Ductwork path recommendations sought
I am restoring an 1891 3-unit apartment building. I am planning one heat pump for each unit with compressors on the roof. I would like to avoid visible or boxed-in ductwork as I have applied for the 20% historic preservation tax credit. The first-floor unit can have its ductwork in the basement. The third-floor unit can have its ductwork in the attic. For the second floor unit, I intended to have the air handler in a utility room in the middle of the second floor and use the Unico or Space-Pak System with 4-inch ducting straight through the 12-inch floor or ceiling joists to the front and back of the building. Another alternative is coming up from the basement with conventional ductwork. I have encountered reluctance to drilling multiple holes through the joists by both my general contractor and the HVAC contractors. Coming up through the basement apparently requires fire dampers in the ducts at each penetration of the floor. Any advice on which way to go, or other alternatives?
Replies
Greetings NK,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
The end move in politics is always to pick up a gun.
R. Buckminster Fuller
Is this for heat only, or heat/ac?
Heat only can be simplified by using modern radiators and a high effiecency boiler.
It would be hard indeed to run new ducts through a 100 year old floor.
If it's also for ac then you'll have to bite the bullet and reinforce the floor or ceiling joists as needed to get the ducts where they need to be.
Beer was created so carpenters wouldn't rule the world.
Heat pumps provide both heating and cooling. So your vote is to cut through the joists, adding reinforcement around the cuts.
it's my understanding that most if not all of what is looked at for the historic tax credits is the exterior and fasade....
you didn't say roof type or if there was an attic....
for the top floor I'd look at a package unit if you have a flat roof... or use'n the attic if it's not a flat roof....
for the secon floor... if you could center your air handling unit or loccate it where most of your duct runs would run in the joist bays and only crossing where you could put in a dropped soffit you might not have any drilling
for the first floor i'd use the basement
all this said without knowing anyhting more than what you have stated.. but just my first thoughts
p
The tax credits require complete restoration both inside and out.My message must have been corrupted or something because I said that there is an attic and that I will use it for the ductwork for the third-floor apartment. And that I will use the basement for the ductwork for the first-floor apartment.The utility room is in the center of the apartment and to get to the front and back, I must go either under or through the joists. I don't, however, want to lower the ceiling or have an obviously boxed-in trunk line. That's the dilemma.
The tax credits require complete restoration both inside and out. what that refers to is that they want the building to be put back into use not just a pretty shell...
I have been dealing with historic structures since 1980 and have never had an issue with anything i did inside... infact in some places there are low interest loans to add updated mechanicals to historic structures so that they may be put back into commerical use... electric lights and indoor plumbing are nice
p
I saw a similar project once where owner didn't want lowered or boxed trunk.
What they did was to put in the trunk at the ceiling then built real classy book shelves & cabnets below the box-in so it was not noticeable as such.If you have a problem, don't just talk do something to set it right.
Jim Andersen
Thanks. I have actually done something similar before, but I hadn't thought about doing it here. I'll look it over with a new eye.
In a strange twist of fait, we found a solution that just might work quite well for your sitatuation as well.
We have about 1000 sqft of space that we were planning on using a high velocity system on, but our hvac guy came up with a company that makes remote hot/cold blowers that are placed in individual rooms and fed from a larger heatpump outside.
They have individual remote controls and are roughly 9" tall x 36" wide x 7" deep.
Instead of cutting a number of 4-1/2" holes through a bunch of steel beams we're only running the colant lines.
In our case the cost savings is significant, probably half what the high velocity system was going to be.
I can't remember the name of the outfit that makes these off the top of my head, but can dig the brochure out of the client's hands if this sounds interesting.
Beer was created so carpenters wouldn't rule the world.
The individual units are large would be intrusive in a Victorian room. I can see that such a system would be of value in some situations; however, unless the fire dampers are exorbitantly expensive, I believe that the best alternative is going to be installing conventional ducts up from the basement through the first-floor apartment's walls, with the air handler in the basement. But thanks for the creative suggestion.
1891?
What are your existing ceiling heights on the second floor?
Dropping the ceiling 1' may be you best option. Not an accustical drop ceiling, but framed and drywall to preserve the period look. Drop them all on the second floor and it won't be as noticable as soffits.
Cutting load bearing joist? Hope you have an engineer to look over that solution.
Pentrations through joist by plumbers and HVAC trades in new construction seems to be a an on going rant around here. Hacking up load bearing joist and then "reinforcing them" without a designed solution by an engineer is asking for some serious trouble IMO.
Dave
The ceiling on the second floor is 9.5 feet and the door and window trim reach to within a couple of inches of the ceiling. Dropping the ceiling is not an option for me. I can't believe that cutting 4-inch holes for the Unico or Space-Pak system in the middle of 12-inch joists will reduce the load-bearing capacity to a significant degree. Confirmation of that assertion is what I seek. Perhaps I'll need to hire a civil or mechanical engineer.
how about an exposed spiral duct in the center of the ceiling. Go for the industrial look.
I wouldn't mind that. I did that in my own house, but that is frowned upon by the Pennsylvania Historical and Museum Commission for a tax-credit project.
use an old, historical duct. lol
You'd have to hire a structural engineer, not civil or mechanical.
All of your doors and windows have trim within inches of the finish ceiling?
I checked my 2002 IRC.
Excert:
R502.8.1
The diameter of holes bored or cut into members shall not exceed one-third the depth of the member. Holes shall not be closer than 2 inches to the top or bottom of the member, or any other hole located in the member. Where the member is also notched, the hole shall not be closer than 2 inches to the notch.
There is also a restriction limiting the placement of notches to the end 1/3 of the span. It does not specifically exclude holes from the the center 1/3 of the span.
Still a structural engineer is most likely needed. You would need a full 12" joist depth for a four inch hole. Modern 2x12 lumber has a nominal demension of 11 1/4" in depth. Your circa 1891 joist could well be deep enough for a 4" hole, if that is all that is needed. If the inside diameter of the duct is 4", the hole wlii need to be larger to accomidate the wall thickness of the duct, and throw you over the IRC limit.
Hope this helps.
Dave
It helps very much. Thank you. Now I have something concrete to use for comparison with the extra cost of adding fire dampers for every duct if I come up from the basement through the first-floor apartment. I'm assuming that I do not need to add any structural support to the cut joists if I stay within the guidelines you quoted.The Unico and the Space-Pak system tubular ducts have interior diameters of 2 inches, I believe. With insulation, the OD should be 4 inches or less.
You might be ok, but a call to your AHJ is really what you need. Ask them what they will allow without an engineers stamped drawing.
Telling a BI that the guys at Breaktime said it was ok, probably won't make a good impression <g>
Dave
I have seen decorative soffits (with lots of crown moulding) that still maintain the Period look and high ceiling. Also in one of the last issues of FHB there are non-structural box beams.
Thanks, but the room and wall configuration in the apartments doesn't permit it. The HVAC contractor has come up with a good plan to come up from the basement in three places (chases in a closet, the utility room, and a flue bump-out) with fire dampers at the floor penetrations, and then going sideways between the joists to reach all the rooms.