Metal flashing

donedeal

Do you think metal flashing below stapled up watts onyx tubing is good to help reflect/ disperse heat? Or is it absorbing too much heat rather than it going up towards the floor. There's prob a 1-2 inch gap between the metal flashing and tubing between the joists. Then FG below that. I'm also planning on foam boarding below that to create a nice tight seal. Just wondering if the flashing is causing more harm than good.

hot_rod

If the aluminum contacts the tube then it may move some additional energy via conduction. With thin gauge aluminum it is tough to get a good tight contact to the tube, and also solid contact to the floor. Even a paper thin air gap will lessen the energy transfer.

If you suspend the plates below the tube the intention is to reflect some heat energy up. the plates would need to be fairly shiny and stay that way to reflect. that rarely happens in a joist bay.

There is not a lot you can do to improve the heat transfer with bare stapled up tube systems, cranking the supply temperature may fudge some additional heat, but keep any wood in contact below 140F, especially wood products like plywood and wafer products, the glue starts to get weird at extended, elevated temperatures.

Good insulation below, as much as you can get into the joist bay. Seal the rim joists well with spray foam and rigid board foam 6, 8" or more. Looks for tube that was over stapled and would restrict flow. Also look for staples that do not keep the tube tight against the floor. A block of 2X4 is a good way to tighten loose sections.

Outdoor reset control on the system may help keep the system running consistent and allow the highest ramp up temperature on those cold days.

Do you have a room by room load calc? Some suggest 20 BTU/ft is about all you can expect from bare tube staple ups.

I did an experiment years back to determine just how well the tube actually contacts the floor in those rubber staple up. See here.

hot_rod

example of over, and under stapled tube. the staple should not distort the tube, and it needs to contact the tube.

donedeal

Awesome. Great info as always on this board thanks. We just bought the house recently and no load calcs avail at this time. How challenging of a job is it to add an ODR to a pre-existing set up? I would prob hire someone, not asking for specific prices but is this a high cost typically?

hot_rod

Impossible to answer without knowing what type of boiler and installation you have. Many of the newer boilers have this function already onboard the control. There are multiple aftermarket controls also.

See if the Find a Contractor button on this site helps, most all here understand and can upgrade as mentioned.

The RPA website also has some contractor links.

Do some homework so you can ask the right questions and be assured the contractor is on the same page.

I assume you are here because the system is under-performing. Is it just on the coldest days, or is it behind on any heating day?

Floor coverings make a huge difference in floor output, carpet and throw rugs are tough on radiant, especially the borderline cases. A good contractor should look into all that.

Usually the original installer has a design and load calc, Watts/ Heatway and their reps were good about doing the calculations. The local rep may still have those calcs or the files, that would help.
But the rubber didn't always meet the load, or road .

http://tekmarcontrols.com

HBXcontrols.com

donedeal

It's under performing in one room (an addition above a crawl space). I'm beefing up the insulation next week, currently the rim joists are uninsulated. I'm hoping that makes a world of difference but I like the idea of reaching out to the local watts rep and will pursue ODR since perusing the forum that seems to be a big efficiency factor. I have a triangle tube boiler.

hot_rod

There is a good chance that boiler has ODR already onboard. I'm not a TT expert, post a picture and model numbers, someone here will know if you have ODR function already.