Although the regulations do not oblige investors to use a domestic hot water circulation system in single-family homes, sometimes it can be very useful. Such a solution only slightly increases electricity consumption, but in return saves water and significantly increases the comfort of using the hot water installation. The key element of such a system, apart from the additional water return pipe, is the circulation pump . How does such a device work and what should be considered when choosing it?
In this article you will learn:
- what is a circulation pump used for,
- what to consider when choosing a circulation pump,
- what additional functions do circulation pumps have
- What does the installation of a circulation pump look like?
Circulation pumps for single-family houses - characteristics
It is worth installing a circulation pump in a domestic hot water installation, especially when the collection points are located far from the water heater or tank. When using a system without a circulation system, one must accept the loss of water resulting from waiting for the inflow of heated water, while too cold water is wasted unproductively.
Not only is this uncomfortable, but it also translates into significant losses over the course of a year. Assuming that the distance between the domestic hot water tank and the draw-off point is 20 meters, and the pipes are 20 mm in diameter, there are about 6 liters of water in the pipe. Draining it 3-4 times a day means a loss of up to 6 to 9 thousand liters of water per year!
It is precisely such unnecessary costs that domestic hot water circulation systems are designed to prevent. An additional water pipe and a pump enable the circulation of heated water in the domestic hot water installation when the taps are closed, so when the tap is opened, hot water is immediately available.
This is not the only advantage of circulation pumps. It is also worth mentioning that the movement of warm water in the pipes minimizes the risk of so-called stagnation. These in turn promote the growth of bacteria that can cause a deterioration in the taste and smell of drinking water and even be the cause of a dangerous disease such as legionellosis.
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What to consider when selecting a circulation pump?
Due to the working environment, the circulation pump must meet a number of restrictive requirements. First of all, it should be resistant to corrosion and sediments precipitating from water. To meet this criterion, the material from which the bodies of such pumps are made is primarily brass of a specific composition, as well as bronze or stainless steel. On the other hand, the impellers of these pumps are currently built from modern plastics - composites. Contact of these materials with water does not negatively affect its quality. Confirmation of the product's adaptation to drinking water installations is a hygiene certificate.
Another criterion for selecting a pump — in addition to the materials used and certificates held — is its power. Importantly, this value does not have to be particularly high. The task of the device is only to overcome the resistance of water flow through the pipes. For this purpose, a lifting height of 1-1.5 m is sufficient. Modern, electronically controlled domestic hot water pumps consume only a few watts, older models may be more energy-intensive. You should also pay attention to the efficiency of the circulation pump, which will depend on the amount of water in the installation. It is recommended that the medium is replaced 3-5 times per hour, so for use in a single-family home , a pump with a maximum flow of 0.5 m3/h (500 liters per hour) is sufficient.
Design of a modern glandless pump with a spherical motor
The rotor with a permanent magnet is spherical and supported by a spherical ceramic bearing. It operates completely submerged in the water it pumps.
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It is also worth taking a look at the additional functions offered by the pumps, which may affect the comfort of their operation, energy efficiency and the efficiency of the circulation system.
Such functions include, for example:
- Automatic pump venting – a special operating mode that, when turned on, helps to remove air accumulated around the pump impeller. An air-filled pump works louder than usual, but less efficiently.
- Built-in control clock – allowing you to program the hours at which the pump should operate - water circulation is of no use when no one is at home!
- Automatic adaptation of the pumping to the demand for hot water,
- Temperature control – allows you to set the temperature range maintained in the installation so that the water is neither too hot nor too cold.
- Superheating support function – if the installation uses superheating of water for disinfection purposes, the pump should be adapted to this – to withstand a short-term water temperature of 72 – 95 C. This procedure is used, for example, in hotels and guesthouses.
Domestic hot water circulation pumps
Installation of a domestic hot water circulation pump
The domestic hot water circulation pump should be placed on the hot water circulation line – return – directly before the heater. This means that the pump supports the return of water from the hydraulic system to the heater. Such an installation reduces the demand for pump power because it only supports the natural movement of water – heated – upwards, cooled – downwards.
The position in which the pump is installed can be almost any, but this should be verified in the operating instructions. The manufacturer usually informs which operating position is not recommended - for example, due to excessive load on the rotor bearings or the possibility of condensed water collecting outside the installation in the area of the electronics or pump connection cables. Another important issue is ensuring easy access to the pump, especially if it has additional functions that require access to the device to be activated. There should be shut-off valves before and after the pump, and a non-return valve is also important to prevent the flow direction from changing when the pump is switched off.
Some pumps are supplied complete with such valves and an insulating sleeve which, by covering the hot part of the body, reduces heat loss in the circuit. This may be an additional factor influencing the purchase.
During installation, it is also worth paying attention to the issue of air in the system. This can occur if the circulation pipe is connected to the hot water pipe above the point where the water is fed to the battery. Air then collects at the highest point of the circulation pipe. To prevent such problems, an automatic float air vent should be installed at the highest point of the circuit.
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Circulation pumps in the Onninen offer
To ensure your customers the comfort and safety of the domestic hot water system, choose only circulation pumps from proven manufacturers. You will find high-quality devices in the assortment of our online wholesaler. You have at your disposal, among others, such models as:
- GRUNDFOS COMFORT 15-14 B PM circulation pump , power consumption 5-7 [W], popular constant speed pump equipped with a 1.5 m cable with a plug and thermal insulation.
- GRUNDFOS COMFORT 15-14 BA PM AUTO-ADAPT circulation pump , power consumption 5-7 [W], with AUTO-ADAPT system that adjusts power to demand. 1.5 m cable with plug and thermal insulation,
- GRUNDFOS COMFORT 15-14 BXDT PM, power consumption 5-7 [W], with built-in timer, equipped with 1.5 m cable, non-return valve, shut-off valves and thermal insulation sleeve,
- WILO STAR-Z NOVA A circulation pump : power consumption 3-5 [W], with shut-off ball valve and non-return valve with G1" thread
- WILO STAR-Z NOVA T circulation pump : power consumption 5-7 [W], with built-in time controller, temperature control and thermal detection and support function
system for switching on the circuit disinfection function on the boiler side. Complete with thermal insulation, shut-off ball valve and non-return valve. - ONNLINE CP 15-1.5 circulation pump : power consumption 28 [W], basic, constant speed, cheap circulation pump.
- ONNLINE PRO 15-1/65B circulation pump : power consumption 3-9 [W]; with power regulation, automatic air venting function, equipped with a non-return valve and thermal insulation sleeve.
These are just a few examples from the rich offer of the Onninen installation wholesaler , which offers circulation pumps from renowned manufacturers. A wide selection of products will allow you to find a circulation pump perfectly suited to the needs of your customers!
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