How to choose a circulation pump for a heating system

Effective and efficient heating of your entire house depends on selecting the proper circulation pump for your heating system. When it comes to transferring hot water from your boiler to radiators, underfloor heating systems, or hot water tanks throughout your home, a circulation pump is an essential component. The market is filled with different types and models of pumps, so choosing the right one can be difficult. Nonetheless, the decision-making process can be made simpler by being aware of the needs of your heating system and taking important factors into account.

The capacity or flow rate of a circulation pump is one of the main factors to be taken into account. The flow rate, which is commonly expressed in liters per minute (LPM) or gallons per minute (GPM), controls how much water the pump can circulate in a specific amount of time. To ensure optimal performance, it is imperative to match the pump’s capacity with the requirements of your heating system. Selecting a pump with an excessive capacity can result in needless energy consumption, while a pump with an insufficient capacity may provide insufficient heating.

Another important consideration when choosing a circulation pump is efficiency. Choosing an energy-efficient pump will have a positive impact on the environment in addition to lowering your heating expenses. Seek for pumps certified by groups like ENERGY STAR or with high Energy Efficiency Index (EEI) ratings. These pumps are an economical and environmentally responsible option for your heating system because they are made to use less energy while still providing the necessary performance.

Take into account the kind of heating system you have as well as the pump’s compatibility. Certain kinds of pumps may be needed for the proper operation of various heating systems, including combination boilers, hydronic radiators, and underfloor heating. For instance, to circulate water through small pipes embedded in the floor, a pump with the capacity to handle lower flow rates but higher pressure is required if you have a radiant floor heating system.

Any circulation pump must have both durability and reliability. Long-term, purchasing a high-quality pump from a reliable manufacturer can spare you from having to replace or repair it frequently. For added peace of mind, look for pumps made of sturdy materials, fitted with dependable motors, and covered by warranties. Another way to determine a pump model’s dependability is to read customer reviews and ask heating experts for recommendations.

Factors to consider Questions to ask
Size of the heating system How large is the area the pump needs to cover?
Flow rate How much water does the system need to circulate?
Head pressure What is the vertical distance between the pump and the highest point in the system?
Energy efficiency Does the pump have a high Energy Efficiency Rating (EER)?
Noise level How quiet is the pump during operation?

Choosing the right circulation pump for your heating system is crucial for optimal performance and energy efficiency. A circulation pump is like the heart of your heating system, pushing hot water through the pipes to keep your home warm. When selecting a pump, consider factors like the size of your heating system, the type of fuel you use, and the flow rate required for your specific setup. Look for pumps with variable speed settings to adjust flow rates according to your needs, helping you save on energy costs. Additionally, opt for models with high efficiency ratings to minimize energy consumption and reduce your carbon footprint. Don"t forget to check compatibility with your existing system and ensure proper installation for reliable operation. By making an informed choice, you can ensure efficient heating while minimizing energy waste and costs.

The most "running" models of pumping units

Manufacturers provide a large range of devices with varying capacities that are intended to pump liquid media with different specifications. However, we are only interested in testing models that operate in hot water supply and home heating networks.

How to differentiate centrifugal and other types of pumps from circulation units:

  • in the form – an electric motor and impeller are installed in one case, the pipes go along the sides of the lower part (not in the middle);
  • according to the presence of a "wet" rotor, significantly reducing the noise of the impeller rotation;
  • 2 sizes with mounting length 130 and 180 mm;
  • The conditional passage of the pipes is 15, 20, 25 and 32 mm, joining – coupling (threaded);
  • Passport pressure – 0.4, 0.6 and 0.8 bar.

Simply marking the product makes it easy to determine the indicated parameters. For instance, the numbers in the name Wilo Star-RS 15/4 denote the water column pressure of 4 m (0.4 bar) and the inner diameter of the connecting pipes, which is 15 mm (DU 15). Example 2: When the Grundfos Alpha2 25-60 equipment is linked to DU 25 pipes, 0.6 bar (6 meters) of pressure is developed.

Citation. Manufacturers usually create a broader range of products. Wilo, a German brand, sells circulation superchargers with water pressures of 2, 4, 6, 7, and 8 m. Art. However, "fours" and "sixes"—and, less frequently, "eights"—remain "running" models.

Of course, there are stronger pumps available that have pressures of up to 1–10 bar, but they are not utilized in private homes. Large units (18 cm, 1 and 1 ¼ ") crashing into heating highways are typically replaced by small units, 130 mm long, with ½ and ¾ inch nozzles, which are placed inside the boilers.

Methods for selecting a pump

The most accurate method is to perform a comprehensive hydraulic calculation and precisely ascertain the pump’s developed pressure and performance. This is how apartment buildings and industrial buildings are designed with their centralized heat supply.

What can we say about average homeowners, though, given that not all masters engaged in the installation of autonomous water systems are under the control of the engineering calculation methodology? What is a more straightforward method for selecting a circulation pump for heating?

  1. In the case of replacing the old worn unit, a new one is acquired with similar parameters. The price and quality of the product comes to the fore.
  2. Order a project of a home heating system engineer – the engineer. Below we will explain the advantages of this option.
  3. Calculate the required pressure of the pump by a simplified method.
  4. Believe the many years of practice of our experts and buy an apparatus, guided by their advice.

Suggestions made by specialists. Suburban homes and apartments up to 250 m² in size have enough household pumps to develop 0.4 bar, or 4 m of water column, of pressure. Purchasing a more potent unit with a 6 m (0.6 bar) pressure on a quadrature of 250–500 m² is preferable over purchasing an 8 m–500 m² water tank. Art.

Although it costs money to develop the plan and order engineering calculations, it will be more than worthwhile. Equipment and component purchases are made with a reasonable margin—just in case—whether you choose to hire workers or install the heating yourself. A clever designer will provide a convincing argument for why a smaller power pump and pipe are required. Savings will be made possible as a result, and the price of electricity will go down later.

Use the following method to choose a heating pump based on your own calculations if you don’t trust the installers or just the numbers. Remember to confirm the unit’s computed characteristics with professional advice; the outcomes will undoubtedly be comparable.

Calculation of the characteristics of the pump

When the necessary amount of heat is applied to all batteries or warming floor contours, heating functions efficiently. In other words, the pumping installation must overcome the hydraulic resistance of the pipes, fittings, and reinforcement to supply the necessary coolant flow rate in every system segment.

You must use the following formula to determine a pump’s performance before selecting one:

  • G – massive flow rate of the coolant, kg/h;
  • Q – the general load on heating, W;
  • Δt – the difference between the temperature of the water in the feed and reverse line, during calculations it is usually taken equal to 20 ° C.

Reference: In simplified calculations, mass consumption is assumed to be equal to volumetric since water’s density does not change significantly when heated above 100 degrees. For instance, G = 300 kg/h, or 300 liters per hour.

The SNiP methodology can be used to precisely calculate thermal load. Here, we’ll keep things simple and just measure the heat in the area.

For instance, 22 kW of heat will be required to heat a two-story home in the middle lane that is 200 m² in size. From this, it is simple to compute the coolant flow rate and the pump’s necessary performance: G = 0.86 x 22000 /20 = 946 kg/h = 0.95 t/h = 0.95 m³/h.

It is immediately suggested that the diameter and section of the main highway leading from the boiler, where the planned pump is located, be ascertained:

  • F – the area of the pipe cross morned, m²;
  • ʋ – water speed, is taken 0.5 … 1 m/s.

There is less friction resistance against pipe walls, reinforcement, and fittings the slower the water flow rate.

Using the speed of 0.6 m/s, we can calculate the highway’s cross section as follows: f = 0.95 /3600 x 0.6 = 0.00044 m². Next, we determine the aisle’s diameter, which comes out to be 0.024 m or 24 mm, using the area of a circle formula. As a result, the pump’s connecting fittings and pipe have an internal diameter of 25 mm.

Once the pumping device’s required performance has been determined, we calculate the available pressure. The calculations for the floor heating system, the boiler circuit of the strapping, and the network of radiators will be completed independently.

Heating circuit with batteries

The pump’s job is to move coolant from the first to the last radiator in the pipes at the appropriate volume. He is stopped from turning on fittings and adjusting valves by the force of the fluid’s friction against the wall and the resistance of the duct narrowing.

We recommend applying the following straightforward formula to determine the value of the resistance that the circulation unit needs to overcome:

  • H is the desired pressure drop in meters of the water pillar;
  • R – specific resistance to friction, is considered in m. water. Art. 1 meter linear pipeline;
  • L – the length of the longest branch of heating is measured from the heat source to the last radiator;
  • Z – local resistance coefficient.

Remark. While the formula is significantly simplified, the hydraulics engineering calculation is far more intricate. However, it enables you to select a heating pump that is appropriate for your home’s needs. We looked into an alternate option: online calculators that were available from different websites. After observing a 30% discrepancy in the results, we draw the conclusion that manually calculating the pressure is preferable.

Methods of computation:

  1. Since the pump creates the same pressure at the entrance to each heating branch, select the most long line and determine its length in meters. This is the indicator l in the formula. With a two -pipe system, both lines are taken into account – the reverse and the supply.
  2. We take the specific resistance R equal to 150 p/m or 0.015 m water column per 1 m. P. highways (for plastic pipes).
  3. If the duct through the batteries is regulated by thermostatic valves, we take the coefficient Z = 2.2. Option Second: radiators are equipped with ball valves and balancing valves, then z = 1.5.
  4. We calculate the required pressure and select the appropriate supercharger model.

Suggestions. The feed and return lines are added to the line of dead end and ring circuits, which is the same length. We use the entire length of the ring for the single "Leningradka" pipe. The internal dimensions of the house—Size I floor + ceiling height + II floor width—determine the length if the scheme is not present at the time of calculation.

We use our example to calculate the pressure. The building’s dimensions are (10 + 3 + 10) x 2 = 52 m, where z = 2.2 and length, l, is concerned. A pressure of 0.015 x 52 x 2.2 = 1.716 ≈ 1.7 m will be needed. We obtain a 2.7 m water column by adding a supply of 1 m to the boiler’s unaccounted resistance plus additional equipment.

We mark the performance and pressure line on the graph that is attached to the pump passport, and then we choose the appropriate model—in this case, the Wilo Star-RS 25/4 brand.

As you can see, the computations’ findings are consistent with professional advice: a two-story building’s 200 square feet of heating network can be adequately supplied by a pump with a 0.4 bar output. We recommend watching the video to gain a better understanding of the calculation process:

A crucial aspect. Three to seven operating modes are frequently offered in contemporary discharge devices, and the instructions depict the same number of schedules. Select a characteristic (the third is the second) that corresponds to the average speed for calculation.

Warm floors loops

Coolant is usually delivered to the floor contours using a separate pump in conjunction with a mixing valve. Furthermore, there are no shaped sections and the loop’s maximum length does not exceed 100 meters. Local resistances include the mixing three-way (or two-way) valve and the collector’s thermostatic valve.

The aforementioned algorithm works well for calculations:

  1. Find out the number of contours, the maximum pipe length and the total flow rate of the coolant through the comb. We scheduled all the calculations on warm floors in a separate publication.
  2. We take the longest loop and consider the required pressure of the pump unit on it, using the above formula. We substitute similar values r, l and z.
  3. We select the pump for the hinges of floor heating according to the schedule presented in the passport of the product.

For instance. Consider the same two-story home with a maximum loop length of 80 meters, a heat load of 22 kW, and a water consumption of 0.95 m³/h. The pressure is equal to h = 0.015 x 80 x 2.2 = 2.64 m when value r = 0.015, Z – 2.2. We don’t account for the highway’s resistance because the boiler has a pump of its own. Thus, the collector unit’s final pressure is at least 2.64 m.

Note: By lengthening the loops to 100 meters, you will raise the pump pressure bar and use more electricity as a result. Verify: 3.3m = 0.015 x 100 x 2.2 = h. We choose any model whose graph is positioned above and draw the corresponding horizontal line on the diagram. Wilo Star-RS 25/6 is the closest unit.

Boiler circuit

As you are aware, a separate pump is intended to be installed in the circuits of the solid fuel boiler strapping, which will force water through a small ring and a three-way valve or buffer capacity. The primary/secondary ring system, which connects hydroelectric power plants, warm floors, and radiator heating lines to the main contour, operates on the same principle.

There is almost no resistance encountered by the pump when pumping water through the main ring because the highway is short and has few fittings and reinforcement. As a result, the secondary superchargers’ pressure, which transfers coolant to heating devices, is frequently higher than the pressure of the main unit.

An important nuance. The most important thing is to match the heat generator’s power with the intended water consumption in the main circuit. Proceed in the same manner to determine the required coolant volume based on the boiler’s productivity and compute the available pressure in order to choose the pump model. The video provides comprehensive instructions:

Choice by size

As you have undoubtedly observed, there are units in the assortment of companies that share the same features, but the pipe sizes and dimensions vary. How to select the pump’s external parameters:

  1. For installation on pipelines, bypasses and mixing nodes of floor heating, standard supercumberries of 180 mm long are used. “Shorty” 130 mm are placed inside heat generators or on highways in a highly limited space.
  2. The diameter of the connecting pipes is selected under the section of the main pipeline. An increase in the size is permissible, a decrease – it is categorically not recommended. That is, on the DU 25 pipeline you can put an unit with fittings 32 mm.
  3. Pumps with Ø32 mm pipes are used on primary rings and boiler contours, as well as in modernized gravity systems.

Note: Store-bought bypasses are pre-made and sized to fit a standard pump with an 18-cm mounting length.

The supercharger’s number of speeds is not particularly significant. Three modes is more than enough at home; the second one runs at the fastest speed. You shouldn’t purchase products with a separate air tower because air from units is pulled through a side screw.

Manufacturers and prices

Even with the large selection of pumps available in stores, selecting a truly high-quality item can be challenging. The market is overflowing with Chinese imports and knockoffs of popular brands. First, we enumerate the well-known manufacturers in the CIS:

  1. The highest price category is Grundfos (Denmark), Wilo (Germany). Prices for original "Germans" start from 75 euros, Grundfos of the UPS series – 65 euros.
  2. The middle category is DAB, Aquario (Italy), Sprut (high -quality China). The cost of units of various models ranges from 40-100 euros.
  3. Other cheap pumps (Oasis, Neoclima, Vorthar, Caliber and so on to infinity). Price – from 20 euros apiece.

Remark. It’s possible that some excellent products that fit into the middle or highest price range were left out. Here are the brands that are most widely used.

How can cheap, fake pumps be distinguished from premium superchargers?

  • service life – 1 … 3 heating seasons;
  • The product number is applied only to the sticker, the body of the unit is clean;
  • Passing devices from one batch often go with the same numbers;
  • By weight, the fake is noticeably different from the original (it is easier);
  • Low quality unit begins to make noise and squeak, having worked season 1 in a closed heating system, the case is very hot.

Occasionally, imitation heating pumps are identical to the real thing—they are just half as expensive. The secret is in an aluminum winding that lowers the product’s price. How to make sure: On the company’s official website, find the mass of the original model and compare it to a market copy. The knowledgeable seller will most likely decline to weigh the fake device or admit right away that the goods’ origin is unknown.

The efficacy and efficiency of your heating system greatly depend on the circulation pump you select. With so many options on the market, it’s critical to take into account aspects like your heating system’s size, the necessary flow rate, energy efficiency, and compatibility with your current setup.

First, determine the dimensions of your heating system and the unique needs it has. A stronger circulation pump might be needed for larger systems with more radiators or underfloor heating in order to guarantee sufficient heat distribution throughout the room. Conversely, less powerful pumps may be adequate for smaller systems, which can reduce energy usage.

Another important factor to take into account when selecting a circulation pump is flow rate. The flow rate affects the system’s overall heating performance by dictating how quickly hot water can move through it. Make sure the pump you choose can supply the required flow rate to satisfy your heating setup’s requirements without putting undue strain on the system.

Homeowners are placing a greater emphasis on energy efficiency in order to cut down on their utility costs and lessen their environmental impact. Seek out circulation pumps that have been certified by ENERGY STAR or other programs that have high energy efficiency ratings. These pumps are made to operate at peak efficiency with minimal power consumption, which lowers long-term costs and leaves a smaller carbon imprint.

To guarantee smooth integration and operation, compatibility with your current heating system is imperative. Make sure the circulation pump fits your system’s power supply, pipe connections, and control mechanisms by looking over its specifications. Installing an incompatible pump can result in malfunctions, inefficiencies, and possibly expensive repairs in the future.

In conclusion, careful consideration of a number of factors, including system size, flow rate, energy efficiency, and compatibility, is necessary when choosing the appropriate circulation pump for your heating system. By devoting time to thorough investigation and seeking expert advice when necessary, you can select a pump that maximizes heating efficiency, lowers energy usage, and guarantees the system’s long-term dependability.

Video on the topic

How to choose a circulation pump for a heating system?

How easy it is to choose a pump for heating + selection of pipes diameter + selection table

Influence of the height of the heating system on the pressure of the pump

What type of heating you would like to have in your home?
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Anna Vasilieva
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