cold air return locations question

[corvairbob]

i have a new modular home that came with the cold air returns in the living room and both bedrooms. the walls are 9' high and the returns are 2' from the ceiling. we live in muskegon mi. so we do not see 9 months of needed a/c and we do not have central air. and i notice just before the furnace starts, i can feel a cold draft and then about 5 minutes the furnace starts up. so i'm kind of debating with the home builder company heckaman that they may need to be lowered. they said they do not need to be lowered as that is how new homes are now being built. but i still think they should be lowered as in the old house we never had that cold draft just before the furnace started, but we were in the upper section of that raised rance. the lower was a family room a bedroom a bath and utility room.

so can anyone tell me if it may be me or will it be better to move the cold returns down the wall to the floor level. the returns go into the attic as the house is now a ranch and has on lower living space anymore so the builder put the returns in the top of the wall and open into the attic.

now it may be the attic being cold and as the rooms start to cool that cold air is settling down into the rooms and we feel it. and my theory is if the returns are down at the floor level that cold air will be trapped and will not draft as the registers are at the floor also. and the CS is 95 or more sealed and has 4 heat vents down there as well.

so does anyone have a theory on this? should i leave it or lower them? thanks

 

[Reach4]

and i notice just before the furnace starts, i can feel a cold draft and then about 5 minutes the furnace starts up. so i'm kind of debating with the home builder company heckaman that they may need to be lowered.

I wonder if the furnace is set up properly. Classically a gas furnace's blower is controlled by bonnet temperature. So the thermostat controls the gas. Therefore there is a delay before the blower turns on.

Another possibility is to have a switch to run the blower continuously.

 

[Sponsor]

 

[corvairbob]

the furnace is 2 years old what is going on is not the furnace as we can hear the draft inducer start up and then about 15 seconds later the furnace start. the draft is kind of like someone opens a door just a bit to let the dog out, and we feel it for maybe 5 minutes and then the furnace starts. i'm kind of leaning on as it starts getting close to the furnace to start, the cold air is settling down in the room and we feel it as it drifts downward, until it gets to the t-stat and then that gets the clod and starts the furnace.. keep in mind the cold air returns not only are high on the wall but they are in the cold attic. i went up there a few weeks ago and took a IR reading and the wood all around the area was 20 deg f and the cold air ducts were 25 deg f so that 5 deg difference for a few 15' runs is quite a temperature differential. thanks

 

[Reach4]

If you are measuring 20°F on an inside surface, you really need some insulation and/or sealing.

https://www.washtenawblowerdoorservices.com/ says

As of February 2016, all new homes, alterations, and additions are required to have a blower-door test performed. This is done to make sure there's no major flaws in the thermal envelope, and to ensure the efficiency of the home.
Michigan Energy Code N1102.4.1.2 and N1101.3.1 (additions, alterations,renovations, or repairs). Chapter 11 pg 447 of the 2015 Michigan Residential Code book.

 

[corvairbob]

i'm measuring the 20 deg on the surfaces in the attic, not the inside if i'm understanding your reply correctly. i took the IR up and shot some of the surfaces around the attic. i then shot the duct work as you see in the photo. the structure read 20 deg f and then the ductwork had 25 deg f on that surface. those ducts look like they are insulated but because i have that 5 deg f difference that is telling me i'm losing heat at those ducts. today i took some batt insulation i had up there and wrapped a few of the runs but not all of them got covered. i had that batt insulation laying on the marriage wall up there and when i pulled it up to start covering as much as i could with what i had to work with i had moisture on the batts. that is telling me i'm losing heat thru that marriage wall at the ceiling a s well

 

[corvairbob]

this is the cold air ducting thye put in the attic. and today i put some batts over and around some of the runs as much as i had here with me. the builder is trying to get the house mfg to provice more insulation. i measured the fill and it is 12" and in muskegon mi i should have maybe 20 to 24" for the r 50 to r 60 the code said i need.

 

[Reach4]

i then shot the duct work as you see in the photo. the structure read 20 deg f and then the ductwork had 25 deg f on that surface.

Ahh... that is better. The colder on the outside of the duct insulation, the better.

this is the cold air ducting thye put in the attic. and today i put some batts over and around some of the runs as much as i had here with me. the builder is trying to get the house mfg to provice more insulation. i measured the fill and it is 12" and in muskegon mi i should have maybe 20 to 24" for the r 50 to r 60 the code said i need.

I wish you luck on that. If they blow in insulation, make sure you run any attic wiring first.... Ethernet, antenna, etc. Also that makes the attic pretty useless for storage.

 

[corvairbob]

reach4. thanks i have all the wires running in the CS. the mfg ran the power thru the attic but if i ever need to add outlets as i have done already i can go thru the CS my CS is from the old house with cement floors so i use a setup creeper to scoot round down there.

an as you said i have ran the antenna wire in the attic already . i do not plan to use that space for storage as i have an attached garage and it i did need any storage i can use that it is not insulated.

i have 12" up there now for r30 but for muskegon mi the code says r50 to r60 so i'm trying to get the mfg to come out and put more in the attic to meet the code they should have done. the old house originally had 4" i added 6" of bats and then later put 6" more of batts and then 2 years ago i the vets gave me a new furnace and the code said i needed more insulation so they blew in another 12" so that made 12" of fiberglass and 16" of blown in. i found all that out when the ceiling crashed down on my stuff after they put the fire out that was in the attic burning the trusses. the living space did not see fire but lots of foamy water and smoke but for the utility room. i was in there as it burned and saw the smoke going up the stairs. no smoke made it to the utility room so i got the furnace and water heater out and my security system. thanks

 

[Fitter30]

Brand and complete model number. Usually in burn compartment on either side panel. Tic a pic with your phone is easier tring to read the numbers . Return grills can you look into the wall cavity from the floor?

 

[corvairbob]

i did a stud finder yesterday and it has fire stops in the walls. i think that is just now code.

but i do not believe the furnace is the issue the furnace is a tempstar n95esn o6o1714a1 s# a223164066

 

[Fitter30]

Insulation doesn't stop the transfer of heat just slows it down.
Post 9 re-read about the return grills
Volume damper are normally placed at the supply take offs.
Your other post by extending the time the blower is delayed might help
ductworks.net/product/round-pipe-dampers/ copy and paste

 

[corvairbob]

yes i know the extra insulation will not keep all the heat in or a match would heat a home. but like i said having the 5 deg differential at one point on the cold air returns ducting in the attic and multiply that by the 4 10' to 15' runs means i'm losing quite a bit of heat to them. i used up the batt insulation i had on hand just to add some. but i know adding more is going to help because when i added more to the old house everytime the gas bill dropped.

 

[RetiredInGueydan]

What is the R-Value of the cold air return flex ducting? That should be at least R-8 for an unconditioned attic.

 

[corvairbob]

yes your correct it has r-8 on it but r-8 is quite thin when the rest of the attic needs to be r-50 to r-60 per code. anyway i foamed the marriage wall and put some batt insulation over those ducts and it seems a bit better, not as good as before but better. i'm going to have them get it to r-60 just to make sure it is what i had before. thanks.

 

[corvairbob]

ok since i first posted the question i have added r19 rolled insulation to the cold air return ducting in the attic. and that draft i felt about 10 minutes before the furnace started is gone.

and i lowered the bed room return vent to the floor and that room now has no draft that i can feel all night long. so this week the living room gets lowered. that was my question that went a bit off track.

also i'm going to add 2 filtered floor vents in the floor in the hall and living room next to the walls like the plumbed vets now are. these will let me get that air the installer vented in the sealed up CS i was down in the CS the other day and it was hot and those vents did not put out much air so if i open the floor to the CS i will get that air those 4 vents are there to deliver.