Full Description

The demand after World War II for more freezer space with sub-zero temperatures resulted in many heaved floors. The installation of additional insulation did not solve the problem of heaving. It was determined that in order to control the heaving, that additional heat must be added to the substrata.

Various methods were used to introduce this heat, such as electrical heating, grid piping, heaters and pumps circulating various kinds of liquids. Two types of underfloor ventilation to add heat were used; one system using blower fans to add the energy under pressure. The system this paper discusses is a gravity air system for under slab heating to prevent heaving. The salient points being the importance of sub grade compaction, to eliminate moisture accumulation, thus preventing ice lens growth, which is the main heaving force. Ambient energy becomes the preferable heat source as utility rates spiral.

Citation: Symposium, ASHRAE Transactions, Volume 87, Part 2, Cincinnati, Ohio