Issues around the supply of hot water to milking parlour dairies have come to the surface since chlorine was banned as a cleaning agent for milking equipment. Chlorine is a very effective cleaning agent and its loss has left its mark in terms of dairy hygiene as alternative products are struggling to achieve the same level of performance as chlorine. This is mostly seen in an elevation in TBC and thermoduric bacteria in milk tests over time.
Alternative wash procedures require more hot washes and they require water at a very high temperature. Teagasc says that the temperature at the start of the wash should be 750C to 800C and that it should be 450C by the time the wash finishes. However, some cleaning agent manufacturers recommend water temperatures higher than this.
In some ways, suggesting that there is insufficient hot water is an easy excuse for company representatives to make as it deflects attention from possible deficiencies in their own products. It must be remembered that not all chlorine-free products on the market are working well.
Trials by Teagasc and milk processors have found some products to be inadequate. Of course, that is not to say that water temperature isn’t important because it is. Thermoduric bacteria by their nature are impossible to clean unless water temperature is high.
A common issue is that an electric water heater is insufficiently sized to provide enough hot water to fill the trough
The next issue is the quantity of hot water and this is probably an area where some farmers have a job of work to do. The recommendation is to have 9l of hot water per milking unit in the hot wash cycle. So a 10-unit parlour will need a 90l wash trough with 90l of water at over 750C. The problem on some farms is that the wash trough is incorrectly sized for the number of units and/or there is insufficient hot water capacity to fill the trough.
A common issue is that an electric water heater is insufficiently sized to provide enough hot water to fill the trough, or else the electric heater is choked with limescale and is operating at lower than specified water capacity. As a result, when the hot water in the heater is used up it is replaced by cold water and, as a result, this reduces the temperature of the water in the wash trough.
Heating options
There are four common methods of heating water in Irish dairies. These are the aforementioned electric storage heaters, oil-fired burners, instant gas burners and instant diesel burners. Each system has its own strengths and weaknesses. When considering what system is best suited to your farm, the first key thing to consider is how much hot water is needed on a daily basis.
Gas burners for instant hot water.
The main draw on water is for cleaning the milking machine and the bulk tank. Smaller quantities of hot water are often required for calf feeding and/or cleaning calf equipment, but this is usually needed at a lower temperature than that required for cleaning the milk plant or bulk tank.
In terms of the milking plant, the requirement is 9l per milking unit so a 10-unit parlour will require 90l and a 20-unit parlour will require 180l of hot water to wash the plant. Most of the new chlorine-free wash protocols require a hot wash daily. For bulk tanks, the general rule of thumb is that the tank will require 2% of its capacity for a hot wash. So if the tank has 10,000l of capacity, then 200l of hot water is required for the wash.
Even though the bulk tank might only be washed every second day, there needs to be enough capacity in the system to wash the plant and the tank in the one day. So for a 10-unit parlour with a 5,000l bulk tank, there is a daily requirement for 190l of hot water. For a 20-unit parlour and 10,000l bulk tank, there is a daily requirement for 380l of water.
According to John Upton from Teagasc, it is only when the daily requirement for hot water exceeds 300l per day that alternatives to electric water storage heaters should be considered. This is because the capital costs of alternative heating options can often be too high relative to the daily requirement for water. Electric storage heaters are cheaper to install.
The key point with electric storage heaters is to have night-rate electricity as this more than halves the cost of electricity
Alternatives such as oil and gas are more expensive to install but where the capital cost can be spread over a higher daily water requirement (more than 300l/day), the cost per litre of hot water becomes competitive.
A 300l water tank costs in the region of €500 to buy excluding VAT. Even in situations where more than 300l of water is required, capital costs can be reduced by buying two electric heaters and plumbing one to the milking plant and the other to the bulk tank and for cleaning utensils/feeding calves.
The key point with electric storage heaters is to have night-rate electricity as this more than halves the cost of electricity.
Recent costings compiled by John Upton suggest that the cost of heating 100l of water at day rate is €2.10 while the same quantity at night rate costs 94c. The heaters should be wired up with a timer on the trip switch so that they only come on at night.
Alternatives
There are alternatives to electricity. Gas and oil have been around for a good few years and some farmers heat water or pre-heat water using solar power. Oil burners heat and then store the water in cylinders, while gas provides instant hot water with no water storage.
In recent years, a new player in the hot water field entered the market in the form of Dairy Geyser. The Dairy Geyser provides instant hot water in much the same way as gas does but instead of being powered by gas it is powered by diesel, which reduces the capital costs of installation as most farmers already have a diesel storage tank on their farm.
The Dairy Geyser is also mobile and can be self-installed on the farm.
The manufacturers claim that the machine can heat water from an ambient temperature to 850C at a flow rate of 20l/min or 30l/min depending on the machine.
If you have a requirement of 180l of hot water, it will take nine minutes for the trough to fill at 20l/min or six minutes at a 30l/min flow rate
An important thing to consider when it comes to instant water heaters is the flow rate. While instant water temperature is important, the flow rate is as important because if the wash trough is slow to fill then the water will be cooling down before it gets to circulate.
If you have a requirement of 180l of hot water, it will take nine minutes for the trough to fill at 20l/min or six minutes at a 30l/min flow rate.
Extra capacity in the form of additional gas or diesel burners will be required if more water is required. With a storage heater, the hot water is ready to be used and the only restriction is the diameter of the pipe from the heater to the wash trough and the water pressure.
A 20l/min Dairy Geyser costs €2,850 excluding VAT, while the 30l/min model costs €3,600 excluding VAT. The cost of installation of gas products varies depending on the size of the storage tank and the distance from the tank to the boiler but typical costs of installation are around the €3,000 to €4,000 mark, excluding VAT.
As can be seen in Table 1, oil and gas have lower running costs than electricity. Take note that in this table, sourced from Teagasc, oil or kerosene refer to conventional oil burners and hot water storage, as opposed to instant oil burner costs.
The lower costs associated with oil and gas need to be offset against the fact that capital costs of installation are higher. Other considerations include the fact that there are limited suppliers of gas and also that oil prices are historically low at present.
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Issues around the supply of hot water to milking parlour dairies have come to the surface since chlorine was banned as a cleaning agent for milking equipment. Chlorine is a very effective cleaning agent and its loss has left its mark in terms of dairy hygiene as alternative products are struggling to achieve the same level of performance as chlorine. This is mostly seen in an elevation in TBC and thermoduric bacteria in milk tests over time.
Alternative wash procedures require more hot washes and they require water at a very high temperature. Teagasc says that the temperature at the start of the wash should be 750C to 800C and that it should be 450C by the time the wash finishes. However, some cleaning agent manufacturers recommend water temperatures higher than this.
In some ways, suggesting that there is insufficient hot water is an easy excuse for company representatives to make as it deflects attention from possible deficiencies in their own products. It must be remembered that not all chlorine-free products on the market are working well.
Trials by Teagasc and milk processors have found some products to be inadequate. Of course, that is not to say that water temperature isn’t important because it is. Thermoduric bacteria by their nature are impossible to clean unless water temperature is high.
A common issue is that an electric water heater is insufficiently sized to provide enough hot water to fill the trough
The next issue is the quantity of hot water and this is probably an area where some farmers have a job of work to do. The recommendation is to have 9l of hot water per milking unit in the hot wash cycle. So a 10-unit parlour will need a 90l wash trough with 90l of water at over 750C. The problem on some farms is that the wash trough is incorrectly sized for the number of units and/or there is insufficient hot water capacity to fill the trough.
A common issue is that an electric water heater is insufficiently sized to provide enough hot water to fill the trough, or else the electric heater is choked with limescale and is operating at lower than specified water capacity. As a result, when the hot water in the heater is used up it is replaced by cold water and, as a result, this reduces the temperature of the water in the wash trough.
Heating options
There are four common methods of heating water in Irish dairies. These are the aforementioned electric storage heaters, oil-fired burners, instant gas burners and instant diesel burners. Each system has its own strengths and weaknesses. When considering what system is best suited to your farm, the first key thing to consider is how much hot water is needed on a daily basis.
Gas burners for instant hot water.
The main draw on water is for cleaning the milking machine and the bulk tank. Smaller quantities of hot water are often required for calf feeding and/or cleaning calf equipment, but this is usually needed at a lower temperature than that required for cleaning the milk plant or bulk tank.
In terms of the milking plant, the requirement is 9l per milking unit so a 10-unit parlour will require 90l and a 20-unit parlour will require 180l of hot water to wash the plant. Most of the new chlorine-free wash protocols require a hot wash daily. For bulk tanks, the general rule of thumb is that the tank will require 2% of its capacity for a hot wash. So if the tank has 10,000l of capacity, then 200l of hot water is required for the wash.
Even though the bulk tank might only be washed every second day, there needs to be enough capacity in the system to wash the plant and the tank in the one day. So for a 10-unit parlour with a 5,000l bulk tank, there is a daily requirement for 190l of hot water. For a 20-unit parlour and 10,000l bulk tank, there is a daily requirement for 380l of water.
According to John Upton from Teagasc, it is only when the daily requirement for hot water exceeds 300l per day that alternatives to electric water storage heaters should be considered. This is because the capital costs of alternative heating options can often be too high relative to the daily requirement for water. Electric storage heaters are cheaper to install.
The key point with electric storage heaters is to have night-rate electricity as this more than halves the cost of electricity
Alternatives such as oil and gas are more expensive to install but where the capital cost can be spread over a higher daily water requirement (more than 300l/day), the cost per litre of hot water becomes competitive.
A 300l water tank costs in the region of €500 to buy excluding VAT. Even in situations where more than 300l of water is required, capital costs can be reduced by buying two electric heaters and plumbing one to the milking plant and the other to the bulk tank and for cleaning utensils/feeding calves.
The key point with electric storage heaters is to have night-rate electricity as this more than halves the cost of electricity.
Recent costings compiled by John Upton suggest that the cost of heating 100l of water at day rate is €2.10 while the same quantity at night rate costs 94c. The heaters should be wired up with a timer on the trip switch so that they only come on at night.
Alternatives
There are alternatives to electricity. Gas and oil have been around for a good few years and some farmers heat water or pre-heat water using solar power. Oil burners heat and then store the water in cylinders, while gas provides instant hot water with no water storage.
In recent years, a new player in the hot water field entered the market in the form of Dairy Geyser. The Dairy Geyser provides instant hot water in much the same way as gas does but instead of being powered by gas it is powered by diesel, which reduces the capital costs of installation as most farmers already have a diesel storage tank on their farm.
The Dairy Geyser is also mobile and can be self-installed on the farm.
The manufacturers claim that the machine can heat water from an ambient temperature to 850C at a flow rate of 20l/min or 30l/min depending on the machine.
If you have a requirement of 180l of hot water, it will take nine minutes for the trough to fill at 20l/min or six minutes at a 30l/min flow rate
An important thing to consider when it comes to instant water heaters is the flow rate. While instant water temperature is important, the flow rate is as important because if the wash trough is slow to fill then the water will be cooling down before it gets to circulate.
If you have a requirement of 180l of hot water, it will take nine minutes for the trough to fill at 20l/min or six minutes at a 30l/min flow rate.
Extra capacity in the form of additional gas or diesel burners will be required if more water is required. With a storage heater, the hot water is ready to be used and the only restriction is the diameter of the pipe from the heater to the wash trough and the water pressure.
A 20l/min Dairy Geyser costs €2,850 excluding VAT, while the 30l/min model costs €3,600 excluding VAT. The cost of installation of gas products varies depending on the size of the storage tank and the distance from the tank to the boiler but typical costs of installation are around the €3,000 to €4,000 mark, excluding VAT.
As can be seen in Table 1, oil and gas have lower running costs than electricity. Take note that in this table, sourced from Teagasc, oil or kerosene refer to conventional oil burners and hot water storage, as opposed to instant oil burner costs.
The lower costs associated with oil and gas need to be offset against the fact that capital costs of installation are higher. Other considerations include the fact that there are limited suppliers of gas and also that oil prices are historically low at present.
Read more
Dairy prices slump at GDT as uncertainty remains
Dairy management: grass growth, fertiliser and alternative medicines
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