macv, our HVAC designer is the one who determined one toe kick register would be sufficient for our bathroom that is about 10'6 x 10'6 and split into 2 parts. The register doesn't even keep the 5'6 x 10'6 part on the ICF north wall (with the tub on the ICF garage wall) warm enough. He never showed us a plan--just walked around with me and pointed to where he thought the registers should be. DH was the one who had all of the discussions with the HVAC people as to everything having to do with the geothermal. I remember lots of discussions about heat loads(?), and sizing the furnace due to our extra tight construction, and about other parts of the house, but don't remember them talking about the master suite. As with many subs, things can get missed. I'm mentioning this to give a heads up that people need to think about as many aspects of their new house as they have time for in order to avoid misses like this one. If I had just thought about the fact that all of those walls were exterior, I would have asked questions that probably would have resulted in more ducts in this part of the house. Anne

brickeye, Good point--I didn't think about that we need space for a vent. I imagine this can be done by making the wall to the chase 6", as kirkhall mentioned, or by making the chase larger. The rest of the plans have 2x6 walls for vents, I just didn't think about it here. Ultimately, this plan will be reviewed by my builder, who should catch these things--I'm trying to figure out the best placement now, and as I've mentioned, I have a few inches of wiggle room to accommodate things like a 2x6 wall instead of 2x4. So hopefully we're a ways from disaster status... energy_rater, the equipment will be in the basement. Good to hear that high-efficiency is becoming the norm. This is the last major change before I get these plans to the builder, and we can go over these things in detail. I don't know who he is going to use for HVAC, but during the first meeting going over these plans, he got them on the phone to double check that we can do a single unit with dual thermostats for this plan. So we can verify these kinds of details, too. Thanks for your thoughts.

I barely hear my ahu running. it is located in a closet with return in living room. very very quiet. while my heat pump is single stage my ahu is variable speed. great dehumidification, even here with high humidity the norm. there are ways to quiten areas where ahu and return's are located. I see on your plans you have a mechanical room is this not where equipment would be located? when you talk about ducts in crawlspace.. you mean basement? or under house between ground and house? not being in an area where we have basements I can't commnent on ductwork installs in that location. I do read that basement ductwork is seldom mastic sealed or insulated. personally I'd have a problem with that. if I'm paying to condition air...I want control over amount delivered and temp of delivered air. unsealed ducts leak. uninsulated ducts lose degrees of heat/cool. when you talk about minisplits..keep in mind that you need someone who is familiar with the install. ionized if you recall, even your very knowledgable hvac contractor had input from someone with more hands on install of mini splits. aside from minsplits with multiple ahu's that hang on the wall..there are also casette ahu's that are installed in the ceiling. OP have you thought about an energy rating? someone you hire to give you specific to you information? in my area for new construction the value of the energy saved can be added to appraised cost of home. the rating takes house from just meeting code to including the upgrades and gives you a home energy rating score. HERS rating. just fyi. I've never had a new construction home plan on minisplits. that is usually a retrofit option. around here there are maybe 10 of 50 companies that have experience in minisplits. and of the 10..only 5 do it well and attend classes as they become available. research the companies well if you go mini split route. I'd limit upgrading efficiency to 18 SEER actually I find that ROI is better for 15-17 SEER. above that the cost for more efficiency takes longer to re-coup, for little benefit. knowing the actual efficiency from ARI is important. those yellow tags don't reflect true efficiency or total unit. there are certian matches to achieve certain efficiencies. others less. best of luck.

The biggest problem with HVAC zone systems is knowing when to choose it as a solution and when not to. Some HVAC companies it's about "sell, sell, sell" whether or not it works... there's more money in "sell, sell, sell" --- when it's only about money? So does the comment above mean I do it for free? No. If you think that you are reading things that aren't there. New construction? best to choose separate systems 9 times out of 10. In order for a zone system to work, you have to know what you are doing. Most HVAC companies staff (the techs they send you) are 20-30 year olds. How much practical experience could they possible have? It's best for HVAC zone systems to be an elegant solution. A HVAC zone system is a tool in the tool bag. Not all homes are suitable for zone systems. Some homes there is no other way, and in some cases complications to those problems will make an HVAC zone system design possibly more prone to problems. You have a problem now, do you want more problems. These decisions among others are decided "in person" --- so considering that becareful what information you decide upon from the internet. Just because it's here doesn't necessarily mean it's true. That said: Depending on equipment level chosen, how many different floors you have in your structure, how much room you have available... will all be factors that make you decide one way or another. From there it's in your best interest to pick a contractor that is skilled: especially when it comes to HVAC zone systems. (there's a lot of garbage out there.) (click to enlarge if necessary) I service the Katy, Texas area.