New sheds offer precise airflow control

New heat exchangers that manage air temperature with precision while scrubbing both ammonia and odour from expelled air are in operation at a south Shropshire farm.

When H Timmis Farms, run by Rob Timmis, made plans for expanding its broiler operation from 200,000 to 300,000 birds last year, it turned to the firm that had installed its 1.3MW ground-source heating system for its first four poultry houses.

At the time of installation, that ground- source system was considered the largest of its type in the UK. It draws latent heat from the fields that surround the broiler units and delivers it to an underfloor heating system, with those first sheds ventilated conventionally.

The expanded sheds have been fitted with a radically different way to manage airflow – air-scrubbing heat-exchange units that capture ammonia and odour and recycle warm air.

Recycling heat

“For some time, we had thought it was madness to heat poultry houses and throw the warmth out through vents,” explains Matthew Evans of IPT Technology.

In 2014 the firm began to look at heat recovery, and partnered with IET, a specialist in heating, ventilation, and air conditioning (HVAC) systems for a range of commercial buildings, including data centres.

“When we were talking to the IET engineers about the idea and the development of the product, we were saying how critical temperature and humidity is in poultry farming,” adds IPT’s John Gill. ”They just laughed, because 0.1 of a degree in a data centre is critical to them. If you have a 2°C swing everything stops working – their critical and our critical were two different things.”

Design

The resulting system – VentMax – was 4 years in the making. It was designed and manufactured in Bromsgrove specifically for poultry production. It featured a number of modifications to make the system suitable for poultry farming, including developing special plastic components resistant to ammonia corrosion, and is integrated into a Fancom system, supported by JF McKenna engineers.

Construction of the 2 additional poultry houses at Rob Timmis’s farm concluded in autumn last year, with the ground-source heating system expanded by 200kW to cope with the additional capacity. Underfloor heating remains the main source of warmth, with eight VentMax units affixed to the walls in each 24,000sq m house.

The new barns are specced to grow for retail contracts, with windows allowing natural light to enter and enrichments such as perches and pecking bales provided. The farm opted for Multibeck pan feeders that prevent chicks from climbing into – and defecating in – their ration. In addition, the water system flushes automatically. The houses themselves were produced by Turkington.

John Gill and Matthew Evans of IPT, spent four years developing their VentMax air scrubbing heat exchangers. Photo: Richard Stanton

Results

For the first 2 batches through the system, the farm as a whole achieved EPEF (European Production Efficiency Factor, a measure of broiler performance) scores of more than 400, with the 3^rd batch set back by the “Beast From the East” disrupting feed deliveries and bird collection. Despite this, the score was still an impressive 390.

“It’s crazy that, on this site, we consider that a bad result,” says farm manager Lee Spoor. He adds that the first four poultry houses, which are conventionally ventilated, proved a challenge to keep at a consistent temperature as the wind and icy temperatures battered the farm, which is situated on a gentle slope with a prevailing south-westerly wind. But the two new units held a far steadier temperature throughout – the poultry houses are managing to maintain temperatures within half a degree, whereas the older units can fluctuate by up to 5°C.

Mr Spoor says the atmosphere in houses is “far better” than any system he has worked with before, and to date birds have performed better in the newer units, though he concedes there is still work to do in learning how the system operates.

“It will take a full 12 months to work out exactly how to get the best from the houses,” he says.

Cooling

One boon of the heating system Mr Spoor is looking forward to trying is the ability to cool houses as well as heat them. When temperatures rise above 25°C poultry production can become a challenging prospect – after 10 days of age, the birds’ own body temperature rises enough to require cooling ventilation, rather than heating.

Conventional systems rely on a high turnover of air through ventilation. With this system, the underfloor heating can remove warmth while the VentMax units can cool incoming air, keeping temperatures down without increasing air flow and making for a more comfortable atmosphere for the birds.

Farm manager Lee Spoor is impressed with the poultry houses’ atmosphere and stable temperature control. Photo: Richard Stanton

Incoming air is also filtered and can either pass through the heat exchanger or through a coil connected to the ground-source heat pump system if heating is needed (the coil can also cool air, if that is required).

In the houses, directional nozzles can be adjusted, depending on requirements, but the default is to throw air over the birds. The shed itself has no side inlets, but includes conventional gable-end fans and roof ventilation for extremely hot days, and as a backup if required.

Smells

In addition to recovering heat, the units filter and scrub ammonia and odour from the air as it exits the house. Anyone familiar with poultry production will know that odour can be a legitimate objection from those who live close to units. The air conditioning units are far more common in Western Europe – notably the Netherlands, where space is at a premium, and parts of Germany, where they are compulsory for new poultry houses.

IPT has been working with Adas to measure the level of reduction achieved, based on an Environment Agency baseline, and Mr Gill says that the system is already reducing emissions by up to 90%, with some modifications planned that may improve that figure.