- Why wall-mounted double
- Heating circuit options
- Budget option with a flow-through heat exchanger
- Comfortable version with storage water heater
- Where to place a double-circuit boiler
- Equipment disadvantages
Equipping a full-fledged gas boiler house is not cheap. It is more profitable to solve the problem of providing the house with heat and hot water supply by installing a wall-mounted double-circuit boiler. Let’s understand the advantages and varieties of these compact dual-use devices.
Why wall-mounted double
The key feature of wall-mounted units is 100% availability. The boilers are equipped with everything necessary for the functioning of heating and water heating. On site, only basic installation and prestarting is required.
The boilers have modulating burners that regulate the temperature of the medium at the command of the microprocessor. They work stably at low gas pressure and do not burn out prematurely, unlike atmospheric burners.
Boiler diagram: 1 – heat exchanger; 2 – expansion tank; 3 – pump; 4 – flow switch; 5 – burner; 6 – three-way valve; 7 – plate heat exchanger; 8 – gas reducer.
Automation of “wall mounts” guarantees independent functioning of devices all year round and protects equipment from extreme situations. On the basis of wall-mounted boilers, they organize heating of a house or garage, arrange a warm floor, heat the water in the pool.
Heating circuit options
The power of wall-mounted boilers reaches 42 kW, which is enough to heat a cottage or apartment with an area of up to 250 m2. Using a cascade connection, you can heat housing and outbuildings of any size. The power of the unit is selected with a 30% margin to ensure an intensive supply of hot water.
A gas boiler with piezo ignition is started manually both initially and after a power outage. Models with electric ignition are switched on automatically, keeping the original parameters.
The budget method of setting heating involves the installation of a room regulator. The equipment reacts to a cold snap in the house, but this happens later than outside. Temperature “jumps”, excess fuel is consumed. To save money, install a programmable regulator and set the day / night or weekend / weekday modes.
It is more convenient to use boilers with temperature correction by two sensors – indoor and outdoor, located on the north side of the building. Automation changes the gas pressure depending on the weather and provides a comfortable microclimate in the house.
Budget option with a flow-through heat exchanger
These modifications are the cheapest and turn on the DHW mode only when necessary. In summer, with an inlet fluid temperature of 15 ° C, the output is 40 ° C. In winter, the water is cooler (10 ° C) – a stream comes out of the tap, heated to 35 ° C. By reducing the pressure, they achieve a more comfortable temperature. The maximum that wall-mounted boilers are capable of is about 60 ° C, but the flow rate will not exceed 9 l / min..
A wall-mounted boiler with an instantaneous water heater can simultaneously supply water to a kitchen sink and a shower head, or fill a bath. You can’t get more out of it, so it will suit consumers who are accustomed to using electric heaters. Residents of city apartments may not have enough hot water temperature.
When the tap is opened, heating starts automatically, but the priority is in effect: hot water first, and then radiators. In everyday life, there is rarely a need for a continuous flow of water for more than 2 hours, therefore, hypothermia at home will not occur.
In inexpensive models, plate heat exchangers are used for quick heating, which have the disadvantage of being overgrown with salt deposits. With hard water, plugs between the plates can form after a couple of months. The main method of combating limescale is to prevent overheating above 60 ° C, and this should be monitored by the boiler automation. Another solution to the problem is additional anti-scale devices, for example, a permanent magnet.
For copper heaters of a coaxial design, the DHW pipe passes inside the heating heat exchanger and the salts are deposited more slowly. The liquid in them does not boil, and the circulation pump switched on when the mixer tap is closed quickly cools the tube, which prevents scale deposits.
The actual water consumption varies depending on the tapping points used. With a sharp drop in pressure, the temperature of the jet from the mixer rises, if it is not equipped with a thermostat. In some boilers, the problem is solved by a special “turbine”, the rotation of which depends on the specific water flow.
Comfortable version with storage water heater
Double-circuit wall-mounted boilers equipped with an internal storage boiler require more installation space and are more expensive to use, as they consume fuel to maintain the water temperature. They are chosen by those who value comfort.
The capacity of a conventional built-in boiler is 50-60 liters, and this supply of hot water is ready at any time. It will be enough for most household needs, and if there are pauses in heating, then only when several residents want to take a bath at the same time. When there are a lot of hot water consumers at the same time, then a boiler with a capacity of 90-120 liters is selected, which allows you to immediately receive 300-450 liters of hot water and almost the same after 10-15 minutes.
Advice! When choosing a boiler with a built-in tank, give preference to a device with the option of protection against legionella (bacteria appearing on the inner walls of the tank). The automatics will “clean” the boiler weekly by heating water over 60 ° C.
Where to place a double-circuit boiler
A gas source of hot water supply and heating with a capacity of less than 60 kW is allowed to be installed in a non-residential and non-passable room of any floor that meets the requirements of SNIP. A suitable option is a kitchen, where a place for a boiler can be provided even at the stage of furniture manufacturing, away from the sink. Units with a capacity of 60-150 kW require a separate “compartment” in the basement or on the ground floor.
The chimney is a decisive factor in the selection of the location of the double-circuit boiler. With a flue duct arranged inside the wall, it is logical to purchase an inexpensive device equipped with an open combustion chamber. When there is no chimney or it does not give the required vacuum, it is more advisable to buy a device with a closed chamber, and exhaust gases by means of a coaxial chimney.
From a closed firebox, combustion products are removed by a fan of the smoke exhauster or a blower cooler in front of the burners. The latter does not come into contact with hot gases, due to which it lasts 2 times longer.
There are several weak points of wall-mounted double-circuit boilers that can be argued with:
- Shorter service life (7-15 years) – initially, much depends on the quality of the device, and subsequently – on maintenance.
- Noisy work – the boiler will not stand in the bedroom, and among the floor-standing analogs there are also “quiet” units.
- The incompatibility of copper elements with aluminum radiators is rather a problem of equipment selection.
Even taking into account that for the successful operation of both modes, a double-circuit wall-mounted boiler must have a significant power reserve, the purchase of a device is more technically and financially justified than installing a single-circuit device paired with a separate boiler for hot water supply.