Navien Combi Water Heater
At first glance I was taken back a little by the material being used in this water heater system. I have never seen black rubber hose being used in a in-floor application. It was not only the rubber hose being used but the size of the hose, 1/4" Id just does not seem like a lot of surface area to me for in-floor.
Existing Black Rubber Hydronic Hose
The black hose simply pushed into the copper pipe to make a manifold, the pressure of the system keeps its sealed. My research concludes that 45psi is the max these connections could hold back. We are running 12 to 20 psi.
Older Combi core HWT
Here you can see the older Combi-Core water tank that was used to heat both their domestic as well as there hydronic heat. The mixing valves being used appeared faulty and both expansion tanks where bad.