Seeking radiant heat in enclosed porch advice

van_2

You should look into radiant ceiling in addition to the radiant floor. This give you more surface area so you can get more heat into the room than just the floor. Same idea as on floor with PEX and plates. Another alternative for the ceiling is electric radiant heating panels. Very responsive so you don't always have to have them turned on. One brand is Solid State Heating Company in CT. They come in many sizes for either 120V or 240V and many output (BTU) ranges and they don't look half bad. If you place them over where people will be, they do a great job of making folks toasty.

Anthony Ferrer_2

Seeking advice on radiant floor in enclosed porch

I've been told on other forums that this is the best place for advice on this subject, so here goes:
I'm in the process of enclosing our porch. It's attached to the building on one side and has windows on the other three walls, as well as 4 skylights. The entire porch sits 9 feet above the ground and there is nothing under it - all outside space. The walls are 2x4 construction, the ceiling is 2x6 and the floor 2x8. I'm having the walls and ceiling insulated with spray foam and want to use hydronic radiant heat in the floor. The floor is 3/4" tongue and groove fir laid directly over the 2x8 framing which is on 16" centers. My plan is to put 1" foam on the perimeter joists, 6" fibreglas insulation below the radiant tubing (between the joists)and 1" foam board under the joists. It's the actual tubing and how to maximize heat transfer that I have questions about. The job is going to be a staple up, as the finished floor is down and I have access from below. I've read in other forums that you absolutely must use a radiant barrier like Super R and that the radiant barrier does absolutely nothing. Wood isn't good for radiant floors and that I should tear it up and pour a concrete floor and wood is just fine for radiant floors. Aluminum plates are unnecessary and absolutely required. You can understand my confusion. I'm assuming that something to improve transfer is needed. I got a quote from Radiantec which spec'ed 8" tube spacing and aluminum plates. Their estimated heat requirement is 10,000 BTU, though, and the system would produce 8,500. I'm looking to see if there's any way to improve that. 6" tube spacing? Better heat transfer somehow? Some other improvement on the system?
Here are some drawing of the structure. Any advice would be appreciated.
Thanks,

Timco

Wirsbo joist trac. 1/2" tube snaps into the trac nice & tight, and makes a great transfer to wood floors.

Tim

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Weezbo

sounds like you definitely need more going for the space

than some tubes in the floor....

like you i am not inclined to belive everything i read. the devil is in the details as it were.

hyopthetically speaking i might be inclined to

1. install heavy plates with 1/2"

2,add some means to further drop the heat loss Window Quilts...something to slow the radiant out to atmosphere.

3 designe the BTU output of the floor with the idea of lower temps and less reliance on it alone..maybe a rad panel or some radiant wall...


as a thought.

realolman

I have a 12 x 12 sunporch with three sides 3/4" baseboarded. It's very nice. You'll like it.

The reason for my reply is Weezbo's mention of window quilts. I think that would be an excellent thing to have, but boy are they expensive.

Jeff Lawrence_25

Where are you located?

If you're in the southern part of the continent, the heat requirements won't be as high as it would be if you were in Canada or Alaska. That plays an important part of the requirements. The internet company you speak of may not have done an accurate heat load on the sun porch.

If putting tubing in with Joist Track (as other people mentioned, as really great idea) isn't enough to overcome the cold air, you may need supplemental heat, such as panel radiators.

Sbergerson

Insulation under tubing

I would install aluminum joist plates to increase heat transfer as mentioned above. I would also consider using spray foam insulation in the joist cavities as well as the walls and ceiling. This should decrease your heat loss and air infiltration even more, not to mention ensuring all the heat from the tubing goes up to the floor.

Anthony Ferrer_2

Thanks for the input

Forgot to say that I'm in Northern Westchester, New York state. I wanted to use radiant instead of baseboards because the room is going to have window seats around the three sides with the windows and I didn't want the radiators sticking further into the room. Now that I'm thinking about it, though, I suppose I could build the baseboards into the window seats. But would that be any more effective than the floor heat? I don't want to spray foam into the floor joists in the event that I need to access the tubing. What are window quilts? Is that a type of window covering?
Thanks,

realolman

window quilts

http://www.1windowquilts.com/

Uni R_2

Window Seats?

Why not run the heat through the window seats and use them as the heat emitters? What temp range does the rest of the system use primarily?

Anthony Ferrer_2

Cast iron window seats...

...would probably get too hot to sit on and would probably be too heavy for the floor to support, so you must mean something else. How would I do that? I'm thinking that I would build a recess into the window seat and put radiators, either cast iron baseboards or slantfins, into the recess. Would that provide more heat than the radiant heat in the floor? The rest of the system is cast iron standing radiators and they run at 150170. If I used just the heating element of a SlantFin type radiator, forgoing the large and (IMHO) ugly metal box, I could use a lower profile recess. That would also probably be the least expensive option and I could then also spray foam the underside of the joists since access wouldn't be an issue. Amount of heat remains the issue. If I go with radiant floor or SlantFin (what is the generic for that, anyway?) it needs to have a separate zone, so the temp of the rest of the system won't matter. Or how about a toe kick heater such as this? (VRV QUIET-ONE Kickspace Heater) http://www.plumbingbyaspiremart.com/proddetail.asp?prod=KS2004&from=
Thanks,

Anthony Ferrer_2

Thanks for the link. Since we just installed all those windows to provide light in a rather dark house, something that covers them would not go over well with the wife.

Uni R_2

Simpler

Leave about a 6" airspace under them and run some 3/4" copper under them. I think the responsiveness would be good if you spend winter mornings there with setback, otherwise just 3/4 black iron in some pattern. Not quite sure of the heatloss for black iron.

realolman

I'd just do it at night...no way in the daytime. They're not the best looking things but...

If you look at their infrared photgraphy, it's kinda impressive

Rit Roberts_3

porch heat

I have found that a sun porch, such as you describe is a very difficult area for successful radiant heat. Because of the large exposure to the cold (three side walls, ceiling and floor) you need a great deal of tubing and plates to get enough heat. The more restricting factor is the amout of glass. The glass has a great deal of loss on cloudy or dark days and tremendous gains on sunny days. These large gains and losses do not lend themselves to the slow response of radiant. I think you will be more comfortable with fin baseboard or convectors. They will heat up quickly and cool down quickly.