Which pump to choose for the boiler? It all depends on your project

When it comes to the project of the heating system, of course, the question arises which pump to choose for the boiler. Data on pumps are collected in special catalogs of manufacturers, which simplify the choice not only for unique qualities, but also for a given performance and pressure that the pump must create. Engine power is also taken into account in accordance with the number of revolutions. To understand the issue, let's pay a little attention to the types of pumps and compare them with each other.

 

Pump types and applications

On sale, each of us met a large number of pumps, without thinking about the scope and mode of action. Meanwhile, these qualities significantly affect the features of the operation of this device. The most common are centrifugal pumps. Compared to pistons, they have the following advantages:

• compact body;
• speed;
• connection to the electric motor;
• high performance;
• uniform work;
• simplicity of design, which allows it to be made from chemically resistant materials that are difficult to process;
• pumping liquids with impurities without affecting the operation of the pump;
• easy installation on a light foundation.

These qualities determine the predominant use of centrifugal pumps in the chemical industry. And if we talk about efficiency, then this indicator for centrifugal pumps is 75-90%, and for piston pumps - 65-85%, which is significantly lower. But keep in mind that pumps of small and medium power with a centrifugal device have a lower efficiency, by about 10-15%, so they don’t win much compared to piston pumps. This is typical for circulation versions and is important if you choose a pump for the boiler.

The drop in efficiency is associated with design features that are especially well manifested when pumping highly viscous liquids. Although propylene glycol and glycerin coolants cannot be called high-viscosity, cheap pumps for this type of boiler will be characterized by a loss in efficiency due to design flaws. This is due to vortex formation near the edges of the blades of the rotating wheel, as well as to the overflow between the suction and discharge cavities due to large gaps. Such a pump for the FOCUS boiler will hide the benefits of fine-tuning the coolant temperature.

Areas of use

Centrifugal pumps pump fairly low pressures, so they should not be purchased for communal heating systems in apartment buildings. It is also possible to reduce efficiency due to increased network resistance and other problems. Pumps for a heating boiler that supplies coolant from a thermal power plant should only be purchased from reputable manufacturers who improve traditional designs of centrifugal pumps.

Piston pumps are not recommended for small flows and the need to pump high pressure (50-1000 atmospheres). They also do not handle viscous liquids well and are not used for explosive mixtures.

For systems that require liquid supply up to 1500 m3 / min, but a small head up to about 10-15 m, propeller-type pumps are used. They are characterized by maximum hydraulic efficiency, compact size and performance. They are also used for pumping contaminated media and crystallizing mixtures.

For viscous liquids, fuels and petroleum products, screw pumps are recommended. Fluid deliveries typically correspond to 300 m3/h at pressures up to 175 atmospheres and a rotation speed of 3000 rpm. This type of pump operates silently, is compact and does not change performance with pressure changes. The efficiency is 75-80%.

For highly viscous solutions, including liquid plastics, single screw versions are used. In terms of cost and performance, they are similar to centrifugal pumps, but more economical at pressures above 10 atmospheres. For these purposes, at high pressures, gear pumps are used, which work effectively with small water supplies.

Vane pumps are used for clean liquids at moderate pressure. For high heads up to 250 m and low flows up to 40 m3/h, vortex pumps are used. With all the advantages, the efficiency of this type does not exceed 50%.

Boiler pump

Looking ahead a little, let us clarify that for the organization of circulation in closed heating systems. Circulation pumps are a version of the centrifugal pump that suffers pressure drop when pumping viscous liquids and has a number of design problems.

In this regard, it makes sense to select this element of the heating system with special attention, depending on its features. Disadvantages, as a rule, do not appear on small circuits with a collector installation scheme, but are already felt on single-circuit systems and when using coolants with the addition of viscous liquids. Circulation pumps of the cheap segment can also be sensitive to contamination of the pumped liquid and other shortcomings, but, in general, they are characterized by stable performance and reliable operation.

We recommend to use for installation of heating system pumpstested while working with solid fuel boilers FOCUS.