Basic planning parameters for gas boiler hydronic floor heating systems by Devex Systems
According to Devex Systems , several factors must be taken into consideration prior to the installation of gas boiler-based hydronic floor heating systems to minimise installation and running costs.
These factors include minimum heated floor area requirement, manifold and boiler locations as well as zoning layout.
Minimum Floor Heating Requirements
Hydronic floor heating systems that use gas boilers must have a minimum area of 60m² – 90m² to heat, which is calculated based on the minimum boiler output. Gas boilers will have a ‘high’ and a ‘low’ gas flame setting while the boiler output will be based on the gas consumption at these two fixed gas settings.
Hydronic floor heating systems require a network of pipes, manifolds and controls. Devex Systems recommends one zone per room to ensure lower running costs and more control over comfort levels, though it may result in higher upfront costs.
Short cycling, resulting from heating an area less than 60m² can lead to serious problems with the boiler.
Gas boilers are designed to run for specific periods of time. Where their capacity significantly exceeds the heat load of the floor, the boiler will run on a rapid repeat ON/OFF cycle (called ‘short cycling’), which can cause significant damage to the unit.
Small areas such as bathrooms and en-suites must be heated as part of a larger heated area in order for the hydronic floor heating systems to run efficiently and economically.
Boilers are typically located inside or outside and mounted to the wall. When located inside, they can be flued out through the wall or roof. Keeping the fluing distance down is a very important factor in keeping the overall costs down.
Though typically located outside in Australian buildings, boilers are preferably installed in a basement or plant room because of better shelter from the elements.
Boilers are connected to the manifolds with fixed piping. It is important to keep the distance between the boiler and the manifold to a minimum to avoid unnecessary use of additional feed pipe and insulation, which can lead to higher installation costs.
Best located in a fairly centralised and accessible place including linen cupboards, kitchen islands, laundry cupboards, garages or next to the boiler, the manifold must be installed after considering height and width restraints.
Since the floor heating water pipes connect directly to a manifold, it is important that the manifold be located within close proximity to the heated area. The manifold not only has to be at the highest point of the areas connected to it, but it must be located within close proximity to those zones. A single manifold can service an area of 240m².