High-efficiency boilers

photo High-efficiency boilers


Boilers now available on the market are much more energy-efficient than older models. If your boiler is 15 years old or more, or needs to be replaced, it is highly recommended that you acquire a high-efficiency boiler: condensing boiler or low-temperature boiler, in Category A.


What is a Category A boiler?
• Energy efficiency ratings, generally indicated by a letter from A to G, are available for boiler equipment. These ratings indicated the energy efficiency of the boiler; category A boilers are more efficient than those in category B. If you replace your boiler, be sure to choose a new Category A boiler. Energy efficiency ratings are not mandatory, but are used on a voluntary basis in a number of countries.
Quality labels applicable to boilers
• The main energy label used in Europe was introduced with EU Directive 92/42/EEC. This label applies to hot water boilers fired by liquid or gaseous fuels. Make sure that your new boiler achieves 90%, or even 95%, energy efficiency, according to the terms of this directive.
• In the United Kingdom the marking "Energy Saving Recommended" (label scheme managed by the Energy Saving Trust) indicates a Category A boiler.
• Many new boilers in the UK have a SEDBUK rating (SEDBUK = Seasonal Efficiency of a Domestic Boiler in the UK). The SEDBUK rating label resembles the EU energy efficiency rating scale applied to home appliances, from A to G.

What is a condensing boiler?
• Condensing boilers are identical to non-condensing boilers, except that they have larger heat exchangers to extract more heat from combustion gases.
• With larger heat exchangers, condensing boilers are more efficient than non-condensing boilers.
• Today's models achieve about 90% efficiency, putting most condensing boilers in the high-efficiency category A.
• The most recent generation of condensing boilers are called modulating condensing boilers, more efficient than non-modulating boilers.

What is a low -temperature boiler?
• A low-temperature boiler is designed to operate with a water temperature below 40°C (conventional boilers operate with a water temperature between 70°C and 80°C). Low-temperature heating systems have lower heat loss in the distribution circuit, lower no-load losses, and are more efficient.
• A low-temperature boiler installation involves changing the water distribution circuit and radiators, because these elements must be sized to match the boiler. This type of boiler can be installed only when major renovation work is done at the hotel.
What other boiler alternatives can be considered?
• Solar and biomass-fired boilers can be good alternatives to conventional boilers.
• An installation comprising several stage-fired boilers instead of one large boiler can also be a good choice. A large boiler that often operates below full capacity will certainly be less efficient, while a stage-fired boiler offers the option of operating only some of the boilers, lowering the time that a given boiler operates below full capacity.

Organisational aspects
• Group rooms open to guests in heated zones of the hotel,
• Lower heat in rooms that are not occupied,
• Choose programmable thermostats to set temperature limits, to avoid overheating by customers,
• Program lower set temperatures after 10 p.m. (or earlier) to benefit from heat accumulated during the day,
• Air rooms for no more than 15-20 minutes when cleaning, to retain heat,
• Salt, laundry detergents, paints cannot be stored boiler rooms, and drying laundry a boiler area is strictly forbidden.
Maintenance and operations
• The boiler and boiler room must be clean and well aired. A dirty environment can create problems, increasing soot in the boiler and augmenting energy consumption (2% per mm of soot). Regular cleaning and a fresh air inlet are essential.
• Boiler maintenance: At the end of the heating season the boiler must be inspected by a cleaning technician, and the burner checked by a qualified technician; combustion efficiency must be measured every two to four years. The inspection reports must be visibly displaced in the boiler room.
• Boiler cycles of at least 6 minutes: If the boiler cycle is too short the start-up losses will be too high, soot deposits will build up and CO2 emissions will be high.
• Heating regulation: An outdoor temperature probe for preregulating temperature, combined with a thermostat, ensures efficient heating. Regular verification of temperature settings and functions. Make of note of settings for high and low tourism seasons, and for winter and summer.
• Boiler operation : If the boiler operates fewer than 2,200 or 3,0000 hours a year, it may be set at an output level that is too high, causing it to heat too much. Lower burner fuel injection.
• Verify circulation pumps. If the pumps are too powerful too much hot water may circulate, consuming a lot of electricity. Rule of thumb to determine how much hot water should be circulating: the temperature difference between hot water leaving boiler and return water is at least 15°C
for low-temperature radiators, 12-15°C for conventional radiators, and 8-10°C for underfloor heating.
• Insulate hot water pipes Particularly in the basement: insulation thickness should be appropriate to pipe diameter, 3 cm of insulation generates notable savings.
• Set thermostatic radiator valves: All radiators and underfloor heating should be equipped with self-regulating thermostatic valves, particularly in south-facing rooms. Thermostats should generally be set at 20°C, and 16-18°C for rooms not in use.
Boiler replacement
Installing a high-efficiency boiler when a heating system is rehabilitated or at the time of an expansion project can generate substantial energy savings and help protect the environment.
A number of heating improvements, for heat production and distribution, qualify for energy savings certificates. Among them:
• Low-temperature and condensing boilers • Insulation of heat distribution piping
• Heat pumps (electric and gas) • Gentle heat radiators
• Thermostatic valves
The list of all standard energy-saving operations that are eligible for certificates under the ECS scheme can be found on the French ministry website www.developpementdurable.gouv.fr/-Operations-standardisees-.html


What are the steps for choosing and installing a new boiler?
• Given the technical complexity of this operation, we recommend that you consult a qualified installer for advice on the boiler best suited to the specific needs of your hotel.
What are the steps for choosing an installer?
• Installer certification schemes are in place in many countries. Contact the specialised energy agencies and/or professional associations in your country to obtain information on existing certification schemes.
• In the UK gas-fired heating systems must be installed and serviced by a heating technician registered with the Council for Registered Gas Installers (CORGI). Liquid and solid fuel systems must be installed and serviced by a member of the Oil-Firing Technical Association (OFTEC) or the Heating Equipment Testing and Approval Scheme (HETAS) respectively.
What are other points to be examined to ensure that the heating system at my hotel is efficient?
• If you install a condensing boiler, the installer must make sure that the rest of the heating system is designed and operated in a way that does not cause boiler temperature to be too high. The efficiency of a condensing boiler depends on the temperature of return water; if the return water is too hot, condensation will not be sufficient.
• Thermal regulation of the boiler is an essential component of the system. Proper thermal regulation will include:
- a programming device that manages heating and sanitary hot water separately,
- ambient temperature thermostat and hot water thermostat (cf. solution no. XV),
- motorised valves to control heating and hot water separately,
- controls to operate the boiler only when necessary.
• Boilers must be regularly maintained to ensure efficient operation. Have your boiler serviced at least once a year.
• If your hotel has seen successive expansions and transformations, adding new rooms, more piping has been added for heating and for sanitary hot water, increasing heat losses. To reduce these losses, one solution is to install several separate smaller boilers for different zones in the hotel, matching the needs for each zone.


Approximate cost:
• variable.
Approximate payback time:
• < 2-5 years
It should be noted that costs and payback times are highly dependent on the local setting and the initial situation of the hotel.


Located at the foot of the slopes the Pra-Loup ski resort (Alpes de Haute Provence), the Marmotel hotel was rehabilitated in 2012. At this hotel built in the early 1970s, with 96 rooms and a restaurant seating 100, the renovation work targeted wall and roof insulation, windows, lighting and heating systems.
The hotel is now equipped with a 150 kW woodchip-fired boiler (with a 200 kW gas-fired condensing boiler for backup and emergency purposes). The heating system is also used to top up sanitary hot water production,
supplementing a solar thermal array measuring 170 m². After having been closed in 2000 for lack of maintenance, this full renovation, at a cost of €6 million, brought the building up to the low-energy building requirements of the BBC (Bâtiment base consummation) label.
The inn Le Chamois in Colmars-les-Alpes is the result of the rehabilitation in 2013 of an earlier hotel that closed in 2008. The former installation had a heating oil boiler. For replacement of this boiler, the fuelwood option was rejected, due to the difficulty of installing a boiler room with wood chip silo at ground level, as the building is located in a flood zone. Instead a water/water electric heat pump was installed, serving low-temperature radiators; for backup heating hot water coils are placed at ventilation vents.
The Le Gentil holiday village La Plagne Montalbert (Var) was given a low-energy building renovation (Bâtiment Basse Consommation, BBC). The original 3,053 m² building had 48 rooms with 185 beds, and a heating oil boiler. When the building was expanded and storeys added, energy efficiency measures were taken, installing insulation and a woodchip boiler that meets 90% of heating and sanitary hot water needs (the existing heating oil boiler supplies the rest).
The existing distribution circuit was kept and extended.
As part of its renovation project the Ecolodge des Chartrons (Gironde) decided to install a gas-fired condensing boiler for room heating. The boiler is also used to back up the sanitary hot water system. The space beneath the skylight will soon be heated by a wood pellet stove.
After a full renovation the Hotel de la Clape (Narbonne Plage), built in 1970, has obtained the low-energy building label BBC Renovation (Bâtiment Basse Consommation). Cooling and heating is provided by an air/air heat pump and double-flow mechanical ventilation, with a 60% efficiency exchanger rating.
The Rosamar hotel, in Catalonia, decided to lower nocturnal ( from midnight to 7 a.m.) temperature settings for common areas by 2°C.
According to estimations by the French Environment and Energy Management Agency ADEME, lowering the indoor temperature by 2°C can economise about 12% of heating energy consumption.
Several chalets in the Alps managed by Duret Electricité are equipped with an optimisation system, in the form of an eco-regulator that reduces the number of times the burner fires. To optimise boiler operation and avoid cycles of just a few minutes, the regulator imposes a time lapse between the demand for heat (space heating or hot water) and the burner firing, based on the temperature of outgoing and return water, the temperature gradient and the generator's overcapacity. Chalets equipped with these regulators have economised on average between 25 and 33% of monthly energy consumption for heating and hot water.


Cost savings
Energy savings:
• The cost premium for purchase of a Category A boiler instead of Category B boiler is generally very small, and the energy savings generated by Category A equipment are substantial.
• Condensing boilers are more expensive than non-condensing boilers, but their energy efficiency will generate monetary savings from the very first day of use. Overall, the added cost should be amortised in 3 to 5 years.
Installing a high-efficiency boiler can generate savings of up to 35% of heating energy consumption.

Reduced CO2 emissions
• For a hotel of 1,000 m² that uses 130 kWh/m² of natural gas heating annually, and applying emission factors for France, a 30% savings in energy consumption represents:
8.33 t CO2 eq of avoided emissions each year
Emission factors for electricity in France: 84.3 g CO2 / kWh.
Emission factors for natural gas in France: 331 g CO2 / kWh (Source: ADEME).


Set an appropriate indoor temperature to ensure energy savings: raising indoor temperature by 1°C will increase consumption by about 7%.
For hotel and restaurant businesses in the Provence-Alpes-Côte d'Azur region, replacing a heating system with a better technology will generate an estimated 38% savings on heating energy consumption. Replacing heating oil and gas-fired systems generates savings on the order of 60%, by improving efficiency. Replacing an electrical system with another electrical system generates savings on the order of 25%
Existing electric heat systems can be replaced by more efficient options: replacing convection heaters with a fuel pump system, for example, will reduce electricity consumption by 50 to 75% (this work is more complex than replacing single units).
Solutions / Implementation / Investment / Benefits
Organisational measures ++ ++ +
Use of appropriate heating -- -- +
Regulation and programming devices + + + +
Boiler maintenance ++ ++ -
Heat recovery - -- +
Optimised production - ++ -
Boiler replacement ++ -- ++