Radiant system with no expansion tank or relief valve

Inspecting a house today in VT with a radiant floor system running off a tankless heater. The system first off appears to be an open loop with no distinction between dhw and radiant in floor water (plate exchanger or indirect tank).
The system also does not have an expansion tank nor a relief valve. To me this does not seem to be correct. Am I wrong?

Did you see a pipe style hammer arrestor? Any system without a TPRV means have a plumber check this system out.