Technical data

3
1.0 general
1.1 general notes
These instructions are intended to assist the installer, commissioning engineer, maintenance engineer
and user with the installation, maintenance and use of the Midimat HT gas fired condensing boiler.
Please read this manual fully before commencing the installation of the appliance. RVR Ltd. Ltd shall
not be responsible for any damage resulting from failure to carefully observe the instructions given.
The Midimat HT must only be installed by persons deemed to be competent i.e. Corgi Registered. This
manual must be handed to the user following completion of the installation.
1.2 certification details
The Midimat Ht complies with all relevant European Directives and has been independently Certified to
comply with the requirements of prEN 483 for use in GB and IE with Gas Category II2H3P. (Natural gas
G20 @ 20 mbar inlet pressure, and Propane G31 @ 37 mbar inlet pressure).
The flue classification (depending upon the required flue option) is either B
23
, C
33
, C
43
or C
63X
.
PI. No: 0085/AR/0462
2.0 product
description
With modulating outputs of 44 to 220kW and 66 to 331kW the Midimat HT models 220 and 330 are high
output, floor standing, fully condensing boilers. Both appliances are suitable for either Natural Gas or LPG.
The Midimat HT offers ultra high efficiency and low harmful emissions whilst maintaining very compact
dimensions. Each appliance may be room sealed if required and is suitable for flow temperatures of up to
85°C and a maximum working pressure of 6 bar. The boilers include a wealth of enhanced operating
features as standard and create bench marks for their appliance class.
Fully modulating heat output
The output of each boiler is fully variable, modulating between 20% and 100% of maximum output
automatically, and instantly adjusts to match the needs of the system. The percentage of heat output at
any given time can be dictated by either outside air temperature, flow temperature, room temperature (or
a combination of each) or stored domestic hot water temperature.
Ultra high efficiency – fully condensing
The Midmat HT boilers are geared towards optimum operating efficiency and reduced fuel consumption.
Hot flue gases pass from the primary heat exchanger through the cool return water zone created by the
parallel downstream secondary spiranox stainless steel condensing heat exchangers. This principle allows
efficiencies up to 109% nett to be achieved under condensing conditions and results in the exhaust gas
temperature being at most only 10K above the return water temperature.
High quality materials
The use of high alloy 316L stainless steel for the Econox premix radiant burner and the Spiranox
condensing heat exchangers achieves excellent corrosion resistance, heat conduction and strength affording
long life and reliability.
Extremely low harmful emissions
At the heart of the boilers combustion system is the 5:1 modulating radiant cylindrical burner. The
burner is fed with premix gas and air, which burns almost without a visible flame. The heat of combustion
is released predominantly by radiation and the very low thermal surface loading guarantees low combustion
temperatures and extremely low emission of harmful substances.
The Midimat HT boiler releases <40mg/kWh NOx (28ppm DAF) and <20mg/kWh CO (19ppm DAF)
which is particularly environmentally friendly for a boiler of this size.