NO place for HVAC in Green home
We are Owner/Builders.
We designed our new 2 story home to allow for duct work inside 14" and 18" floor truss systems. The unit would sit inside our single story kitchen attic and connect through a single wardrobe (We used wardrobes instead of closets) in our master bedroom and then fit perfectly inside our truss systems for delivery to the rest of the house. The master bedroom is on the second floor.
Unfortunately, due to a series of early setbacks in other areas, no one thought to make sure that the truss designer, even though he was aware of our HVAC intentions, left a clear path in his trusses for the duct work - BIG LESSON LEARNED. Every path seems to be completely blocked or too small to handle the standard ducts needed.
Our HVAC contractor has come up with only one way to put in the standard ductwork. He wants to hide the duct work in at least THREE large spots inside our master wardrobes AND he has to add a 3 foot chase to an adjoining room. We are deeply concerned, not to mention disappointed that this will kill our closet space and appraisal value.
Our home uses passive solar design and we've selected an 18 SEER amana with a lifetime warranty. We selected this unit after determining several months ago that a Daikin was out of our price range. Now we've signed a contract with an HVAC contractor who doesn't handle Daikin and so I'm not sure that's an option any more. We've been looking into the spacepak products, but along with some noise issues, our contractor is saying the ducting and handlers are 40% more expensive and that our 18 seer would be reduced to a 13.
Our new home is 2500 square feet plus another 1000 in the attic which we plan to cool separately. We will have an insulated envelope that includes attics and a sealed crawlspace that vents into the house and mixes with the indoor air (a vapor barrier will be installed down there). Insulation is 6" of spray in foam, rigid foam, osb and siding on the walls. The roof is spray foam, attic wrap, osb/radiant barrier decking and regular shingles. We are located in north central Texas in a mixed humid climate.
Here's what we contracted the HVAC guy to install before we realized we had a space issue.
Amana - ASZ18036 heat pump 3 ton 18 SEER
Amana – AEPF3036 Variable speed fan coil unit with 10kw Aux heat and TXV
Honeywell – HK322 Zone control panel
Honeywell - Zone dampers
Honeywell programmable thermostats
Filter system with UV
Copper line sets
We've worked for three years on this project and the web trusses were always our plan for duct work, electrical, plumbing etc. We experienced a series of early setbacks during construction and checking for a path just got overlooked. The HVAC setup is intergral to our whole house design, both in function and placement.
I have never seen a good duct system that was installed up into a truss system because of space concerns. Each and every one was a compromise with poor results.
"When the people find they can vote themselves money,that will herald the end of the republic" - Benjamin Franklin
"Government is not reason, it is not eloquence, it is force;like fire, a troublesome servant and a fearful master. Never for a moment should it be left to irresponsible action"- George Washington
compromise is right
10' flexible is the largest you can hope for and each (zone) and those supplies had better be sized and installed correctly because there's no going back to repair or damper adjustment. we have done quite a few with first floor and finished basement using two systems. you need a lot of mechanical room to get that maze run correctly. labor, labor and more labor. takes hours just to lay it out and draw it up and still there is a certain amount of boxing in to be done. your not going to like it but, if your contractor asks for some part of a room for ducting it's because he is trying to deliver the proper air flow. without that ,high seer just became lower. my favorite smart-a$$ saying is just draw some arrows on the wall a maybe the air will follow.i'm sorry, sounds like your'e trying to build the right way though. i wish you good luck without too much compromise.
remember, with electronics; when its brown,its cooking and when its black, its done!!!
No place for HVAC in Green home
Look into a ductless heat pump/A/C system like Mitsubishi. No ductwork required, just two fluid lines. Could install 3-4 units per condensor I believe. Total cost may be more efficient than trying to get ductwork installed.
Thank you to everyone. It looks as though we have finally found a good path for all the standard ductwork!!!
I guess if you stare at web truss ceilings long enough, you eventually find a wy through - course we also moved the location of our unit and lost some bonus room square footage, but way better than cutting into wardrobe and primary rooms.
i have never worked on one or installed one but this maybe a candidate for a high velocity system. smaller ducts may be the answer.
I say go ..." exposed " ....radical twisted transitions , rectangular to round y branches , spiral round pipe...hey it was an idea not mentioned. And look at the drywall trees youd be saving ( lol ? ).
Consider a high velocity heating and cooling system using small diameter ducts that can be more easily threaded through floor, ceiling, and wall cavities. High velocity systems operate quietly and improve dehumidification, room air mixing, and energy efficiency over standard air-delivery duct systems.
High velocity heating and cooling systems use a special fan coil and air handling unit that generates high pressure air forced through small diameter ducts. The main supply trunk is either a rectangular or round duct that supplies air to flexible, insulated, 2" diameter plastic feeder ducts. Air passes through sound-suppressing tubing at the end of a duct run before entering the room through a plastic collar fitting. Air is supplied at 440 to 1200 cubic feet per minute (CFM).
High velocity systems use standard outdoor condensing units for air conditioning and heat pump systems. Adding a bank of electric heating elements to the air handler can provide heating capability to a high velocity air-conditioning system. High velocity system air handlers can satisfy cooling capacities between 18,000 and 60,000 BTUH and heating capacities between 24,000 and 143,000 BTUH.
SpacePac and Unico are tow manufactures of high velocity systems.
How effective is the passive solar? Is the heat pump mainly there for cooling and supplement to the solar? You might want to consider a multizone ductless system.
Mark? What's the SEER ratings for the hi velocity systems?
He said he wants to get 18 SEER.
Originally Posted by Mark T
The conventional view serves to protect us from the painful job of thinking.
Work sucks, lets go skydive
HVAC as an afterthought? Good luck
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