Thread: mystery supply registers

7 year old townhouse with gas warm air furnace and central AC.

Floor supply registers blow nicely. There are adjustable registers low down on the walls and non-adjustable (return?) grills up high on the walls that don't seem to do anything, whether in cooling or heating mode. This is in the bedrooms only.
Any ideas what's going on here?

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Sounds like balance air returns.

When heating or a/c blows into a room, the room pressurizes, which then limits the heating or a/c blowing into the room.

The solution is to install balance air ducts or return air ducts in each room with a supply which has a door which can be closed.

The old fashioned way was to undercut door, I say "old fashioned way" instead of "inefficient and insufficient way" , as the old fashioned way of undercutting the doors never did work very well.

That worked okay with wood floors and gravity hot air or hot water/steam heat at the radiators, but once people started blowing heated and cooled air around, and then started installing carpet, you might as well block off the undercut door or undercut the door 3", which leads to noise and privacy complaints.

Jerry - Thanks very much. I've never seen a set-up like that before.

Originally Posted by Jerry Peck

Sounds like balance air returns.

When heating or a/c blows into a room, the room pressurizes, which then limits the heating or a/c blowing into the room.

The solution is to install balance air ducts or return air ducts in each room with a supply which has a door which can be closed....

So, is there a rule of thumb about when to open or close the adjustable ones? Open them if the door to the bedroom is closed most of the time?

Originally Posted by John Arnold

7 year old townhouse with gas warm air furnace and central AC.

Floor supply registers blow nicely. There are adjustable registers low down on the walls and non-adjustable (return?) grills up high on the walls that don't seem to do anything, whether in cooling or heating mode. This is in the bedrooms only.
Any ideas what's going on here?

When you have multiple return vents around the home each one you add will make all the rest draw less per return vent. Sometimes you cannot even feel it if you put your hand up to it. I will take a piece of paper and put in on the return to make sure it is drawing. In general I find the HVAC system air flow noise much more liveable as well.

Returns in all closed door rooms, especially bedrooms makes the entire home much more comfortable and you can almost garantee that all rooms will be close to the same temp and humidity level. Of course all that depends on a good design for the home for the HVAC system

Originally Posted by John Arnold

There are adjustable registers low down on the walls and non-adjustable (return?) grills up high on the walls that don't seem to do anything, whether in cooling or heating mode.

John,

Here is another way to read what you wrote, maybe this applies?

Making a different presumption here - the adjustable registers down low are directly beneath the non-adjustable registers up high.

I was originally presuming the non-adjustable registers were returns as I see them all the time, for the reason I gave.

With the new presumption, the registers are in the same stud cavity, there are two possibilities I can think of: 1) the non-adjustable registers up high are not actually connected to a return system but are simply allowing air to circulate by gravity to the lower adjustable registers, someone's idea of a gravity air balancing system?; 2) the non-adjustable registers actually are connected to a return air system and someone thought they would also cut in lower return air registers and make those where they could be closed off, say during the summer?

After thinking more about what you stated, and wondering if the high and low openings are in the same stud space, that brought up all kinds of 'self-engineering' possibilities.

Now, if those are not in the same stud cavity ... then I don't have the foggiest idea of what the low adjustable ones are for.

Originally Posted by Jerry Peck

...

Now, if those are not in the same stud cavity ... then I don't have the foggiest idea of what the low adjustable ones are for.

They are in the same stud cavity.

Open nearer to floor registers in winter, so warm air comes into room and rises; close nearer to floor registers in summer so cool air comes out of the higher to the ceiling registers then falls into room when the AC is running.

Furthermore, a quick check near the air handler would prove the presence of a damper type system for FA/Central AC shared circuit system.

Originally Posted by H.G. Watson, Sr.

open nearer to floor registers in winter, so warm air comes into room and rises; close nearer to floor registers in summer so cool air comes out of the higher to the ceiling registers then falls into room when the AC is running.

Except that those are not supply registers.

Originally Posted by John Arnold

Floor supply registers blow nicely.

Originally Posted by Jerry Peck

Except that those are not supply registers.

Says who? They do not have to be adjustable up near the ceiling. If there are directional fins they do not have to be adjustable. For example there might be a thermostatic booster fan in-line and/or a thermostatic controlled servo-motor driven damper.

Originally Posted by H.G. Watson, Sr.

Says who? They do not have to be adjustable up at the ceiling. For example there might be a thermostatic booster fan in-line.

In the master bedroom for example, there are 3 floor registers blowing just fine, in heat and cooling mode.
I couldn't feel any air movement to speak of at the wall registers, bottom or top. Of course, I opened the bottom adjustable one.
Perhaps if I'd made sure all the windows were closed and the bedroom door closed I would have felt return air. I was too flummoxed to do that.

Originally Posted by John Arnold

They are in the same stud cavity.

John,

I'm suspecting that the non-adjustable one up higher is the installed return and that the stud bay is being used (and probably improperly so) as a return duct.

Then, when the lower adjustable registers were added, they figured they would used the stud cavity as an air flow duct. A couple of likely things which would prevent this would be that the stud cavity would originally have been terminated just below the upper register, there should be fireblocking installed in that wall, and the stud cavity is not allowed to be used beyond the floor or ceiling.

Of course, there are always other ways to install those return ducts in the stud cavities, such as was originally done in our house here in Ormond Beach, built in 1978: The original returns in the bedrooms (yes, they actually installed returns in the bedrooms and actually each of the other rooms too, even rooms with no doors) and they installed those original returns down low, taking the entire stud bay from the attic down to the bottom plate as the return air ducts - no top plate fireblocking, no intermediate fireblocking, no ... etc.

If that house was done as ours was, then the upper vents may not be original and the lower vents may be, with the upper vents added and the fixed return grilles moved up there and new adjustable grilles installed at the original lower locations.

As you can see, many, many possibilities, and all that leads to a - Why? Don't know.

Originally Posted by H.G. Watson, Sr.

Says who?

The original poster, that's who.

Are there multiple levels of this townhouse? Where is the Furnace/Coil/Air Handler in relationship to the two bedrooms? Where do the supply trunks run (i.e. basement ceiling, crawlspace, under a slab cavity, or are their attic falls)?

Originally Posted by John Arnold

7 year old townhouse with gas warm air furnace and central AC.

Floor supply registers blow nicely. There are adjustable registers low down on the walls and non-adjustable (return?) grills up high on the walls that don't seem to do anything, whether in cooling or heating mode. This is in the bedrooms only.
Any ideas what's going on here?

Originally Posted by Jerry Peck

The original poster, that's who.

No he hasn't said that actually, YET. He has not indicated that he CLOSED the floor supply registers either, nor indicated if he checked if they were inter-connected (easily done with a mirror and a flashlight).

Originally Posted by John Arnold

So, is there a rule of thumb about when to open or close the adjustable ones? Open them if the door to the bedroom is closed most of the time?

You close the ones nearer to the floor in the summer months so the upper ones return warm air, open the ones nearer to the floor in the winter months so the system returns cold (near the floor) air, if it is (as I suspect due to only being a 7-years old townhome) an interconnected (dampered)return. If there is a dampered system at the air handler, then the upper may be an alternate supply source for AC months.

John,
There's a lot of good opinions about the arrangement you found on your inspection and just to throw another twist at you... Or, to offer another IMHO...
I've seen this arrangement before, albeit rare... but non-the-less, it does exist...
It is a different type of transfer arrangement used in colder climates... warm air is collected at the ceiling and transfered to another floor sometimes the system is powered but most of the time it's passive...



Just a thought...

Bob

Originally Posted by Bob Phoenix

It is a different type of transfer arrangement used in colder climates... warm air is collected at the ceiling and transfered to another floor sometimes the system is powered but most of the time it's passive...

Bob,

Hopefully, that is in duct work and not a stud cavity as, if it was in a stud cavity it would need to be fireblocked at the ceiling and floor.

Also, I can understand that working with the mechanical fan, but you said some are passive, and it seems to be those passive ones would only bring cold air down by allowing a chimney effect of warm air rising in that duct.

Originally Posted by Jerry Peck

Except that those are not supply registers.

Originally Posted by H.G. Watson, Sr.

Says who? They do not have to be adjustable up near the ceiling. If there are directional fins they do not have to be adjustable. For example there might be a thermostatic booster fan in-line and/or a thermostatic controlled servo-motor driven damper.

Originally Posted by Jerry Peck

The original poster, that's who.

The original poster titled the post "Mystery Supply Registers". He said that, Jerry Peck disputed it.

Hopefully, that is in duct work and not a stud cavity

Oh yeah... of course...!

But, no, the few that I have seen... (And, I have to emphasize few...) were ducted systems, with fans... and only up North... But in theory, they worked by moving the warmer air from the top of the room to another room down stairs...
Theoretically, because John's scenaro involves a forced air system it could be pasive... which would be the same as an air balancing grill (just directing warm air to another section of the house using the force of the HVAC blower)...

I'm still baffeled with having A/C registers near the floor... That's just plain weird...

I have seen un-lined stud cavities used for venting before... (Before I was called for the inspection, but not after my inspection though...)

BTW: Ever seen the outside walls of a balloon framed 3 story house used for dryer venting before...? That's just wrong on so many levels...

Originally Posted by H.G. Watson, Sr.

The original poster titled the post "Mystery Supply Registers". He said that, Jerry Peck disputed it.

Watson,

I've been giving you a break recently since you came back, but ... if you want I will drown you again in your idiocy.

Your call, DA.

Unlike a certain blow hard, I've been doing (and getting paid the big bucks) what he aspires to do.

Have at yourself. How you get yourself all blown up when you're caught stuffing words into another authors posts, which speak for themselves, is downright amazing. Talk yourself in circles, its amusing.

The original poster still hasn't said what you claim he said.....YET.

Watson,

Here is an example of your lack of knowledge (i.e., idiocy):

http://www.inspectionnews.net/home_i...html#post97394

From the above post: "Don't be disarmed by the use of the words "should not". Recommendations and the use of should in listings and manufacturer's instructions are NOT elective nor voluntary."

Actually, Waston, the word "should" *IS* both *elective and voluntary*.

The word "should" is a "strong recommendation" but is not the same as "shall" - "shall" is a command and one shall, or shall not, do something. Whereas with "should" one is strongly recommended to do, or not do, something.

Originally Posted by Jerry Peck

Watson,

Here is an example of your lack of knowledge (i.e., idiocy):

http://www.inspectionnews.net/home_i...html#post97394

From the above post: "Don't be disarmed by the use of the words "should not". Recommendations and the use of should in listings and manufacturer's instructions are NOT elective nor voluntary."

Actually, Waston, the word "should" *IS* both *elective and voluntary*.

The word "should" is a "strong recommendation" but is not the same as "shall" - "shall" is a command and one shall, or shall not, do something. Whereas with "should" one is strongly recommended to do, or not do, something.

Jerry Peck,

There you go cross-posting again. You want to take that up on the original post string I'll respond. You lost that argument with UL Regulatory 10 years ago and still can't let it go.

You confuse your warped understanding of Code language with the Regulatory and Listed language of Manufacturer's Listed Instructions and what the Standards say.

The SHALL comes into play in the CODE. The Code requires use within its Listing. The Listing includes the Standards for Safety and the Instructions.

You were proven wrong repeatedly by UL, they have stated it on the record repeatedly I have quoted UL Regulatory Staff repeatedly and have provided links to their site repeatedly.

That you still cannot comprehend how the GuideInfo site works, how to read Standards for Safety, what a Category Code is, or how to use the White Book is frankly sad, but understandable for one with such a horrendously unsuccessful and flawed history of endeavors and failed employment.

Originally Posted by H.G. Watson, Sr.

You lost that argument with UL Regulatory 10 years ago and still can't let it go.

Nope, I did not loss that argument.

You were proven wrong repeatedly by UL, they have stated it on the record repeatedly I have quoted UL Regulatory Staff repeatedly and have provided links to their site repeatedly.

Quite to the contrary, *I* post what I get from UL, word for word, whereas *YOU* post your interpretation of what you think UL said and expect us to believe it, lock, stock, and barrel - with no specific evidence to support what you say.

That you still cannot comprehend how the GuideInfo site works, how to read Standards for Safety, what a Category Code is, or how to use the White Book is frankly sad,

Seems that you are the one who cannot comprehend how to read and understand what is written. You have shown that here over and over again.


Watson,

If you would take even just 1/4 of the effort you waste in trying to find something wrong with what I say, and put that effort into providing good and useful information here, you could be a good asset.

But yours is not the type of personality to actually want to be helpful to others, your is the type of personality which only want to do what they can to try to derate or degrade others as that is the only way you can build your own self-esteem.

A sad and wretched state to be in for a human being.