rerouting 6" heating duct

[iron]

as part of my basement remodel, i'm redoing the bath as well. the previous bathroom was poorly done and when they installed the 3ft x 3ft shower, its wall split a heating grill in half so that part of the grill was in the shower and part was outside of it.

well, my new shower will be in the same place, but will be a 3ft x 6ft shower with a walk-in entry at the far end. glass wall divider that won't go up to the ceiling. but, i don't see an easy way to relocate the heating duct as there is plumbing in adjacent joist bays. i've thought about running a reducer (6" to 4" round) and then going into an insulated 4" flex duct and down through the interior wall i'm building, but that seems problematic on several levels (1. connecting to a new heating duct would require a 6" pipe; 2. flex duct seems iffy; 3. don't really want to screw up the static pressure on my hvac system)

any thoughts on alternative ways to route this line so that it's not over my shower glass divider?

 

[iamlucky13]

What about going all the way back into the room the duct comes from, and rerouting a couple joist bays down from there, potentially dropping it down below the joists in a soffit if necessary?

Admittedly, that means tearing into the drywall in a room you weren't doing work in.

Also, I doubt changing out a single 6" duct for a 4" will increase the total static pressure of the system enough to matter.

 

[iron]

the duct coming into the bathroom comes off the main trunk from the furnace. the furnace is about 4 ft away from where the existing duct is located. access to the trunk is a SERIOUS PITA, plus, all the joist bays that land within the bathroom are filled with plumbing that i don't want to/can't move.

 

[stee6043]

Another option would be to abandon that vent altogether and install a separate electric zone for your basement with one or two (or more) in-wall electric units.

The ceiling vents in my basement did a horrible job of keeping my basement warm. Not enough heat, too high in the room, it just never worked. Electric has made my basement livable. Life changing stuff. ha.

 

[iamlucky13]

I suspected access in the other room would not be good.

Thinking about your idea to run flex duct between your standoff wall and the outer wall - that standoff wall is non structural, right?

I can't tell from the pictures exactly how much room there is, but it looks like maybe part of that wall could be shortened (reworking framing isn't the worst thing in the world), with only a minimal (2x2?) strip for supporting the top of the sheetrock nailed to the joists, the 6" duct run over the insulated pipe visible in the photos, doing a 90 downward, then another 90 to follow the wall at the top of the standoff wall, and then you can install the register a few feet away, either from the standoff wall or by doing a couple more 90's back into a different joist bay.

Or stee6043's electric heater idea actually seems pretty good to me. Even a 120V hardwired, in wall, forced air heater can warm a small space like a bathroom reasonably quickly, so you can leave the thermostat turned down most of the time to save energy.

 

[iron]

yes, there's just about enough room for a 4" pipe to fit between the wall and the foam insulation. i could gouge out some of the non-struct wall there and make it fit. i'd have to reduce from 6" rigid to 4" flex and then back up to 6" rigid at the vent (i couldn't find one with a 4" adapter).

i bought a bunch of supplies and will see what i can make fit.

i am also thinking of the electric heaters. need to experiment a bit this weekend with the furnace to see what i can get the downstairs temp up to readily. i also see there are HVAC retrofit zone kits where you could install dampers throughout your existing ductwork and then have room by room control of the temperature. probably a lot of hassle, but might be nicer than installing 3-4 electric wall heaters or a ductless heat pump system with 3 zones.

 

[gzecc]

Have you considered dropping down at the wall, building a soffit and running it along the top of that wall?

 

[iron]

no, because the old basement config had a soffit for the plumbing and i didn't like it at all. plus, in this bathroom, a soffit would look horrible with the future layout of the shower.

 

[cableman]

You cant just cut or drill a hole through the next floor joist and put it there? long side of vent running with joist? Im sure the cut joist could be shored up.

 

[moey]

You can buy oval duct, square duct, heck bend your own. I would suggest trying to make the duct work. For me at least with electric heaters Id rather be cold then turn them on. Home Depot has a pretty good selection of duct work on their website its all special order ship to store or pay shipping. Like someone else said changing from 6 to 4 inches would change the static pressure so little. Id be willing to bet if someone actually sized your bathroom it called for a 4 inch duct a 6 inch is likely oversize.

 

[iron]

half the joists in this room have already been hacked to $hit by the original plumber. i don't want to touch any more, especially since they support a tub.

i will try the 4" flex line and will probably do some mods to some off the shelf products to make them fit. i read about some people using plywood for ducts, but understand that's not allowed per code for supply ducts.

 

[stee6043]

For what it's worth I ended up buying two heaters for my basement, one 4000W and one 3000W, both 220V. After installing the 4000W I ended up not needing the other. It easily heats about 650 square feet. I bought my own enclosure and relay 220V so I could control it with a normal thermostat. Pretty cheap and simple. Couldn't be happier.

With my house t-stat at 70 my basement generally holds at 63 in the winter. This is finished, insulated. So I leave my basement t-stat at 55 and bump it to 70-71 when we go down there. Quick to heat up and very comfortable.

https://www.amazon.com/gp/product/B0039PFHFG/?tag=hearthamazon-20

 

[iamlucky13]

You cant just cut or drill a hole through the next floor joist and put it there? long side of vent running with joist? Im sure the cut joist could be shored up.

Not that large of a hole. Holes in conventional wood joists should be less than 1/3 the height of the joist, if I remember right. Screwing reinforcing straps above and below the hole might be ok, but technically that sort of thing should be checked by an engineer.

I was tempted to suggest boxing in a small section of each joist bay, sealing, and using several smaller holes in the joists to allow the appropriate airflow to another joist bay, but actually getting everything well sealed with numerous pipes to deal with would be somewhat difficult. I don't think there's anything in the building code against doing this, but most inspectors seem to hate it because they always see it done badly.