Packy?
I posted earlier but didn’t see it go through are you back?
Hope all is well after your procedures.
Godspeed.
Joey Massapequa Long Island NY

although most of my friends were not happy that i survived because i am a yankee fan, i am here and still rooting for the bronx bombers. thanks joey..

Packy,
Not sure if you remember me, you helped me out immensely prior to COVID probably like 3 years ago, I had "a guy" who thought he knew about installing radiant, and reconfigured my setup to add a zone to existing boiler (most of my house is radiators hot water) while the tubing install appeared to be correct at the control end/boiler side he wound up using cold water (supply) to the mixing valve instead of Tee-ing into the return water to mix, to make matters worse he tapped off the cold water supply before the pressure regulator which caused my pressure relief valve on the boiler to open, to remedy this he put in a check valve! which didn't have any effect on the system so I just shut the valve off and that's when I found this site, which was a godsend. I also (on my own) smoked the aquastat by applying line voltage to it, shame on me. You suggested, actually told me to throw the guy out of my house and diagnosed all of my issues and resolved everything. I can't thank you enough for your help.
I am getting ready to perform a kitchen renovation and going to add to the radiant manifold, "my guy" had me purchase a 7 circuit manifold, to which we only utilized 2 circuits for my small room that I put the radiant below prior to the mud job for tile floor.
I am in need of your help once again, here's the breakdown of the job.

Radiant loops- I am considering using 3/8" tubing, I know this may not be ideal but I am concerned about floor heights as the area is my entrance door as well as a sliding door that leads to the outside from the kitchen. overall it's 2 rooms, entry is at Living room and flows into the kitchen, my plan is to demo current flooring in Living room (all hardwood flooring) and the kitchen (stick down over lineoleum existing floor) tile guy paper and lathe and then I come in and lay down the loops, tile guy comes back muds over radiant loops, thinset and tile. overall tile job is 530 square feet, including under cabinets which to my understanding doesn't need the radiant placed under, not sure where you stand on under cabinet heating.
Everything takes place over a partially finished basement to which I can reach the current manifold by drilling through the subfloor as a pathway for the tubing.

First question that comes to mind, when drilling through the floor I first thought that making that transition through the sill plate at an exterior wall, gave it a bit more thought and came up with drilling directly through the subfloor on about 45 degree angle and just feeding the tubing through the floor so as not to have the pex transition through a 90 degree connector within the tile or behind a wall through the sill plate.

Second thing is I have a 1/2" manifold and not sure if this would have any negative effect on pressure or heating now that I would have to put a 3/8 x 1/2 reducer on the manifold.

Third thing is the current zone of radiant in my den (slab on grade that my "guy" installed 3 years ago) controls the manifold, and I have only 1 single control for this zone, question here is, would I just make the kitchen and living room (the den zone is 4 stair steps down from my kitchen) control the whole radiant loop system? Add manifold zone valves to the supply only side of the Den system (requiring only 2 zone valves)
Again if I were to just stick with leaving this all on the same zone considering we use both areas equally (kitchen and den) and with regard to temperature would it be better to leave the thermostat in the Den or the one in the kitchen? Not sure about the whole heat rises issue that might come into play here as I also have a fireplace in the Den so during the winter we usually will put that on when coming in from outside or basically just for ambiance (gas fire place, I ain't trying to deal with the wood and ashes!)

Second part of the job and equally important is moving the plumbing, not the water, the water is pretty straight forward, its the drain waste issue.

My sink is currently positioned close to my vent and drain its on the exterior wall but is in a corner, the new position of the sink remains on the same exterior wall but is moving about 5-6 feet to the left and will have a window right above it. Now here I am having some issues mostly with this I looked at this a few different ways but cannot get over the fact that at some point I will have to drill through a king stud I have read about this and there are all sorts of equations for how much stud can be cut out etc. I was thinking about drilling a hole from the outside of the house directly in the center of the sill plate which is a 2x8 and running the drain (would 1.5" or should I use 2"?) from the outside through an open bay (floor joists) in the basement securing it where I can get to it (as there is a drywall ceiling above in this portion) and maintaining a pitch down it would go across the whole house about 20' where I would have to tie it into the 4" main so I would 90 long sweep down this down, cut the cast iron and put the drain into here not sure if I would use a sanitary Tee 4" x 1.5"
I was also going to vent out directly outside into a soffit above my kitchen window.
The other method would be to retain the current DWV which would require piecing together or notching every stud to get to where the drain is, and probably have to add in a vent due to distance?
Another method would be to notch out the bottom of the cabinets (my wife would kill me) and pitch to the existing.
your feedback is greatly appreciated. I can take some pictures of everything as I am sure that would help as well.
Lemme know what you think,
And hope your doing well.
Joey

Joey...

when you think about seperate zones for radiant heat you have to remember the slow response time once the floor has cooled down. my inclination would be to just pipe the circuits and go thru a season to see what it's like. you can always add those screw on zone valve/s at the manifold and wire them accordingly.
[www.watts.com]

as for heat rising from the floor, this doesn't happen with radiant because the floor temperature is approx. 85-90 der F..

no heat under cabinets. but if they are on an outside wall then you need a thermal break (piece of styrofoam) between the in floor tubing and the cold sill.

i have no problem drilling thru king stud. they make metal brace to restore the strength.
[factorydirectsupplyonline.com]

Packy,
Thank you once again, any issue with 3/8” tubing for the radiant? Now the piece of styrofoam, should I be placing this on perimeter of exterior walls throughout? And about how wide are se talking? 3” butted against sill plate? Obviously will be thick as 1/2” +\~ 1/4” depending on mud job.

as long as you can get manifold fittings for 3/8 tubing, i have no issues with it.
i have only done one mud job and it went smoothly.
yes, you will need a thermal break all along the outside perimeter.
my memory tells me it was only 1 inch wide strips of 1 inch styrofoam butted up to the sill. my job had a 1 inch slurrry poured all over the floor in a couple of rooms. BTW, it heated very well.