Slant fin as underfloor radiant heat?

Users who are viewing this thread

rbrtferry

New Member
Messages
3
Reaction score
0
Points
0
I am currently in the process of reconfiguring my 3/4 inch baseboard heat pipes ...to match the requirements of zone 1(bedrooms) and zone 2 (kitchen & cathedral ceiling LR). In one of the busy circuits, I was thinking of installing a length of slant fin heater directly under the center of the bathroom for radiant heat. I figured on putting in some sheetmetal first (to spread the heat) then sweat in the slant fin with the fins touching the sheet metal, then covering it with insulation, maybe a piece of foam board type, creating a pocket in the bay.

Anyone ever do this? I didnt want to get into a pex project at this time. I am a novice plumber but competent.
 

CHH

New Member
Messages
224
Reaction score
0
Points
0
Location
Denver, CO
I'd say that running 180 degree water as underfloor radiant heat would probably be a bad idea. Most (all?) radiant systems use lower temperature water. Barefoot on a surface that exceeded 120 degrees would "cause the subject to display signs of discomfort" or some such understatement for a rather dry laboratory description of pain.

You might get away with it if the 'heat spreader' had a pretty good air gap under the subfloor. There would be no need to use a slant fin radiator since the sheetmetal would prevent convection through the radiator.
 

BiffNH

New Member
Messages
27
Reaction score
0
Points
1
Location
Squam Lake, New Hampshire
I did this but did not use the sheetmetal. Instead I just put sections of the lenghts of the radiator fins under the floor between the floor joists in a serpentine fashion in the middle of the bathroom floor. I then placed my cement board and ceramic tile down. It works very well!! It is now 4 years since I built the bathroom and it was well worth the small expense and time. I fit foil-faced polyisocyanurate 2" insulation panels in between the joists under the radiator sections.
 

BiffNH

New Member
Messages
27
Reaction score
0
Points
1
Location
Squam Lake, New Hampshire
No - not expensive at all and efficient as well. The baseboard sections are in series with the 4 foot baseboard section on the wall providing immediate heat while the underfloor sections keep the tile floor warm and provides a longer heat source due to the thermal mass of the cement backer board and the tile. The water going through the under floor sections is the normal 180 degreee that goes to the baseboard unit - no tempering valve is needed. It seems to work very well.
 

BiffNH

New Member
Messages
27
Reaction score
0
Points
1
Location
Squam Lake, New Hampshire
The "pocket in the bay" is just the volume between the floor joists. In the bathroom that I have done this in had a full unfinished basement so access was easy when I plumbed it. I ran the sections of finned baseboard pipe (minus the finished sheet metal) in the middle of the first bay, turned to the next, back down it and then turned to the next and so on. I have about 5 sections of radiator pipe done this way. Hope this helps.
 

Leejosepho

DIY scratch-pad engineer
Messages
2,483
Reaction score
0
Points
36
Location
200 miles south of Little Rock
Website
www.nonameyet.org
I ran the sections of finned baseboard pipe (minus the finished sheet metal) in the middle of the first bay, turned to the next, back down it and then turned to the next and so on. I have about 5 sections of radiator pipe done this way. Hope this helps.

I am thinking about doing the same kind of thing for heating a 15'x23' second-floor room. I have found some slant-fin tubes (sans covers) that will give off 350 btu/hr/ft from 140* water at 1 gpm, and that makes a lot more sense to me than using PEX at about 1/7 of that output:

350 sq.ft. x 50 = 17500 btu minimum

17500 / 350 = 50 ft. @ $7/ft for slant-fin ($350.00)
17500 / 50 = 350 ft. @ $.5/ft for PEX ($175.00)

Am I thinking clearly here?
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks