What kind of radiant coils?

Hydronic is considered a whole house system, an expensive but much admired alternative to baseboard or other types of heat exchangers.

Electric elements meant to be installed in kitchens and baths to take the chill off but not provide 'whole room' heat are also expensive but beloved.

It's not clear what you are asking. Are you asking if it is possible to install flooring over radiant heating coils or are you wondering about adding radiant heating coils to your family room?

I'm asking if anyone has radiant/electrical coils under hardwood, how they like it, etc. We have carpet now, and were thinking about coils and hardwood. Wondering if it would keep this big room warm, we have a wood burner and want to quit using it.

I have electric radiant under a tiled bathroom floor. The bathroom is over a crawl space. It was a DIY job and we like it a lot. The floor is nice and toasty under foot now in the winter. I doubt it gives much ambient heat to the room, but you can get 220V radiant heat that is more suitable for raising room temps (ours is 110). Since the bath is only 15sq/ft we are going to add to the existing thermostat to heat the walkway areas of our adjoining kitchen which will have solid red oak floor on top. The manufacturer of our heating coils says they can be used under hardwood, heres how:
On top of your subfloor, you attach 3/8 or 1/2 inch wood sleepers, spaced by the width of the heating mat (typically a foot and a half), after you lay the mat between the sleepers, you cover with self-leveling compound up to the level of the sleepers and let cure. When you nail your hardwood, you make sure you nail into the speepers. I have some worries though about the uneven direct heating of the hardwood floor given solid wood's tendency to shrink and expand. So even though I still plan on doing it, and the radiant flooring company says yes, stiill t scares me a little.

Now it is much less complicated if you want a floated or glue down installation. Follow the recommendations of the various radiant floor heating companies.