central air/radiant floor heat, new home
| Posted in Energy, Heating & Insulation on
Hi everyone. I’m a first time user to any type of chat room, but was talked into trying this site for some much needed help. We are in the middle of a new construction, and even though we have a general contractor we are doing some work ourselves. We are installing radiant floor heat using a Utica Boiler but also want central air. Does anyone have any suggestions about the type of air handler we should use? We were looking into the Unico system because we liked the small ducts, but the complete system is more than we want to invest. Can we use their type of duct work with a different air handler?
Replies
Welcome to BT. You'll find a knowledable crowd here.
You'll find that most of the experts will want lots of information about your application before they provide answers.
I'd be interested to know what type of radiant floor system you have.
You also might want to try
http://forums.invision.net/index.cfm?CFApp=2
Just a search and browse through the threads will prove fascinating, and I believe there is lots of discussion of air handlers there, although alot of it is pretty esoteric discussion of the details hydronic heating of all types.
Our radiant floor heat is installed under the cement in the garage and basement. The main floor has open floor joists. This is the one part we have not tackled yet. We are to run the loops three inches below the subfloor, and are using the "ultra-fins". Then we will run insulation about three inches below that to create a pocket for the air to heat evenly. The main floor of the home is 1550 sq. ft. with the kitchen, living room and dining room being all open with a cathedral ceiling, height 16 ft in center. These three rooms total 775 sq ft. The main floor is the only section we want to air condition. We are holding off running the tubing until we decide on the a/c because we are afraid the duct work may create a problem. Our basement has a 9ft clearance, but if the duct work can also run thru the floor joists, we would like to save all our head room. As far as any other information on the radiant floor, this is the closed loop design, using a natural gas Utica boiler. We will be hiring an experienced contractor to hook up bioler and hopefully the a/c.
With all due respect, I would hold on a bit before doing the suspended tube/fin method, unless you feel totally confidant that your contractor (or are you the contractor?) has experience in a variety of methods and is convinced that the suspended tube/fin method is the best one for your situation. Did you have a heat-loss calculation done and know how many btu's your system will need to supply on a design day? Will it also perform well in the "shoulder" seasons..spring and fall?
Pros for the suspended system are less installation cost, but cons include higher water temperatures required, and especially in your case, potential interference with your A/C ducting.
At least look into (if you haven't done this already) aluminum heat transfer plates holding the tubing in direct contact with the subfloor. Lower water temperatures, faster reaction time, more space for A/C ducting, still relativly low installation costs given an experienced contrator with the right tools and knowledge.
Read a whole more about the advantages of plate installs here:
http://www.rpa-info.com/forums/Ultimate.cgi
The more I get into this, the more I realize that designing, installing, and operating in a really good radiant floor system is much more a balancing act than doing the same with forced air.
Yes, we had the heat loss calculated with all the windows & ceiling height taken into consideration for the loop designs. We are using a 140,000 BTU boiler which sounds like over kill but it will not only heat the house, basement and attached 26x28 garage but also a well insulated pole garage 32X60. We have a GC, but he has no experience with this type of system and did not feel comfortable handling it. We are on our own here, but are working with a reputable designer, and we will have the boiler hookup installed by a professional. All we did was lay the insulation and loops according to the design, and had them pressurized before the cement was poured in basement and garages. As I stated, we are holding off doing the sub floor until we decide on the A/C.
Sounds like an exciting project! Where-abouts?
Does the reputable designer have experience with heat transfer plates?
I'm thinking that with so many different heating requirements, you have opted for simplicity with 180* or so supply temps for all the buildings? Or does your boiler modulate and condense at lower temperatures? Your ultra-fin in the bays will probably handle that pretty well.
I would also be interested to know how you are relaying the heated fluid to the remote shop building, and did you also rough-in control wires for a separate sensor in that building? If your supply/return tubes are buried, what did you use for insulation around them? How long is the run?
I imagine you will be running propolene glycol as well?
We are located in north eastern Pennsylvania, but not so far north as Erie. We buried the suppy and return line to the pole building 4 ft. deep. The line was wrapped in double bubble then placed in a plastic pipe. We then wrapped this pipe with some sort of insulation sheeting but I cannot recall the name at this time. We also buried a thermostat wire along with the line. The building is 50 ft. away from the house. We will be using anti freeze in the lines. Looking back it definately would have been easier to use the supply line that is already in foam and made for this purpose; trying to save a buck but don't think it was worth the hassle. The one inch suppy line was not very flexible and kept trying to coil as we wrapped it with double bubble. Then trying to shove it/pull it thru the line with just my husband and I was quite a job. The pole garage will have its own zone, as will the basement,attached garage, bedrooms and bathrooms. Only the kitchen, lr and dr will be on the same zone. We also purchased the "hotline" indirect water heater that works with the utica boiler. Yesterday we met with our designer of the system and decided to go with the a/c unit in the attic. We were told all the pros and cons and decided we can prevent the possible problems from occuring. The unico system was too pricey.
I know all about trying to save a buck and finding out too late that it was a net loss in time and agravation.
Did you look into plate-type systems?
Sounds to me like you are on the right track. Let us know how it turned out.
The high-velocity systems work best with air handlers designed to do what the name implies...move air at higher velocities.
Unico puts out a good product (with the exception of their fiber duct). They're also the best known, as they spend the $$ on advertising and marketing. Years ago Unico used to be Space-Pak. Unico is a comapny that broke away form the mother ship.
Look into Space-Pak and Energy Savings Products. When it somes to dealing with non-HVAC subs, those two companies are a little less "stuffy" than Unico, and the literature for installing and setup backs that up.
Hi-V can be a DIY installation. You just need to adhere to the minimum length for supply and return duct runs, and not bend the ducting smaller than the recommended radius. That's all for controlling sound from air turbulence.
Each outlet is "rated" at supplying so many cooling BTUs. If you have a room that's right at the limit for one supply duct, it's often better to supply the room with two ducts runing at 50% than one duct at 100%. Restrictor plates make balancing the system pretty straightforward.
As to your RFH system...blow off the suspended setup that'll concume most of your joist space.
If your house is of average construction and not in an extreme climate, I'd bet that you can run a simple staple-up with no Al plates, with nothing more than RFBI between the joists, circulating 120-130 degree water. This would only use 2-1/2" of your joist space, leaving you the rest for your mechanicals.
If you still want the plates, run with them...and you can even make your own if you're up to the challenge. Still, I've only seen one installation where they've been required, and that was a RFH remodel with large volume rooms...in the Colorado Rockies...at an elevation of about 7500'...that had floor-to-ceiling glazing...and even then they were only needed within 4'-6' of the exterior walls.
Back the the original Q.
Look at Space-pak, look at ESP. Gotta say, I haven't peeked into ESP for a few years, I hope they're still around.
Did a quick search, here's ESP: http://www.hi-velocity.com/
Space-Pak: http://www.spacepak.com/
54334.1
From the archives I see that you have installed a Unico HvAC system and hope that you can help me. To complete my split level ranch home rehab I need to get rid of the large central forced air return. Since I also need to replace my present furnace and AC system anyway I thought of using something like UNICO or Spacepak. I've done a lot of DIY remodeling projects but not any HVAC. However, the higher cost of UNICO (or simillar) products requires that I do as much of the work myself as I can to justify replacing forced air. Any advice you can offer would be appreciated. For example, how to determine heating /AC requirements with these systems and where to place the vents. How much of the air handler, heating equipment and compressor is DIY friendly? Thanks.
Carlos
I remember those old threads. Some good info on them.
While I can't give you everything you need to know, you first need to run some numbers on your house to figure out, rom by room, the cooling requirements per room. There are programs online that will handhold you through the process.
Each unrestricted flow Unico outlet is good for about 2000 BTUs. If you need less than 2000 you put a restrictor plate on the line. If you need more than 2000 you run more than one outlet per room. Restrictor plates are 50%, 35%, and 15%. You donlt balance at the outlet, you ba;ance with a restrictor plate where the supply guct comes off the trunk line. Quieter that way.
Often times it's best to use more outlets than fewer. Reason...one unrestricted outlet is noisier than two outlets at 50%. Still, you need a minimum number of outlets per ton of conditioning. If I recall, Unico is 6 outlets per ton.
There are restrictions regarding the minimum length of the supply ducts, the ducts that run from the trunk line to the outlet. Too short and you'll get a lot of noise at the outlet. Too lng? With hi-velocity, it really isn't a problem as well as the system id balanced.
Same with minimum bend radii for the supply duct. Bend it too tightly and you'll get turbulence noise at the outlet.
The handlers are well made. I think a competent person could install the handler, the trunk, the supply ducts and the outlets. Bring in an HVAC guy for the brazing and coolant.
Not all suppliers will sell to DIY folk.
The Unico and Spacepak manuals do have valid and useful design and installation details in them. You might be able to acces PDFs of them online to see if it's something you're up for.
Used to be another company that was directed towards DIY installations. Very detailed directions, etc. I'll do a quick search and edit them in if I find them.
Edit: Couldn't find the other company. Thought it was called "Hi-V" and up in Canada.
Double Edit: Manual J the easy way: http://www.hvac-software.com/main.asp
Edited 2/17/2005 10:01 pm ET by Mongo
Edited 2/17/2005 10:04 pm ET by Mongo