I have sold, trained, operated and supported a few ten of thousand VF htrs over the years. VF heaters are intended as supplemental and are not to be used as a sole source of heat. In USNY, you will be undersized at 30k btu in 1500sq ft. Looking at the Empire sizing guidelines for VF they put you in Zone 5 and give a 750 sq ft capacity on the 30's. Empire makes the best Infra-red and blue flame heaters today. Rinnai makes the finest VF made anywhere in the 824, but it too is undersized for you and you pay for the features.
In your case, during construction you will certainly have ample make-up air. Be aware that if you are doing any painting or refinishing whatever odors are airborne are going to go through the flame and I guarantee that they will come out smelling worse than they went in, much worse.
Are they safe? Yes, when operated properly. You will put moisture in the space when running them. In the cold NY months that is usually not a problem unless they are run in a confined space without proper ventilation. As dry as it get in NY this time of the year you likely will not notice the moisture in that sized space. Another key to success is to keep them clean. Many people get odors out of them due to dust/debris which accumulates on the burner surfaces and especially the pilot assembly. A can of compressed air with the tiny tube blowing straight down the pilot tube will clean the ODS pilot.
