Gas condensing water Heaters

Gas Condensing Water Heaters
September 13, 2019 – 09:44 am

Known as gas condensing boilers they are high efficient water heating systems with energy efficiency of over 90%

Gas condensing water heaters are high efficient units that are designed with the energy factor (EF) of over 0.9, which is much higher than on conventional tank-type (0.6) and tankless units (0.82).

Residential gas condensing water heaters are very popular in Europe, where they are usually called condensing boilers, combi boilers and cylinders. And, for example, in UK, combi boilers are found in close to 70% of homes.

Government legislation and higher demand are driving the need for greater energy efficient water heating systems, or condensing boilers.

There are also well known in North America for commercial use... and because of all its benefits, rising gas prices and lower costs for operation, condensing models are becoming more and more popular in the residential water heating application as well.

Condensing water heaters - How they work

Condensing hot water heaters are fuel fired units with the very similar water heating process as conventional models. The problem with the conventional heaters, the most popular heating systems in NA, is that too much energy and heat is wasted when the gases are vented out.

The very smart solution comes with condensing or such energy efficient water heaters where the heat of the flue gases is recaptured and used, so less heat / energy is wasted. They achieve this high efficiency by removing the heat from the burning fuel and also cooling the products of combustion.

That is why condensing boilers have to have larger and more efficient heat exchanger than traditional boilers and some other additions.

The water vapor produced by the burning of gas in the boiler, condenses back into liquid water, releasing the latent heat of vaporization from the water. Because latent heat is a significant source of energy, condensing boilers have efficiency ratings up to 98%.

Good example is Weil-McLain that offers the Ultra Gas condensing boiler with efficiency ratings up to 98% in low water temperature applications.

Video: AO Smith Vertex - Condensing Heater - 96% Efficiency

condensing water heaters

Tank-type condensing water heaters are equipped with a super performing helical heat exchanger, which is completely surrounded by water. A typical example is . This fully-condensing design heater provides a high 96% thermal efficiency and performance that rivals much larger heaters.

The flue spirals around and inside the tank so that the combustion gases spend more time releasing the heat until the water vapor in the gas — a natural by-product of the combustion process— condenses, releasing even more energy. The spot where the flue exits the tank is barely warm to the touch.

The main disadvantage of these high efficiency water heaters is the higher initial investment, but since they are very economical, it can repay that extra cost in energy savings.

The condensing boilers are the most environmentally friendly heating systems, with reduced CO2 and NOx emission. They feature a stainless steel heat exchanger, which is usually larger than conventional or dual burners, providing longer life and much better performance.

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Popular Q&A
Natural gas water heater condensation pipe?

Welcome to the forums.
That leg is there to collect condensation and any debris that may be in the gas line. Most gas companies (therefore bldg. codes) require it. Very rarely would it ever need emptying or cleaning, and then only if a servicing plumber finds it to be a problem. Install one at your friends when you are replacing the WH.
No, it has nothing to do with cusshioning. The gas line (after the meter) is only operating at a few PSI.

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