Unit heaters are used to heat places like workshops, large stores, and projects that have a central hot water or steam boiler. The following content provides information, technical specifications, capacity estimation, and the best price guide for hot water and steam unit heaters, so keep on reading.
Unit Heater Review, Selection, and Pricing
Unit heaters receive the hot water or steam for their heating coils from the building's central boiler usually located in the engine room. They are devices that can heat large spaces such as sports halls and factories, in the shortest time.
Types of Unit Heaters
Unit heaters are divided into several for providing ambient heating in terms of installation location, fluid type, and airflow direction.
Installation Location: In terms of installation location unit heaters are divided into two categories: ceiling unit heaters and wall unit heaters.
Fluid Type: In terms of the heating fluid unit heaters are divided into two categories, steam and hot water.
Airflow Direction: in terms of air direction unit heaters can be divided into horizontal airflow and vertical airflow.
How Unit Heaters Work
In unit heaters, the required hot water or steam flows from the engine room to the coil of each unit heater by circulator pumps (flow rate and friction head must be calculated by facility engineers).
After hot water or steam enters the finned coils of the unit heater, the air passes through the coil assembly and the heating fins, which are usually 8 fins per inch of the coil, and is then heated by the axial fan or propeller. It is pushed forward and causes the air in the installation area to heat up.
The operation on or off and even the change of the engine speed of the hot air blower unit heaters is regulated by the thermostat installed at the height of 140 cm from the floor of the space and away from the hot air flow of the unit heater or direct sunlight.
The amount of air ejection and the volume of air output in unit heaters are also different based on the capacity and power of their engines. Still, normally, the power of air ejection and effective heating in the space in front of each unit heater can be considered from 8 to 20 meters.
If you use a steam unit heater, pay attention to the important point that the amount of heating in the steam unit heater is directly related to the steam pressure entering the heating coil of the unit heater.
In other words, if the inlet steam pressure is equal to 5 psi, the heating value of the same unit heater is much lower than when the inlet steam pressure is 15 psi. Therefore, when choosing a steam unit heater, pay attention to the available steam pressure to provide heat energy.
Advantages of Unit Heaters
The following are the most important advantages of a unit heater:
No need for an independent heating system
Having adequate heating power
Less space, especially in wall and ceiling models
Better distribution of hot air in the environment
High speed in heating the environment
The ability to install and throw air horizontally and vertically
Controlling the ambient temperature using an indoor thermostat
Equipped with hot water or steam coils
Unit Heater's Capacity Approximate Estimation
You should calculate the approximate capacity of the unit heater for a space based on a few factors:
The weather conditions of the area (temperature outside in the winter)
The dimensions and usage type of the area (temperature inside)
The type of materials used in the construction of the area
You can consider the heating capacity of about 250 to 500 btu/hr per cubic meter of air volume according to the decision of the constructors.
Consider about 250 to 300 btu/hr per cubic meter for warm cities such as:
Saudi Arabia: Yanbu, Jeddah, Mecca, Al Wajh, Al Hufuf, Unayzah, Buraydah
Note: These numbers are 100% accurate and for proper results, the decision of the constructor is required.
Unit Heater's Heating Capacity Calculation
The following is the formula you need to calculate the thermal capacity of a hot water/steam unit heater:
QT = (U1 x A1 + U2 x A2 + U3 x A3 + … + An ) x ΔT + (V x 0.0749 x 0.24 x ΔT)
QT: heating load of each unit in kilocalories per hour.
U1: to Un heat transfer coefficient of each surface between the inside and outside of the building in terms of BTU/ft2.hr. °F, which should be determined based on the material of each wall, using engineering reference tables.
A: is the area of each of the peripheral surfaces of the corresponding unit that transfers heat to the outside of the building. This area (in square feet) includes walls, windows, doors, and ceilings.
ΔT: the temperature difference between the inside and outside of each unit under normal conditions, which is in °F.
V: Total amount of air infiltrating through door or window seams (CFH) in ft3/hr.
Constant factor 0.0749: air density in conventional conditions in the English unit system.
Constant coefficient of 0.24: specific heat capacity of ambient air in conventional conditions in BTU.
In this formula, by calculating all the parameters, you can get accurate results to determine the heating capacity and the number of unit heaters required for your place.
Note: Accurate values of U and A for each of the surrounding surfaces must be considered based on specific details in each building and engineering tables of the heat transfer coefficient.
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Unit Heater Components and Parts
Unit heaters usually consist of five main parts:
The Body: The cubic body of the device is usually made of steel sheets.
The Coils: Hot water or steam coil set with heat exchange fins that increase the heat energy transferred from hot water or steam to the air coming out of the unit heater.
The Electric Motor: The electric motor can be used to drive the axial fan of the unit heater, and based on the order of the respected buyer and the production of the factory, a single-turn or two-turn electric motor may be used.
The Axial Fan: The axial fan, which is actually the ventilation fan of the unit heater, sucks air from the back of the device, passes it through the coils and heat exchange fins of the hot water or steam, and then releases the hot air from the front of the unit heater.
The Vanes: The vanes are installed in front of the unit heater and are able to direct the hot air coming out of the unit heater.
Factors to Keep in Mind when Installing a Unit Heater
The following factors will help you install your unit heater correctly:
Installation of unit heaters is usually done based on the dimensions and weight of each unit heater on a frame made of a corner or steel shield of size 3 to 5, and the suitable installation height for wall unit heaters is at a height of 2.5 to 3.5 meters from the floor level. Environment (based on the capacity of the unit heater and the height of the installation location).
In the hot water unit heater, the hot water inlet pipe is connected to the bottom of the device, and in the steam unit heater, the steam inlet pipe is connected to the top of the steam unit heater.
The hot water and steam coils of the unit heater may be one or two rows, but please note that before ordering the unit heater needed for the project, you must declare whether the inlet and outlet pipe of your unit heater is on the left or right.
It is necessary to install an automatic air valve in the return water path from the hot water unit heater.
It is also necessary to install the barrel nut and valve on the pipes connected to the inlet and outlet pipes of each unit heater.
Calculation of the water flow rate in the circulator pump of the hot water unit heater:
If you need to calculate the flow of hot water, divide the capacity of the unit heater (BTU) by 10,000 to get the amount of G.P.M of hot water circulating in the unit heater. If you need more advice, you can contact the experts of DamaTajhiz HVAC.
How to Choose a Unit Heater
Before choosing the heating capacity and motor power of the required unit heaters, you must first determine the type of heating fluid available (hot water or steam) and how the unit heater will be placed (wall or ceiling).
Due to the noisy operation of the unit heater fan at 1400 rpm, it is better to order the unit heater with a two-speed or 900-speed motor (but with a higher heating capacity).
In some cases, specifically for climates that have moderate summer temperatures and also have a central cooling system (chiller), unit heaters can be used to provide cooling in summer. In this situation, in addition to the existing and standard two-row coil, another coil must be added as an option for cooling, as well as the corresponding drain tray under the cooling coil of the unit heater.
Buying a Unit Heater
In order to choose and buy a suitable hot water or steam unit heater, you must first determine the type, capacity, and brand of the unit heater.
On this website, the technical information of dozens of models of unit heaters from reliable brands with warranty has been presented in order for you, dear ones, to enjoy the good feeling of an optimal and smart purchase.
Also note that in the specialized HVAC group of Damatajhiz, all the unit heaters are only sold in bulk. Therefore, if you want to wholesale any of these products, feel free to contact us.
The Price of Unit Heaters
Choose and buy all types of unit heaters at the best price on the website of the specialized DamaTajhiz HVAC.
The price of unit heaters varies according to the variety of models and brands available; it should be noted that the prices presented in the heating equipment collection are updated, and the discounts desired by consumers are included in these prices for wholesale purchases. So that these prices also include the part guaranteeing the best prices on the DamaTajhiz HVAC
Dear Users:
While thanking you for your trust in the technical opinions of the sales experts of DamaTajhiz HVAC Group, it should be mentioned that the determination and selection of the desired product brand based on history, brand strength, service, and product price is ultimately determined by the buyer.
But in Unit Heater, most of the users and buyers purchase best-selling brands such as DamaTajhiz and Saran according to their quality, price, and after-sales service.
If, after reading the above pieces of information, you still have questions about the decision to purchase the type of unit heaters you need, you can get advice from the sales experts of the Heating Equipment and Machine Room Department by contacting the DamaTajhiz HVAC Group and calling extension numbers 107-108-121-122. And ask your questions.
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