Heating A Private House With Underfloor Heating: Pros And Cons

2023 Author: Douglas Hoggarth | [email protected]. Last modified: 2023-05-24 11:23

• Benefits of hidden heating
• The main disadvantages of a water-heated floor
• Materials for the device
• Do I need a backup heating system
• Preferred types of boilers
• Connection diagram

Benefits of hidden heating

One side of the attractiveness of underfloor heating systems lies in the hiding of utilities. The harmony of the interior will not be disturbed by either radiators, or a heating pipeline, or shut-off and control valves. However, this is not the only plus of the stealth of the heating system.

If pipes in living rooms do not pass through and over the wall ceilings, this will greatly facilitate the finishing work. For leveling and applying decorative materials, the entire plane of the walls is available, moreover, there are no difficulties with cutting the floor covering, there is no need to hide the passage of pipes when installing stretch ceilings. The absence of visible communications when changing the layout is especially beneficial.

In addition to aesthetic advantages, there are also technical ones: uniform heating of the floor creates an optimal distribution pattern for warm air. Since the main emphasis is not on convective heat transfer, but on its direct radiation, there is no need to warm up the upper uninhabited zone. This ensures a reduction in heating costs of the order of 10-15%. What is most interesting is that savings here are not at the expense of comfort: in the leg area, the temperature is maintained around 20–22 ºС, in the head area - 3-4 ºС lower.

The main disadvantages of a water-heated floor

The main disadvantage of the underfloor heating system is the complexity of its design. The process of laying heating elements on the floor is quite technological and time consuming, but if we are talking about a water heating system, additional difficulties arise with organizing the piping and adjusting the heating operation.

This is not at all a reason to refuse to use a warm floor. When using quality materials and installation systems, observing the technology of laying pipes in the floor and installing flooring, all efforts will pay off handsomely. Underfloor heating is a really effective, economical and durable heating system, but, we repeat, only if it is arranged in compliance with a number of key requirements.

Of the complexities of the device, it is worth mentioning separately the need for a careful choice of material for the floor screed. In addition to strength properties, it must meet the standards for heat capacity and thermal conductivity, as well as the ability to emit heat in a certain spectrum - about 9-10 microns. In principle, when heated to 40 ° C, almost all cement-based materials emit heat in this range. It remains only to achieve the maximum possible density of the coating and uniform distribution of thermal energy in the warm layer of the screed. For this purpose, steel fiber, liquid glass or special polymer additives for underfloor heating screed can be used - plasticizers C-3, HLV-75, BV 3M and the like.

Materials for the device

As already mentioned, underfloor heating systems require an extremely careful selection of materials. Even one and a half to two decades ago, everyone was content with laying a metal-plastic pipe in the floor, convincing themselves that apart from corrosion, the heat exchanger in the floor was not in danger. This approach has a number of disadvantages that are revealed during the first 3-5 years of operation.

In order not to repeat other people's mistakes, tubes should be used for underfloor heating, which, if damaged, are able to restore the polymer structure over time and have the highest thermal conductivity. It cannot be guaranteed that they will not be broken during the installation of the pipes, and in fact for metal-plastic it is, without exaggeration, a death sentence. Cross-linked polyethylene behaves best in this regard, the alternative to which is copper. In the latter case, there are a number of additional advantages: an even higher thermal conductivity, a scanty coefficient of thermal expansion and the ability to remember the shape during deformation.

For open heating systems, the absence of excessive pressure can lead to the ejection of gas molecules through the walls of the tubes; over time, gas particles can collect in rather large plugs. To exclude such phenomena, modern pipes for underfloor heating are made composite with a built-in oxygen barrier.

From materials for the device of a warm floor, insulation cannot be ignored. Its choice is of decisive importance for the durability of the heating system and the floor as a whole. The thermal barrier must be incompressible, retain its shape and, of course, with a high resistance to heat transfer. Of all the options, extruded polystyrene foam and polyurethane foam are most suitable for use as a thermal cutoff, less often polyisocyanurate plates are used.

Do I need a backup heating system

You can often hear the opinion that water floor heating systems are unreliable, and therefore, when they are used as the main source of heating, there is not an illusory risk that over time the house will be left without a single source of heat. This misconception is associated, first of all, with the experience of operating underfloor heating systems, which, in essence, are budget fakes of the original technology.

Judge for yourself: in the case of using low-quality pipes for a heat exchanger, the risk of their clogging, breakage and destruction of the screed due to thermal expansion increases significantly. It really makes sense to combine floor heating with the installation of radiators, although this option of the heating system is fraught with difficulties in setting: you constantly have to adjust the flow, otherwise the temperature in the room rises to truly uncomfortable values.

However, if the warm floor is designed taking into account all technological requirements, it can work as the main heating system for many decades. Attentiveness and sensitivity at the stage of installation of thermal insulation, pipes and when pouring the screed eliminate the main risk factors both for the appearance of leaks and for damage to the floor covering or the base on which it is laid. In general, the costs of organizing a backup heating system and the correct installation of a water heated floor are approximately equal.

Preferred types of boilers

The main disadvantage of water floor heating systems is considered to be their extremely low resistance to overheating. Basically, this rule applies to heat exchangers made of polyethylene - this material has one of the highest coefficients of linear thermal expansion. For copper pipes, this figure is much lower.

In connection with such restrictions, the correct choice of the boiler unit and the corresponding setting of its operating mode are required. Natural gas and electricity boilers are considered the most suitable. Their thermoregulation system makes it possible to exclude the supply of too hot heat carrier to the underfloor heating system.

The least suitable for connecting a water floor heating system can be safely called solid fuel boilers. Their peak power is nearly impossible to limit, especially when changing fuel from time to time. That is why such systems require the inclusion of special devices in the hydraulic circuit that maintain the temperature of the water in the heating circuit by mixing in liquid from the return.

Connection diagram

The final argument against underfloor heating systems is the complexity of the organization of the coolant distribution scheme. If there is more than one underfloor heating circuit in the system, installation of hydraulic manifolds with flow controllers is required.

Heating scheme of the house with underfloor heating. A - gas heating boiler; B - combined mixing unit and collector group; B - underfloor heating contour. 1 - boiler with a built-in circulation pump; 2 - security group; 3 - expansion tank; 4 - three-way mixing valve; 5 - circulation pump; 6 - ball valve; 7 - needle valve or valve with servo drive; 8 - pressure reducer; 9 - flow meter

On the one hand, installation and commissioning of such complex networks is comparable to the additional costs. However, all efforts to organize underfloor heating are more than offset by the comfort of its use: each room can easily adjust its own thermal regime, while the entire system can be easily and efficiently balanced even with several dozen "loops".

Otherwise, the underfloor heating is connected according to the classical scheme of organizing a closed heating system with overpressure. The only addition is the water treatment unit at the make-up inlet: since the heat exchanger is represented by rather narrow channels located at the lowest point of the system, it is required to remove from the water all mechanical impurities that can settle and eventually completely clog the tubes.