A boiler needs makeup water, which means a connection between the building supply and a closed loop of hot, often chemically treated water.
Whether it is a health hazard comes down to what is in the loop. Treated boiler water carries corrosion inhibitors and conditioners that nobody should drink. An untreated system is a lower classification — but "untreated" has to be true and stay true, and a system that gets treated later without the assembly being reconsidered is a real and common problem.
A boiler also generates backpressure by design. Heat expands water and the loop is pressurized, so the system can push back toward the supply without any help from a pump.
Scope on this one: we test and repair. Assemblies inside the building are not ours to replace — that is licensed plumbing work — but a failure is far more often a rebuild than a replacement, and rebuilds we do on the spot. The device types, and where our work stops.
Schedule a backflow test or call 970-835-9661