Drywall dust and other construction debris can do terrible things to a forced air furnace, leaving the new homeowner with what is basically a used furnace that may neither performs as intended nor last as long as it should.
As a result, the Heating, Refrigeration and Air Conditioning Institute of Canada (HRAI) is urging all furnace manufacturers to revise their furnace installation manuals to prohibit gas furnaces from being used in construction heat, effective Sept. 1.
This has been a major concern for the HRAI and it’s member manufacturers, wholesalers and contractors for over 15 years, reported the HRAI in a position paper released Jan. 29.
Until 2000, the Canadian Standards Association (CSA) did not allow forced air furnaces to be used for construction heat. Some manufacturers specifically prohibited the practice in their installation manuals while others did not, leading the CSA to revise its gas furnace standard to allow it if certain criteria were met.
The Technical Standards and Safety Authority (TSSA) in Ontario realized that this was in conflict with the Ontario Gas Utilization Code and subsequently, on Feb. 1, 2000, stated that gas furnaces could be used for construction heat where it is permitted in manufacturer’s instructions and where manufacturers have issued letters of authorization to inspectors to allow it.
And that’s when the problems began. A significant number of HRAI members voiced concern that contractors and builders were not, for the most part, complying with TSSA’s advisory and new homeowners were, in fact, getting a used furnace.
Manufacturers and contractors were also subject to a number of issues resulting from the poor condition that the units are being left in.
Onus on contractors
HRAI received a request from the Toronto Residential Air Handlers Group asking manufacturers to change their position and not allow furnaces to be used for construction heat since it quickly became apparent that builders were not taking on the responsibility to ensure the furnaces and ductwork were cleaned and put in good operating condition. The responsibility therefore fell onto the installing contractors.
Cleaning the heating systems proved no small task. Once drywall dust accumulates in the furnace the secondary coil becomes clogged and it is necessary to pull out the entire heat exchanger in order to do a proper cleaning which, HRAI has been told, was not being consistently performed in the field. It was also agreed that the inspection process becomes difficult since, in order to determine the amount of cleaning necessary, it becomes quite extensive and involves more than a quick look.
In fact, the entire blower assembly would have to be removed, taken apart and put back together. This procedure would typically take two hours to complete.
Another key concern is that the stated efficiency of the furnace would be difficult to reach, not to mention the state that the ducts would be left in upon occupancy if the homebuilder did not clean them.
High efficiency issues
Since 2010 only condensing gas furnaces with a 90 percent AFUE rating or higher can be sold in Canada. High efficiency units have a secondary heat exchanger, unlike older models with only a primary heat exchanger. TSSA staff, at that time, stated that it would be much easier to enforce the fact that the furnace could not be used as opposed to inspecting it to see if it met certain criteria.
In the fall of 2015, once again the Residential Heating Ventilation Contractors Association (RHVCA) reported to HRAI that the proper procedures were not being followed consistently in the field when using gas furnaces for construction heat. They once again called for a prohibition on the practice.
HRAI received an overwhelming response from manufacturers and contractors over the past several months who agree that such a prohibition is in the best interest of all manufacturers – a position endorsed by the HRAI Manufacturers Board in November.
HRAI officials note that homebuilders have alternatives such as natural gas and propane heaters, enforcement does not always seem to be taking place and the criteria for proper cleaning procedures is really not feasible. HRAI is therefore asking manufacturers to revise their furnace installation manuals to prohibit gas furnaces from being used for construction heat effective Sept. 1. While it’s a relatively short timeline, it will allow manufacturers sufficient time to revise their instructions and inform the industry.