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As long as the boiler provides the valve with hot water at the temperature specified in the relevant valve
instruction booklet then the valve should work satisfactorily.
All Horne TMVs up to and including DN20 can operate with imbalances in supply pressures, providing the lower of the two supply pressures is more than 0.2 bar dynamic (i.e. measured with the water running). Valves from DN25 - DN50 require nominally balanced
inlet pressures, i.e common source of supply for both inlets.
A thermostatic mixing valve or shower valve is an automatic proportioning device. It has a thermostat element that expands or contracts in response to changes in the inlet water supplies temperature and pressures. As it expands/contracts, it moves a slide
valve, which alters the amounts of cold and hot water entering the valve's mixing chamber to maintain a steady temperature at the outlet. The animation on the main
Thermostatic Mixing Valve page shows this process and also how the valve reacts when there is a failure of the cold water supply.
Hot on the left and cold on the right, as seen by the user of the shower.
You've got the
low level servicing valves closed.
This is dependent on the available water supply pressures and temperatures, the number of outlets and also the required flow rate at each outlet. The Horne
Valve Selector is a tool that will help you to determine the correct size of valve for your application.
here for Installation, Commissioning, Operation and maintenance instructions for all product families.
Request a password to access the
Maintenance & Support section of the site where routine procedures are shown in narrated video clips.
Yes, Horne TMVs are not orientation sensitive and can be mounted any way up. Just make sure that you leave adequate room for servicing the valve (access to strainers and to remove the cover).
The deadleg is the section of pipe between the TMV and the outlet it is serving. The deadleg will cool to ambient temperatures when the outlet is not in use and may provide favourable conditions for Legionella and other waterborne bacteria to proliferate.
The deadleg should, therefore, be kept to a minimum and must not exceed 2m in healthcare applications. Ideally, the TMV should be connected directly to the outlet or be integral with the outlet. The
Optitherm Thermostatic Tap has an integral TMV immediately upstream of the outlet. Stagnation of water should also be reduced by regularly flushing infrequently used outlets.
Yes, spares kits are available for all valves made within the last 10 years. Generally a Seals Kit (fit every 3 years) and a Seals and Thermostat Element Kit (fit every 6 years) are available. Full spares lists can be viewed
here for Installation, Commissioning, Operation and Maintenance Instructions for all product families.
You probably have the Hot and Cold supplies swapped over.
See dimension drawings for each product.
We always recommend that the circulator pump is positioned on the flow. A full explanation for this is given in our Blog post
Circulator Location - Flow vs Return
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All HORNE products are manufactured under our Quality Management System to BS EN ISO 9001:2000. Certificate No. FM 1224
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