Hot water heating boiler consisting in cast aluminium elements each directly connected to the same lower (inlet) and upper (outlet) manifolds. Elements (from two to seven, depending on boiler size) are contained in the same frame but each of them has its burner and its electronic card controlling combustion.

Is it a Modular boiler?
If so, is it required each module (above named element) to have its safety valve and pressure gage? Since there is no valve from the modules and the manifold the safety valves and the pressure gages may be positioned on the outlet manifold. In parallel, one besides the other, it seems a nonsense. Is it possible to have only one safety valve of the capacity for the aggregate modules and one pressure gage only.

It is not a modular boiler. Actually each element is not independent because if all are switched off and only one is fired the pressure would raise on all elements and the temperature would raise as well. If it is not a modular boiler one s.v. and one pressure gage fulfill the Sect. IV requirements.

Any comments.
Mauro