How many outlets can I have per Thermostatic Mixing Valve (TMV)?
In TMV2 applications the number of outlets is dependent on the pressure and flow rate required at the outlet, however, it is quite common to see 3 or 4 outlets. The system parameters would need to be checked against the working parameters of the valve in order to decide how many it should serve. The maximum pipe run after the mixing valve should be such that the required mixed water temperature reaches the furthest outlet within 30 seconds.
These requirements are put into place primarily to prevent the growth of Legionella bacteria but also serve a practical reason as users dislike waiting for the water supply to warm up at the outlet. A typical push button shower control keeps the water running for around 25 seconds and if the user has to press the button more than twice to obtain suitably hot water, this could give rise to complaints.
For TMV3 applications, it is strictly one valve per outlet unless the two outlets are back to back. The maximum pipe run from the valve to the outlet is 2m in high risk areas such as ICU and Neonatal Units. In all other situations the 30 second rule applies.
What are the Service Intervals for TMV’s?
For a TMV2 the performance should be checked on an annual basis and verified against the original installation performance. Carry out the cold water supply isolation test by isolating the cold water supply to the TMV, wait for five seconds, if water is still flowing, check that the temperature is below 46°C.
If there is no significant change to the set outlet temperature (±2°C or less change from the original settings) and the fail-safe shut off is functioning, then the valve is working correctly and no further service work is required.
For a TMV3 to comply with current NHS guidelines it should be tested against the original performance results 6-8 weeks after installation. If the temperatures have remained set to within 2°C and the fail-safe function is operating correctly, then a six monthly cycle of performance testing can be implemented.
If there is no significant change to the set outlet temperature (2°C or less change from the original settings) and the fail-safe shut off is functioning, then the valve is working correctly and no further service work is required.
Are temperature spikes permitted when first using an outlet supplied by a TMV?
NHS D08 permits a 7°C temperature ‘spike’ to last for 1.2 seconds, with 50°C permitted for a maximum of 0.5 seconds. Therefore as long as a TMV ensures temporary temperature spikes last no longer than these times, it will still be safe for use.
Which is the Flow Connection and which is the Return Connection on the Thermomix Underfloor Heating (UFH) Valve?
The Flow and Return Connections are labelled H (flow) and C (return).
Which way do I turn the adjustment mechanism to increases the temperature on a TMV?
It is Anti-Clockwise to increase and Clockwise to Decrease.
On what media can I use your Pressure Reducing Valves (PRV)?
Our Pressure Reducing Valves are compatible with: 28 sec oil, compressed air, paraffin/kerosene, natural gases and natural non adhesive fluids. They should not be used on salt water, petrol or diesel.
What Glycol levels are suitable for your PRV and what are the Opening and Closing tolerances?
Ok up to a 50:50 ratio, Water to Glycol. Opens at +5%, Closes at -10%, A 6 bar relief valve discharges from 6.3 bar and reseats at 5.4 bar.
In what orientation can I install the Tenant Valve and what size is the Water Meter connection?
They can be installed in any orientation as long as the water meter is not facing the ground. It must be upright or on its side. The standard connection port for a Class A water meter cartridge is 2”. The Class D adaptor required for fitting a Water Authority supplied Class D water meter cartridge, reduces the connection port down to 1.1/2”.
What is the Expansion Vessel Capacity?
The capacity declared of the vessel is referred to the volume of the tank and not the quantity of water you can put inside. This is a common definition in the market. The acceptance of water in the tank is 60% of the tank’s volume and you can consider this as a standard for all pressure vessels. Our 12 litre potable vessel, the AR12, will accept 7.2 litres.