What is a circulation pump

Consider your house as a living thing with a circulatory system of its own that keeps it warm, comfortable, and energy-efficient. A circulation pump is a tiny but powerful component that powers this entire system. It might not be the center of attention, but its function is vital to preserving a cozy interior atmosphere while maximizing energy usage.

In a nutshell, a circulation pump is an apparatus that maintains the flow of hot water through the heating system in your house. The circulation pump makes sure that hot water moves effectively from the boiler to the locations where it is needed and back again for reheating, whether you have underfloor heating, radiators, or a combination of the two.

Consider the circulation pump to be your heating system’s engine. It works nonstop in the background to ensure that every room has an equal amount of warmth by forcing hot water through the radiators and pipes. Without it, especially in the chilly winter months, your house would find it difficult to get to and stay at a comfortable temperature.

What does a circulation pump actually do, though? Well, its main job is to get rid of resistance in the heating system so that hot water flows through it evenly and smoothly. In addition to keeping your house warm, this helps avoid problems like cold spots and inefficient heating.

Features of the unit

The creation of continuous liquid circulation in the system without altering the pressure indicator is the foundation for the operation of circulation pumping equipment.

A circulation pump is a device that circulates water through a pipeline while functioning in a closed heating system. The coolant in the system is kept at a specific temperature by the unit. The device does not fill the system or replace the coolant that has been lost. A specialized pump or a specific pipe pressure fills the system.

The foundation of circulation pumping equipment’s operation is the creation of a constant liquid circulation within the system without requiring adjustments to the pressure indicator. The primary requirements for such pumps are low noise levels during operation, economical energy consumption, durability, ease of use, and reliability because the device operates continuously after installation.

Crucial: while in use, circulation pumps are quiet, small, and compact devices that take up little room.

Circulating units can be used in a wide range of heating systems. Installed are they:

• in traditional radiator systems;
• when installing underfloor heating;
• in geothermal systems;
• When organizing hot water supply of cottages and summer houses.

Larger diameter pipes are not required for this pumping equipment, in contrast to forced circulation systems. The gadget also offers the following benefits:

• rapid heating of the room;
• The boiler can be installed in any suitable location;
• coolant losses and air locks are minimized;
• Thermostatic relays provide automatic temperature control;
• energy costs are reduced through the use of autoregulation of rotor speed;
• The wet rotor pump is made of stainless steel, cast iron, bronze or aluminum.

Varieties of circulation pumps

The "wet" rotor pump can be composed of aluminum, bronze, cast iron, or stainless steel. There is a steel or ceramic motor inside.

It is essential to comprehend the distinctions between the two kinds of circulation pumping equipment in order to comprehend how this device operates. While the basic design of the heat pump-based heating system remains unchanged, the operational characteristics of the two varieties of these units vary:

1. The wet rotor pump is available in stainless steel, cast iron, bronze or aluminum casing. Inside is a ceramic or steel motor. The technopolymer impeller is attached to the rotor shaft. The rotation of the impeller blades sets the water in the system in motion. This water simultaneously performs the functions of the engine cooler and lubricant for the working elements of the device. Since the wet rotor unit does not use a fan, the unit is practically silent. This equipment works only in a horizontal position, otherwise the device will simply overheat and break down. The main advantages of the wet pump are that it is maintenance-free and has excellent maintainability. However, the efficiency of the device is only 45%, which is a small disadvantage. But for domestic use, this unit is the best suited for this purpose.
2. The pump with a "dry" rotor differs from its counterpart in that its motor is not in contact with the liquid. This makes the unit less durable. If the unit is operated "dry", the risk of overheating and failure is low, but there is a threat of leakage failure due to abrasion of the seal. Since the efficiency of a dry circulation pump is 70%, it is advisable to use it for municipal and industrial tasks. To cool the motor, the scheme of the device provides for the use of a fan, which causes an increase in the noise level during operation, which is a disadvantage of this type of pumps. Since in this unit, water does not act as a lubricant for the working elements, during the operation of the unit, it is periodically necessary to carry out maintenance and lubrication of parts.

Conversely, "dry" circulation units are separated into multiple categories based on how they are installed and connected to the motor:

• Cantilevered. In these units, the motor and the casing have their own place. They are separated and firmly fixed on it. Drive and working shaft of such a pump are united by a coupling. To install this type of unit, a foundation will be required, and maintenance of this unit is quite expensive.
• Monoblock pumps can be operated for three years. The casing and motor are located separately, but are combined as a monoblock. The wheel in such a device is mounted on the rotor shaft.
• Vertical. The utilization period of these devices reaches up to five years. These are hermetically sealed advanced units with an end face seal made of two polished rings. Graphite, ceramics, stainless steel, aluminum are used to make the seals. When the unit is in operation, these rings rotate relative to each other.

Commercial versions of more potent units with two rotors are also available. The unit can operate more efficiently at maximum load thanks to this dual arrangement. The second rotor can take over the functions of the malfunctioning one. Because only one rotor runs when the heat demand is lowered, this improves the unit’s performance while also saving energy.

How the unit works?

A sump pump and a circulating unit work on essentially the same principle. By catching the fluid on one side and pushing it into the pipeline on the other, this device, if installed in the heating system, will move the heat transfer fluid.

The principle of operation of a circulating unit is very similar to that of a sump pump. If this device is installed in the heating system, it will cause the movement of the coolant by capturing the liquid on one side and pumping it into the pipeline on the other side. All this happens due to centrifugal force, which is formed in the process of rotation of the wheel with blades. The pressure in the expansion tank does not change during the operation of the device. If it is necessary to increase the level of coolant in the heating system, a booster pump is installed. The circulation unit only helps the water to overcome the drag force.

The device’s installation plan looks like this:

• A circulation pump is installed on the hot water pipe coming from the heater.
• On the section of the main line between the pumping equipment and the heater, a flow valve is mounted.
• The pipeline between the check valve and the circulation pump is connected to the return pipeline by a bypass connection.

According to this installation plan, the unit’s coolant is only released when it is filled with water. At the end of the pipeline is a receiver with a check valve to allow the liquid to stay in the wheel for an extended period of time.

Home circulation pumps can increase coolant speed to up to 2 m/s, while industrial circulation pumps can accelerate coolant to up to 8 m/s.

It is important to remember that all circulation pumps draw their power from the electrical grid. Given that household appliances have a motor power of only 85 W and large industrial pumps have a motor power of 0.3 kW, this equipment is quite economical.

In the world of home heating and insulation, understanding the role of a circulation pump is crucial. A circulation pump is like the heart of your heating system, responsible for moving hot water or coolant around your house. It ensures that heat is distributed evenly, keeping your rooms cozy and comfortable. Essentially, it helps your heating system work more efficiently by reducing energy waste and ensuring consistent warmth throughout your home. Whether you have a radiator system or underfloor heating, a circulation pump plays a vital role in keeping your house snug during chilly weather. So, if you want to optimize your heating setup and keep those energy bills in check, knowing about circulation pumps is definitely a smart move.

Pump design

A cup composed of carbon or stainless steel separates the motor stator from the rotor now that it is energized.

A circulation pump’s primary components are:

• casing made of stainless steel, bronze, cast iron or aluminum;
• rotor shaft and rotor;
• a wheel with blades or impeller;
• motor.

The impeller is typically composed of two parallel disks joined by blades that curve radially in both directions. There is a fluid leak hole in one of the disks. The impeller is fastened to the motor shaft by a second disk. At the location where the impeller is fixed, the coolant that runs through the motor serves as both a lubricant and a coolant for the rotor shaft.

A cup composed of carbon or stainless steel separates the motor stator from the rotor now that it is energized. The cup’s walls have a thickness of 0.3 mm. For sliding, the rotor is fixed on ceramic or graphite bearings.

Selection of a circulation pump for a heating system

Systems with forced circulation and systems with natural (gravity) circulation make up heating systems. Installing a circulation pump is required in systems that use forced circulation. Its responsibility is to guarantee that the coolant flows through the system at a specific pace. Additionally, the appropriate circulation pump must be selected in order for it to accomplish its job.

Purpose and types

As previously stated, the circulation pump’s primary function is to guarantee that the coolant moves through the pipes at the proper speed. Only in these circumstances will the design capacity for forced circulation systems be reached. The system’s circulator slightly raises pressure while it operates, but this is not its purpose. More of a side effect, this. To raise the system pressure, there are dedicated booster pumps.

More people use wet rotor water circulation pumps.

Circulating pumps come in two varieties: wet and dry rotor. They have different designs but serve the same purposes. Understanding the benefits and drawbacks of each circulation pump type will help you make an informed installation decision.

With dry rotor

Received its name due to the peculiarities of the design. Only the impeller is immersed in the coolant, the rotor is in a sealed housing, it is separated from the liquid by several sealing rings.

The part of a circulation pump that is only submerged in water is called a dry rotor.

The following characteristics of these devices:

• They have high efficiency – about 80%. And this is their main advantage.
• Require regular maintenance. In the process of operation, solid particles contained in the coolant get on the sealing rings, breaking tightness. To prevent depressurization and maintenance is necessary.
• Service life of about 3 years.
• They make a high level of noise during operation.

Installing this combination of features in residential heating systems is not highly recommended. Their primary benefit is their high efficiency, which results in lower energy usage. Because of this, dry rotor circulators are mostly utilized in large networks because they are more cost-effective there.

With wet rotor

The name of this type of equipment makes it obvious that the rotor and impeller are both in the fluid. A metal hermetic cup encloses the electric component, which includes the starter.

Only the electrical component of a wet rotor pump is dry

The characteristics of this kind of equipment are as follows:

• Efficiency of about 50%. Not the best indicator, but for small private heating systems it is not critical.
• No maintenance required.
• Service life – 5-10 years depending on the brand, mode of operation and condition of the coolant.
• Hardly audible during operation.

Choosing a circulation pump by type is not difficult based on the aforementioned characteristics; most people stop at devices with a wet rotor because they are better suited for use in an apartment or private home.

How to choose a circulation pump

Every circulation pump has a unique set of technical specs. They are chosen according to the specific requirements of every system.

Selecting technical characteristics

First, let’s address the selection of technical attributes. There are numerous formulas for professional calculations, but average norms can be used to choose a pump for a heating system in a private home or apartment:

• The capacity of the pump is equal to the capacity of the installed heating boiler. That is, if the boiler stands at 35 kW, then the pump is selected with a capacity of 35 l / min.
• Then it is necessary to calculate the required head (lift height). On average, it is considered that for 10 meters of pipeline there should be a pump head of 0.6 m. To determine how much head a circulation pump needs for a system, divide its total length by 10 and multiply by 0.6 meters per second. For example, if the total length of the heating system, for example, 80 m, the required head will be: 0.6 m * 8 = 4.2 m. That is, in the technical specifications, the head should not be less than that.

It is better if the speed of movement of the coolant in the system can vary. This will make it possible to adjust the heat output depending on the temperature outside: the higher the speed, the more heat is transferred. Therefore, it is better to choose models that can operate at several speeds. But in any case, the speed of movement of the coolant should not exceed 1.6 m / s. This is the threshold of silent operation of the heating system, if you accelerate the coolant faster, there will be noise.

Electric power of the circulation pump is selected depending on the diameter of the pipes. The smaller the cross-section of the pipe, the greater the hydraulic resistance it has. That is, for systems divorced by pipes of small diameter require more powerful pumps.

It is not difficult to choose a circulation pump for heating following these rules. Calculations are elementary. But it should be said that these figures are average statistical figures. If your house in some point is very different from the "average figures", it is necessary to make corrections either in the direction of increase, or in the direction of reduction of technical characteristics. For example, you have well insulated the house, the capacity of the previously purchased boiler was excessive. In this case, it makes sense to take a pump with a lower capacity. In the opposite situation – the house is freezing in extreme cold – you can put a more productive circulator. It will temporarily solve the problem (in the future it is necessary to insulate or change the boiler).

Model selection

Examine the graph showing the pump’s pressure characteristic before selecting a model. Locate the intersection of the head and capacity values on the graph. It ought to be situated in the curve’s middle third. The model with the closer graph is chosen if it does not fall on any of the curves, which typically represent a few different models. Choose the less effective option (the one below) if the point is in the middle.

The center of the graph is where the operating point should be.

What else to pay attention to

The technical specifications of circulators contain a number of additional items that are important to take note of. The pumped medium’s acceptable temperature comes first. That is, the coolant’s temperature. This indicator is within the range of +110°C to +130°C for high-quality products. It can be as low as 90°C in inexpensive ones (and in fact 70-80°C). It is not a big deal if your system is built for low temperatures, but if your boiler runs on solid fuel, the maximum temperature at which the coolant can be heated is crucial.

First, you should select a circulation pump based on its features.

It’s important to take note of the highest pressure at which the pump is capable of operating. Private homes rarely have heating systems that are higher than 3–4 atm (for two-story homes); 1,5-2 atm is more typical. Nevertheless, keep an eye on this signal.

The source material used to make the case is something else to consider. Ideal: cast iron; less expensive; composed of a unique heat-resistant polymer.

Size and kind of connection. The connections on a circulation pump can be flanged or threaded. Both internal and external threads are possible with the right adapters chosen for each. Connectivity levels include G1, G2, G3/4.

It is also important to consider whether protection is present. Potential dry run protection exists. It is highly desirable in wet rotor circulators because the moving medium cools the motor. The motor overheats and breaks down in the absence of water.

An additional form of defense is that against overheating. Theromorelle cuts the power supply and the pump stops if the motor heats up to a critical value. The equipment’s lifespan will be increased by these two features.

Manufacturers and prices

The method for choosing circulation pump manufacturers is the same as it is for choosing any other method. Equipment from European manufacturers, who have been in the market for a long time, is preferable if at all possible. In this industry, circulators Willo (Willo), Grundfos (Grundfos), and DAB (DAB) are regarded as the most dependable. There are other reputable brands, but you must read reviews for them.

Circulation pump for heating – how to choose inexpensive and effective

Water heating systems have traditionally been constructed using the idea of natural water circulation. It is evident that the horizontal pipes in older homes are inclined. The working principle is the same as that of a kettle. Warm water rises to the top and cools down.

Due to the high resistance of the water in the pipes, these circuits have low efficiency. The process might come to an abrupt halt if the coolant encountered an air lock. Large-diameter pipes were therefore installed in order to use gravity-flow systems to heat the house. It was costly and not visually appealing.

Details: This plan was only applicable in cases where the boiler was put in right inside the home. When heating is centralized, a pump is the only device that moves hot water through the heat pipe.

Such a system, with thin pipes and a short coolant path, is appropriate for small rooms. Use gravity flow for small cottages as a result. The entire system takes a while to warm up. It is essential to have a boiler circulation pump if your home has three or four rooms, especially if they are on different floors.

You will have to wait for the diffusion effect to start if you don’t. In this instance, the rate at which the heat moves through the pipes is 10 cm per hour.

What is a circulation pump for heating

Actually, it’s just a regular vane (turbine) type water pump. Although they exist, piston pumps are not utilized in heating systems.

An electric motor powers a turbine that is located inside. The fluid flows in one direction when the sockets rotate due to a pressure differential.

The materials used in the pump must be resistant to heat and corrosion because it operates at high temperatures in the heat transfer medium:

Composite material housings are available, but they fall into a different price range.

Special polymers are used to make the turbine impeller. Few people will want to frequently disassemble the heating system in order to replace the pump components, so the calculation is for long-term operation.

It is easy to find the perfect one because there is a wide variety of designs and sizes. But there’s more to the differences than just looks.

Water pump – differences in design

Despite the abundance of options, pumping pumps fall into two categories:

Dry rotor

Immediately apparent is a distinctive difference: the pumping chamber and motor are clearly separated.

The working turbine and the drive can be separated according to the design. Water only comes into direct contact with the impeller. A lengthy shaft connects the exterior-mounted motor to the water chamber. Oil seals, akin to those found on ship propeller shafts, guarantee tightness.

One of the system’s benefits is its high efficiency. The best models have an efficiency of up to 80%. This is the best option if your branched system requires a strong pump. Pumping a lot of coolant will result in lower energy costs.

There are a number of drawbacks as well. This pump produces a lot of noise, so it should only be installed in separate boiler rooms and not in residential areas. Continuous operation causes the motor to overheat.

Needs a casing radiator, which makes the pump larger. Oil seals are a vulnerable area. Rubbers tan and become out of order very quickly when exposed to hot water and tiny calcium particles.

Consequently, maintenance is needed for the dry pump following each heating season. Water may reach the motor windings if a leak is overlooked. A three-season lifespan is the average.

Wet rotor

The primary benefit is its neat appearance and compact size.

The pumping chamber serves as a "bath" for the impeller and motor rotor. This design offers good bearing lubrication and heat dissipation regardless of the medium’s temperature.

For those who are skeptical about water’s ability to lubricate, consider the layout of a car engine water pump.

The electrical component is completely shielded from moisture infiltration and is housed in a separate compartment.

Practically silently operates. When selecting a circulation pump for homeownership, this parameter is essential. The pump also requires no maintenance. Functions in accordance with the "set it and forget it" principle. 6–8 years is the service life. Particularly when compared to the preceding category, the unit is small.

One drawback is its lack of efficiency. Seldom does efficiency get to 50%. However, the pump’s capacity is more than adequate for a modest cottage or apartment.

How to choose a circulation pump

It is unlikely that size and appearance will be decisive factors. The circulation pump can be placed in practically any area of the heating circuit, and the boiler equipment is not situated in the front living room.

The main parameters that interest the buyer

Performance

It has a linear relationship with the boiler output to make calculations easier. A one-liter-per-minute pumping capacity must be offered for every kilowatt. That is, select a pump with a minimum flow rate of 50 l/min if your boiler has a 50 kW capacity.

A speed regulator should be installed on the recirculation pump if the weather in your area is erratic, meaning that it could abruptly warm up in the winter or experience frost in April. The rate of heat exchange increases with the coolant’s velocity through the pipes. It is possible to maintain the boiler’s output.

Water back pressure

The floor level of the house affects how the circulation pump is calculated. Regardless of the length of the heating system, 1.5 to 2 atmospheres is sufficient for running water on one level. Each floor after that doubles the amount. That is, the back pressure needs to be at least 4 atmospheres for a typical two-story cottage with a warm attic.

Temperature mode

Working with hot coolant is implied by the heating pump’s specifications (at least from a common sense perspective). But water temperatures differ, and material quality is compromised by pump manufacturers.

Consequently, it is essential to consider the highest temperature at which uninterrupted operation is ensured. Make sure to purchase a pump only in the heating mode. The temperature at which the boiler exits must be 10% below the pump’s maximum temperature.

An essential part of heating systems, a circulation pump is vital to the effective distribution of heat throughout a home. It provides constant warmth throughout your house by moving hot water or coolant through the pipes, which raises comfort levels and lowers energy usage.

Comprehending the functioning of a circulation pump can enable homeowners to make knowledgeable choices regarding their heating systems. In essence, the pump transfers hot water to radiators, baseboard heaters, or underfloor heating systems by forcing it through the pipes from the boiler or heater. A continuous loop of warmth is created when the cooled water returns to the boiler to be reheated and circulated once more.

Selecting the appropriate circulation pump is crucial for maximizing energy savings and reducing running expenses. The selection process is influenced by various factors, including the desired level of control, the type of heating system, and the size of the house. Purchasing an energy-efficient, high-quality pump can ensure dependable heating performance as well as long-term utility bill savings.

A circulation pump’s lifespan can be extended and smooth operation ensured with regular maintenance. Easy maintenance procedures like pump cleaning, leak detection, and lubricating moving parts can save expensive repairs and breakdowns. Furthermore, keeping an eye on the pump’s performance and taking quick action to fix any problems can help prevent the heating system from being disrupted.

To sum up, a circulation pump is an essential part of any home heating system that distributes heat in an effective and efficient manner. Through comprehension of its operation, appropriate pump selection, and upkeep, homeowners can relish cozy living areas while reducing energy costs. A circulation pump can contribute to a warm and energy-efficient home environment for many years to come with the correct maintenance.

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