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| 03/10/2006 9:27 AM |
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I'm prepping to build a 1200sqft addition (with a 1200sqft basement+garage) onto a 1000sqft house. I've been wanting to use radiant heat for comfort and health benefits including retrofitting to the existing house when I remodel it and replace all the flooring.
I have a few questions i'd like to clear up.
- can an electric flash heater be used or are there electric boilers available rather than having to add natural gas to the home?
- for the sandwich construction everything I've seen has used plywood. why not use gypsum wallboard, could even just lay the sheets down and router all the pex paths and then lay sheet aluminum ontop after the pex in is place. as far as filling the gaps it should work very well, but how about for its thermal properties?
- do area rugs reduce the effectivess of the floor heating enough to create cool zones?
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Davee
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Posts:25
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| 03/10/2006 10:01 AM |
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can an electric flash heater be used or are there electric boilers available rather than having to add natural gas to the home? The price of electricity for heating suggests you look at the natural gas. Legalett have electric in floor heaters as well as water coil units.
I have a fuel comparison spreadsheet if you want to send your E -mail address. It allows different efficiencies & current prices of oil electric,propane& Natural gas to be compared.
do area rugs reduce the effectivess of the floor heating enough to create cool zones? Not to any extent - the floor underneath will just get a little closer to supply temperature
1200sqft addition (with a 1200sqft basement+garage) -- have a look at Legalett for the addition - very easy to install & use your existing hot water tank as the heat source! http://www.legalett.ca/Index.htm |
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Unregistered
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Posts:2321
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| 03/10/2006 10:19 AM |
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part of the reason I'm asking about electric is that the cost of natural gas is potentially going to double in my state this year, but electric is stable.
Oh and I forgot to ask.. are the under subfloor setups really that inneficient compared to the dry above floor systems? it really would make it easier atleast for the older portion of the house.
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Davee
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Posts:25
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| 03/10/2006 1:44 PM |
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| Is electricity going to stay "stable" if Natural gas doubles ? I read that Natural gas was stabilizing also? Where does your state get its power? |
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Unregistered
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Posts:2321
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| 03/10/2006 4:28 PM |
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Maryland has a few nuclear plants and atleast one hydroelectric dam, coal is a backup power plant source also-
I'll probably end up using natural gas and install a gas fireplace while I am at it.
anyone have an idea on the possability of gyp board in the sandwich construction instead of more plywood? scoring and snapping off 7" wide strips is a lot easier than ripping down plywood (and cheaper)
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Unregistered
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Posts:2321
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| 03/10/2006 4:43 PM |
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what about the underfloor extruded plates like this
http://www.houseneeds.com/shop/Images/extrudedplatesinstalled2_xlarge.jpg
aren't those almost as good as the above floor methods?
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mattmarbos
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Posts:3
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| 03/10/2006 9:24 PM |
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Watts-Radiant has an EPDM tubing call Onix. It can be stapled to the underside of your subfloor and no plates are needed. The tubing is more expensive than pex but once you add the plates and labor it is actually cheaper to install and much faster. The Tubing is much more durable than Pex and will give you more residual heat than Pex. Another method would be to use Gypcrete ( light weight concrete ) over pex tubing. The gypcrete will give you a good thermal mass and even temperatures. www.wattsradiant.com for info
MDM |
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Unregistered
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Posts:2321
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| 03/11/2006 10:01 AM |
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I definately like many aspects of the Onix tubing, everything from the flexability, UV resistance, to the simplified termination/fittings that don't require the special crimp tool but normal band clamps.
does anyone have any information on the efficiency of using onix staple up as the primary heating?
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Unregistered
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Posts:2321
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| 03/11/2006 10:03 AM |
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to clarify - all i'm really trying to do is be atleast as efficient as standard forced air - but with the added comfort/allergy relief of the radiant floor
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Unregistered
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| 03/13/2006 1:35 PM |
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have a plan of action now, just want to see what the experienced people think about it..
underfloor staple up
double foil bubble insulation attached directly bellow the pex
then spray foam insulation of about 3-4 inches under that (closed cell r-7 per inch)
should minimize air space and radiant heat loses - as well as upgrade all the insulation of the existing house and be an easy retrofit without having to tear up the floors for sandwich or having to use the expensive heavy plates
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Unregistered
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Posts:2321
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| 03/13/2006 1:40 PM |
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for the heat source i'm planning a Trinity wall mount natural gas boiler with domestic output
what I haven't quite figured out yet is how many zones I want..
-garage
-basement
-main floor laminate wood
-main floor carpet
-main floor tile
seems to me each of those might require a seperate mixing valve.. or can they be run at the same water temperature?
Thanks for all the help
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Unregistered
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| 03/13/2006 1:58 PM |
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I also thought of using the heat plates only in the carpeted areas to compensate for their more insulated nature and run all the zones at the same temp.
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Davee
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Posts:25
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| 03/13/2006 5:20 PM |
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-garage
-basement
-main floor laminate wood
-main floor carpet
-main floor tile
I would think two zones & plates to help under the carpeted section if it is to be a large sq ft of the main floor The garage & basement could be one if you plan to use the basement sparingly . I heat my lower level to a "base temperature" & boost quickly with a small electric heater when using the room. The radiant heat is typically slow to respond so the base temperature ensures I waste less heat when not using the room. Radiant does little on its own to reduce heating costs so get a highly efficient boiler or hot water tank |
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Unregistered
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| 03/13/2006 8:43 PM |
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thanks for the feedback - i like the idea with heating the basement to a base temperature.. I may not even heat the garage with radiant floor - I was actually concidering something that would heat it much faster like baseboard or something like that.
the boiler I have my eye on now is a natural gas unit rated at 98% efficiency - should blow my current heatpump with electric backup out of the water. as well as replacing my 20 year old electric domestic water tank.
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NRT.Rob
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Posts:386
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| 03/14/2006 12:52 PM |
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Some basic answers:
Plywood is used for sandwiches because you have to allow for installation of finished floors on top (say, holding screws or nails firmly for tile backer, wood, etc).. you need it to be firm.. and you need it to withstand getting wet unless you have antigravity to fight spills and leaks ;)
Simply laying aluminum across the top is not that useful. You want good contact between aluminum and pipe.
Onix has its place, but it's staple up, which means it's weak output at higher water temps. It is more powerful than PEX stapled up, as it can deform and gives better subfloor contact, but staple up of any kind stinks, really, IMHO. suspended tube, if a weak higher temp radiant method is appropriate, is a better choice... less chance of heat striping.
Rugs can really mess with you if you aren't careful with their selection. Depends on your zoning and loads and installation methods.
If you're using a Trinity, try to keep your water temps down. Do a one-temp system and eliminate mixing, run it at condensing temps, you'll have a nice system.
Skip the reflective foil under the staple up, just focus on sealing and R-value. IF you are using plates, no airspace needed.
Extruded plates under are almost as good as light plates over. Extruded plates over, of course, are even better, but we usually only use those in high load areas and use lights elsewhere when we're over the subfloor.
-=Northeast Radiant Technology, LLC=-
www.NRTradiant.com |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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| 03/14/2006 9:03 PM |
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thanks for the help rob..
you mention suspended tubing, is that just pex with no plates?
and what determines if that sort of system is appropriate? a combination of local climate and the homes heat loss characteristics?
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NRT.Rob
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Posts:386
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| 03/14/2006 11:09 PM |
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Suspended tube is tubing hug about an inch off the bottom of the subfloor in a 2" airspace. You basically get some radiant to the subfloor and a heated plenum, using a convective air current around the pipes to transfer heat. It's a bit weaker than Onyx stapled to the subfloor... about the same as PEX stapled to the subfloor... but true staple up bare tubing is an installation method that has fallen out of favor with everyone except Onyx distributors, basically. You simply don't get enough lateral transfer from the pipe to get a nice even floor surface temp with it stapled right to the subfloor. It does heat, however, to some degree. Not saying it doesn't work.. it just doesn't work *well*. Of course that word *well* means different things to different people.
When I'm figuring out how to go in terms of an installation method, I look at several things. Heat load, floor coverings, usage patterns, climate/solar gain/other heat sources, building usage, heat source, other heating systems connected to the heat source.. lots of things.
For instance, if you have an existing baseboard system and want to add floor warming to your first floor... simple cheap suspended tube is fine.
If you have a new house with very low loads, I may skip radiant floor altogether.. the floors won't be that warm.
If you have a modulating/condensing boiler, I'd just through serious hoops to avoid doing a two-temp system, and I'd want to keep all the temps low. Not "as long as possible at any cost", but "as long as can be achieved for modest cost increase".
In some homes suspended tube is ok. I myself have used it in homes with very mild climates, or in superinsulated homes in warmer climates. But I do find it's pretty rare that it's the best choice from any vantage point.. by the time your loads drop to the point where it works well, you might as well skip the floor ;) Or, you can run it at very high temperatures, in which case you might as well have a baseboard system from an efficiency standpoint. And hope your construction quality is as good as you think it will be... for a long time...
-=Northeast Radiant Technology, LLC=-
www.NRTradiant.com |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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| 03/15/2006 7:16 AM |
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i've been searching the net for a while and thats some of the most helpful info yet.
I'm comfortable finding and installing boilers tubing etc. but when it comes to the control system, setp, and knowing which type of heating to run I'll probably have to go with a pro. I may be contacting your company soon for more info.
I had looked at the possability of using some of the newer styles of baseboard heating, they don't look as clunky as the stuff I grew up with. And I noticed on here there has been a sizable amount of talk about radiant ceiling heat.. seems to me that radiant ceiling heat would feel about the same as forced air without the airflow.
do you still need plates for radiant ceiling?
have you ever done a mixed environment using hot water baseboard in carpeted areas and radiant under the wood and tile?
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NRT.Rob
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Posts:386
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| 03/15/2006 10:20 AM |
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There are about a thousand ways to skin the heating cat.
Radiant ceiling is still radiant... think sunshine. You do use plates to transfer heat to the drywall. However, you are usually running at 16" o.c. and may not have to cover the whole ceiling.. since you're not walking on it, there is no issue with even surface temps. Much cheaper that way and still low temp and very effective in most cases. Not likely you'll want to throw a rug down on it later.. that's nice :D but it won't heat the floor like a radiant floor would of course. Depends on what you're looking for.
You can do baseboard/radiant hybrids, but you have two choices when you do that: either try to get all temps in the same range, which means either using radiant panel radiators instead of baseboard w/low temp radiant, or use baseboard w/high temp radiant. OR, do a two-temp system, which means adding mixing hardware and running the heat source at a higher temp.
As I noted, I'd usually jump through a few hoops to avoid a two-temp system if possible. With the mod/con boilers out there these days, it's pretty attractive to do one-temp low-temp.
-=Northeast Radiant Technology, LLC=-
www.NRTradiant.com |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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Unregistered
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Posts:2321
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| 03/15/2006 3:12 PM |
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hmm - thats really helpful info for making the sytem more affordable
for the carpeted areas i couldn't care much less if it was radiant floor or not - carpet rarely feels cold - so radient ceiling or baseboard would be a good option for me on those areas..
i really want radiant floor in the tile bathrooms to keep them comfortable even at night.
I would like to have the radient under the wood floor (24x28 livingroom over the garage and connecting hallways) but other hypoalergenic system would be acceptable.
since the basement is going to get poured I may as well make that radiant floor, the garage I only want to heat on the ocassions that I need to work on the car in it so something that heats up faster would be nice.
the other factor is half the house is existing retrofit - the other half is under the design/permit phase, the wood floors will span the existing and new, which might complicate underfloor heating.
does your company design and sell essentially customized kits? or only installs?
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