How to connect a plate heat exchanger?

TIPS ON CONNECTION AND OPERATION OF SOLDERED PLATE HEAT EXCHANGERS

The first and most important information is that the proper functioning of the exchanger in the installation begins with its correct selection. The exchanger should be selected by experienced individuals, although not everyone who has installed an exchanger or works in the hydraulic industry can be considered experienced in selecting such devices. The appropriate model should be selected, considering the most important parameter of the exchanger, which is the heat exchange surface area, rather than just the nominal power (kW). Properly selected equipment must be oversized within a healthy range. In the case of undersizing the exchanger, even correct connection and operation will not help achieve the expected result.

Technical data and nameplate of the heat exchanger

The nameplate contains the model name, which for traditional Nordic Tec plate exchangers starts with the letters "Ba" (e.g., Ba-23-20). The middle designation indicates the surface area of a single plate (for Ba-23-20, it is 0.023m2). The last number indicates the number of plates (for Ba-23-20, it is 20 plates).

Below are the limit parameters, such as working pressure, etc. Of course, at this stage, it should be checked whether the system in which the exchanger is to operate does not exceed the allowable parameters. Relax - in principle, this does not apply to home heating installations, as they do not have too high pressure requirements and are based on the simplest media such as water, occasionally a water-glycol solution (permissible). The pressure in such a heating system rarely exceeds a few bars, so there is no problem because exchangers usually have working pressures between 10 and 30 bars. The issue of possible working pressure arises when using high-pressure media such as Freon or R agents (but we consider this to be a slightly different application than traditional ones), for example, in applications with heat pumps (as a condenser).

Ba-115-50 2"

NT Ba-115-50

1 099,99 €

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Ba-27-70

NT Ba-27-70

354,99 €

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Plate Heat Exchanger NORDIC Ba-16-22 1" 100kW

NT Ba-16-22

109,99 €

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Copper solder and copper residues on the heat exchanger

The exchanger has copper solder, always undergoes a soldering process, which means that in some cases, it may have copper residues (e.g., on the top plate) resembling corrosion. It should be remembered that this is not corrosion but copper elements that do not in any way reduce the efficiency of the device or affect its potential damage in the future. They are only aesthetically significant and are not a basis for replacing the device or warranty with any of the manufacturers.

Flow direction indicated on the nameplate of the plate heat exchanger

The sticker with data contains arrows that suggest counterflow connection. In fact, the Nordic Tec plate heat exchanger is a counterflow device, which means it is designed to achieve its maximum efficiency only when the fluids flowing through it move in opposite directions (e.g., following the arrows on the sticker). Connecting without adhering to the counterflow principle may result in the exchanger not performing as expected, causing the entire installation to operate inefficiently.

IMPORTANT - if connecting according to the arrows poses a problem for us, the exchanger should be reversed and connected opposite to the arrows. This changes the flow direction, but to maintain counterflow, the flow direction must be changed on both channels.

Channels of the plate heat exchanger - which channel for the heating side?

One channel is intended for the heating side, usually the circuit of the heating device - boiler, fireplace, heat pump, or solar panel. The other channel is intended for the heat receiving system.

In the case of the Nordic Tec brand - it doesn't matter which channel we choose for which system. It's a matter of freedom and convenience because both channels have the same flow parameters, identical capacity, and throughput.

Manufacturer's warranty

The warranty is 60 months and covers manufacturing or material defects. In practice, it is important to connect the exchanger according to the art and recommendations. The warranty does not cover damage resulting from incorrect installation or resulting from contamination or fouling of the exchanger, including leaks caused by scaling, clogging, contamination, exceeding parameters, working with hazardous media, or self-interference with the product's construction.

Preparation for plate heat exchanger installation - VERTICAL POSITION (the only correct one)

The heat exchanger should not be exposed to excessive pressure and temperature fluctuations. Additionally, it should be protected from excessive vibrations - it should be securely mounted on the wall. We recommend using dedicated wall brackets, but other solutions can also be used if they provide stability and protection against vibrations. The mounting should be chosen appropriately for the weight of the heat exchanger together with the media flowing through it.

The exchanger should be mounted vertically (i.e., on a stub). Mounting the exchanger in a different position, e.g., horizontally, does not guarantee proper venting of the device and will cause blockages or poor heat transfer if air bubbles do not escape from the device. Generally, a horizontally connected exchanger will not operate correctly (in a standard heating or domestic hot water system). Clogging of the exchanger can lead to irreversible damage, such as leakage.

Below - plate heat exchanger connected in the incorrect (horizontal) position, where it has become clogged due to lack of proper venting. The construction of this device means that it will not function correctly in this position.

Filters on the inlet of plate heat exchangers from each side (mandatory element)

The manufacturer strongly recommends using filters, but does not specify the type of filters. Filters should be placed on both sides before the exchanger, regardless of whether they are also present in other parts of the installation.

In most new installations, a simple mesh filter is sufficient, but the choice of filter and responsibility for it lies with the person who inspected the installation and assessed the potential risk with professional judgment. In some cases (in old, potentially contaminated installations), it may be worth considering a magnetic filter / separator in addition to traditional filters. This is very important because any clogging of the exchanger due to contamination from the installation is not a basis for warranty, but essentially means a disruption or significant limitation of heat exchange.

Filters should definitely be installed before the exchanger already before the trial run of the system, not afterwards. The first start-up of the pumps can cause blockages more likely than continuous pump operation. Therefore, any ideas like "let's check if it works, and then we'll add filters" can cost us a lot.

Additional assortment for plate heat exchangers (not mandatory, but recommended) - ball valves and thermometers, thermal insulation for heat exchangers

The device can operate without ball valves in front of it, that's obvious. However, it is advisable to install ball valves on both sides of the exchanger so that they can be closed if necessary, allowing the device to be removed from the installation without draining the entire system. This may be useful for cleaning the exchanger (which should be done from time to time) or in case of failure, leakage, etc. Plates are installed with the assumption that they will operate for 10-15 years, so we never know when a shut-off valve may be very helpful.

Thermometers are not necessary, but their presence on both sides allows for ongoing assessment of heat exchange efficiency, as they enable us to evaluate the amount of heat loss occurring on the exchanger. If the loss increases, we have insight into the situation and can decide whether to clean or replace the device with a newer one. It's worth considering specially designed ball valves with thermometers, which are used for various devices such as underfloor heating manifolds. You can find them here.

Thermal insulation is recommended, but if our criterion is a lower installation cost for the heating system, the exchanger will operate correctly even without it (provided correct selection and connection). However, in the long run, it contributes to heat savings and definitely pays off over time.

Connections of Nordic Tec soldered heat exchangers

The Nordic Tec manufacturer uses the most common type of thread, namely external BSP thread. The connections are permanently attached to the exchanger by hard (vacuum) soldering, and any attempt to remove them may result in damage to the exchanger.

Connecting threads to the rest of the installation should be done according to accepted practice, ensuring sealing.

Any modifications to the connections or interference with the thread structure may be considered as non-compliant usage and may affect the warranty.

Air venting of plate heat exchangers

It is recommended to install an air vent in close proximity to the exchanger, naturally positioned higher than the device. This applies especially to the hot / heating side, as at high temperatures the solubility of gases is relatively lower, increasing the risk of air entrapment in the device.

Proper operation and cleaning of plate heat exchangers

Nordic Tec heat exchangers are durable devices, but they require proper selection, installation, and use. They are almost maintenance-free devices, but it's worth following the recommendations to maintain the device's full efficiency, which also translates into lower heat consumption costs.

Recommendations:

1. Prevent contamination of the installation and exchanger in general.
2. Avoid operating above the working pressure and above the maximum temperatures.
3. Avoid sudden pressure and temperature fluctuations.
4. Perform periodic cleaning of the exchanger, which in heating systems should be done once a year, and in domestic hot water systems every six months. These are general recommendations, but more frequent cleaning may be required if conditions indicate, such as water condition.

In so-called open systems, water treatment devices should be used, while in closed systems, treated water should be used!