HVAC puzzle

[Tig]

Our building code requires adjustable LOCKABLE dampers at the boot for all supply registers.
The accepted practice is to put those round dampers in the pipe just before the boot and snug them down. Which is fine for the first floor. My crawlspace will always be accessible for adjustment and locking of the dampers to make seasonal adjustments.
The second floor is another story. The wingnut locks will be in the ceiling so once the drywall goes on there will be no more access to unlock or lock. Which would be OK if my heating and cooling airflow requirements were equal, but they are not. So one must reach down the register and adjust, without backing off the lock or re-locking.

In my last house all dampers were accessible in the basement and seasonal adjustment took a minute. the bedrooms were always cool, winter and summer. Just the way we like em. This arrangement does not meet code.
I rather not install dampers just for the sake of inspection, since they will inhibit seasonal balancing.

So I'm looking for a lockable register or lockable damper for the boot. The lock is simply a lock nut or bolt.
Has anyone seen such a product?

 

[Misfire]

No, but I have to say that is just a bizarre requirement. Any idea what they were thinking?

 

[plumberroy]

Access panels?

 

[Tig]

Here is the wording;
6.2.4.6. Adjustable Dampers and Balance Stops
(1) All branch supply ducts for residential systems shall be equipped with volume control dampers at the boot to permit balancing or shall be fitted with a diffuser incorporating an adjustable and lockable volume control device that can be set in a fixed position.

Seems to be all about balancing the airflow while standing at the boot. I guess they want a one man operation with no running up and down stairs.
I have also heard various iterations of "dampers must be at the end of the duct to keep the velocity up in the rest of the duct". But flow is flow, so what goes in comes out at the same rate, regardless of where the flow control is. The only difference would be pressure in the duct, but I've not heard that mentioned.
Maybe someone with some HVAC experience can shed some light on this.

 

[Misfire]

Locked wide open dampers above the ceiling (sucks I know) and an accessible damper on the trunk near the air handler/furnace?

Personally, I wouldn't want dampers in unconditioned or inaccessible space. They all leak at the shaft.

 

[Tig]

Access panels?

Plumbing access panels worked out well. Closet and pantry ceiling.
Only two of the seven upper floor registers would be in places where access panels would work. One in the pantry, another concealed by a kitchen cupboard. The rest would be in the dining, living and master bedroom ceilings.

 

[Tig]

Locked wide open dampers above the ceiling (sucks I know) and an accessible damper on the trunk near the air handler/furnace?

That would pass, but it seems so silly to put boot dampers in the duct if they serve no functional purpose.

 

[dave1949]

Could you modify/re-engineer the to-be-buried boots such that the lock-nut is accessible from the register/diffuser? Do some drilling and soldering (assuming metal) to fix the outside bolt head in place?

 

[Tig]

Could you modify/re-engineer.....

These are the dampers used in the duct at the boot.
Don Park | Volume Damper 5 In. | Home Depot Canada
It's pretty flimsy and simple. Bolt is spot welded to the damper. Wingnut and handle go on the outside.
It looks like this when installed;
SPEEDI-COLLAR | 10 in. HVAC Connection Collar with Damper | Home Depot Canada

 

[plumberroy]

Plumbing access panels worked out well. Closet and pantry ceiling.
Only two of the seven upper floor registers would be in places where access panels would work. One in the pantry, another concealed by a kitchen cupboard. The rest would be in the dining, living and master bedroom ceilings.

they can be had as small as 6x6 (15cm x 15 cm just noticed you're in Canada) we paint them the ceiling color where you have to have them

 

[dave1949]

Maybe a "radial style damper" ? See pic on right side of page.
ALAN Manufacturing Inc's Home Page

 

[dave1949]

These are the dampers used in the duct at the boot.
Don Park | Volume Damper 5 In. | Home Depot Canada
It's pretty flimsy and simple. Bolt is spot welded to the damper. Wingnut and handle go on the outside.
It looks like this when installed;
SPEEDI-COLLAR | 10 in. HVAC Connection Collar with Damper | Home Depot Canada

If you put in a complete side-to-side damper axle that is rigidly attached to the connector boot/ring, you could mount a nut on the damper, need to hold it up a bit with side supports, that bridges the axle, then run a bolt through the nut and against the axle so it acts like a set screw. The first one will only take 8 eight hours :laughing:

 

[1969grandpa]

Thats crazy. If the system is installed properly, you should never have to adjust the dampers. Make sure your contractor knows what he's doing. Every time I design and install duct, it is balanced from the start.

 

[kenmac]

Once the system ( air flow) is balanced. There should be no reason to adjust for summer / winter

 

[Tig]

Why rebalance?
Office: 169 cfm cooling, 119 cfm of heat.
Crawl space: 5 cfm cooling, 240 cfm of heat.
Living and dining rooms each are: 282 cfm cooling, 140 cfm heat
As per the design.

By personal preference, in winter I push very little hot air to the upstairs bedrooms. In summer, I go to the other extreme and push a lot of cool air to the bedrooms and less air to the other rooms. So year round I have cool bedrooms and warm sitting rooms. It only takes a minute to make the change over if the dampers are all in the crawl space.

 

[Tig]

Radial damper looks interesting. But I'm thinking about a damper in the boot or locking the diffuser. Something that I can see when I adjust and lock it. I prefer simple solutions. The less moving parts the better.
Dave, you'll have to draw me a picture of that one. but if it's in the duct and requires a blind reach and twist then it's not what I'm looking for.

 

[kenmac]

You should be pushing more CFM'S in the summer without moving the dampers. The fan runs on a higher speed for cooling. Lower speed for heating less CFM'S. I just never have to go out on service calls & move the dampers for winter & summer. But then ,I'm not even close to your area. They may do things differently up there. I know it's not required by code to install dampers

 

[aczlan]

How about something like this: Dampers, Diffusers, Grilles, Louvers, Registers | Diffusers | Damper for round ceiling diffuser | B28944 - GlobalIndustrial.com ?
The vents in the ceiling at work have those incorporated into them and they work well.

Aaron Z

 

[Tig]

It's a geothermal unit with passive cooling (no compressor in summer). 1200 cfm winter and summer.
I'm on the great lakes so we typically don't get a lot of 100 degree days, but humidity is pretty consistent in the 80% range.
Winters can be cold and windy, although it's been a long time since we've had a -40 night.
Some rooms take more air in summer, some less, changing fans speeds would not help.
The summer/winter cfm change is in the design, but as near as I can tell no one else actually pays attention to it. When I mentioned it to the inspector, he looked surprised, but he got it once I explained.
For me it's a comfort thing. It probably also saves a bit of energy.

 

[Tig]

How about something like this: Dampers, Diffusers, Grilles, Louvers, Registers | Diffusers | Damper for round ceiling diffuser | B28944 - GlobalIndustrial.com ?
The vents in the ceiling at work have those incorporated into them and they work well.

Aaron Z

Thanks, that would work. The one shown is surface mount but modification may be possible. I'll have to look for a supplier.

EDIT: A 4" x 10" rectangular version of this product would be perfect. I'd attach it to the grill and drop it in the boot.