The Agricultural Heating system is primarily used as a central system dedicated to the generation and distribution of heat to multiple agricultural buildings and grain drying applications. The use of coal or biomass (primarily wood chips, wood pellets, MSW or agricultural residue) for agricultural heating applications has increased significantly since the first systems came into operation. Many communities across Canada and the USA have chosen to embrace Triple Green Flame Stoker™ technology to lower their heating costs and reduce their impact on the environment. Solid fuel biomass combustion systems used in agricultural heating system applications are more complex than fossil fuel combustion systems and generally require additional components beyond the simple combustor/boiler system. The heating system components must be carefully integrated to ensure successful, trouble-free operation. Although not used in all systems, the main agricultural central heating system components generally include:
Heat generated at the central boiler room is transmitted to individual buildings as hot water (or steam) in a closed network consisting of two pipes (supply and return pipes). Heating pipes are laid in the ground, usually at a depth of 4 to 6 feet. The pipes have thermal insulation that prevents heat losses. Various types of piping are used for heat distribution. Steal piping has been used by contractors for many years but other types of piping (fibreglass and Pex) are becoming more popular in recent years. The advantage of using fibreglass piping is reduced labour cost, reduced friction losses and no corrosion to the pipe. On an average, heat losses in the distribution network account for less than 3 per cent of the energy transmitted in the pipes. The water circulating in the pipes releases its heat to the individual buildings via the use of hot water unit heaters or fin pipe loops and/or in-floor heating configuration. In addition hot water used for washing down the barns is available through the use of plate heat exchangers. The return pipe conveys the water back to the central heating boiler plant for reheating. The temperature of return water from the individual buildings to the central boiler ranges between 15 and 30 °F. This project was set out to demonstrate the viability of linking up the central hot water boiler system with number of existing agricultural buildings and grain dryer. A network of underground insulated fibreglass pipes was used to connect the hot water boiler to hog barn, chicken barn, turkey barns and grain dryer. The primary circuit is a 180ºF temperature water (160ºF return), with constant flow, and medium pressure (20 Psig) system. During the grain drying season the supply water temperature is busted to 200ºF. The fibreglass pipe is suitable for use at temperatures of up to 210ºF and pressures of up to 150 Psig. The selected pipe is oxygen diffusion-proof. The insulating material is a closed cell non-absorbent foam with densities over 2 Lbs.