From UB's links:
Use insulating tape and wrap it over the entire length of exposed pipe. You can also use flexible molded pipe sleeves. Cover all valves, pipe fittings, etc. with insulating tape or fiberglass. We do not recommend electric heat tape for insulating water lines.
I never can understand why people think just insulating pipe will prevent freezing without a heat source inside the insulation. All insulation does is retard the flow of heat, not eliminate it. Piping installed on the warm side of building insulation has a heat source of course, but a water line simply wrapped with insulation does not. An insulated pipe will still freeze, just more slowly than a non-insulated pipe. What may make people think this does work is that
IF the line is flowing, new water is constantly being added which makes up for the heat loss through the insulation. Bare pipe looses enough heat to freeze even with flowing water. However if there is no flow, an insulated pipe will freeze. The smaller the pipe, the quicker it will freeze. This may work acceptably for a well used line in an location where temperatures drop below freezing only part of the day. But for a remote line where it can be consistently below freezing for several days in a row, the pipe will need a heat source.
I agree that heat trace is less than ideal, and it is a matter of
when not
if it fails. If there is any other possibility such as running piping on the warm side of building insulation or a heated chase, that is the only way to go. This is similar to a sewage lift station - if there is anyway to gravity flow it should.
The only time I design with heat trace is for systems that are expected to be shut off in the winter, but where the fall/spring can still require water service and experience
occasional freezing conditions. Cooling tower make up is one example (although there are usually ways to avoid exterior piping there as well). If heat trace is used, it must be insulated to keep the heat in.
Unfortunately, I am not sure that OP is a violation of 305.6. Heat trace is a source of "heat". This section makes no mention of reliability of that heat source. If there is a way to run the pipe on the warm side of the insulation it should be (why is the insulation on the ceiling in the first place, rather than as rigid insulation above the deck as is common with bar joist buildings). I would understand if you used the "because I said so" clause to make 'em do so.
