Why is the underfloor heating not heating?


The heat­ing sys­tems that our apart­ments and hous­es are equipped with are dis­tin­guished not only by their man­u­fac­tura­bil­i­ty and effi­cien­cy, but also by their reli­a­bil­i­ty. The degree of reli­a­bil­i­ty of heat­ing sys­tems depends on numer­ous fac­tors, among which the prac­ti­cal­i­ty and func­tion­al­i­ty of the heat­ing equip­ment includ­ed in the home heat­ing kit is not the last. Water heat­ed floor among the used heat­ing sys­tems is con­sid­ered the most reli­able. Thanks to the tech­nol­o­gy and design, such a heat­ing scheme is very con­ve­nient to use. In terms of main­te­nance, a work­ing water floor does not require spe­cial atten­tion and spe­cial efforts.

Despite the high per­for­mance char­ac­ter­is­tics of the heat­ing sys­tem, “warm floor” can fail. Often, dur­ing the heat­ing sea­son, we won­der why the floor in our house does not heat, the warm floor has bro­ken, or the acci­dent is caused by rea­sons of a dif­fer­ent kind. You can under­stand the essence of the prob­lem either on your own or by invit­ing spe­cial­ists — heat engi­neers to exam­ine your heat­ing sys­tem.

If you have an idea of ​​how your heat­ing sys­tem works, you can try to solve the prob­lem your­self. Your under­floor heat­ing does not work — this means that at some point dur­ing instal­la­tion an error was made or one of the ele­ments of the sys­tem failed. Let’s find a way out of this sit­u­a­tion togeth­er.

Introduction to underfloor heating

In order to know the prob­a­ble rea­sons why your home heat­ing is inter­mit­tent or not work­ing at all, you need to know how the heat­ing sys­tem works and how the main parts and struc­tur­al ele­ments func­tion. If your water floor does not heat well, not meet­ing the spec­i­fied para­me­ters, the main rea­sons lie on the sur­face. It’s all about the tech­ni­cal short­com­ings made dur­ing the lay­ing of the water floor. Usu­al­ly these are vio­la­tions of the instal­la­tion tech­nol­o­gy, incor­rect­ly select­ed con­sum­ables and addi­tion­al equip­ment.


The specifics of the instal­la­tion of equip­ment lies in how cor­rect­ly the water cir­cuit is laid and the pipeline is cor­rect­ly con­nect­ed to the heat­ing sys­tem. The lack of cor­rect hydraulic cal­cu­la­tions, incor­rect set­ting of the mix­ing unit lead to the fact that the heat­ing medi­um begins to flow into the pipeline inter­mit­tent­ly, or its tem­per­a­ture is sig­nif­i­cant­ly low­er than required.

Eval­u­at­ing the entire struc­ture, you can focus on the fol­low­ing struc­tur­al ele­ments of the heat­ing sys­tem. Under­floor heat­ing most often does not heat for the fol­low­ing rea­sons:

  • the ther­mo­stat and tem­per­a­ture con­trol sen­sor failed;
  • the bal­anc­ing valve is out of order;
  • the cir­cu­la­tion pump stopped work­ing;
  • the over­head ther­mo­stat-fuse broke;
  • the dri­ves of the inlet pipes of the col­lec­tor are out of order;
  • the integri­ty of the water cir­cuit has been vio­lat­ed;
  • bypass prob­lem.

Each of these ele­ments can fail, mak­ing your under­floor heat­ing non-func­tion­al.

On a note: fail­ure of the ser­vo dri­ve, tem­per­a­ture con­trol sen­sors, there is a high prob­a­bil­i­ty of fail­ure of the ther­mo­stat. The sit­u­a­tion is sim­i­lar in the bal­anc­ing valve. A failed valve will not be able to pro­vide a nor­mal admix­ture of cooled water to the hot coolant. Accord­ing­ly, the tem­per­a­ture of the water in the water cir­cuit will be insuf­fi­cient for heat­ing.

You can list the prob­a­ble break­downs of indi­vid­ual ele­ments of the heat­ing sys­tem for a long time. In each indi­vid­ual case, you will have to look for the imme­di­ate cause, due to which the warm floor does not turn on or works inter­mit­tent­ly.

Con­sid­er sep­a­rate­ly, the most com­mon types of dam­age to the warm floor.

The floor is not warm enough. Low coolant temperature


A typ­i­cal and com­mon prob­lem that own­ers of city apart­ments and pri­vate hous­es have to face when com­plain­ing about the unsat­is­fac­to­ry per­for­mance of a warm floor is uneven heat­ing. Dur­ing nor­mal oper­a­tion, the water cir­cuit must com­plete­ly and even­ly heat the con­crete screed or floor cov­er­ing, cre­at­ing the nec­es­sary con­di­tions for heat­ing the home.

In this case, the prob­lem is the uneven flow of the coolant along the water cir­cuit. Due to the fact that pipelines can have dif­fer­ent lengths, due to the same heat car­ri­er sup­ply inten­si­ty, the degree of heat­ing of each pipe is dif­fer­ent. Usu­al­ly, before start­ing in the col­lec­tor cab­i­net, the lev­els of the elec­tric dri­ves are set to the required posi­tion.

For ref­er­ence: The actu­a­tors are con­nect­ed to a dis­tri­b­u­tion block, which in turn is con­nect­ed to an out­door ther­mo­stat. The sig­nal com­ing to the elec­tric actu­a­tors from the ther­mo­stat actu­ates the rods, thanks to which the inten­si­ty of the coolant flow in each pipe is adjust­ed.

Before start­ing the sys­tem, the opti­mal para­me­ters cal­cu­lat­ed for each cir­cuit are ini­tial­ly set. By mea­sur­ing the tem­per­a­ture of the coolant in each water cir­cuit, the actu­a­tors are set to the appro­pri­ate posi­tion. Con­se­quent­ly, the heat­ing tem­per­a­ture of the coolant in the sys­tem changes, and the degree of heat­ing of the water cir­cuit also changes.

The way out in this sit­u­a­tion is as fol­lows. We are look­ing for a water cir­cuit in which the coolant does not heat the water floor in accor­dance with the set tem­per­a­ture, then man­u­al­ly increase the flow of boil­er water.

Water circuit damage


Pres­sure drops in the sys­tem can lead to rup­ture of the pipeline. Leak­age in this case is the most unpleas­ant fac­tor, which will have to be elim­i­nat­ed urgent­ly. A slight depres­sur­iza­tion of the water wire caus­es a decrease in the inten­si­ty of the coolant flow. Accord­ing­ly, the floor does not warm up even­ly enough. The screed may soon col­lapse. There are many ways to deter­mine the loca­tion of a leak. About the sim­plest options, using impro­vised means, there is a lot of infor­ma­tion mate­r­i­al. The fastest and eas­i­est way in this case is to use a ther­mal imager. This device with high accu­ra­cy will deter­mine the loca­tion of the dam­age to the water pipe.

On a note: your floor does not work, then there is not enough coolant in the water cir­cuit. To begin to elim­i­nate the leak, it is nec­es­sary to turn off the coolant sup­ply through the col­lec­tor. Through the return pipe, water is drained from the water cir­cuit.

The tech­nol­o­gy for elim­i­nat­ing leak­age depends on the pipes used.

For exam­ple: instal­la­tion of a water cir­cuit made of cross-linked poly­eth­yl­ene pipes is the most com­mon and afford­able option for lay­ing a water floor. How­ev­er, some­times you will have to pay for the cheap­ness of con­sum­ables dur­ing oper­a­tion. At the slight­est mechan­i­cal dam­age, the pipe los­es its integri­ty. You can solve the prob­lem by installing a fit­ting. The instal­la­tion loca­tion of the fit­ting must be marked on the lay­out plan or at the instal­la­tion loca­tion of the man­i­fold cab­i­net.

After mount­ing the fit­ting, the edges are crimped. If you turn on the coolant sup­ply after repair work, you should wait two or three days to make sure that the con­nec­tion is reli­able. Only after this, the integri­ty of the screed and the type-set­ting floor struc­ture is restored.

The option using PVC pipes looks prefer­able. Such con­sum­ables have the nec­es­sary strength. How­ev­er, improp­er han­dling of con­struc­tion tools dur­ing con­struc­tion and repair work can eas­i­ly cause dam­age to the water cir­cuit. The liq­ui­da­tion of the acci­dent is car­ried out accord­ing to a sim­i­lar sce­nario. First, dis­man­tling the old screed. Next, the dam­aged sec­tion is replaced with a whole pipe frag­ment. Work is car­ried out using a sol­der­ing iron and a repair sleeve.

A new pour­ing of the con­crete screed is car­ried out only after check­ing the con­nec­tion for tight­ness.

Failures in the operation of electrical equipment

The last impor­tant point to con­sid­er in case of prob­lems with under­floor heat­ing is the fail­ure of elec­tri­cal equip­ment. This includes all devices and units that have elec­tri­cal pow­er. The main ele­ment in this group is a cir­cu­la­tion pump, a ther­mo­stat locat­ed on the equip­ment of the mix­ing unit. Devices can fail due to a lack of volt­age in the elec­tri­cal net­work.

To deter­mine whether the pump is work­ing or not, you can use the char­ac­ter­is­tic sound of oper­a­tion that a run­ning unit makes. To iden­ti­fy prob­lems with the ther­mo­stat, you can do the fol­low­ing:

  • with the cor­rect oper­a­tion of the device, the moment of rota­tion of the stem is clear­ly vis­i­ble. In the event of a break­down, this process does not occur;
  • there is no need to repair the ther­mo­stat. It is bet­ter to buy a new device that will ensure reli­able oper­a­tion of the entire heat­ing sys­tem in the future.


Hav­ing con­sid­ered the main prob­lem­at­ic points due to which the under­floor heat­ing may not work, a num­ber of com­mon fac­tors that affect the effi­cien­cy of the heat­ing cir­cuit should be not­ed.

A prob­a­ble cause of weak heat­ing of the water cir­cuit may be insuf­fi­cient pow­er of the heater or a large num­ber of heat­ing radi­a­tors, which take large quan­ti­ties of coolant from the sys­tem.

The sys­tem may turn on nor­mal­ly, but after a cer­tain time it will stop heat­ing. This often hap­pens due to the pres­ence of an air lock in the pipeline. If the sit­u­a­tion does not improve when the air is removed, then there is a prob­lem with the instal­la­tion of water­proof­ing. In almost every sin­gle case, you your­self are able to iden­ti­fy the cause of the insuf­fi­cient­ly effi­cient oper­a­tion of the under­floor heat­ing. Com­pe­tent cal­cu­la­tions and adher­ence to tech­nol­o­gy dur­ing instal­la­tion will allow you to avoid sim­i­lar sit­u­a­tions in the future.

The clut­ter of the liv­ing space, the pres­ence of car­pets on the floor and a large amount of fur­ni­ture sig­nif­i­cant­ly reduces the heat trans­fer of the warm floor. Con­nect­ing a water cir­cuit in a cen­tral­ized heat­ing sys­tem through a bat­tery can lead to a dete­ri­o­ra­tion in the qual­i­ty of space heat­ing, both through radi­a­tors and with a warm floor.


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