Insulating a chase

4 floor (plus cellar) wood frame two family row house in New York City. All of the water (and most of the drainage) service above the first floor is served off piping in a chase approximately one foot by one foot (depending how it is framed out on each floor). The chase is framed by the essentially uninsulated exposed rear wall and on the other non-interior side it is against another vacant and partially gutted rowhouse (being held for speculative purposes) that is totally exposed and unheated. This was the condition for the past two years. Our pipes froze two years ago during a winter cold strech and that situation was avoided last year by having all the faucets on a slow drip and a slow leak forced in the toilet.

The water pipes in the chase are mostly galvanized steel and insulated only over a portion of their length. The drainpipe is cast iron. There is no to access the pipes to apply insulation or heat tape without tearing out the interior chase sheetrock walls.

I was wondering whether there was any way to insulate the interior of the chase via blown in other insulating techniques? Is this the kind of thing that a professional would do?

The basic principle with insulating in this case is to insulate between the pipes and the exterior walls, while leaving the pipes exposed to interior heat. If you simply fill the chase with insulation, yes it is insulating the pipes from the exterior cold, but it is also insulating them from the interior warmth. In this case, you might get away with it because the insulation is helping to retain what little heat there already is in the water. Assuming people use the water at night and then again in the morning, it may get you through the night on those cold nights. But if you go away for the weekend, you are back to needing to have the drips.

Best thing to do is figure out how to put insulation only between the pipes and outside walls. Depending on how tight the space is, you may be able to slide pieces of rigid insulation down the chase, figuring out how to minimize the number of access holes you need to make.

Ken