Should I be worried about what I am observing and hearing (radiant heat install in process)?

I don't see markings on the pipe are the oxygen barrier PEX? If they are barrier pex, rub a tube against the wood joist, if they squeak, they will make a lot of noise when runnig. For this type of setup you want oxygen barrier pex with an outside PE layer, ie non squeaky pex.

I would second the Ultrafin option for this type of retrofit. Works great and comes with all the bits and pieces to keep the pipes at the right location and away from nails. It also means much lower supply temperature which is good for efficiency. Plus you only need one pipe run per joist bay.

"air sealing of the joist bays is critical to performance" This should be highlighted. Air sealind doesn't mean stuff some batts at the end but either sealing with spray foam or with rigid foam board sealed in place with canned foam. Without proper air sealing , this type of setup will not provide much heat (been there, tried it, didn't work).

For insulation you want regular cheap batts. Shiny bubble wrap doesn't do anything, just looks good, it is really equivalent to R2 of insulation. I know it feels like it should but at temperatures here low enough that this "reflective" bit doesn't matter.

Without knowing exactly how much heat you will be needing above that floor I hesitate to make a blanket statement, but having retrofit my own old house and done some other design/install of floor radiant heat, this install is NOT going to work for anything beyond some minor floor warming. Even with a high water temperature and a correctly sized air cavity above the correctly installed insulation below, you will not be satisfied. Just for starters, the heat will not be evenly spaced on the floor and you will have warm and cold stripes.

Also, the higher the water temperature in the tubing, the more movement of the tubing which will mean noise as it slips back and forth through the holes in the joists and past those half-clip tube supports. Those are not the correct support for this type of installation.

This install is not even close to correct for Ultra-Fin either. I've installed that product too.

I don't know how the contract is drawn up, but stop this job immediately until you can be shown the design criteria for the job, how it is supposed to work and the operating parameters of the system. I don't know everything about floor heating but I know enough that this install at best will not work well and maybe even not at all.

I have seen floors running that hot start to smell. In one case the asphalt impregnated paper used under the old narrow strip hardwood started to emit an oil smell as it got hot. It was a direct staple up, similar to what you have but attached to the floor.

One of the things that I remember from selling PEX for radiant floor heat was in a seminar that I attended by Wirsbo who conducted it about 30 years ago. When you are using suspended tubing in the floor joist the way that you have it, or the way that UltraFin is designed, you are creating a heated plenum using the floor, the Joist and the insulation below the tubing. What many installers forget about is the end caps of the joist space. At each end of the joist bay there is a 14"x 8 to 10" box plate on the exterior wall and there is a 14" x 8 to 10" opening at the center support that is often forgotten about.

If those ends are not sealed properly, air can enter at one end and exit at the other end, as a result of the higher temperature in the joist bay. This will create a convection current that will remove the heat from the floor and end up out into the walls or outside, thru wiring holes and unsealed seems. Before you place the bottom insulation in the joist bay below the tubing, you MUST caulk all the wire openings, all the corner seams, all the end caps at the box plates and place insulation at those exterior box plates in order to seal the plenum tight like a refrigerator door gasket. Then you install the bottom insulation. Then you caulk the bottom insulation to the floor joist.

Can you count on your contractor doing that? You want to see how that floor joist cavity is sealed before you let them put the bottom insulation in place. Once that is done you will not be able to see the cut corners that might happen.

Not goint to comment on the heating, but… there is one picture which shows 8 closely space holes drilled holes with about 4 feet of the end of a joist. That joist no longer has any real safe load capacity, and will take a rather fancy sister UNDER it to restore strength…

I would highly recommend the aluminum extruded plates. They provide a solid grip on the tube to avoid the squeaking of the tube moving in thin aluminum plates.

Thin plates can also make an “oil can” pop sound as they expand and contract.

Most of the radiant tube manufacturers offer the extruded plates.

But, the load calc will answer all the questions on what installation method is best for your application. There are a number of load calc programs online. A free demo at www.hydronicpros.com of the load calc I use. If you want to try one yourself.

https://radiantdesignandsupply.com/new-page

Any number of holes as long as they are near the center and spacing between them is met as per Hotrod's earlier picture. LVLs are a different story, so if they ran pipes through a beam, that can sometimes be problematic.

From your pictures, I don't see an issue with the drilling of the joists but always good to get a professional to check it.

Grinding nails is ugly work and never perfect. This is my earlier recommendation of the Ultrafin install, simpler and it also keeps the tubes away from future errant nails.

About the only thing you need to do is a bit of air sealing around exterior rim joists, not a big job. A couple of sheets of 1.5" rigid insulation, cut it into squares about 1/4" smaller than the joist end space, foam it in place with canned foam. You don't need to air seal around the interior. If you are using faced batts for bellow the joists (easiest to use), staple the batt and facer to the subfloor near the interior walls. This somewhat closes the end off and limits airflow.

Your dual pipe install can still be used with ultra fins. What I have done before is split the UF pair and put one half on each pipe with the fin pointing towards the center. You'll need more turn keys to do this.

Make sure to confirm that the existing pipe is oxygen barrier pex. If not, remove and start from scratch.

I hate to see shavings coming off the tubing, but to be fair, it happens. I literally take my knife and remove the sharp edges of the hole before pulling it in, but I am paranoid. Those scrapes (unless really severe) will not compromise the strength of the pipe but it is removing a bit of O2 barrier. After system has been in operation for a while it makes dark spots on the tubing evey place the O2 is getting in. The damage to the O2 barrier during install is one reason pex systems still get more O2 into the system than good old copper/steel systems.

As someone who has done floor heat for years, I still do staple up on a typical room on almost all jobs. The bath on the outside corner or the sunroom will get plates. On a typical job I am happy if my design temp is 140* and some jobs it is a good bit higher. You may say 110 would be much better and more efficient! Sure. But seriously, the $1000s that joist trak will cost to add to a whole house will not be recouped in savings for …. what… decades??? If doing plates on a floor with nails, use the extruded style because the tubing snaps in the underside of plate thus the tubing won't be pushed against the old nails.

As others have posted, you must know what all layers the floor consists of. If you take a shot in the dark, expect to miss sooner or later.

If you use HTP , you must grind off any protruding nails thru the subfloor. I use the following grinder and wear eye protection when grinding. You can buy this grinder for peanuts at Harbor Freight stores. Cheaper than a pack of cigarettes in New York city.

https://www.harborfreight.com/5-amp-4-12-in-slide-switch-angle-grinder-58092.html

My house has gone through two generations of radiant—20 years ago was staple up. 12 years ago was the sandwich. Anyway, when you grind, you'll get some smoke in the home (burning some wood) and you'll have burn marks everywhere. You really want the nails inside the wood, or at least flush. It's not a fun job but if you just put your nose to the ground, it goes pretty quickly.

Or if you still own a pencil and eraser, here is another free download

All of these various load calculators are based on the Manual J from ACCA, so results should be similar