The choice of heating devices for the water system always remains the prerogative of the homeowner, even when the installation is done by hired craftsmen. But picking up batteries on the advice of sellers or reviews of Internet users is not easy - the former often do not understand the topic and repeat the advertising slogans, the latter “praise their swamp”, which is understandable. To find out which heating radiators it is better to choose for an apartment or a private house, we suggest using a simple and understandable algorithm.
Battery Instruction Manual - Simplified Approach
Before you buy or order new heating radiators, you should quickly study the catalogs of large online stores. This will allow you to find out the price order and see the existing types of batteries. All convection water heating appliances are divided into 4 groups:
- sectional aluminum;
- bimetallic - sectional and monolithic;
- cast iron;
- steel - panel and tubular.
Lyrical digression. You can read reviews and articles on resources that publish ratings of products of various brands. But the information will not bring much benefit - there are endless debates on forums and fake responses are written, and ratings are often compiled according to the TOP-10 manufacturers from the first pages of the search.
To select the power of heating radiators, you must first calculate the amount of heat spent on heating each room. Calculation methods - by area, volume or heat loss of a building - are published in a separate article. How to choose the right batteries:
- Estimate the cost of a future purchase, filter out more expensive and too cheap options for heaters.
- Select the models that you liked in appearance, shape and color, which fit well into the home interior. Pay attention to the height of the batteries so that they fit in niches.
- If you live in an apartment in a high-rise building (9 floors or more), open the page with the technical specifications of the selected radiators and find out the maximum working pressure of the water - the device must withstand at least 12 Bar.
- For owners of private cottages, the pressure parameter is not of interest - models with any characteristics are suitable. If the house is heated by a wood or coal boiler, it is worth checking the maximum temperature of the coolant - the higher the indicator, the better.
- Ask about the connection methods provided by the manufacturers of the selected batteries. The lower eyeliner allows you to better hide the heating mains, with a lateral version of the pipe you have to muffle in the wall or leave it in sight.
- Find out the weight of the product and the installation method - floor or wall. Find out if the radiator is equipped with mounting brackets and futors, otherwise there will be additional costs. Radiator valves and a Maevsky tap are usually purchased separately.
- Make the final choice of model and determine the size of the radiators by power. How the real heat transfer of 1 section (panel) is calculated, we will tell at the end of this instruction.
Please note - we did not mention the materials of manufacture and types of devices. In fact, this factor does not play a big role. Modern radiators differ little in technical parameters, only the indicator of heat transfer remains important. The lower threshold for working pressure is relevant only in multi-story buildings.
Next, we consider the device and the characteristics of various batteries, compare their advantages and disadvantages. But first, dispel popular myths invented by advertisers.
Myths about heating radiators
In order to promote this or that product, three common fables were invented about heating appliances made of various materials:
- the heat transfer of aluminum radiators is much higher than steel and cast iron;
- Cast iron radiators are massive, so they warm and cool for a long time, supposedly store heat;
- in the central heating network, water hammer and pressure arise, which only bimetal heaters withstand.
Note. Here are the main established myths, we will talk about others in the process of describing radiators.
Compared to ferrous metals - steel and cast iron - aluminum conducts heat much better. Let us confirm with figures: the thermal conductivity coefficient λ of aluminum products is 209 W / (m • ° C), steel - 47 W / (m • ° C), cast iron - only 42 W / (m • ° C). What is the catch: the heating devices are not made of pure aluminum, but of an alloy of the AK12 group - silumin, where 11-13% of silicon and other impurities are listed in the table above.
The purpose of silicon additives is to increase the strength and corrosion resistance of the alloy. The physical properties of silumin are different, the thermal conductivity is noticeably lower - 168 W / (m • ° С). Considering the wall thickness of the batteries is 4-5 mm, the difference in heat transfer between aluminum and iron devices is not noticeable in practice. Put in the room 2 such radiators of the same power - you can not determine which one works more efficiently.
The best heat conductor is copper. From it make plate skirting heaters and copper-aluminum water convectors.
A stumbling block is the price of copper products. On the right photo there is a Thermia heater with a cost of 70 oz. e., dimensions - 400 x 400 x 90 mm, heat flux - only 430 watts.
The following factors strongly influence the transfer of thermal energy from any metal battery:
- temperature and flow rate;
- surface area of the device;
- temperature difference between the room air and the water in the pipes.
Reference. The difference between the average temperature of the coolant and the heated room air is called the temperature head (DT). The value will come in handy later, when calculating the power of devices.
We will dispel the remaining myths by points:
- When heating / cooling, the mass of cast iron does not play a role, since its heat capacity is 9 times lower than that of water inside (0.54 kJ / kg • ° C versus 4.18 kJ / kg • ° C). Therefore, the cast-iron battery will cool simultaneously with the coolant, not longer. Silumin and steel cool faster because they contain much less water.
- Hydraulic shocks inside district heating networks simply do not happen. The maximum pressure in operating mode is 10 bar, and the test pressure is 12 bar. Modern aluminum appliances calmly withstand such a pressure.
Design and advantages of aluminum appliances
Radiators of this type are manufactured by injection molding or extrusion. The finished product is a vertical single section or a solid non-separable battery (both varieties are produced by the well-known company Rifar). From individual sections, a heater of the required power is dialed, the connection method is a threaded nipple with a gasket.
Inside the silumin radiator section, shown in section in the photo, 2 horizontal collectors were made, between them there was a vertical connecting channel of oval section. External heat exchange part - convection fins coated with heat-resistant powder paint. The shape of the fins and the number of plates are determined by the manufacturer.
Reference. The height of the battery is calculated by the distance between the centers of the horizontal collectors. Aluminum products are offered in 3 standard versions - 35, 50 and 80 cm. The permissible pressure in the radiators is 14 ... 16 Bar, the heat transfer of the section with a center distance of 500 mm is about 190 W according to the Italian brand Global.
Advantages of aluminum alloy batteries:
- light weight;
- attractive appearance;
- effective heat transfer contributes to a large surface area;
- small water capacity - 0.2 ... 1 liter, depending on size;
- relatively low price of 7 ... 10 y. E. per section, Chinese models - from 5 y. e.
The lack of aluminum is considered to be low corrosion resistance, although in practice, heaters serve in apartments with central heating for 20 years. The statement should be attributed to private houses where too hard water saturated with magnesium and calcium salts is used as a heat carrier.
The second minus is inherent in any sectional batteries - when pouring non-freezing coolant at the joints, leaks occur. Whole modifications, for example, Rifar Monolith, do not experience such problems.
Pros and cons of bimetal
As the name suggests, the heating devices are made of 2 metals - silumin and steel. Externally, the batteries are indistinguishable from aluminum sections, but inside the collectors and vertical channels, iron tubes are welded together. The steel frame is designed to solve 2 problems:
- protection of the silumin part from the chemical effects of the coolant in old centralized systems;
- improving the reliability of the radiator by increasing the operating pressure threshold to 20 ... 30 Atm.
For reference. There are bimetallic models with double vertical channels made to improve the flow of water and heat transfer. An example is the Rifar SUPReMO series of non-separable batteries, pictured below in the photo.
For other technical characteristics, bimetal differs little from aluminum - the power of 1 section, weight and capacity are almost the same. The operational advantages of radiators are also preserved, but a couple of disadvantages appear:
- the price of batteries is 30-50% higher, for example, the original Global Style Plus bimetallic section with a center spacing of 500 mm costs about 15 oz. (970 rub.);
- due to different coefficients of thermal expansion of silumin and steel, the tube core can burst at the welded joints, repair and repair the leakage is unrealistic.
An important addition. On sale sometimes there are defective bimetallic radiators with steel tubes embedded only inside the collectors. The vertical channel of the section remains unprotected.
Features of cast-iron "accordions"
Gray cast iron batteries are familiar to most homeowners. Like the aluminum "fellow", the heater is recruited from separate sections, twisted with nipples through gaskets (you need a long socket wrench).
The cast-iron batteries on the market are conditionally divided into 2 groups:
- Products of the Soviet model of the MS-140 brand, the standard center spacing is 300 and 500 mm.
- Design models cast in the style of modern, retro and so on. The distance between the plugs is arbitrary.
Inexpensive "accordions" of the MS series significantly lose to any radiators in appearance, they are used mainly in industrial premises. The heat transfer of the 50 cm section is 160 W, the operating pressure is up to 9 Bar, the enclosed volume of water is 1.45 liters. Cost - from 6 at. (420 rubles).
Beautiful designer batteries from different brands differ greatly in size, power and other parameters. The table below shows the characteristics and prices of decorative heaters from Czech, Turkish and Russian brands (excluding the cost of decorative shut-off valves).
Note. The numbers after the product names indicate the center distance and thickness of the heater in millimeters.
Cast-iron "accordions" are reliable in operation, durable and completely not afraid of corrosion. In appearance, retro-radiators confidently occupy the first position among all heating appliances. Now reveal the negative points:
- sky-high price of design sections - this is noticeable according to the table;
- cast iron is brittle, cracking from shock loads;
- solid weight of the product;
- the battery holds 2-4 times more coolant than radiators of other types.
The so-called inertness of the cast-iron sections is explained by just increased capacity. Two liters of water cools much longer than 0.2-0.6 liters in the aluminum section. Particularly heavy modifications, for example, Retro Style Anerli, are made in the floor version and are equipped with legs.
Advantages of steel radiators
Manufacturers offer 2 options for iron batteries:
- panel - flat and profile;
- vertical tubular (sectional).
Comment. Both varieties are available in a design vertical version (see above in the photo). Famous brands in the post-Soviet space: Kermi, Korado, Purmo, Arbonia and others.
Heating panels are welded from stamped steel plates 1.2 ... 1.5 mm thick. On the side or bottom of the radiator, fittings are installed for connecting the hoses. Convective fins are mounted between the panels. Batteries are divided into types depending on the number of heating panels and profile fins, as shown in the table.
Performance indicators of panel heaters (taken according to the German radiator "Kermi" type 22, installation size 100 x 50 cm):
- permissible pressure - up to 10 bar;
- thermal power of 1550 W at a water temperature of 75 ° С at the feed, 65 ° С at the return;
- heat carrier volume - 5.4 l;
- unit weight - 28 kg, price - 95 oz. (6300 rub.).
The characteristics of tubular radiators are not too different from panel ones. If we take a two-row device Arbonia 3050/22, comparable in size to the Kermi option under consideration (500 x 1014 mm), we get a power of 1481 W with the same working head and weight of 25.9 kg. Only the price of the product is different - 430 y. e.
Since we are considering affordable options, we list the advantages of panel batteries:
- steel panels - the most budget option among all radiators;
- resistance to chemical corrosion;
- acceptable design and appearance;
- one-piece design allows you to pour antifreeze into the system and not be afraid of leaks;
- the ability to select power without resizing - by adding heating panels and ribs (from 1 on Type 10 to 3 pcs. on Type 33).
The minus of radiators is considered a low threshold for operating pressure - 6 ... 10 Bar. We will not refute this, but will offer to watch the video of our expert, where an inexpensive steel panel is pumped up by a pressure pump to break the weld (pressure over 20 Bar):
How to find out the real heat transfer
Choosing heating appliances in the online store, it is difficult to find the real power indicators of the panel or one section. It is more profitable for sellers to declare maximum heat transfer, which is practically unattainable when heating a country cottage or apartment. According to the passport, the temperature of the water in the supply pipe should reach 90 degrees, the return - 70 ° С, room air - 20 ° С.
Reference. In modern household heat generators, the heating temperature is limited to 80 ... 85 degrees.
The selection of sections for heat transfer, we recommend doing so:
- Open the official website of the manufacturer of the battery you like and download the instruction manual for the device. It accurately indicates at what temperature head DT the radiator generates a nominal amount of heat. Be guided by the 70/50 ° C mode.
- If there is no instruction, take the manufacturer’s data for truth and multiply the heat transfer by an increase factor of 1.5–1.8. Having made a one-and-a-half supply, you definitely will not lose.
- Select the last radiators of the single-pipe system with a double margin, since they receive the least amount of thermal energy.
The most accurate selection method is to calculate the heat transfer at a given temperature head. The calculation algorithm is described in detail in the corresponding material.
Conclusions and recommendations
We hope that the previous description helped you figure out which heating batteries are best for the apartment in terms of price and technical indicators. Finally, we give some practical tips:
- Use the instructions at the beginning of this publication. Choose radiators that suit your design and budget.
- The working pressure of the coolant is important only for apartments of high-rise buildings, only bimetallic and aluminum batteries can withstand pressure above 10 bar. For cottages and private cottages any water heating appliances are suitable.
- With a limited budget, feel free to buy steel panels - they are not inferior to other heaters or convectors in terms of heat transfer.
- For a gravity flow system, you need to take radiators with a large cross section of the internal channels. It is better not to install stamped steel heaters, only tubular ones.
- In terms of price - quality and aggregate operating parameters, the first place is occupied by sectional batteries made of light aluminum alloy.
- It is worth paying for bimetal when there is no confidence in the parameters of the coolant - pressure is unknown, hard water is used.
- Try not to purchase frankly cheap radiators, molded from unknown material in China. They will warm, but certainly not for long.
Conclusion regarding cast iron. Heating radiators of the old type MS-90 and MS-140 are cheap, but they look unpretentious. Beautifully designed models are incredibly expensive, and therefore inaccessible to ordinary homeowners. Cast iron is becoming a rarity, and obsolete "accordions" of the MC series are a thing of the past.
If the budget allows you to put designer heaters, carefully choose each battery in size. In a narrow wall niche it is better to place a vertical steel heating radiator, under the windows - stylish cast-iron products. Heavy floor versions are preferably additionally mounted to the wall with a pair of brackets.