Sealing Floor Registers

[Bolson32]

Hey All,

My house was built in 1987 and the ductwork is mostly original. We do have a new air handler, furnace and AC in the last few years. Our master bedroom is on the 2nd floor and it's honestly brutal up there in the summer so I'm trying my best to think of little tweaks that will help it be more tolerable up there this summer.

Wondering if we have any HVAC pros in here that can advise me on whether it's worth it to seal my ductwork at the floor registers. I recently replaced the registers and I noticed they are ill fitting with massive gaps and I'm sure there's a ton of air being dumped between the floor joists on both the main floor and the upstairs. Would it help if I sealed them all up, and maybe closed down some vents on the main floor? For example last night I had to turn the thermostat down to 68 just to get it to about 76 upstairs. It was frigid on the main floor and hotter than hell upstairs.

We live in Minnesota and have a finished basement if that matters.

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[The Cobbler]

I helped a friend years back and we ran a new duct inside closet up to the master bedroom to get more air flow for A/C . put a damper on it to close it off in winter as the heat was fine, just not enough flow for comfortable A/C .

 

[Bolson32]

I helped a friend years back and we ran a new duct inside closet up to the master bedroom to get more air flow for A/C . put a damper on it to close it off in winter as the heat was fine, just not enough flow for comfortable A/C .

We do only have 1 vent in the bedroom but we have one in the closet and 1 in the bathroom and they send enough air out to the bedroom I think.

Running another duct would be a nightmare. I'd probably just get a mini-split for up there if it came to that.

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[karoc]

Guessing you have one system for two story house and the furnace is down in basement?
Couple things come to mind, is the coil clean and not restricting airflow? And if you have a return upstairs and downstairs, is it the same chase or two individual chases. Check to see if they are sucking in air from attic space or from uncondition space.
How many sq ft is your house and what size system do you have?

 

[Bolson32]

Guessing you have one system for two story house and the furnace is down in basement?
Couple things come to mind, is the coil clean and not restricting airflow? And if you have a return upstairs and downstairs, is it the same chase or two individual chases. Check to see if they are sucking in air from attic space or from uncondition space.
How many sq ft is your house and what size system do you have?

1: Yep, 2 story house, furnace in basement.

2: Coil is clean, tiny bit of fuzz towards the top of the unit outside but I can't imagine it to be an issue. The air feels cold.

3: there is one return upstairs, 2 on the main floor and one in the basement. The main floors and upstairs are on the same chase, I'm pretty sure.

4: 2880 sq ft total. Not sure on unit sizing. Is that somewhere on the outside unit?

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[yeldogt]

How many rooms up there ?

How large is the room?

 

[Bolson32]

How many rooms up there ?

How large is the room?

3 bedrooms, 2 bathrooms and a closet. ~800sq ft 2nd floor. Master is probably 250 of it.

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[larry4406]

In our new construction homes we mastic seal the floor register boot flange to the subfloor to prevent leakage into the floor system.

 

[TractorJeff]

All my first Floor Ducts are buried in Concrete. When We moved here the Floor Registers were EXTREMELY Ill fitting! I put a Rubber Tube on a Caulk Nozzle and with a Mirror to guide by, pumped the all the Gaps full of Caulk. Now if you close a Register in Winter you do not feel the Floor heat up around it from the Air Leakage.
You could try this?

 

[Jim greengo]

Are your cold air returns uncovered?

 

[BillK]

Dont know how much sealing will help but I have been in my house since it was new in 1978 and every year its my routine to close most of the registers downstairs during the summer and vice-versa during the winter.

 

[Bolson32]

In our new construction homes we mastic seal the floor register boot flange to the subfloor to prevent leakage into the floor system.

Yep, I know this is the practice now and has been for a few years. Honestly if I closed the registers now they'd just bounce the air back into the subfloor. There are 1/2 to 3/4" gaps around some.

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[Bolson32]

All my first Floor Ducts are buried in Concrete. When We moved here the Floor Registers were EXTREMELY Ill fitting! I put a Rubber Tube on a Caulk Nozzle and with a Mirror to guide by, pumped the all the Gaps full of Caulk. Now if you close a Register in Winter you do not feel the Floor heat up around it from the Air Leakage.
You could try this?

Yep, this is my thought. Actually it looks like aluminum tape followed by a thin layer of mastic is the preferred method to seal these up.

Are your cold air returns uncovered?

Yep, wide open.

Dont know how much sealing will help but I have been in my house since it was new in 1978 and every year its my routine to close most of the registers downstairs during the summer and vice-versa during the winter.

I'm going to try and close some off, if nothing else to keep the main floor a little warmer so the AC runs longer. But right now there's 1/2" to 3/4" gaps in spots. If I close the registers it'll just redirect around the registers and into the floor joists.

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[karoc]

That be about 5 ton unit,name plate M# letters then should be 60 in there someplace or 48 which be 4 ton . Has this always been problem or something that just started?

 

[Bolson32]

That be about 5 ton unit,name plate M# letters then should be 60 in there someplace or 48 which be 4 ton . Has this always been problem or something that just started?

Always been a problem. Also, I see the back of the coil is a little dirtier. But... **** is this a 2 ton unit?

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[bigdav160]

But... **** is this a 2 ton unit?

I'd add a cheap mini split

 

[MeentSS02]

My experience:

House built in same general time frame (1988); single unit to heat and cool two floors. House sits on a slab. The air handler sends air down into the slab where it gets distributed to the rest of the house from there. That means the two upstairs bedrooms get fed last...in one of them, you can hardly feel any airflow at all.

I've tried everything...closing off everything downstairs results in the same amount of airflow upstairs (little to none). There is a return in the upstairs hallway, but it pulls no air. It literally can't even **** up a feather, even with the downstairs return fully blocked off.

My conclusion (also backed by 3-4 different local HVAC companies that came out to see if they could find a way to improve it): the system was poorly designed, and it would essentially take gutting most of the house to make it work properly. A couple suggested going with a larger air handler, but wouldn't guarantee that it would work any better.

My solution: installed a separate mini-split system that just handles the upstairs bedrooms. They have now become the most comfortable rooms in our house year-round.

It wasn't cheap, but it worked.

My opinion is that a horribly designed system just can't be fixed. The other houses in our neighborhood that were built later seem to have much better designed HVAC systems.

 

[Bolson32]

My experience:

House built in same general time frame (1988); single unit to heat and cool two floors. House sits on a slab. The air handler sends air down into the slab where it gets distributed to the rest of the house from there. That means the two upstairs bedrooms get fed last...in one of them, you can hardly feel any airflow at all.

I've tried everything...closing off everything downstairs results in the same amount of airflow upstairs (little to none). There is a return in the upstairs hallway, but it pulls no air. It literally can't even **** up a feather, even with the downstairs return fully blocked off.

My conclusion (also backed by 3-4 different local HVAC companies that came out to see if they could find a way to improve it): the system was poorly designed, and it would essentially take gutting most of the house to make it work properly. A couple suggested going with a larger air handler, but wouldn't guarantee that it would work any better.

My solution: installed a separate mini-split system that just handles the upstairs bedrooms. They have now become the most comfortable rooms in our house year-round.

It wasn't cheap, but it worked.

My opinion is that a horribly designed system just can't be fixed. The other houses in our neighborhood that were built later seem to have much better designed HVAC systems.

Did you run a head to every bedroom? Or how did you handle the different rooms?

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[karoc]

That’s Carrier,looks to be 2.5 tons 30 that indicates size. You being up north HVAC company’s may use different sq ft per ton.Here in Tx it’s about 600sq ft per ton. But you may be under size to push air that far to upstairs room. Sizing system correctly is out my comfort zone,May want call HVAC company tell them how many sq ft living space you have and it’s two story or story and 1/2 as them to give you quote and size system you needs.It’s just question to give ideal only

 

[honcho]

Take a look at your heat gain from outside the house. Window tinting and attic insulation can help. Trees strategically placed can make a huge difference but will take years to become effective. We have one upstairs room on the SW corner that has a lot of glass area and it's all but uninhabitable during the summer. Good luck

 

[Bolson32]

That’s Carrier,looks to be 2.5 tons 30 that indicates size. You being up north HVAC company’s may use different sq ft per ton.Here in Tx it’s about 600sq ft per ton. But you may be under size to push air that far to upstairs room. Sizing system correctly is out my comfort zone,May want call HVAC company tell them how many sq ft living space you have and it’s two story or story and 1/2 as them to give you quote and size system you needs.It’s just question to give ideal only

You're onto something. My brother in-law is an HVAC guy and I talked to him last night. Apparently you don't include basement SQFT for sizing up here, so I'm more like 1600sq ft. And he said 2-2.5 tons sounds about right off the cuff. He mentioned sealing the boots on the main floor registers and making sure the fan is set to high on the blower. I'm trying to find out how to do the second part. The schematics are a touch confusing for a novice.

Take a look at your heat gain from outside the house. Window tinting and attic insulation can help. Trees strategically placed can make a huge difference but will take years to become effective. We have one upstairs room on the SW corner that has a lot of glass area and it's all but uninhabitable during the summer. Good luck

Attic insulation definitely needs to be addressed. But you're right, the master is southwest facing and it may just be a fact of life. I did snag a portable 8000btu for this summer. Should at least help keep our room tolerable. I'm mostly concerned about the nursery as we have 5 month old twin boys. Their room is on the north east corner though, it's pretty small and has its own register. It should be slightly more comfortable in there. We did just replace the upstairs windows too. Hopefully help when we're in the thick of it. We've got white faux wood curtains everywhere too, which help reflect a fair bit of heat gain away.

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[karoc]

Good point by your friend, you will have look at wiring diagram and find blower motor which may be black,white, purple, but I am guessing. Or look at blower section and follow wires. Sometimes there is wiring diagram on blower housing.

 

[Holt]

Check to see if your return is blocked. A thought is you could raise the return and put it up high to remove the hot air that raises.

Have you taken your phone and took a pic of the inside of your vents. My old house had about 2 inches of dust on each wall. Had a company come out and clean them and I couldn't believe the amount of airflow increase we had.

 

[240sxguy]

The HVAC in this house is pretty abysmal. We've got a serious lack of cold air returns. I am having an HVAC company come out and give me a quote to redo the ducting and add returns to the existing system. So while it's a different problem, I feel your pain!

 

[Bolson32]

Good point by your friend, you will have look at wiring diagram and find blower motor which may be black,white, purple, but I am guessing. Or look at blower section and follow wires. Sometimes there is wiring diagram on blower housing.

l found the wiring diagram. I just have no idea how to decipher it [emoji23]

Check to see if your return is blocked. A thought is you could raise the return and put it up high to remove the hot air that raises.

Have you taken your phone and took a pic of the inside of your vents. My old house had about 2 inches of dust on each wall. Had a company come out and clean them and I couldn't believe the amount of airflow increase we had.

The returns aren't blocked and we have 4 of them.

They could stand to be cleaned, but there isn't 2" by any stretch.

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[karoc]

May see on diagram High,Medium and Low which be 3 different color wires. Maybe post pic of diagram,someone may be able help out

 

[MeentSS02]

Did you run a head to every bedroom? Or how did you handle the different rooms?

There is one head in each upstairs bedroom - they hook into the same outdoor unit. They operate somewhat independently of each other...what I mean by that is that as long as they are both set to heat/cool, you can set each room to a different temp to suit your needs. If one is set to heat and the other to cool, I'm pretty sure cooling takes priority, so the other unit goes into standby.

 

[Bolson32]

May see on diagram High,Medium and Low which be 3 different color wires. Maybe post pic of diagram,someone may be able help out

I found a YouTube video of someone explaining it on my exact unit. Cooling is already on max.

There is one head in each upstairs bedroom - they hook into the same outdoor unit. They operate somewhat independently of each other...what I mean by that is that as long as they are both set to heat/cool, you can set each room to a different temp to suit your needs. If one is set to heat and the other to cool, I'm pretty sure cooling takes priority, so the other unit goes into standby.

Honestly, this might end up being ideal in the long run.

With that said, we're probably going to look at a master suite addition in the next couple of years as the boys get older and we don't want to be on the same floor as them. I'll probably use the portable for a few years and re-evaluate the entire thing then. I like the idea of adding a big zoned mini-split for the upstairs and the addition if the furnace could handle the load in the ultra cold months.

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[ericm]

Our house is the same age as the OP's and the same sq footage. Two of the upstairs rooms are serviced by a small diameter duct that goes through the poor ventilated attic space. The one on the far end manages to be cold in the winter and hot in the summer.

We had a house efficiency audit done. One of the problems they identified was leaky ducting. Another was a single return duct downstairs in a hallway. When we had the furnace and AC replaced we had them add a second return duct and seal the forced air ducts. That and some insulation recommended by the audit made a huge difference in comfort.

 

[Bolson32]

Our house is the same age as the OP's and the same sq footage. Two of the upstairs rooms are serviced by a small diameter duct that goes through the poor ventilated attic space. The one on the far end manages to be cold in the winter and hot in the summer.

We had a house efficiency audit done. One of the problems they identified was leaky ducting. Another was a single return duct downstairs in a hallway. When we had the furnace and AC replaced we had them add a second return duct and seal the forced air ducts. That and some insulation recommended by the audit made a huge difference in comfort.

Did you do any duct sealing as well? Or just the new return, insulation, and new units?

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[ericm]

Yea, we had them do duct sealing. The consultant (after doing some measuring) estimated 15-20% loss from the original 1980s ducts. The house was not constructed all that well so I wasn't that surprised.

 

[karoc]

Back when I use to run service calls yrs ago there was this neighborhood where the builder only put in one system for 2 story house. I swear I think they only sold them during winter cause that was only time it was cool upstairs. We would install starting collars with dampers and close them down some to try force more air upstairs. It was never a cure but it did help out. But homeowners had to stay on top of their game cause the least little problem then you be able to tell it upstairs.

 

[Bolson32]

Quick little update. We haven't hit the real bad summer heat yet, but I did go through and fix all of the floor vents on the main floor. A couple of them had fallen completely off the subfloor and needed to be nailed back down. I sealed them all with foil tape and installed new registers. Now when I close all of the main floor vents it seems to be quite comfortable upstairs. I used to just leave all of them open and with some smarter register management, I think this is going to do the trick.

We could still definitely use another vent in our bedroom, the other two bedrooms are much smaller and have a single vent in them but are MUCH more comfortable. In the master we have one vent in the room, and one in each of the attached bathroom and closet. Which is kind of stupid, but we're still able to get some air out of those rooms with the door open. It would be much better to just have the extra vents in the bedroom and leave those rooms alone.

 

[Bolson32]

81 today, turned the AC on and set it to 74 with all but two registers on the main floor closed. Easy 72 in our bedroom upstairs. Hallelujah.

Maybe this will help someone else.

 

[Jackfre]

A good reason to seal registers was brought up by my daughter yesterday. She was walking through the house when she stubbed here toe on a register that had become displaced. It sheared her big toe nail off cutting cleanly down both sides of the nail. Gives me the willies just thinking about it.

 

[Higgins]

Hey All,

My house was built in 1987 and the ductwork is mostly original. We do have a new air handler, furnace and AC in the last few years. Our master bedroom is on the 2nd floor and it's honestly brutal up there in the summer so I'm trying my best to think of little tweaks that will help it be more tolerable up there this summer.

Wondering if we have any HVAC pros in here that can advise me on whether it's worth it to seal my ductwork at the floor registers. I recently replaced the registers and I noticed they are ill fitting with massive gaps and I'm sure there's a ton of air being dumped between the floor joists on both the main floor and the upstairs. Would it help if I sealed them all up, and maybe closed down some vents on the main floor? For example last night I had to turn the thermostat down to 68 just to get it to about 76 upstairs. It was frigid on the main floor and hotter than hell upstairs.

We live in Minnesota and have a finished basement if that matters.

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Yup, we had the same problem. Est. Cost $22,000. The issues we experienced there wasn't any way to install new ducts, or increase duct sizing, increase the HVAC size. Not to mention the requirement to add an additional CAR vent!

HVAC survey summary was to add 3 additional ceiling ducts in lower lever, and increase the size of the 2 that were there. Main floor, increase the size of the supply for the 6 floor registers. 3rd flr. no way to get any ducts up there. Solution was to add a mini - split (was ugly solution!!) _

lower level - We added a 30,000 BTU wall heater to the lower level. Relocated a 12 x 12 RCA vent to the wall in the lower level. - Fixed the problem.

2nd floor - No changes. However some heat migrated from the bsmt into 2nd floor mail level.

#rd floor Master. Left it alone as the temp were comfortable!

AL

 

[Bolson32]

A good reason to seal registers was brought up by my daughter yesterday. She was walking through the house when she stubbed here toe on a register that had become displaced. It sheared her big toe nail off cutting cleanly down both sides of the nail. Gives me the willies just thinking about it.

Ooof! Yes, another good reason to take care of it!