Installing «warm floors» in an apartment building with central heating is permitted only after obligatory coordination of the installation with the organization which operates the heating system.
There are two variants of installation: reconstruction of the existing heating system, and a commercial connection. Reconstruction involves dismantling of one or several heating radiators and installing in their place contour of «warm floors» with a supply of warmth carrier which is equal to the supply in the removed radiators. A commercial connection allows a connection of the contour of «warm floors» without removing the radiators but with the installation of heat flow meters. Of course, the capacity of the central heating system must be enough to provide warmth to the extra installation without damaging other inhabitants of the building.
It is practically useless to connect «warm floors» to the return pipeline of the heating system on the first floor, if there is the «upper setting» (see Figure 102). At this point, the vertical pipe of the return pipeline is connected with the main pipeline which delivers water to the boiler room. If you connect the «warm floors» here, they will take the warmth away from other apartments.
Apartment «warm floors» can be connected directly to vertical heating pipeline or through a heat exchanger (see Figure 103). The direct connection to the vertical pipelines in the obligatory manner must be protected with installation of filter-sumps, but even their presence and periodic cleaning will not guarantee that the floor heating contour will not get clogged quickly with dirt and slime and stop working. Connecting through a heat exchanger makes the floor heating independent but requires additional equipment: heat exchanger, replacement unit with a sump, expansion tank, and safety group.
As a rule, «warm floors» in large houses and suburban houses are connected from one boiler together with the contour of the hot water supply. The boiler room works to the maximum temperature regime, i. e. the regime which is necessary for preparing hot water and heating. Therefore for «warm floors» units for decreasing the supply temperature are needed. Decreasing temperature is done by installing in the heating contour two-way thermostats, three- and four-way mixers on the supply or three-way valves on the return (see Figure 103). The mixing unit of the «warm floors» contour can be installed in the boiler room while making the boiler piping or attached in the scheme of high temperature radiator heating and attached to it right before the collectors of the «warm floor» setting. So, for example, in the unit with three- and four-way mixers, the cooled water of the return mixes with the hot water of the supply and through the collectors is sent to the heating contours of «warm floors». The supplying collectors themselves can be equipped with supply meters or without and on the return collectors it is necessary to install balancing taps or to make heating rings of the same length. For safety, a bypass with a built-in bypass valve is added to the mixing unit. If the pressure in the mixing unit jumps over the planned limit, the valve will work and will release pressure into the return. The presence of bypass in the mixing units with three- and four-way mixers is desirable and in the units with two-way is a mandatory element of the system. Besides, in the unit with two-tap (see Figure 103 a) it is necessary to include a pre-set balancing valve which regulates the flow of the cooled warmth carrier through the bypass. The percentage of water mixing in the T in the pipeline of the hot water depends on the quantity of the water coming through the bypass. The amount of water which comes into the T is equal to the amount of water which goes out of it; in this case, the water after the two-way tap and from the bypass comes to the T; in the T it mixes and, forced by the pump, flows into the collector of the «warm floors».
It should be noted that in Figure 103, main schemes of mixing units are shown; in fact, there are many more of them. For example, it is possible not to mix water before the collectors but provide each outlet of the collector group with its own thermostat, supply meters, and balancing valves (see Figure 37). It is particularly convenient to use such collectors for boilers of not high capacity. Usage of collectors with built-in units of regulation allows connection of several different temperature heating contours — hot water supply, radiator heating, and «warm floors» — to one collector group.
Separately for floor heating nowadays it is possible to purchase commercially available mixing units with built-in automatics both very small for an area of 20 square metre and units for large areas (see Figure 104).
