Creating a warm floor is a great opportunity to provide a comfortable microclimate in your own home. The popularity of this heating system (CO) is due to the high availability of modern materials, thanks to which any home master who knows the basics of heat engineering and plumbing can install the system.
Before proceeding with the creation of this heating system, it is necessary to carry out complex calculations and preparatory work. How to calculate a warm water floor and will be discussed in this publication.
Calculation of the power of water heated floors
Important! The methodology given below is quite complicated and requires certain knowledge, experience and design skills. It is necessary to order the calculation of a water-heated floor and heating in a specialized organization. All formulas and this technique are given for informational purposes only.
On the Internet and specialized literature, there are a lot of ways to calculate a warm floor, among which most of the publications do not inspire confidence. In addition, almost every manufacturer of these products suggests using data and nomograms in calculations that contradict logic and regulatory documents (in particular). There is a method for calculating a water heated floor, which is used by design organizations.
Initial data
To perform calculations, you must have the following data:
- The temperature at the supply in the underfloor heating system (TP) t p;
- Return temperature TP t o;
- Estimated air temperature in the heated room t in;
- The temperature in the room is below the calculated t low;
- The inner diameter of the pipeline from which the TP coil is made D c;
- The outer diameter of the pipeline from which the TP coil is made D n;
- The coefficient of thermal conductivity of the pipeline λ tr;
- Heat transfer of the surface under the heating substation (underlying, horizontal) α n;
(determined according to SNiP 23-02-2003 and SP 23-101-2004). - Heat transfer coefficient from the coolant to the inner wall of the pipe α ext;
- The heat transfer coefficient of the floor α p; (as a rule, this value is in the range of 10-12 W / m 2 K);
- Thermal resistance of the floor materials located above the coil of the water transformer substation.
For the convenience of calculations, the initial data must be arranged in a table:
Further, summing up the thermal conductivity (according to the tables) of the materials used in the screed, it is necessary to calculate the thermal resistance above the coil and under the underfloor heating pipeline. For example: 
For the convenience of further calculations, we compile a table, for example: 
Method of calculation
A similar technique is incorporated in some programs for calculating underfloor heating, distributed on a paid basis.
Simplified Method
Tip: As you can see from the example above, the exact calculation of water PT is a very complex process that is best left to professionals.
The simplified method is based on the following algorithm: the heat transfer of a warm floor should compensate or exceed by no more than 25% the heat loss of the room. To calculate underfloor heating according to the area of the room, it is necessary to have data on heat loss, planned temperature and some structural features of the floor covering.
- The first thing to do is to draw up a plan-scheme of heated rooms with a detailed designation of window and door openings.
- We calculate the heat demand for each room. To do this, we calculate the heat loss of the room.
Having the necessary step values, the table can be used to determine the diameter of the pipeline, the recommended average temperature of the coolant.
The table presented above allows you to calculate the length of a pipe for a warm floor, knowing its required amount (with a selected diameter) per 1 m 2 of the heated area.
Tip: When designing this CO on your own, you should be aware that the length of the pipeline in one circuit should not exceed 100 pg.m. For example, to heat a room with an area of 20 m 2, 200 running meters are needed. pipes with a diameter of 16 mm. For the correct operation of this CO, it is necessary to create at least 2 separate circuits of 100 running meters each.
Choose the type of coil installation. As a rule, when creating "warm floors" on their own, two main laying patterns are used: "snake" or "snail". The location of the pipeline depends on the areas with the greatest heat loss. Such areas are the floor near the entrance and window openings. Choose a scheme in which the pipeline in these sections will have the highest temperature.
If difficulty arises at this stage, then the simplest method for calculating pipes for underfloor heating is a calculator that can be found on specialized portals.
Pipe selection. As a rule, pipes made of metal-plastic, propylene and cross-linked polyethylene are used to create this CO.
Tip: Professionals recommend paying attention to the pipeline made of cross-linked polyethylene, which has the lowest coefficient of linear expansion than the presented analogues. If the choice fell on propylene, then use only reinforced grades of this material for underfloor heating.
where:
G - pump capacity l/h;
0.86 - coefficient for converting W / h to kcal / h.
Δt is the temperature difference between supply and return.
We calculate the required power of a warm floor per 1 m 2 according to the formula:
where: Q is the total heat loss index; F is the area allotted for laying the TP coil.
Based on the data obtained on the power of the TP, we select the pipeline pitch (the distance between the turns).
Important! You should know that the pipeline laying step corresponds to a certain heat load: 15 cm - from 80 W / m 2; 20 cm - from 50 - 80 W / m 2; 30 cm - up to 50 W / m 2.
Calculation of electric floor heating
Most often, with the independent arrangement of electric heated floors, there is a need to calculate resistive (cable) products.
- We calculate the heat loss of the room in order to know how much heat should be supplied to the room to create a comfortable microclimate.
- Draws up a plan-scheme to determine the area on which the heating cable will be located.
Choose a laying step (from 10 to 30 cm.)
Important! The larger the step, the less evenly the floor will warm up. Perhaps the appearance of a "thermal zebra".
- We calculate the required cable length using the formula: L=S/Dx1.1 where: S is the heating area; D - laying step; 1.1 - correction for bends.
Today, most manufacturers of these products indicate the power of the cable for a certain length of it. For example, the DTIP-18 cable is sold in 22-meter lengths and is marked: 220/230; 360/395. The first two digits are the supply voltage; the second - the power of the segment at 220/230 V. The marking has the number 18, which indicates the power of 1 running meter of cable - 18 watts. It is easy to check this statement: 395/22= 17.95 per 1 meter of product.
