Replies

1. 
   experienced | Dec 01, 2005 02:09pm | #1

   Go with water. Then you can always use the cheapest fuel to generate the hot water. Or does elctricity dominate because of your location? Is there talk of any future LNG there?

2. 
   NRTRob | Dec 01, 2005 05:52pm | #2

   I'm a wethead, for the reason experienced noted; you have flexibility of fuel. Also, I think tubing will last longer than electrical cables, and you can always use an electric boiler if you want to use electricity as a fuel.

   However, I have a hard time imagining that there is much of a load in hawaii. At low loads, radiant floor, while still very efficient, isn't very warm to the touch. If a toasty floor sensation is what the clients are looking for, they may not get it. This can be changed with floor minimum temperature sensing, or perhaps the load is bigger than I imagine from up here in the frosty north, imagining palm trees and bikinis ;)

   -------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com
3. 
   vinniegoombatz | Dec 01, 2005 08:33pm | #3

   go with tile      wood over radiant should be quartersawn or rift & quartersawn so it doesn't crown up in center of floor boards like plainsawn will    white oak is best wood stabilty wise, need humidifier     just looked at floor over radiant, used plainsawn white oak    this stuff crowned up a quarter inch, house izza mess

1. 
   NRTRob | Dec 02, 2005 03:42am | #4

   was the moisture content of the wood watched prior to installation?That causes problems whether you use radiant or not, if the wood isn't installed properly.-------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com

1. 
   vinniegoombatz | Dec 15, 2005 02:28am | #5

   just saw thiz   wood was in howse for two weeks because of concern over radiant heat and checked with a meter   the installer is a good company, but didn't know about using vertical grain goods above radiant

1. 
   ndege | Dec 16, 2005 02:38am | #6

   What is your experience installing radiant into older homes using one of the retrofit systems? I don't know the brand names, but most seem to use PEX and a reflective backer. Do these retrofits work well?

1. 
   NRTRob | Dec 16, 2005 06:15pm | #7

   depends on a lot. There are 3 basic ways to install pipe in joists.One is suspended in a 2" air cavity, or its basic equivalent stapling against the subfloor. subfloor stapling has fallen out of favor though as it promotes heat striping and isn't that good for the floor. This method is weakest in output and highest in water temperature, and lowest in cost.The second way is using lightweight aluminum diffuser plates to conduct heat to the subfloor. Better in output, lower in water temps, higher in cost.The third is to use heavy gauge aluminum diffuser plates for conduction. Very good output, low water temps (usually), highest in cost.What you need to do depends on your loads and floor coverings. With all methods, skip reflective insulation and use an appropriate R-value insulation below the assembly. Also, even with the heavy plates there is only so much radiant can do, so very high load areas (high BTU per square foot of floor requirements) may still require supplemental heat. All that said, retrofit installation is definitely a pain in the butt, but I work with clients who do it all the time. It takes time and takes work, but can result in a very nice system. If you're striving for efficiency, think about your envelope first (insulation and windows) before you think about your heating system though for an investment of this size. If it's a comfort addition, great!Heat load calculations are a first step toward any major radiant installation. Without one, you're flying blind.-------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com

2. 
   ndege | Dec 16, 2005 07:04pm | #8

   Thanks for your thoughts. I was chatting with an HVAC guy on a job site who'd used a product called Ultra Fin (spelling?) and was sorely disappointed. I'm thinking about retrofitting my 100 year old house. Are there any good web sources for doing my own heat load calculation? I plan to work with a contractor but I like learning about other trades.

3. 
   johnnyd | Dec 16, 2005 07:11pm | #9

   The best free one I've seen so far is available for download at:

   http://www.weil-mclain.com/

4. 
   NRTRob | Dec 16, 2005 07:39pm | #10

   just remember load calcs are only as good as the operator.. garbage in, garbage out. And heat load calculation on a room-by-room basis is not an exact science unless you're ready to do blower testing, thermographic imaging, etc... it doesn't have to be exact either, but knowing what your reasonable assumptions are is important. Infiltration rates is the big X-factor. If you want to be sure of that, blower testing is usually pretty cheap.-------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com