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Gas boilers for heating
Among the heating equipment most used and installed in homes, we find the gas boilers. In reality, the market offers us a significant variety of models with different systems, with different energy ratings, and, of course, adapted to almost all budgets.
In this article we are going to try to find out about the different types of gas boilers for the home that we find in the market according to its energy efficiency.
First, we should ask ourselves … How efficient is the gas boiler? Compared to other heating systems and their savings, according to daily use.
As information, we wrote an article on pellet stoves - biomass that you can consult from here. As you can see, in the previous image, they are the most efficient!
What types of gas boilers are there?
Innovations, research, and increasingly advanced technologies have made it possible to obtain substantial improvements in the operation of gas boilers.
A boiler is a closed container, where water evaporates thanks to the heat produced by certain gases.
Basically we can distinguish its operation according to these types of gas boilers:
1.- Watertight gas boilers
They are the ones that have the combustion chamber sealed. They do not consume oxygen inside the premises, and are of a very safe type of operation, precisely because the air does not come into contact with the gases produced by combustion.
In sealed gas boilers, the chamber where the combustion takes place is totally hermetic. They are bi-tubular, through one duct they absorb the outside air, and through the other they extract toxic gases and eliminate them through the ventilation pipe.
2.- Low NOX gas boilers
These equipments are also watertight. The fundamental difference is in its design. Its system is similar to condensing boilers, and offers a lower NOX (nitrogen oxide or nitric oxide) emission index. Hence its name.
This type of low NOX gas boiler incorporates a special design in the combustion system. By reducing polluting gases, it complies with ecology and environmental care regulations.
It uses, like the watertight installations, the air of the outside. The burner is cooled by the water circuit, thereby reducing the temperature of the fumes and thus the contamination.
3.- Atmospheric gas boilers
In these appliances, the combustion chamber is open. Quite the opposite of watertight boilers. In this equipment, the air used for combustion is in the same place in the boiler. That makes it less energy efficient, and more polluting.
Atmospheric boilers are no longer installed in Europe, due to their prohibition due to the high level of pollution
Atmospheric boilers have drawbacks, due to the fact that their combustion chamber is not properly isolated from the space in which they are installed. With the system used in atmospheric gas boilers, the combustion gases remain in the air of the homes.
4.- Condensing gas boilers
This type of heating installation is considered a revolution in operation. They are also watertight, but with the added advantage that the energy generated by the water vapor is reused in the combustion of the gas.
European regulations require since 2015 (ErP Regulations) that condensing gas boilers be the only residential boilers to be installed.
Its comparative performance can be greater than 100%. Energy and cost savings, and better production of hot water and / or heating systems.
This is obtained, thanks to the fact that the sealed chamber cools the gases up to approximately 70or So the latent heat that is close to 200 orC is used to generate more energy.
Since the cooled gas is carbon dioxide, what goes mostly to the outside is water vapor, with a low or no pollutant level.
The condensing boiler has the advantage of the highest performance percentage, close to 110%, over the PCB.
As a complement, you can consult our article on oil condensing boilers for heating.
We have seen according to its operation and performance, but also classify boilers according to their installation (How to place them). It is to answer the question of … What is a gas wall boiler?
By the way of installation, there are two types:
- Bottle boilers: They are those installed on the wall.
- Standing boilers: They are those installed on the ground, generally with a higher power level. More intended for single-family homes.
Currently most of the boilers installed for the provision of hot water and heating in homes are of the watertight type. Its emission of NOX (nitric oxide) is very low, although it is polluting.
And, condensing boilers are gaining ground on the market, thanks to their energy efficiency, performance and low polluting power. And, although its price is higher compared to the others, the investment quickly pays for itself with the saving of gaseous fuel.
How to choose the natural gas boiler?
We do have a house with a natural gas connection, of course a very convenient and comfortable option for the heating system is to install a gas boiler.
Today, we can not only use it to heat the water that runs through the radiator circuit to provide heat to the home, we can also have domestic hot water …What should you keep in mind when choosing a gas boiler?
But first, before buying a gas boiler we must review the following points …
1.- How the energy label works in boilers
More or less, we are already used to seeing energy labels. In the case of these teams, they are governed by:
- The European Directive on Ecodesign ErP (Energy Related Products).
- The energy labeling directive ELD (Energy Labeling Directive) that provides us with details on energy efficiency.
Why do we have two energy labels?… Each heating appliance carries an energy label with detailed information. And, on the other hand, heating systems that are composed of different technologies, also carry the energy label of the system.
It is important to choose the system and product with high energy rating to maximize efficiency
With the labels we can respond to … Which gas boiler is more efficient? From a general perspective. If we are looking for an installation where our equipment has the labels that are closest to the highest value "A". We will be able to maximize the efficiency of the entire installation. Increasing our energy efficiency.
2.- Only for heating or also for hot water
If the installation is only for heating, we will not have any problem, but if we want to have hot water, the market offers us different options, which are:
- Simple boilers. Initially, they are only fed for the heating circuit, but a storage tank can be added to obtain domestic hot water.
- Mixed boilers. They come prepared with two circuits, one for hot water and the other for heating.
- Microaccumulation boiler. They have a small hot water tank, so when you open the tap, we will have hot water instantly. With this system, in addition to gas, you will save many liters of water.
- Accumulation boiler. Similar to conventional boilers, but these incorporate a water tank, which is always kept hot. They are the most reasoned for homes with several bathrooms.
Keep in mind that we need to know how much hot water we will use at home. You should think about the number of bathrooms you have, the number of users in the home and their daily frequency of use.
Although on this aspect they will advise us where we buy the boiler, at least we should have an idea.
3.- How to calculate the boiler power I need
We have to look at the power of the equipment that we are going to install at home, since it is not the same to heat a small house of 50 meters, than a large house.
How to calculate the calorific power for a house or room? The estimate is, for each square meter, you will need, on average, approximately 150 W of power (Always ask the store specialist, it is an approximate value, since the value of W also varies according to climatic conditions and insulation of the house, for example).
If we are in a real case with the data previously indicated, if we have a floor of 120 m2 of surface. They are 120 x 150 = 18,000 W, so the boiler you need must have a minimum power of 18 kW.
Remember, we can save more electricity if we install a thermostat, although the most modern equipment already has them incorporated. To learn more from our article on thermostats in home heating.
4.- Which gas boiler is more efficient
Although we have already talked about energy labeling and its importance, it must be recognized that the purchase - sale market has turned over with the condensing boilers for its high performance.
In the following diagram we see a comparison of models in a schematic way of characteristics and price according to equipment:
When we go to buy a boiler we will see that the market offers us practically two types: Low NOx and Condensation. So we have made a comparison to see the differences and advantages:
| Low Nox boilers | Condensing boilers |
| Performance above 90% | 109% Yield. |
| Lower performance and efficiency | Higher performance and efficiency |
| Water return temperatures 70 - 90ºC | Water return temperatures 40 - 55º C |
| Smoke temperature 90 - 120º C | Smoke temperature 40-60º C |
| You do not need a drain to channel the water | You need a drain to channel the condensed water |
| Face hands installation | More expensive installation |
| Less complex installation - Less expensive repairs | More complex installation - More expensive repairs |
| Lowest price on the market | Highest price in the market |
The price of a natural gas boiler is linked to its quality and efficiency. Normally, condensing equipment is the most expensive on the market for homes (Remember that you also have to install it, with installation prices that range between 400 - 600 €)
Taking into account the above considerations, condensing boilers are more efficient than low NOx ones. For this reason, it is advisable for the consumer to install condensation systems.
But…Which condensing boiler is better? Broadly speaking, it is the one that stands out among the technical criteria of:
- The one that offers the best performance.
- The one that offers the best seasonal energy efficiency.
- The one with the lowest sound power.
- The one that guarantees the best hot water production according to the specific flow rate.
- The one with the highest energy rating.
As we can see in the previous video, technically they have advanced a lot, but to choose our installation, remember that the professionals are there to advise us and always ask in various shops, prices vary and also offers.
Similarly, we have other efficient heating systems. You can see the thermal emitters for homes, they are very comfortable to install.
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