Changing over to radiant, need guidance please...

CMadatMe

Joist Heating w/Plates

3/4" Tubing? 30 btu's sqft? Never. I use 3/8" pex with extruded plates. Been doing that since the days of RTI. That goes back 20 years. R-Value of 3/4" sub with 3/4" oak is 1.68 and generally need between 15 and at the high end 24 btu's sqft. With good extruded plates you do not have to worry about the insulation its our friend. No need for the air gap so you can insulate up against and to the plate. May I ask what you do for mixing water temp? Is is a set it and forget it with a thermostatic mixing valve.?



If I was a betting man your boss isn't scared of the plates he is scared of the price. If anything I would be worried about it not working the way you are currently installing it.

AFred

btus

When I say I design for 30 btu sq ft, thats how I size panels, fin tube, CIBB. What would I want for infloor under hardwood? Mixing valve set at 140*.



"If I was a betting man your boss isn't scared of the plates he is scared of the price."

I think you hit the nail on head. He thinks everythings exspensive untill you explain the benifits ie; man hours saved, or less call backs.



I should probly stop asking dumb questions and dust of the old wirsbo design guide, I think it ended up in the garage some how.



Thanks Chris

-Andy

CMadatMe

I Size

Doing a heat loss and providing the space what it needs. I don't ever need that high of a water temp. If I need above 125 it bothers me. 

AlexS

Make up water...

Every diagram I see shows the fill valve (expansion tank, backflow prev.) hooked into the primary system between the LLH and the circulator.   Is it possible to hook it in AFTER the circulator?   It would fit better on the wall if I could hook it in a foot or so past the circulator.  There's still a few linear feet of 1" copper for the water to mix in before the boiler, in case thermal shock is an issue

CMadatMe

Exp/Feed Placement

Should be piped in before the boiler circ. At this point you are pumping away from the point of no pressure change.

AlexS

I'll make it fit...

Does it matter if I Tee in right before the circulator... There's only about 8 inches of pipe between the LLH and the pumps isolation valve....

AlexS

No question here, but...

wow, this thing is cool.... Up and running, making hot water.  Now I can finish off the rest of my remodel and get the floor tubing in afterwards...

AlexS

Back with a dilemma

I unfortunately have to live here while I rebuild this old house, so it's getting done in sections.  My new floor framing wound up about 3/4" lower than where I need it.  Most things could be worked around, but the staircase now has a big first step...

I have a 3/4" Advantech subfloor in, and a pile of JoistTrak boxes waiting to be installed.  I was thinking of returning the JoistTrak and using a panel made by a local company here on Long Island called SunBoard to raise my finished floor height.  



They have 2 styles, both have the full aluminum sheet on top, like WarmBoard..  The first is a thicker aluminum formed into the grooves.  The second is a thinner aluminum and it's perforated over the grooves.  The tubing is pressed in over the perforation, pushing the aluminum into the sides of the grooves.  There's still a decent amount of aluminum contact with the tubing and the manufacturer claims it will still perform better than plates. 



I've spent so much extra for upgrades on this remodel and cant afford the more expensive version.  My choices are:

 A. Continue with the JoistTrak, adding a layer of regular plywood for about $500, and deal with the longer reaction times.

B. Return the JoistTrak and use the perforated aluminum panels for an overall added cost of $1000.



Is it worth the extra cost for the Sunboard, or would the extra plywood really not make much difference with JoistTrak?

STEVEusaPA

well it depends

First, what is your floor finish going to be.  If you use the panels then a floor finish, are you going to end up too high, relative to the staircase?  If not, I would use the panels.  You'll end up with a better job, it will be much easier to install the tubing and you'll use a lower water temperature.  Going underfloor, you'l have to penetrate 2 layers of plywood, plus finish floor (hope it's not carpet).  With the higher water temperature needed, you may get lots o' creeking from the tubing expanding and contracting.  Plus, when you install the second layer of plywood, glued and screwed (or nailed/staples) I assume, you may end up with the underside of the subfloor peppered with protruding screws (or nails/staples), making it even more challenging to get the tubing in.  And you risk missing a protruding fastener, but you're tubing will find it...yikes.

AlexS

hardwood...

Im using Ash hardwood for the flooring.  I'll be at the perfect height in the end by adding a layer of something between the existing subfloor and the hardwood.  No matter what, something has to go down... I just wasnt sure if the JoistTrak was still a decent choice for heating two layers of subfloor plus a layer of 3/4" hardwood. 



I've had a feeling I should change the gameplan and spend a few extra bucks for the panels... Has anyone heard of the type where it's a thinner foil over the entire board, and the tubing pushes through perforations into the groove?  I really am running out of money on this project and cant quite dig up the extra cash for the better line of panel with the aluminum molded into the entire groove.