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Fitting the Right Heating Controls Pays Dividends
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Today’s sky-high prices for heating fuels coupled with concerns about the environment and global warming are very good reasons for using the best possible heating controls. Correct selection of controls applies whether we wish to install one of the latest advanced electronic programmable thermostats or a set of self-acting thermostatic radiator valves (TRVs).
Yes, even these simple controls have been continuously developed during the sixty or so years since Danfoss first marketed them. Today, the difference in performance between the best TRV and worst can be considerable and fitting the wrong ones can prove quite costly. |
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TRVs A TRV is a low-cost, non-electric, self-acting thermostatic valve that controls flow through a heating radiator to maintain the room temperature at desired set levels. These controls have always been very popular with heating installers because fitting is just a simple plumbing job requiring no electrical wiring.
TRVs use expansion and contraction of either a wax, liquid or gas charge in a sensor head to open or shut a central heating radiator valve. Their sensors and valves are usually separate components that are coupled together at installation. One TRV is required per radiator.
Without requiring any external power, TRVs bring total simplicity and accuracy to room temperature control. By just turning the setting knob to the desired temperature room comfort becomes automatic. Not only this, TRVs enable temperatures in individual rooms to be increased or reduced as required. Unoccupied areas of the home can be held at frost protection level, achieving worthwhile energy and emission savings.
The hundreds of millions of TRVs installed all over the world endorse their effectiveness. However, as with all good things, there are a few areas requiring special awareness.
Be aware
The following facts are basic to TRVs:
■ Being non-electric, conventional TRVs cannot be connected to the boiler to switch it off when no heat is needed. This means it is possible for the boiler to keep firing, cycling on its own internal thermostat and wasting heat to the flue. Heating systems using TRVs, therefore, need the overall control of electric thermostats.
■ The compact design of a TRV can bring the sensor within very close range of heat coming from both its hot valve and the radiator. Incorrect installation can allow this ‘temperature dependence’ to affect operation, i.e. early closure due to high sensor readings.
■ The very first TRVs had to be fitted so that the flow through them travelled in the correct direction. Incorrect installation could give rise to ‘water hammer’ type system noise. Most manufacturers now market ’bi-flow’ models but even these are not completely noise-free under all application conditions. The Danfoss ‘Revolver’ design provides the total solution.
Reaction
The faster a TRV reacts to room temperature changes, the more accurate will be the comfort control. The better the control, the greater will be the savings.
As mentioned earlier, TRV sensors can be charged with wax, liquid or gas. Wax, the original filling, is the slowest to react. Liquid (special alcohol blend) is considerably faster and ideal for the vast majority of applications. Danfoss’ market-leading RAS-C2 is liquid charged.
Gas is slightly quicker and best suited to precision commercial controls such as the Danfoss RA20Developing solutions 00 range.Danfoss has addressed the various points raised above and produced solutions that make its TRVs more versatile than ever before.
One of the basic design features of Danfoss TRV sensors positions the sensing element as far away from the valve body as possible. Thus, when the complete unit is installed horizontally (recommended), the sensor is not affected by the hot valve or radiator heat and monitors a true room temperature level. Even so, Danfoss TRVs can still be installed in most applications - in flow or return, horizontally or vertically - providing maximum plumbing convenience and accurate control.
Danfoss Revolver
The Danfoss patented ’Revolver’ mechanism, now fitted to all its TRVs provides the total solution to system noise. Should such noise occur in a rogue system, it can be cured simply by rotating a simple collar through 180° to reverse the flow direction through the valve. There is no need to drain down or remove and refit the valve.
Right first time
When installing heating controls, and more are being required all the time, it is worth getting them right first time. Correct controls ensure comfort and increase energy savings. The cheapest will almost certainly cost more overall. |
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A very safe and reliable choice
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Our products are subjected to rigorous testing during every step of the manufacturing process to ensure that only flawless products reach our customers. What is more, our product range is compatible to enable our customers to put together well balanced heating systems. Our products offer high performance levels and are designed to have long lifetimes. Together this makes Danfoss products the prefered choice for consulting engineers and installers worldwide. |
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