Closing some registers to get additional heat flow in other registers

Reply

  #1  
Old 05-02-14, 10:21 AM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
Closing some registers to get additional heat flow in other registers

This is my Momís and sisterís place so not always there and grew up with baseboard electric heating with ac in windows in summer so very new to this central air/heat!!

York Furnace model: GY9S080B12UP11G installed in 2004.
House is 2250 sq ft with two storeys and unfinished basement. Purchased in 2012.

Basement: 5 registrars [all but one foil tape closed]
First floor: 9 registrars [all open]
Second floor: 7 registrars [all open]

The foil tape closed registrars were done by previous owner.

The air flow/pressure was non-existent in kitchen and very little in two bedrooms on top of garage [so over unheated garage and furthest from furnace].

By adjusting damper screw on left side of the furnace was able to get good air flow/pressure in kitchen and one of the bedroom above garage.

Still have very low air flow/pressure in one of the bedroom above garage.

Have attached various photos. Neighbours tell me that builder had installed one vent going to space between garage ceiling and bedrooms above.

One photo shows 4 vents.

1 going to bedroom towards back of house [above kitchen, not sure why not installed going up back wall].
1 going to bathroom on 2nd floor.
1 going to one of the bedrooms above garage [believe it is to one on front corner above garage that has ok pressure now].
1 going to EITHER 2nd bedroom above garage with very low pressure OR to space above garage and below bedrooms. [I believe going to space]

Next photo shows 2 vents.

1 going to 1st floor at main entrance.
1 going to EITHER 2nd bedroom above garage with very low pressure OR to space above garage and below bedrooms. [I believe going to bedroom with very low pressure as vent pipe in basement slightly warm as opposed to 4 vents on other side that are much warmer].

Seems to be conflicting advice on closing registrars so before I remove all foil tape from basement registrars what is this forumís opinion on closing some registrars to get additional air flow/pressure in other registrars?

Any benefit to remove foil tape and close metal round damper on each of the basement registrar [may already be closed but not sure until remove foil tape] OR should keep all basement registrars open?

Any benefit to partially close individual metal round damper in registrars that are nearest to furnace so that they still get good air flow/pressure but help to get better air flow/pressure to registrars that are further away?

What is suggested to get more air flow/pressure in bedroom above garage?

Thanks.
 
Attached Images      
Sponsored Links
  #2  
Old 05-02-14, 12:12 PM
Member
Join Date: Feb 2014
Location: USA
Posts: 2,104
Received 0 Votes on 0 Posts
I would shut off basement vents. I have mine closed. On the top picture, that take off on the main truck, do you know what room that supplies? Is it low on air?
 
  #3  
Old 05-02-14, 02:25 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,878
Received 20 Votes on 15 Posts
Closing off vents can increase airflow to vents which aren't getting enough, but reduce total airflow through the furnace. The furnace needs to move a certain amount of air to operate properly, and if you close too many vents, it will overheat.

An 80 000 BTU 90%+ furnace is pretty large for a house of your size, newer construction -> You should be getting good airflow everywhere.

The furnace itself may not be moving enough air, so you shouldn't jump to balancing right away.

Start by:

1. Checking the filter for dust and dirt buildup. If you're using one of those 1" allergen filters, switch to a lower grade dust and pollan pleated filter. (merv 7 or lower)

If your filter is only 16x25x1" (as many are), you may have to use fiberglass to get proper airflow through a furnace of your size.

2. Check the blower wheel for dirt buildup -> call a pro to clean it, along with the secondary heat exchanger. (which is right above the blower wheel.

3. Check the temperature difference between the supply and return, near the furnace. (google "temperature rise) If you're getting enough air flow, it'll be in the 40-60F range -> ideally well below 60.

4. Seal all accessible duct joints with foil tape
 
  #4  
Old 05-02-14, 03:21 PM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,298
Received 45 Votes on 42 Posts
What do you have for returns?
 
  #5  
Old 05-03-14, 11:45 AM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
"mitch17
What do you have for returns?"

Returns:

Basement: Not sure unless count flap like rectangle that is open on return ducting.

1st Floor: Two returns [not sure why that are about 6 feet apart i.e. basically 2 in middle of house

2nd Floor: One return in master bedroom, one return each in two bedrooms above gararge and one return in hall outside of bedroom above garage [again not sure why have 3 returns all in same area and then 1 return across the house in master bedroom].

Thanks.
 
  #6  
Old 05-03-14, 11:49 AM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
"I would shut off basement vents. I have mine closed. On the top picture, that take off on the main truck, do you know what room that supplies? Is it low on air?"

Goes 6-7 feet to another area of basement. This is foil tape closed.

Have attached photo.

Basement is unfinished and not usually down there so fine with opening or closing vents as need to make better flow upstairs.

Thanks.
 
Attached Images  
  #7  
Old 05-03-14, 12:14 PM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
Closing off vents can increase airflow to vents which aren't getting enough, but reduce total airflow through the furnace. The furnace needs to move a certain amount of air to operate properly, and if you close too many vents, it will overheat.

An 80 000 BTU 90%+ furnace is pretty large for a house of your size, newer construction -> You should be getting good airflow everywhere.

The furnace itself may not be moving enough air, so you shouldn't jump to balancing right away.

Start by:

1. Checking the filter for dust and dirt buildup. If you're using one of those 1" allergen filters, switch to a lower grade dust and pollan pleated filter. (merv 7 or lower)
‚Äč‚ÄčUsing Filtrete 900 so towards lower end

If your filter is only 16x25x1" (as many are), you may have to use fiberglass to get proper airflow through a furnace of your size.
‚Äč‚ÄčYes, that is size... tried without ANY filter and got bit more flow but nothing dramatic

2. Check the blower wheel for dirt buildup -> call a pro to clean it, along with the secondary heat exchanger. (which is right above the blower wheel.
‚Äč‚ÄčGuess not a DIY task...

3. Check the temperature difference between the supply and return, near the furnace. (google "temperature rise) If you're getting enough air flow, it'll be in the 40-60F range -> ideally well below 60.
‚Äč‚ÄčWill research this

4. Seal all accessible duct joints with foil tape
‚Äč‚ÄčDid the more accessible ones in January/February... will do more now

Thanks!!

Read more: http://www.doityourself.com/forum/ga...#ixzz30gHyhlhl
 
  #8  
Old 05-03-14, 05:19 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,878
Received 20 Votes on 15 Posts
One thing I've observed is that it's tricky to estimate airflow just by waving your hand over a vent; if there's a noticeable effect, the filter is too restrictive to airflow. Even a 10% reduction in airflow can reduce performance, and if you can feel a difference, your allergen filter is probably reducing flow by 20% or more.

The highest grade 1" filter I recommend using is FPR 600 or MERV 7. On an 80 000 BTU, like I said before, you may need to use fiberglass.

Temperature rise measurements can help you determine the impact of balancing on total airflow. (the same can be said for experimenting with different filters)

-----------------
2. Check the blower wheel for dirt buildup -> call a pro to clean it, along with the secondary heat exchanger. (which is right above the blower wheel.
‚Äč‚ÄčGuess not a DIY task...
You can check it yourself by opening the blower compartment.

Dirty blower wheel = dirty secondary heat exchanger.

A good cleaning could make a dramatic difference if there's heavy buildup.
 
  #9  
Old 05-03-14, 08:29 PM
Member
Join Date: May 2014
Posts: 7
Received 0 Votes on 0 Posts
You have an 80k btu furnace with 1200 cfm. Pretty light for Canada eh! Short of changing the furnace and correctly redoing the furnace plenum. Increase Blower speed on heating is your only option. There should be 3 or 4 wires from the blower motor the colour black is the fastest speed it is normally used for A/C. If no A/c then you can use this black wire for heating on the circuit board. For a test to see if this helps first and if you have a fan switch on your t-stat that is wired up, turn it on and check your weak registers for airflow, Fan ON uses the fastest speed. In Michigan we would use 100K btu's and at least a 1600cfm furnace.
 
  #10  
Old 05-04-14, 11:51 AM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,878
Received 20 Votes on 15 Posts
^Canadian building codes are probably much stricter than those in Michigan, and oversizing is less of a problem.

Here if you actually need 80k to heat (remembering that 80k high efficiency replaces 100k mid) a < 3000 sq ft two story house, it better be in western canada or far north.

Same thing for blower cfm - house of the OPs size could probably cooled with 2 to 2.5 tons (1000 cfm), but down there I'm sure you would do something like 1 ton per 500 sq ft.

Hopefully the op will do a temperature rise test to see if the blower is moving enough air -> may need to be on high as you said, especially with a 3m filter.

--------------
Fan ON uses the fastest speed
Not always, especially on the better furnaces.
 

Last edited by user 10; 05-04-14 at 01:57 PM.
  #11  
Old 05-13-14, 07:04 PM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
ChuckToo: You have an 80k btu furnace with 1200 cfm. Pretty light for Canada eh! Short of changing the furnace and correctly redoing the furnace plenum. Increase Blower speed on heating is your only option. There should be 3 or 4 wires from the blower motor the colour black is the fastest speed it is normally used for A/C. If no A/c then you can use this black wire for heating on the circuit board. For a test to see if this helps first and if you have a fan switch on your t-stat that is wired up, turn it on and check your weak registers for airflow, Fan ON uses the fastest speed. In Michigan we would use 100K btu's and at least a 1600cfm furnace.

Do have A/C so guess should not mess with wires?

Not real difference with fan ON.
 

Last edited by gvtormtl; 05-13-14 at 07:22 PM.
  #12  
Old 05-13-14, 07:30 PM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
Had luck with getting better airflow to one of the bedrooms above garage and kitchen by adjusting damper at one of the two main trunks in basement.

Tried with other damper but no luck as of yet. Gonna continue with tinkering of damper setting and closing/opening basement registrars.

One of the neighbors said hvac guy advised him not to foil tape close any basement registrars but rather close the metal round damper inside as that would lessen airflow to basement but since the round dampers do not completely block heat there would be less chance of damage to furnace.

So now based on my research have different school of thoughts when it comes to basement vents:
1. Foil tape close
2. No foil tape but close round metal dampers
3. Close some but not all
4. Close all
5. Leave open

Seems gonna have to try every combo to see what works!!
 
  #13  
Old 05-14-14, 10:36 AM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,878
Received 20 Votes on 15 Posts
^Generally your goal is to balance the system, so partially close vent dampers in areas that are too warm and leave the rest open.

After closing some things off, you have to check the temperature rise to make sure the furnace is still moving enough air -> see here: A DIY Test for Furnaces | The Home Inspector | StarTribune.com

If it's too high, use a less restrictive filter, check the blower wheel for dust and dirt buildup, and consider raising the blower speed.

-------ignore this unless you've identified an airflow issue which is not due to dust and dirt buildup--------
If heat is on medium high already, there's a way to get heating and cooling to use the same speed with a jumper. I'm assuming that the blower needs to be on high for cooling -> in canada it's normal to have a much larger furnace than a/c. If your a/c is less than 2.5 tons, heating in your case requires more airflow than cooling - believe it or not)
 

Last edited by user 10; 05-14-14 at 10:53 AM.
  #14  
Old 01-25-15, 02:43 PM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
Please excuse delay in replies. Out of country and moving.

Updates:
*Did have furnace cleaned
*Using lower end electrostatic filters [3m 900; the basic fiberglass filter did not result in any improvement]
*Did the DIY test for furnace and was fine [did 15 min test; going to redo with thermometer soon as all thermometers at home not go above 100F]
*Will move some stuff in basement in order to foil seal more of the round ducts

Considering two different options to get more airflow on second floor:

1. If see wiring photo the AC has Black wire on Hi Cool and Blue wire on Heat [Black is Hi, Blue is Med to Med Hi, Yellow is Med Lo, Red is Lo per blower chart on furnace cover]. Is it possible to interchange the wires so have Black wire [Hi] on Heat and Blue wire on Hi Cool?

2. Close one of the smaller trunks/round duct coming from furnace. It only runs a few feet to nearby room [no door] and even with this closed would still have four vents in basement. Any issue by closing at spot where it meets main furnace, i.e. unscrew metal plating and then put a metal plate [similar to this ]The Hillman Group 11773 Cold-Rolled Weldable Steel Sheet Metal | Lowe's Canada to cover hole like plates used by duct cleaning companies to close hole made by them to put suction tube in.

Hoping this helps the one registrar on 2nd floor not getting good airflow. If my hypotheses is correct that is also the longest run of duct so may never get airflow like rest of house.

Something I am curious about. In my opinion the ducts layout is not well designed. There are two main trunks that service:
1. Round ducts to individual rooms
2. Smaller rectangle ducts that then service round ducts to individual rooms

Would think that is not most efficient design but no expert obviously.

Thanks all for help.
 
Attached Images   
  #15  
Old 01-25-15, 02:50 PM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
More photos as could not attach in prior message.

Last photo is close up of where want to remove duct and seal.

Thanks.
 
Attached Images      
  #16  
Old 02-06-15, 07:05 AM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
No feedback on updated info.?
 
  #17  
Old 02-09-15, 09:49 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,878
Received 20 Votes on 15 Posts
1. If see wiring photo the AC has Black wire on Hi Cool and Blue wire on Heat [Black is Hi, Blue is Med to Med Hi, Yellow is Med Lo, Red is Lo per blower chart on furnace cover]. Is it possible to interchange the wires so have Black wire [Hi] on Heat and Blue wire on Hi Cool?
Could you give me the model number of your a/c? If your a/c is 2.5 or 3 tons it probably needs to be on high.

You need to do a temperature rise check to see if the furnace is moving enough air. I can't tell you if closing vents will reduce airflow too much - you have measure the split after making adjustments.
 
  #18  
Old 02-10-15, 09:02 AM
Member
Thread Starter
Join Date: Apr 2014
Posts: 30
Received 0 Votes on 0 Posts
Thanks Muggle.

Will update once snow melts and can access a/c outside, Canada eh

Going to go ahead and close one of the vents in basement [one in photo] then check temp rise once get appropriate thermometer.

Any specific thermometer you would suggest?

I'll measure by putting in return just before filter?

Then measure by removing small plastic cover near main trunk [small hole made by duct cleaners then closed with round plastic/rubber stopper]?

Thanks!!
 
  #19  
Old 02-10-15, 02:52 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,878
Received 20 Votes on 15 Posts
Measure in the trunk line, a couple of feet away from the furnace so it doesn't pick up radiant heat from the heat exchanger.

Digital food/meat thermometers work well, as do stem type lab ones.



Start by closing vents in rooms that are unused or too warm, then check the split. If it's still okay and parts of the house are too cold, start partially closing vents in rooms that are comfortable (including where the thermostat is).
 
  #20  
Old 03-23-15, 08:16 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,878
Received 20 Votes on 15 Posts
Snow melted yet in your area?
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: