24\" on center joists and staple up with heavy aluminum plates

Jeremy_14

Our company has used the wirsbo joist track plates for years and we have been very happy with their performance. I think one thing you might consider is how well the house as a whole is insulated. If this is a new house with foam or some other high quality insulation, then you could definately get away with two runs per bay. If it's an old house with drafty windows and fiberglass, I'd be nervous cutting back on the radiant runs.

Big Will

I have quite a few jobs with the thin plates and 16\" on center

But with the 24" on center joists I am inclined to run three tubes in each bay to keep my water temps down. This would mean a lot of extra work to thread the tube through the joists instead of pulling loops from one end. The other thought was the heavy aluminum plates that Wirsbo makes instead of the thin ones from Zurn and stick with two tubes per joist bay. Just looking for input on performance in this situation.

Also he has unfaced R13 bats in the underfloor I ran the numbers against R19 and this made a difference but I really want to use the Johnsmanville wrapped bats to keep air from moving through the insulation. I cant find any numbers about loss between a bat with a vapor barrier and one without. Its always nice to give the customer a number to support the opinion.

Jeremy_14

Our company has used the wirsbo joist track plates for a while and we have been very happy with their performance. I think one thing you might consider is how well the house as a whole is insulated. If this is a new house with foam or some other high quality insulation, then you could definately get away with two runs per bay. If it's an old house with drafty windows and fiberglass, I'd go with three runs per bay like you said.

Big Will

Decent insulation and new windows and doors

Also my design is 32deg outdoor and still less than 40K BTU for 1600 sq. Its northern California so not to cold. I have been told that the heavy plates greatly reduce the water temp over the light weight Zurn plates. I am using them for the first time in a radiant ceiling job now. This would be the first time as a staple up job.

hot_rod

still 1600 sq ft

with a 40K load is 25 BTU/ square foot. I'd still look at a 6 maybe 9" on center spacing. Maybe 4 runs per joist bay?

Extruded plates move the energy to the edges better than thin plates, less stripping. Plus the tube grip is much better with extruded. But it will cost a bit more. For that small of a square footage, why risk under performance.

No less than R-19 in my experience.

hr

Big Will

I looked at the c-dam. If I want to run 12" oc I would need 200' loops to keep it around 1 gpm per loop. I think your right two loops/four tubes per bay. 6" oc X 250'=.625 Gpm per loop. Sounds better.