Valve technology for radiators

Hidden behind the thermostatic sensor head is the actual valve which, indeed, cannot be seen from the outside; however, this does not reduce its significance for the optimum function of the radiator. State-of-the-art valve technology ensures the most accurate adjustability, heating comfort, and energy efficiency in every radiator with valve by Kermi. As a result, Kermi is setting standards in radiator valve technology – particularly in respect of simplified hydraulic balancing.

Hydraulic balancing general

Hydraulic balancing of pipes in buildings is an economic and ecological necessity. This is also promoted in pertinent DIN standards and directives. Only a radiator with enough hot water flowing through it can provide the necessary heat output.

Hydraulic balancing involves limiting the flow rate of the hot water to the respective value which corresponds to the heat demand of the individual radiators in the system. Every heating system with physically separated heat source and heat dissipation to the area to be heated is confronted with the problem of heat distribution in line with demand.

Today's conventional pump hot water system is designed to distribute the heat evenly according to demand from all rooms to be heated. This heat distribution requires a water flow rate which is distributed according to the heat output in the pipeline network. Unfortunately, though, this is provided only very rarely. According to the principle of least resistance the heating water coming from the heat source flows by the shortest path back to the heating centre. This path usually leads through the radiators situated nearest to the circulation pump in the pipe system. This means that radiators farther away from the heating centre in a hydraulically unfavourable position only have an inadequate amount of hot water flowing through them. As a result, rooms that are a long way away are inadequately heated or rooms near the heating centre are overheated.

Experience shows that this problem is often incorrectly assessed. Often pumps which are too small, with a flow temperature which is too low or a heat source which is too small are diagnosed as the supposed cause of insufficient heat distribution. Correspondingly pumps which are too large are installed, the flow temperature is set too high, or the heating control is misaligned. The effects of this are flow noises in the heating system, overheated rooms, and rooms with an inadequate supply of heat. Apart from that, this is associated with increased energy consumption to generate and distribute heat. This problem can only be solved by the optimal use of energy achieved through hydraulic balancing, e.g. by setting the correct k_v values which generate virtually the same resistances for all radiators in a heat distribution network.

System with correctly implemented hydraulic balancing

The

k_v setting on the valve made properly ensures an even distribution of the hot water.

Available ex factory on Kermi radiators with valve for conventional systems.

System with a lack of hydraulic balancing

k_v setting on the valves to “fully open”

The bottom radiator (red) is oversupplied, while the top radiators are undersupplied.

The benefits of hydraulic balancing:

Energy saving (up to 6 %)
Environmental protection (CO2 savings)
Comfort (no excess or inadequate supply, no noises from the radiator)
Meets the corresponding regulations and their control via documentation (e.g. energy pass, EN 15378, EN 18599)
Meets the obligation for hydraulic balancing according to VOB and EnEV
Utilisation of the efficiency of energy efficient heat sources

Heating system without hydraulic balancing

Hydraulic balancing and KfW subsidy

Valve presetting ex factory is a recognised approximation process for hydraulically balancing the radiator valves in accordance with the performance specification by the Union of German Central Heating Management (VdZ e.V.). This means that the requirements for current state subsidy programmes, for example KfW - German Reconstruction Loan Corporation - are met.

Kermi valves with factory preset

[Translate to en_com:] Kermi Ventile mit Kermi Werksvoreinstellung

Detailed information about the Kermi valve guide for Kermi radiators with valve in the current document

Kermi valve guide

Features and benefits

Independently of their heat output, Kermi radiators with valve are equipped at the factory with a preset, adjustable valve insert. With the valve insert fitted as standard, 8 k_v main settings and 7 intermediate settings are possible. To retain the control quality across the entire output spectrum, fine control inserts are used for small radiators. For the factory k_v preset, 5 of the possible 15 settings are used. The factory k_v preset is coordinated for conventional heating systems (e.g. in a single-family and two family house) with a differential pressure (Δp) of 100 mbar.

Tip for the one-pipe system:
If the radiators with integrated valve are used in a one-pipe system, the valve insert should be turned to position “8”.

Valve insert V3K / V4K / V6K-S

with 8 main settings and 7 intermediate settings of possible k_v values

Continuously opening adjustable flange meaning it is infinitely adjustable

finer adjustment possible
easier to clean the inserts (rinsing)
less susceptible to problems

Two different valve sizes

Better control quality, even for small radiators

Colour coded valves – depending on the k_v value

k_v value can be identified immediately
Spare part (always supplied fully opened) can be easily adjusted

Certification according to EN 215

Registration number 6T0002 + 6T0006

Benefits of factory-preset valve

Virtually ideal hydraulic balance for heating systems with up to 500 m² of effective area or with a total length of all sections in the flow and return of less than 100 m.

On average up to 6 % energy savings.

Meets the obligation for hydraulic balancing according to VOB (German Construction Contract Procedures) part C/DIN 18380.

Meets the obligation according to EnEV for the implementation of hydraulic balancing.

Meets the requirements for KfW and BAFA (Federal Office of Economics and Export Control) subsidies. No subsidies or credits without hydraulic balancing!

Positive effect on the building energy pass.

Proper operation of the heating system.

Better level of customer satisfaction – less complaints.

Time saving for designers and installers.

Screw connection with integrated valve insert

The valve shut-off block for Kermi radiators with 50 mm connection

For all radiators with a 50 mm connection Kermi provides a valve shut-off block as an accessory. The alternative screw connection with integrated valve insert and adjustable bypass for switching from two- to one-pipe operation. Angle or straight form are available, each standard with decorative cover. From a compact design, a radiator with valve becomes by this means a first-rate connection situation, harmoniously geared to the radiator.

Integrated valve insert, flowing from both sides, i.e. flow is possible on the left or on the right side
Lockable bypass function, for two and single pipe systems
Connection dimension 50 mm, shutoff device to radiator via valve and spindle
Angle or straight form, standard with cover
Cover in white (RAL 9016), chrome, or stainless steel look

Kermi valves with dynamic flow control

[Translate to en_com:] Kermi Ventil mit dynamischer Durchflussregelung

Detailed information about the Kermi valve guide for Kermi radiators with valve in the current document

Kermi valve guide

Features and benefits

As soon as there are deviations from the design basis (full capacity), even hydraulically balanced systems soon reach their limits.

Particularly during peak times (e.g. in the morning or evening) when there is a peak in heating demand, perfect balancing is no longer provided. If the thermostats on several radiators all open at the same time, the first radiator in the loop can be oversupplied and radiators further down the loop can be undersupplied due to differential pressure fluctuations which occur and then these do not heat up properly. The users react to this by turning up the heating thermostats which, over the course of the day, leads to overheated rooms as soon as the heating demand normalises again. Frequent complaints by customers are tenants are the result.

Another aspect which needs to be taken into consideration is the fact that in existing buildings to be refurbished, there is often no information available any more regarding the pipe system. It takes a disproportionate amount of effort in these cases to carry out hydraulic balancing.

By using the V7K-L valve with dynamic flow control, hydraulic balancing is not only ensured for the design basis, but also for practical use. The valve then controls the maximum flow independently of any actual differential pressure or from differential pressure fluctuations which may occur in peak times and prevents oversupply of radiators happening. The differential pressure controllers usually used in the individual loops then often also become superfluous. Additional time savings are made through no longer having to determine the individual, differential pressure dependent adjustment values of the individual radiators.

Note:
A mixed installation of k_v-preset valve inserts and a V7K-L valve insert is not recommended.

Benefits of dynamic flow control

Even supply of all radiators in the loop.

Avoiding complaints from customers or tenants.

Supports trouble-free operation even for existing buildings with an unknown pipe system.

Practical, hydraulic balancing

Generally, costs savings made by differential pressure controllers becoming superfluous.

Time savings as individual, differential pressure dependent adjustment values of the individual radiators no longer have to be determined.

Screw connection with integrated valve insert with dynamic flow control

The valve shut-off block for Kermi radiators with 50 mm connection

For all radiators with a 50 mm connection Kermi provides a valve shut-off block as an accessory. The alternative screw connection with integrated valve insert with dynamic flow control. Angle or straight form are available, each standard with decorative cover. From a compact design, a radiator with valve becomes by this means a first-rate connection situation, harmoniously geared to the radiator.

Integrated valve insert with dynamic flow control
Connection dimension 50 mm, shutoff device to radiator via valve and spindle
Angle or straight form, standard with cover
Cover in white (RAL 9016), chrome, or stainless steel look