the ON setting vs. AUTO whenever the outside temp is at or above 90, I finf this helps a lot as well.

I had the same problem when I lived in a raised ranch. My neighbor an HVAC supplier suggested leaving the fan ON 24/7. He explained that by running the fan at all times the air is constantly blended and equalized throughout the house.

 

[philjafo]

I have to admire his logic...Don't run the fan continuously because:

1) you PROBABLY have a poorly designed air conditioning system.

2) you PROBABLY have poorly designed duct work.

Running the fan continuously helps poorly designed ducting, not leaking ducting. Yes there is extra cost to run the fan continuously, but there are extra costs with fixing the ducting also.
At 1.5 tons ac and not enough insulation in the attic low run time and humidity are not your issues.
Without doing load calculations for your area on your house (not just guessing with the square footage but a real actual heat gain and loss calc) determining the correct size for your house is impossible, but just guessing you probably should have 2.5 or 3 tons.

 

[pseudorealityx]

Running the fan continuously helps poorly designed ducting, not leaking ducting. Yes there is extra cost to run the fan continuously, but there are extra costs with fixing the ducting also.
At 1.5 tons ac and not enough insulation in the attic low run time and humidity are not your issues.
Without doing load calculations for your area on your house (not just guessing with the square footage but a real actual heat gain and loss calc) determining the correct size for your house is impossible, but just guessing you probably should have 2.5 or 3 tons.

Yeah, I was being sarcastic.

 

[chevelle67]

I had the same problem after I finished the lower level. Both levels together are 3650 sq.ft. my system is a 2.5 ton. I cut in 3 registers off the supply trunk and 1 return grill off the return. It's important to have balancing dampers in the supplies, not just an adjustable register but actual damper. I balanced it as close at possible with a balancing hood and it helped greatly. When it gets real cold out (below zero) it is slightly colder on the lower level. After trying numerous things to fix it I found the easiest way to handle the occasional cold snap was to use one of those infrared cabinet heaters with the quartz bulbs. I set it for 2 degrees under the main floor tstat. I put a data logger on it and found it woul run three to four times in 24 hrs with an accumulated run time of 1.5 to 2 hrs. In the summer the basement is always 2-3 degrees cooler than upstairs but we prefer it that way and use it to our advantage when it's really hot out.

 

[jmlcolorado]

Well I've been runing the fan for a few days to see how that affects the temps. It's helping drastically!
The temps between each floor have almost equalized which is great! This will help out for now till I can get insulation installed in the attic.

 

[philjafo]

Sorry psuedorealityx, sarcasm doesn't always translate to text real good. And that energy vanguard guy p****d me off by saying " well meaning technicians" like none of us know what we are talking about. He does have a point about the humidity thing, there is a very small amount of water that stays in the drain pan, but most of the water drains out through the drain hose so you would never be able to add as much humidity as the ac takes out. If dehumidification is the goal then you need a dehumidifier. One other benefit to running the fan is cleaner air, the filter can only do its job when air is passing through it.