Robert P. Amborsky P. Eng.
Sep 09, 2008
Investigative Report For Alternative Heating Systems Inc.
Heating Elements for Ready to Move Homes (RTMs) By: Robert P.
Amborsky P.Eng - March 10, 2008
Alternative Heating Systems Inc. wanted to know if under laminate heating elements could be used as the primary heat source in a Ready to Move home. A heat loss analysis was conducted on a McDiarmid Lumber 1,390 sq.ft. Creighton model ready to move home for Winnipeg & Thompson Manitoba conditions. Winnipeg is 70 miles north and Thompson is 542 miles north of the Canada/USA border. In all cases of this analysis, it was verified that the under laminate heating elements could be used as the primary heat source
Alternative Heating Systems Inc. (AHSI) is interested in introducing its Under Laminate Heating Element product (ULH) as the primary heat source into the Ready to Move (RTM) Home market. This interest is based on the assumption that there is enough floor area within a RTM to apply heating element and that the capacity of the combined heating elements would meet the heating capacity requirements for that structure. There are several benefits to the use of ULH in RTM homes; the RTM could be shipped with heating supplied, thus eliminating the need for extra heating related work being done at the RTM installation site; the ULH can be installed in a factory like environment thus insuring a quality installation and minimizing the number of people needing to be trained to do the install. AHSI contacted RPA Engineering Inc and ask it to prepare a heat loss analysis study on one RTM and report if ULH could be used as the primary heating device for that RTM.
Using HOT2XP version 2.74, an industry accepted heat loss calculation software provided by Natural Resources Canada the author compiled and entered the building configuration; wall, ceiling and floor compositions; along with standard assumptions for indoor temperatures.
RPA was provided with blue prints and specifications for a RTM manufactured by McDiarmid Lumber; model Creighton 2003. The home was models with two different foundations; full basement made from pressure treated wood and unheated crawl space. It was assumed for this analysis that this home was built with average air tightness. Refer to Appendix A for all detail input/output data.
The HOT2XP software has built in climatic data libraries and from those libraries the RTM was tested against conditions in Thompson and Winnipeg Manitoba. Refer to Appendix A for all detail input/output data.
The analysis was conducted with the main floor being maintained at 70F, basement at 65F and the unheated crawlspace at a minimum of32F to avoid freezing of the plumping system.
Table 1, illustrates the results of the four tests using the software mentioned above. The "maximum capacity" of a heating element installation would be equal to the total floor area of the main floor multiplied by the heating capacity per square foot of the heating element (12 w/ftI\2) which for this instance worked out to be 15.5 kW. The calculated design heat loss represents the maximum amount of heat lost to atmosphere based upon the climatic data for the region tested for. The Space Heating System Design Capacity is the value used to size a space heating system to meet the worst climatic condition plus a safety factor. The calculation for this value can be seen in Appendix A. Dividing the Space Heating System Design Capacity kW by the Max Capacity kW and multiplying by 100 gives us the % Main Floor Coverage required.
Heating System Capacity Requirements
Floor Area - 1,293 ft2
Heater Capacity - 12W/ sq.ft.
Max Capacity - 15,516 kW
For analysis purposes, all the ULH is assumed to be placed on the main floor and in both the full basement and crawlspace models, the Main floor ULH is responsible for maintaining the temperature in those areas. In real life some of the actual heating capacity would have to be moved from the main floor to the crawl space or basement.
As illustrated in Table 1, the ULH meets the Space heating System Design Capacity in all cases. In a real application some of the heating capacity or additional capacity should be installed in the basement and crawl space to maintain the design temperatures.