Heat exchanger offers poultry energy savings

Not only is a novel heat exchange system bringing up to 60% savings in heating energy costs, it is also making the shed environment dryer by cutting the amount of water vapour coming into sheds, through reduced heater use and closed inlets in the brooding period.

The Agro Clima unit heat exchanger was initially designed for drying manure in layer units fitted with manure belts, says Wayne Olbison, technical director of UK distributor Agro Supply. “The main aim was to dry droppings thus removing moisture and smell, thereby reducing the risk of fly infestations and disease.

“Then the company realised that with some work it could be adapted to be used with broilers and provide early minimum ventilation, so they converted the unit into a heat exchanger.”

The primary aim is to replace minimum ventilation in the early days of a crop. “During this critical time, ventilation is difficult to manage and you often can’t get what you want, warm fresh air.

“In older sheds with manual controls, it is easy to make mistakes in the first 12-16 days. Even new sheds with modern ventilation systems struggle during periods of changeable weather, such as in early spring and autumn.”

After approx 14 days, the ventilation system in the shed starts to take over from the Agro Clima unit. In winter, the system is programmed to deliver about seven days extra at 100% operation while in summer it is five days. After this, it falls to 50-70% operation, while at the same time the conventional system is ramped up.

In addition to achieving better climate control is the saving in fuel costs.

“Five years ago, producers were not that worried about the cost of production from a fuel point of view. But in the years since then, the price of LPG and electricity has doubled and now is a significant factor in overall p/kg production costs,” says Mr Olbison.

“This is particularly the case with older buildings which are less efficient having poorer insulation and being less airtight.”

Even producers with newer sheds are seeing an energy saving. Mr Olbison calculates that his clients are seeing an average saving of 50%. “Some growers in Herefordshire are even seeing a 60% saving in heating costs”

So how does it cut energy use? First, starting up the fans on a conventional ventilation system uses a lot of energy. And these fans would typically start up and stop many times a day during the early stages of a crop cycle. This we eliminate; this electrical saving is in addition to heating fuel savings.

In contrast, the fans in the heat exchanger use a frequency controller, which reduces power consumption.

Second, the Agro Clima unit warms fresh air entering the shed using existing heat in the shed. “Warm air coming out of the shed goes through a chamber, containing a series of tubes, and then out of an exhaust fan. The warm air circulates around these tubes, through which passes the fresh air, picking up the heat.”

He stresses: “It is not an air mixer. Unlike some other systems it keeps the air totally separate, so there is no cross contamination.”

Other benefits include reduced levels of ammonia and carbon dioxide in the house during the brooding period, where high levels can affect bird performance.

The lower carbon dioxide levels are due to the gas heaters running for less time. This reduces the carbon footprint of the poultry unit, and could contribute to climate control levy targets.

It also helps producers with their Integrated Pollution Prevention and Control permits. “One section asks producers what they plan to do to reduce their carbon footprint going forward, and installing a heat exchanger is one way to help achieve this.”

Water is another by-product of the gas burners, so there is less water loading into the shed. Litter is, therefore, dryer benefiting bird health.

“The unit is taking some moisture out and is not putting damp air back in, so you get better litter and the inlet air is warm,” he says.

Finally, there is the economic benefit. The initial investment for a 30,000-bird unit may seem unaffordable at £21,500. But assuming a gas consumption of 0.12 litres per bird place and a 50% saving on gas use, a 30,000-bird unit would pay for itself within seven years at a gas price of 22.5p/litre.

Then once paid off, the return on investment the unit will bring is a gas saving cost reduction of £1760 a year assuming a 20-year usage, including the initial seven years, total of £35,000. At a higher gas price of 30p/litre, which it will undoubtedly get to again, the payback falls to just 5.5 years, he says, and a return on investment saving £2700 per year over 20 years equates to over £50,000, he says.

Installation is quite easy, both retrofitting to existing sheds and as part of a new build. “You need to cut a hole in the roof and make it water and air tight. External piping then carries air from the exchange unit, over the roof to the inlet.” Installation except electrical is included in cost price.

Unlike conventional ventilations systems that create a negative air pressure, the system creates a neutral air pressure.

“The exhaust contains a measuring fan which is linked to a computer, so that it knows exactly how much air is being removed and it automatically matches the inlet fan to ensure the same amount is put in to maintain the pressure this inlet air is exactly the amount the birds need at that age/weight.

As with all equipment, how easy it is to clean at turnaround is a key factor. Mr Olbison says that not only does the top open up to allow easy access, but it now has its own internal wash system which we recommend runs every day; the washing system is available to order for existing units to retro fit.

“A sprinkler system flushes away the dirt that accumulates and the washings are then disposed of correctly to comply with environmental rules.” Either flushed through house wall after muckout or flushed to soak away, the operating condensate has been tested and has been found to be nitrate free.

Case study: David Panton, Lincolnshire

David Panton currently runs about half a million birds in 11 sheds at his East Kirby site. And four of these sheds are fitted with the Agro Clima unit, the first being installed over two years ago.

Mr Panton recalled: “The first time I came across it, I was cynical that you would not need any shed fans on in the first 20 days. But it soon became apparent that this is true.

“We knew we wouldn’t get the 50-60% energy savings some others have seen as we are already very energy efficient with the sheds being just a few years old. However, we still got energy savings of over 30%.”

He estimates that in general, the unit has can exhaust about 1000 litres in humid/cold weather, this is a combination of operating condensate and humidity from inside house. The result is that “the sheds feel a lot dryer and litter quality is better, which is having beneficial effects on bird health”.

He has seen an average 10-15g increase in liveweight and an improved feed conversion. The amount of improvement in feed conversion depends on the weather, the benefits being greater on cold days in winter.

“For example, in January last year we saw a 700-1100kg per 1000 birds saving in feed for the four sheds, equating to a saving of just under 24t in one crop.

“I’m very impressed with them [heat exchangers] and would not hesitate in recommending them.”

Looking forward, he is looking to install them across all his sheds.

However, he adds that you need to fully learn how to use them to get the full benefits. “It does improve litter and you do see more performance out of the birds.”