Retrofit full heat/ac system in 60's modern
We're looking at another house renovation & rec'd great advice from the board last time we renovated.
The new project is an architecturally significant modern house (1962) in the NE--post and beam, large window walls--like the Eichler houses in CA. No attic (cathedral ceilings, original flat built-up roof w. parapets). Ballpark the house is about 3800 sf, single story, roughly in the shape of a 'T'. Windows & sliders are all single pane commercial aluminum. I have no idea about wall insulation, or whether there is any insulation in the room deck. The uphill half of the house will need a new roof (top of "T"), & could have insulation added when a new (likely membrane) roof is done.
Construction is over a vented crawl space.
Existing system is a two furnace gas hot air system delivered almost exclusively through floor registers. The smaller furnace feeds the master bedroom/office (top of the 'T'); larger furnace feeds the large open LR/DR/Kitchen as well as the kids' bedrooms. I suspect the zoning was design driven--it looks as if the crawl spaces are isolated by foundation walls. Uninsulated duct work is all through an uninsulated crawl space. Currently the house has no air conditioning system. The existing main furnace is on its last legs (dreaded blower bearing knock by the sound of it...)
We would like to bring the house HVAC systems up to modern standards, add A/C while also generally improve the energy consumption footprint.
I'm a big fan of underfloor water systems, but 2 problems--existing wide plank hardwood floors (that may be salvageable), & you would create a bigger problem as to how to add A/C.
So assuming that you try to work with what's there....
1. How hard would it be (or how efficient is it) to add air conditioning to an existing system as described? (eg no ceiling drops & very difficult to install in roof slab--also you don't want to detract from design)
2. Should the underfloor joists be insulated?
[There are also moisture problems in the house--first contractor has recommended a vapor barrier be installed and a "rat slab" be poured. (I'm inclined to deal with perimeter drainage first...)]
3. Should/can the duct work have insulation retrofitted? Is this wildly expensive? (most of the crawl space is 4' or less...)
Other Improvements may include:
-Window replacement (for all except the clerestory windows that "knife" into the under-roof deck.
Where to begin? Or what is the recommended sequencing to get my arms around the problems???
Last edited by paredown; 01-19-2008 at 06:25 PM.
Load calc ,with various options,better windows,insulation ,etc.,each will effect the size system that will be needed.
Once you decide on those factors,you'll have the load of the finished product.
Then Manual S to select the equipment size,and Manual D to size the ducts,reuse and insulate what you can.May need a different style supply grile,due to adding cooling.
Where are the supplies located?
We did a similar style home retro,guys dubbed it the "glass house" job,real challange ,but fun to see it all come together!
Your ductwork could be lined.
Good chance its too small for A/C.
Follow dashes advise.
Wow, you guys must have already had your morning coffee! Thanks for the quick responses!
I see "Manual S" and "Manual D" mentioned all over the board, & I didn't stumble across a quick definition...
Originally Posted by dash
I'm assuming "supplies" would be what we used to call "returns"? The main one (if I'm reading it correctly) is a large floor one in the cathedral portion of the house. Not sure about the smaller unit.
"Lining" ducts would be the insertion of something inside the existing sheet metal?
Manuals J,S and D ,are from www.acca.org and are the industry standard to deterime the load,select the eqipment and size the ducts.
Lining the ducts is insulation on the inside as opposed to the outside.
Supplies are the ducts and grilles that deliver the air to the space/rooms,location and type grille is critical to even temperatures in each room.
Pictures would help.
Sorry, got it back to front--all I have pictures of are the floor vents--I didn't have my camera when I was down in the crawl space. FWIW, here are a couple of shots first is one of the floor vents, beside one entry door; the second is the LR area--and what I think is main return for that area, just in front of the center white partition.
Partitions are just to define space...
A couple more shots: the first is looking at the window wall; the second is in one of the far kid bedrooms (bottom of "t")
Looks like Supply grilles are the smaler ones by the outside walls.The angle they direct the air at lokks like 45 degres ,good compromise for use with heating and cooling.
They look ok.
Now the only question is how well your ductwork is sized.
Radiant floring is do-able
If the ductwork needs to come out anyway, Put radiant up under the flooring then insulate the joist bays. Reuse the registers with new insulated ductwork. Maybe Hi-velocity will be needed.
I had thought about radiant--my favorite heat for an open plan with lots of windows, but have read that most mfr's recommend not installing them with wide plank flooring.
(Admittedly, we don't know yet if the exising wide-plank solid oak flooring will 'uncup' & relax once we have the moisture inside under control...)
I should get back inside the house tomorrow or Wed. to measure a couple of the ducts, get some furnace specs of the existing units, and generally have another look-see.
Thanks for the suggestions so far.
Well I did the sensible thing--I got a local heating contractor (ACCA member) to come and look. (They are particpants in a NY state energy progam we want to qualify for...)
He will send me details I hope. A little taciturn...
His first thoughts were that
1. ducts were sized large enough to retrofit A/C, but would need to be wrapped (if vented crawl space is maintained) or full crawl space insulated and vents closed)--he thought that lining would be a problem since you would need to remove the ductwork to so so (?)
2. He thought that working with the existing two furnace/two zone system made sense.
3. options would be:
a. no A/C, and basically replace both furnaces using Lenox
b. add A/C condenser, insulate ducts--would require power and pad for A/C for about three times the price
Question--could wrapping ducts be a DYI job?
(The realtor also provided a photocopy of the foundation plan for the house--the detail shows under-joist insulation, so I'm not sure why it was not installed...)
Last edited by paredown; 01-24-2008 at 07:29 PM.
Reason: Oops forgot the no pricing rule...
Forum rules... No Pricing.
Best of luck with this project, what an awesome house. I am a big fan of that style architecture.
There are a handful of Frank Lloyd Wright homes in the area where I live. Would love to have one of them but I'm guessing they all would be HVAC nightmares.
Last edited by SJProwler; 01-25-2008 at 06:26 AM.
Reason: pricing was removed.