Building my retirement home and have been doing so since 2000. Not a pro in any of the trades and have made my share of mistakes but overall things going pretty well.
The next step is to put in AC. Need to get the duct work in next and one of the contractors suggested using the small high capacity duct work since my build configuration is very challenging for conventional duct work.
I like that idea and would put it in myself, but not clear on how to make the connection with my WaterFurnace heating units.
Anybody familiar with this kind of set up willing to get me up to speed on the right questions to ask, next steps, etc?
Replies
Welcome to BT Bick.
Without details, the only recommendation I'd have is to not use hihg velocity ducting. In a short few weeks you likely will wish you had figured a better way after you realize you cannot get used to the noise.
Your ears will thank you for figuring a way around the ' build configuration is very challenging for conventional duct work.'
Thanks for your reply. Sound was one of my concerns. Have several other questions/concerns.
Also wondering whether I should even be considering using the GT system for my AC. I've gotten quotes for duct work and all were very high. At the end of the day, I'll have more in my HVAC system than some people have in their homes. This in a location where I may need AC two weeks a year, maybe a little more to clear out the humidity, but not much more.
From your note "without details" - What details can I put on the post that will make it easier for replies? I've got lots of details but wanted to avoid writing paragraphs of what might be irrellevant stuff.
First, put your location in the profile - click on your own name and the profile screen comes up.
Location is everything in HVAC.
Basic detail, besides location:
What type heat are you using, Heat pump?
How large a house, type insulation and how well insulated, etc..
# of people in the house
Those are the very basics, otherwise any comments are open ended generalities.
Many HVAC pros dismiss flex ducts, but if you have room (maybe not) big fat flex duct is easy DIY and relatively quiet. The duct work in my own house (heat pump) are a carpentry type job - surplus whiteboards with the metal side in.
OK here goes: btw updated the profile
-Northwest portion of Michigan's lower peninsula, on Lake Mich.
-Sustained northwest winds of 30mph plus in the winter. Summer most breezes out of the southwest and the house is blocked on the southwest with a dune. No summer breeze.
-1 story and basement on a 33percent grade lot. 1 long side of basement is underground, 2 short sides 50% underground and other long side 100% exposed. Front door is in the basment on the exposed side with steps up to the main floor.
-Basement ICF's
-Main floor 2x6 with foam insulation / Ceiling 20" of blown in cellulost. / All along the edge the 10" plus domes ceiling were dropped to keep insuation at the 20" plus level right to the sides of the house.
2500 sq feet on main floor - no heating there yet. 1000 sq ft in basement, the balance (1500) is 2 garages. I put in the tubing before the basement was poured and the Waterfurnace GT systems (pump and dump) heat the basement and do a pretty darn good job of heating the main floor which I supplement with 3 spaceheaters when I'm up there on the weekends.
Next steps in order:
-get in duct work or somehow resovle this AC dilemma.
- Finish the tubes upstairs. Cant decide on the upstairs whether I'm going to use some plastic square stuff that the tubes snap into(dont have the name easily at hand), with some aluminum, and foil on top, followed by backerboard. Or just use gypcrete.
Will just be one or two of us in the house with lots' of guests in summer and a few sportmen in the winter.
Hope that gives you something to work with. Just don't know if I'm throwin good money insisting on using the WaterFurnace GT system as the basis for the A/C system.
Just my opinion, but for just 3 weeks of cooling need (that probably is not that hot/humid), I'd not complicate a GSHP (ground source heat pump is the correct term, geothermal is when you get HOT water out of the ground) with AC reversing valve. Be sure your have a txv vs just an orifice for the heat pump, not familiar with waterfurnace specifics.
Leave a basement duct open in the summer and blow cooler basement air upstairs.
I'm confused on the Waterfurnace ... normally I associate that with a ground source heat pump system (including wells). These are great in many climates, but especially ones with cold winters.
Are you saying you have an open loop system that uses a well for the source and then dumps the water?
Not sure why you feel constrained on duct size. Supply air too fast will be noisy ... and potentially uncomfortable. Smaller ducts mean higher air velocity. High velocity on heating can be a big problem.
Thanks for getting back. Anxious for input but don't want to push it, since I've got a pretty unique situation.
The Waterfurnace heat system has been fantastic. On Lake Michigan shore in northwest portion of Michigan's lower peninsula. To your point 1, very cold climate with sustained northwest winds off Lake Mich.
Point 2: the entire house is on a well. One branch goes to the Waterfurnace GT heatpump system and the other branch supplies water to the house. Since I'm on Lake Mich short and sitting on huge aquafer (sp), I'm taking water from the well into the GT system then passing it right out to 100" of corrugated pipe, to flow right back into the aquafer. Have heard it called "pump & dump" fairly frequently.
Point 3, why constrained on duct size? The home is 2 circles, joined together, with a rectangular wing off the larger circle. The walls come in 8' sections and are manufactured by a company in Asheville, NC called Deltec. I put the tubes into the basement floor slab before it was poured, so that is my only current heat. The basement walls are ICF's. On top of the ICF's is the Deltec truss system. Plenty of room for plumbing supply, electric, etc. but no room for ducts. The 2 circles are joined together with a staircase from basement to 1st floor so the only access from one to the other is on each side of the stair case, with one sidie being lam beams, so no ducts going there. That leaves me 1/3 of the house to cool, with only 2 raceways in the connector. the raceways (between joists) are at the same level as the truss system that I cant get ducts through.
Phew!!!! I can't imaging that anyone is following that, so............. I'm really "duct challenged". All of this hugely complicated duct installation challenge is only needed to support 2 to 3 weeks of cooling, maybe slightly more from a humidity standpoint.
So, you have radiant floors in the basement ... and intend to have them upstairs in the framed floors ... for heating. I'm getting it. Single pass well water source serving your Waterfurnace (nice equipment BTW!). Now ... you want to consider cooling. I don't quite follow all the physical constraints that limit your ductwork ... but will take your word for it that there are 'issues'.
Sounds like you need to know/understand your cooling load so you can maximize your system.
Possibly time to get creative ... if only to get you off center to enable you to discover your solution to your problem. Sometimes if I brainstorm freely, I actually come back to a modification of a conventional idea ... or come up with a unique idea that will work!
You MIGHT do radiant floor cooling as well ... but I'd be concerned about condensation on the floor ... if you cool your floor down too much, moisture will condense on it. A lot depends on floor finishes. You also would need to limit the temp of the chilled water ... to maybe 65 deg ... not sure. I suspect Michigan to have hot humid summers, so maybe/probably not a good option.
Sounds like you have a unique house design/style. Have you considered exposed duct work? Done well, it can be really nice. A little bit of the modern industrial look ... without being tacky. It's trendy ... look around at some [well done] commercial applications ... it's amazing what you can get away with. Panted/unpainted spiral ducts installed well can become architectural elements in themselves. Eclectic.
Maybe enclose ducts into finished enclosures/soffits to hide them. Those enclosures become interior elements that can enhance other elements in your house. Remember, you aren't REQUIRED to bury ducts in structural elements.
Pipe chilled water to 'unit vents' or 'unit coolers' to the upper level (air handling units of any sort, really). Again ... ductwork (if any) can run exposed or in soffits. You could place a unit in every major space ... with little or no ductwork. How many spaces you got? No ductwork, but maybe too much money for multiple air handling units w/ coils in them ... maybe prioritize into just a room or two. Could plumb for all and only install a couple for now. Cooling coils may need a condensate drain ... coils 'wring' water out of humid air as a natural part of their process.
You could run high velocity ducts ... but at some point, you need to allow them to be larger to reduce velocity, noise, and drafts. Velocity and supply temp will go together. High velocity, you don't want it too cold or it will not be comfortable.
You've got a unique house ... you may need to think uniquely.
We're doing all radiant at our place also. Tubes in slab on first floor, staple up on 2nd floor and warmboard-radiators on third floor.
The idea of radiant cooling is really interesting for us. Here in the SF Bay area we probalby need AC like a month out of the year tops and its not really humid at all.
Can you tell me more about the ins and outs of radiant cooling?
thanks,
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
Frankly, I've really never seen radiant cooling. It's not really radiant cooling ... it would be more like simply removing some of the day time heat stored with high temperature (relatively) cool water circulation. I would think the SF area would be fairly humid. My house in Oregon, I planned to circulate water in the slab only during the cool of the evening ... e.g. to a coil mounted on the roof that would radiate to the night sky. I figure lowering my slab temp from say 75-80deg to say 65-70 would help the situation the next day.
Mind you ... this is somewhat conceptual stuff. Need to watch the possible dew point temp. It probably won't work very well on framed floor systems (I have 3 levels of framed floor, but was only going to cool the concrete slab zones).
If the dew point temp of the space temp and RH is below what the slab would be, it should be good to go. I really have no idea what the slab temp would be in our summers ... we get up to near a hundred for a couple of weeks. Does that result in slabs at 80 deg? If so, you can precool during the evening and bring the temp down to help during the day. I'm fairly certain that you could NOT cool the slab to say 60 deg and lower ... the typical range for e.g. cooling temps in air systems.
My system was intended to be more of a passive system ... circulate water during the night and dissipate the excess heat. If you actively cooled the water, you could run it during the day as well. But w/ mech. cooling you would really have to watch/control the water/slab temp to make sure you don't overcool it. What is the flooring finish on your slabs? That may impact this choice, too. Bare concrete and tile will probably work well. I'm not so sure about carpet or wood flooring over concrete.
Give you any thoughts to share? ... or are you rolling your eyes at this idea? Eh, you're a mad scientist, so this at least must tickle your curiosity. talk more later?
Yeah I'm a little confused also.
Your Heat system is radiant in slab?
Then the duct work does seam like a hassle.
PS
Geothermal is an accurate name for ground source heat pumps. It's been
argued to many times, and their really is no error.
Geo- Earth
Thermal- Heat
reply to Henley:
Heat system in slab originally intended only as basement heat source. I will be putting tubes on main level as well, when wallet can deal with it. In the interim, the basement slab does a great job of keeping the basment at 70 and the upstairs (main level) at 62 (minimum) when I arrive up north at midnight on Friday nights. Until I get the tubes upstairs, I plug in electric space heaters in main circle, small circle and master. When I get up on Saturday, I'm at 68+ upstairs. On Sunday I unplug (spaceheaters) and leave the GT system in the basement to keep it warm all week when I'm downstate working.
Duct work hassle. See my other reply. Major league PITA, given how little I need it. But honestly, if these (Waterfurnace) GT (units) do have A/C support I might be willing to invest more than payback, just to get everything out of this hugely expensive system. The 2 units (one 50K btu & one 30K btu - I think) don't have any blower equipment as yet, so I need to fully understand what is meant by "these units are fully Heat & A/C capable".
The other side of the issue is that I need to balance by "energy efficiency fanaticism" with some Dollar sense. No need to p... money away if you guys who know & understand all this shtuff think I'm throwing good money after bad.
I have gone overboard in all HVAC/Insualtion respects with basement ICF's, 20" of blown sticky cellulose in basement rim joint (if thats the right term), foam in the 2X6 walls upstairs, caulk in every external vert & horiz abutting 2x6, dropped ceiling at the entire perimeter of the house to maintian the 20+" of blown cellulose in the attick, all the way to the outside wall. Have made the whole place kind of an HVAC high end experiment.
So now it's time to reassess and decide is there an inexpensive reliable way to put wall mounted units in the 3 main rooms upstairs or do the duct work battles and finish a totally GT heat and AC system.
Terminology of GT vs. Ground source etc. ..... I've lurked around here on an off for several years. I have respect for those on every side of the arguements and don't really want to engage. Hoping to consider input from everyone, so I can move on with the experiment, whenever I can scrape up the green to go to the next step.
Thanks for your interest!
You need to contact Waterfurnace about your particular application. From what you seem to be saying, you currently have a unit without a blower and air exchange bonnet. How many cooling BTUs you get is ,maybe, listed on the unit, but check with WF about blower size and configuration. Remember these things are rated in output BTU/hr. Simply installing a high velocity or standard duct system on the unit could be very inefficient if the numbers don't match up.
How many cooling BTU/hr do you need?
What is available from the Water Furnace?
How mant BTUs cooling do you need in each room? That determins supply duct size and CFM. Your whole distribution system should be based on what you need in each room and the best sizing/configuration of duct needed to achieve it.
What about return air circulation? You need to balance each of those areas to achieve effective cooling.
You want to maximize the use of a very expensive system, but haven't bothered to do, or have done, the load calculations.
You have to start with those load calcs. to design an efficient sytem. Why pizz away good money on just a SWAG?
PSGeothermal is an accurate name for ground source heat pumps
Only for HVAC marketing weenies or the ignorant.
I'm with you. It is meant to make these overly expensive systems sexy.
But what harm is there, if it allows people to post
questions and be understood?
What kinda windows you using facing the lake?
Entire house has vinyl casement. Can't recall brand and don't have the file at this house. Think that they were "Hurd" but may be another brand. Did the research at the time (2001 so I'm a little foggy) but using the gov't rating system, these windows were the most energy efficient. Also did a 36" overhand around entire perimeter to limit summer sun exposure.