Joist Bay heating

ERF

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Anybody use fin tube as a heat emitter in floor joist heating, and does it work? </span>

furnacefigher15

I've seen it.

Usually they have a good amount of air space between the sub-floor and the fintube.



They also generally run a little hotter say 140 ish



It can be effective with good insulation underneath.



I've never seen a area more then a bathroom done this way.



I personally have never done it though.

kcopp

I have seen...

pictures of it done that way.... not cheap. It would have to be insulated well.  You could try ultrafin instead.

nugs

Joist bay

I have seen it done and it does not work particulary well because the fin tube needs air flow across it for maximum efficiency and ideally the aluminum fins should be in complete contact with the sub floor which is going to be hard to do.  Better to go with pex and plates

The Steam Whisperer (Formerly Boilerpro)

Lots of systems....

installed in the in northtern illinois in the  50's used fin tube above the ceiling and then blanketed with insulation.  These systems work just fin.  They require higher water temps, so basic boilers are a good choice.  I think the boiler and complete system were a package sold by Allied? or some other local maker.

Steve Whitbeck

Fin tube

I do it all the time.

Install the tube with the fins about 1/2 inch clearence to the underside of the floor.

If it is a 10' long bay I put  5' of fin tube. I put the fin near the end of most heat loss.

If it is an outside wall I keep it 1 ft away from the outside wall and install three ft at that end and then 1 ft away from the other end if it is an inside wall I install the other 2 ft. with copper pipe in the middle. Use about 1/2 the amount of fin for the length of the bay - do every bay or you will have cold spots. Works better than PEX and is silent when it heats and cools. give it room to expand at the ends. You need to put good insulation under it but not touching the fin. Try to make the bay air tight if you can. Don't just insulate under the fin but the entire bay because the heat will travel and fill the whole bay.  I have done large area this way. It takes more time to install but the trick is it is silent if installed properly.

Paul48

insulation

Could you elaborate on the insulation Steve. I have an area for that. Thanks

Mark Eatherton

I deg to biffer...

Or is it beg to differ... Whatever.



I had a bunch of eager students build a test rig for me once up at RRCC, and heres what they found.



Regular fin tube painted flat green put out more heat than regular fin tube, but not as much as plates with PEX, but more than bare naked PEX by  LONG shot.



The good old days...



ME

ERF

Fin Tube

Steve do you run the tube in a serpentine pattern from bay to bay or a reverse return configuration? 

Steve Whitbeck

Fin tube

I install it as a serpentine loop from bay to bay. It has to be on a seperate loop all by itself with a seperate thermostat. I use silver foil insulation under the fin and then put fiberglass under that - You have to have more R value under it than over it.

It costs more but as I said before it is silent if installed as I said. And it will be cheaper to install than Pex and heat plates covering the full run. I have done this for 36 years and never had a problem. The fin tube will put out more heat than the floor can radiate. I have done 20 X 20 rooms this way on one continious loop. still only had 20* delta T. It is important to try to seal the bays to stop airflow past the insulation.

Alan (California Radiant) Forbes

Fin-tube

I've never done fin-tube, but am impressed with Ultra-fin:



http://www.ultra-fin.com/



It needs a 2" air space above and below with R-12 insulation.



I'm in the middle of my first Ultra-fin job right now, but have seen others and it works.  I like the idea of one run per bay instead of two with accelerator plates.

Steve Whitbeck

Noise

The problem with any system that uses PEX is the expansion and noise.

ERF

A big THANK YOU

to all that have responded to my post.  Will be installing this type of system in a front entry way with a marble floor, that is as cold as a morgue, to the touch.  I think it was an after thought to heat  this area with only one hot air vent in a fairly large area.  The fortunate part that iis closed off to the rest of the living space.

Installed Gasification Boiler in winter 2008-2009 to reduce dependence on expensive oil based hot air furnace. Not a fan of hot air heat. The system works exceptionally well using water/air HX in furnace plenum  Some pictures of boiler set up