Mitsubishi Electric ecodan ECOSLIM150L-PP-MEUK Installation Manual page 19

Heat Emitters
13
Underfloor heating
Heat pumps provide lower flow temperatures than traditional gas fired boilers, this means that the installation
conditions and heat emitters need to be managed carefully. These lower flow temperatures suit the conditions
required for under-floor heating systems and if installed and designed correctly can deliver a more comfortable,
consistent temperature whilst also increasing the efficiency. Some points to note when designing the installation are
• Room by room thermostats ensure adequate control in all rooms, interlocking of controls is essential whether
using multiple thermostats or not.
• Temperature difference across the flow and return should be less than 10ºC (5ºC for the Ecodan
• Use of night-set back instead of turning the system to off, reduces the desired temperatures by around
3 - 4ºC from their daytime levels if desired
• Response times from underfloor heating are much slower than radiators and therefore the property will take
longer to heat up initially, making this type of system less suitable for timed heating cycles
• Any additional radiators should be sized on the flow temperatures used for the under-floor heating, this
negates the need for mixing valves, which are detrimental to the efficiency
When specifying under-floor heating there are some important factors to be aware of, as rectifying mistakes will be
costly if not impossible.
• Bad placement of thermostats, where they are affected by external sources of heat or cold temperatures will
lead to poor temperature control.
• Under-floor heating circuits can produce high pressure losses. The pumps provided in our packaged systems
are capable of providing the necessary flow rates on averagely sized primary circuits, but with the inclusion of
under-floor circuits additional pumps may be necessary and potentially a low loss header to ensure the flow
rates remain high across the heat pump (heating and primary circuits in parallel to allow variable flow rate on
heating and constant flow rate on primary).
• The output (W/m
between pipe centres and resistance of floor coverings. If these factors are not considered at the design
stage then the output may not be sufficient at the desired flow temperature negating the benefits of using
underfloor heating systems.
Hydraulic Separators (low loss headers)
These are used to create a neutral point in a hydraulic system and can be advantageous for achieving separated
circuits with varying characteristics. For connection of multiple heat sources using FTC4 control systems Mitsubishi
Electric recommend the use of such items. They can also be utilised on heating circuits if for example constant flow
rates and variable flow rates need to be achieved on a single system. For further information and advice on the
selection of hydraulic separators please contact Mitsubishi Electric pre-sales technical on 01707 278666.
(continued)
) of under-floor heating is affected by water temperature, flow rate, pipe diameter, spacing
2
Pre-Plumbed Slimline Cylinder Installation Manual
®
).
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