1 August 1997

Quartz – definite hot tip…

Using the wrong type of heat is a fine way to waste energy in a milking parlour.

Peter Grimshaw reports on the reasons why experts now recommend quartz heaters

IF someone asks Farm Energy Centre adviser Steve Bettany what is the best way to keep a milking parlour warm, the first thing he recommends is a quartz linear (QL) heater.

"Most milking parlours are wind tunnels, with an enormous air change rate. Heating up the air is just so much wasted energy."

The only serious alternative to QL heating is underfloor heating. This may be successful in some cases and is worth considering for a new milking parlour or major refurbishment, says Mr Bettany.

Floor heating cable is relatively cheap but fitting it can be quite a job as it needs to be laid within the screed. Once done it is safe and robust and provides excellent frost protection and warmth to the parlour operator. It is quite cheap to run as it can be switched on during the off-peak electricity tariff.

One drawback is that because the floor is constantly wet, energy is used to evaporate water. The result may be a sauna-like effect.

Few radiant heaters are built to withstand the dust and damp of the milking parlour environment with safety. Even fewer offer the degree of warming required on a raw January day. Black bar radiant heaters are robust and relatively low cost to run, but their emissions are unlikely to reach the floor of the pit where they are most needed for hands and feet.

That is where QL heaters come into their own. Mr Bettany explains that they emit heat at a wavelength closer to that of light than that produced by black bar heaters, which have a poor radiant throw. The shorter wavelength is not absorbed by moisture in the air.

It can be focused, almost like a torch beam, and uses the established technology of car headlights and floodlighting to direct the rays where required.

Since it does not have to warm up the surrounding air, the result is almost instantaneous, just like the effect when the sun comes out from behind a cloud.

"The warmth has to be experienced to be believed," says heating specialist Geoff Baldwin, who supplies and installs QL heater equipment. "The short wavelength means that, like sunshine, the energy is absorbed by the skin, giving warmth."

Farm Energy Centre advice confirms that QL heating equipment is likely to provide more than comfort for the milker, and possibly for the cows. When linked to a thermostat, the heaters can be set to come on if the temperature falls close to zero. Although they are usually deliberately targeted to avoid the milking plant, when focused on the work area they also warm up the floor. This in turn radiates heat and convects warm air to prevent pipework freezing.

Parlours with low level milking jars can be heated from overhead, and those with low ceilings can be heated from either end using the directed beam, angled to suit.

The fact that QL heaters work at the flick of a switch, giving the full heating effect in a fraction of a second, cuts out warm up time. They are switched off instantly by efficient use of time switches and thermostats.

Running cost of QL heaters is between £50 and £100/kW a year when used for personnel heating and frost protection. This is five times the cost/kW of conventional wall-mounted metal or silica sheathed element heaters, but the tight control and efficiency resulting from avoiding wasted heat will probably mean that there is little difference in electricity bills. More importantly, youll feel warmer.

Off-peak tariff

"Using them in conjunction with the off-peak tariff also makes sense," advises Mr Baldwin.

Two basic heaters are available, based on the same element. A smooth reflector gives a strong directed beam of energy for a specific target area. A dimpled reflector gives a wide, more diffuse beam, which may be useful for frost protection of exposed pipes. The dimpled reflector means heat is less concentrated, allowing the heater to be fitted closer to solid objects without overheating them.

The quartz bulb reaches a temperature of 2200C and should be fitted where it cannot be damaged by animals or machinery or splashed by water. Suitable guards are available. Air must also be able to circulate freely around it.

The heater is normally fitted above eye level to prevent glare. The red glow results from a coloured sheath surrounding the element, which would otherwise give out a very harsh, white light.

Life of the heater tubes is between 5000 and 7000 hours, or at least six years of normal use. Replacement tubes cost between £50 and £70.

Although QL heaters are versatile they are not usually recommended for smaller, enclosed areas such as the bulk tank area or the farm office. More traditional radiant heaters that produce a long wave type output would be recommended here. These can be installed from about £40 and have fairly low running costs. To work efficiently the ceiling height should be less than 3m (10ft).

Quartz linear heaters give instant focused heat, increasing staff – and possibly cow – comfort, says Farm Energy Centre adviser Steve Bettany.

QUARTZ LINEAR HEATERS

&#8226 More expensive to install.

&#8226 More expensive to run.

&#8226 More effective use of heat.

&#8226 Immediate warming effect.

&#8226 Work well in draughty situations.

&#8226 Also give frost protection.