Selection of air handling unit. How to choose a factory heat exchanger for a country house

Production Association KLIMATVENTMASH is one of the largest manufacturers of supply and exhaust ventilation units in Russia.

We would like to present to your attention a series of central air conditioners KKCM (Frame Central Modular Air Conditioner) designed for use in supply and exhaust ventilation systems.

A wide range of standard sizes allows for the optimal choice of the central air conditioner, taking into account the speed of the air processed in the supply and exhaust unit. The range of use of KKCM is from 2.5 to 110 thousand m3 / h.

At present, air conditioning using central industrial air conditioners cannot be imagined without energy-saving technologies. With this in mind, the use of air handling units with recuperation is recommended. However, the calculation and selection of the supply exhaust unit it is necessary to carry out taking into account the peculiarities of the technological process and the parameters of the outside air.

The KKCM central air conditioner is assembled from separate structural and functional blocks that serve to implement air treatment processes for supply and exhaust ventilation systems.

So, for example, as part of the air handling unit for office buildings, rotary and plate heat exchangers can be used. And the supply and exhaust ventilation system of the workshop without harmful emissions can use the recirculation system, i.e. reuse part of the treated (purified, heated or cooled) air with the admixture of the required amount of outside air. This solution allows to reduce both energy consumption and the cost of the flow-exhaust installation.

In explosive industries, a schematic diagram of the system supply and exhaust ventilation completely different. Here, the most efficient from all points of view is the use of a recuperation system with an intermediate heat carrier as part of the supply and exhaust unit. In this case, if necessary, the supply and exhaust parts of the unit can be separated into different rooms.

In some cases, the design features of the building require the use of lighter and more compact units in the supply and exhaust ventilation systems. To do this, KLIMATVENTMASH can offer the customer a range of supply and exhaust units of the SVAN type (Composite Ventilation Unit) - in the case and ABC (Composite Ventilation Unit) - without the case. The units are developed on the basis of our duct fans. The capacity of the units is from 300 to 8000 m3 / h. Installation of air handling units can be carried out in the space above the ceiling.

We are ready to provide our customers with professional advice on the selection of central air conditioners and flow-exhaust units, taking into account all design and technological features.

At the service of design organizations and our dealers in the regions of Russia, the site contains a program for computer selection of central air conditioners KKCM-selection and air handling units such as SVAN and ABC KVM-selection.

The scope of KLIMATVENTMASH brand equipment as part of the supply and exhaust ventilation system is very wide. The units process air according to the following parameters: heating and cooling, humidification and dehumidification, filtration of any purity class. Our air conditioners and air handling units can be used in any technological process: office buildings and shopping malls, microelectronics and medicine, petrochemistry, clean rooms, food industry, Agriculture, sports facilities, etc.

Air handling units and central air conditioners of the KLIMATVENTMASH brand are a serious alternative to imported equipment.

The exact selection of the air handling unit must be carried out by an authorized Breezart dealer. At the same time make a pre-selection suitable model You can do it yourself with a simple technique. To do this, it is enough to determine the required performance of the supply unit, the power and type of its air heater. Detailed information on the ventilation calculation methodology can be found on the website of our partner, and here we will briefly describe the main parameters of ventilation installations.

air performance

To calculate the required performance of the air handling unit, we need to know the area of ​​the serviced premises, the height of the ceilings and the purpose (type) of the premises (residential or office).

First, we need to determine the air exchange rate. This parameter shows how many times within 1 hour the air in the room will have time to completely change. For example, a room with an area of ​​28 square meters with a ceiling height of 3 meters has a volume of 84 cubic meters. A single air exchange for it is 84 m³ / h, a double one - 168 m³ / h, etc. The required multiplicity depends on the purpose of the room, the number of people in it and other parameters. For living quarters usually choose 1 or 2 air exchange; For office - 2 or 3 times. At the same time, at least 60 m³ / h of fresh air should fall on each person in the room, therefore, for office space with a large number of people, the air exchange rate can be increased.

Now, having determined the required air exchange rate, we can find the performance of the supply unit. To do this, it is enough to multiply the volume of the serviced room by the frequency of air exchange. For example, in a three-room apartment with a volume of about 255 sq.m(area 85 sq.m with a ceiling height of 3.0 meters) to ensure 1.5 times air exchange performance required is approx. 380 m³/h.

It should be noted that in technical specifications air handling units always indicate the maximum performance (with free entry and exit). When connecting air ducts with distribution grilles to the supply unit, its performance will decrease, since the air duct network creates resistance to air flow. The degree of performance drop depends on the length and complexity of the air distribution network and is determined by the ventilation characteristics of the selected model. For a simple network with two or three grids, we can assume that the performance drop will be 20-30%. Thus, for this example, when pre-selecting, you can stop at the model, which has a maximum capacity of 550 m³ / h, which corresponds to 380 - 440 m³/h when connecting a simple air duct network. Note that all air handling units have fan speed controllers that allow, if necessary, to reduce performance.

Heater power

Breezart air handling units have a built-in heater for heating the supply air. The heater can be water or electric:

• Air handling units with electric heater easy to install and easy to operate. However, electric heaters have a limited capacity and are therefore only installed in models with a capacity of up to 4500 m³/h. Another disadvantage of electric heaters is the high operating costs associated with high power consumption, especially in winter. With a heater power of up to 5 kW, there are modifications for connecting to a single-phase (220 V) or three-phase (380 V) network. All heaters with a power over 5 kW are connected only to a three-phase network.
• Water heater connects to an autonomous (it can be, for example, a gas boiler in a cottage) or central heating system. The advantage of water heaters lies in their high power, so they are used in air handling units with a capacity of 1000 to 16000 m³/h. It is traditionally believed that models with a water heater are more difficult to install and operate and, moreover, are at risk of defrosting the heater. However, Breezart air handling units, thanks to their design features, practically got rid of these shortcomings. The built-in mixing unit makes their installation almost as easy as the installation of air handling units with an electric air heater. And the automation system with three-level protection against freezing of the heater and the built-in air valve with a return spring completely exclude the possibility of defrosting the heater.

The power of the air heater is determined by the capacity of the supply unit, as well as the air temperatures at its inlet and outlet. For Moscow, the estimated temperature difference between the inlet and outlet is 44°C (from -26°C to +18°C). The table below shows the power of the heater and the corresponding performance, at which the supply air is heated by 44°C.

Note that the power of the heater is often chosen less than the calculated one based on the following considerations:

• Severe frosts occur infrequently and during these periods it is possible to turn on the air handling unit at the minimum speed (in this case, its productivity decreases by 3-4 times).
• All air handling units have the function "Comfort", which provides automatic fan speed reduction when it is impossible to maintain the set temperature due to insufficient heater power.

The above technique allows you to accurately select the air handling unit for an apartment or a small cottage.

For additional advice, please contact our dealers, a list of which is given in the section

How to effectively use the temperature of the exhaust air, which is simply thrown into the atmosphere? How to choose a device that will utilize heat and thereby save energy costs for heating? This article will focus on factory recuperators.

The desire for energy saving often leads to the fact that the house becomes almost a thermos, which keeps heat due to thermal insulation. In such houses, a supply and exhaust ventilation system must be provided, otherwise the residents will have to breathe the exhaust air, which will affect their health. The basis of ventilation is a system of air supply and exhaust channels, on the basis of which you can create individual microclimate systems by connecting various devices and filters. The forced ventilation system is driven by a supply and exhaust unit (PVU), which may contain an integrated heat exchanger.

As you learned from the previous article, the recuperator is part ventilation system premises. Like any other engineering system (heating, plumbing, electrical), it can be entrusted to professionals who will calculate everything, bring it in, deliver it and give a guarantee. In this case, we should not even think about the choice - the experts will offer the best and you just have to pay for their services. In this article, we will tell you how to get an approximate result without overpaying.

It should immediately be noted that the recuperator is an auxiliary device. It prepares the air, bringing it to the desired state. As you know, air conditioners and heaters use a lot of energy to heat or cool the air. The work of a factory (or home-made) recuperator requires very little energy, and sometimes it does occur naturally. Due to this, approaching the initial temperature to the set one even by 2-3 degrees already becomes beneficial in the end - powerful devices have to work less.

Some vital rules for self-installation of supply and exhaust ventilation ducts:

1. The air from the kitchen and bathroom is "charged" with impurities, so before it enters the air handling unit, it must be cleaned with duct filters.
2. The air intake from the kitchen must be connected to kitchen hood with filter.
3. When creating a home-made system on fans (without an air handling unit), select fans with the lowest noise level and the so-called duct mufflers.
4. The estimated time for complete air exchange of the room is 1 hour. Choose fans of the appropriate performance.

Depending on which option is chosen - a factory air handling unit (PVU) or a home-made one on fans, further actions are divided into:

1. Selection of a factory PVU with a built-in heat exchanger and its integration into the finished system.
2. Selection of a factory heat exchanger and its installation in the system.

The principle of calculation when selecting a PES with a heat exchanger

In both cases, we expect approximately the same calculations. At the "head of the table" is the performance or air consumption. Productivity - the amount of air passed per unit of time. Measured in cube. m/hour. To select this indicator, we calculate the volume of air in ventilated rooms and add 20% (for the resistance of filters, grilles). The resistance of the built-in heat exchanger is already taken into account in the passport data of the unit.

Attention! When calculating independently, rounding and tolerances should be done with an increase towards the margin (power, productivity, volume).

Let's look at an example country house with ceilings of 2.4 m, served by 2 bedrooms (12 m 2 each), a living room (20 m 2), a bathroom (6 m 2) and a kitchen (12 m 2).

Total air volume: (2 x 12 + 20 + 6 + 12) x 2.4 = 148.8, accept 150 m 3 .

Note. The choice of a more powerful installation is justified if it is possible to increase the area of ​​​​the premises and to increase the resource of the unit.

Air handling units with built-in heat exchangers

Index	PES model
		VUT 200 G mini	VUT 400 EH EC ECO	Dantex DV-350E	DAIKIN VAM350FA
Manufacturer	VENTS, Ukraine	VENTS, Ukraine	VENTS, Ukraine	Dantex, England	Daikin, Japan	Daitherm, Denmark
Productivity, m 3 / hour	100	200	450	350	350	520
	86	116	300	140	200	350
Heat exchanger type	Plates, paper	Plates, aluminum	Countercurrent, polystyrene	Countercurrent, polymer	Counterflow, aluminum	Plates, bimetal
	68	85	98	88	92	95
Note	Coarse filters	G4 filters, heating optional	Filters G4, F7, heater	3 operating modes, filters	Fully automatic, replaceable filters	Full automatic, room version
price, rub.	13800	16500	20800	32200	61700	85600

For those who fundamentally do everything with their own hands, the system performance calculations will concern the fans built into the channels. Their performance should already be calculated during the design (calculation) of channels, depending on the volume of air. To select the appropriate heat exchanger, we calculate the total capacity of the fans operating for the inflow to the heat exchanger, and subtract 25% (for system resistance, variable cross section and synchronous operation). One duct fan must also be installed at each inlet and outlet of the heat exchanger.

For our example:

• 1 supply and 1 exhaust fan is installed for each room;
• required capacity of each fan:
  1. Bedroom 1: , accept 35 cu. m/hour.
  2. Bedroom 2: 12 x 2.4 = 28.8 + 20% = 34.56, accept 35 cu. m/hour.
  3. Living room: 20 x 2.4 = 48 + 20% = 57.6, accept 58 cu. m/hour.
  4. Kitchen: 12 x 2.4 = 28.8 + 20% = 34.56, accept 35 cu. m/hour.
  5. Bathroom: 6 x 2.4 = 14.4 + 20% = 17.28, we accept 18 cubic meters. m/hour.
• total cumulative performance of system fans: 35 x 3 + 58 + 18 = 181 cu. m/hour;
• heat exchanger load: 181 - 25% = 181 - 45,5 = 135,75 , we accept 150 cubic meters. m/hour.

Factory heat exchangers

Question: What do the numbers 40-20 mean in the marking of factory recuperators?

Answer: Dimensions of inlet and outlet channels in millimeters. 40-20 - minimum dimensions factory heat exchangers.

When installing such a device in a cold place, for example, in the attic, remember that it and the air ducts should be insulated.

Another type of recuperators is autonomous channel heat exchangers. They are also called ventilators. These devices serve only one room and belong to the so-called decentralized ventilation system. They do not require calculations, it is enough to choose a model for the volume of the room.

Air ventilators

Index	Model of duct ventilator
	PRANA-150	VENTS TWINFRESH R-50/RA-50	O'ERRE TEMPERO	MARLEY MENV 180	SIEGENIA AEROLIFE
Manufacturer	Ukraine	Ukraine	Italy	Germany	Germany
Productivity, m 3 / hour	up to 125	60	62	68	45
Consumed energy (without heater), W	7-32	3-12	12-32	3,5-18	8,5
Heat exchanger type	Plates, polymer	Plates, bimetal	Channel, aluminum	Plates, bimetal	Channel, bimetal
Recovery efficiency, up to %	67	58	65	70	55
Note	Remote control, "winter start"	4 modes, 2 filters	32 dB, 5 modes	40 dB, G4 filters	Synth. filter, 54 dB
price, rub.	9 300	10200	14000	24500	43200

Vitaly Dolbinov, rmnt.ru