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Principle and purpose of a temperature limiter or thermostatic control valve for a water heater
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Principle of a thermostatic control valve for a hot water storage tank or a water heater
When installing a new water heater, the piping used may be rigid (copper) or flexible (braided hose) but in any case must be able to withstand a temperature of 100°C and support a 10 bar pressure. If this is not the case (multi layer synthetic material or PEX) you must use a temperature limiter (anti-disaster safety). The limiter is an essential safety element distributing only mixed water (anti-scald safety). This safety device is mandatory in new constructions and for major renovations. With this, the hot water consumption is reduced (use of mixed water in the pipes and not hot water) and scaling in the piping and valves is limited.
The temperature limiter allows a water temperature adjustment from 35 to 50°C for a maximum pressure of 10 bar. At pressure of 3 bar, it generally allows a flow rate of 30-35 litres per minute. The adjustment is made with the ABS operating button allowing to obtain a mixed water at constant temperature.
Moreover, limiting the temperature of the hot water coming out from the water heater (thanks to this accessory), allows to raise the water temperature in the water heater to at least 60°C, temperature at which the bacterias are eliminated.
Qualitative characteristics sought
- An automatic limiter allowing to stop the supply in case of a cold water cut. At a temperature of 60°C, you need just 2 seconds to get a second degree burn. It is therefore an anti-scald accessory. Compliant with EN1111 and EN1287 standards.
Mixing temperature block thermostatic control valve source WATTS
- The body is nickel-plated brass (anti-corrosion) and the spring is stainless steel.
- Prefer a product with a sanitary compliance certificate.
- Control knob with a scale (5 adjustment positions Min. to Max.) with a 6 sided locking screw. Accuracy of ±1,5°C between 35°C and 45°C (with balanced dynamic pressure).
- Indicative minimum flow: 5 litres/minute. Indicative flow at 3 bar: 50 litres/minute.
This safety accessory costs between £40 and £100.
Water Heater Thermostatic Control Valve Connection
The temperature limiter is mounted on the hot water outlet of the water heater, by means of a FF 20/27 sleeve and a teflon tape for sealing. Can be installed vertically or horizontally.
connection principle diagram of the security unit Source Thermor
Warning: it is compulsory to install, between the water heater outlet and the thermostatic control valve MMV-C, a copper pipe having a length of 50 cm (DTU 60.1).
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