What is industrial heating oil? Exploring the uses and benefits of Flame 35
Rising operating costs continue to challenge farms and commercial sites across the UK. From grain drying and livestock housing to warehousing and workshop heating, energy demands rarely fall in line with tightening budgets. Many operators are looking for ways to reduce fuel spend without sacrificing reliability, output, or the resilience they depend on day to day. One solution gaining momentum is Flame 35, a cost-effective alternative designed for industrial oil heating systems and industrial oil-fired boilers.
Here, we explain what industrial heating oil is, how Flame 35 works, where it can and can’t be used, and why so many agricultural and commercial businesses are making the switch.
What is industrial heating oil?
Industrial heating oil (IHO) is a specialist fuel formulated for use in industrial oil heating systems and industrial oil-fired boilers. It provides a like-for-like thermal performance compared to gas oil (red diesel) but at a significantly lower cost and with far fewer emissions. For businesses heavily dependent on high-volume heating – such as farms, factories, manufacturing plants, and processing sites – those savings can quickly accumulate across seasonal peaks.
Flame 35 is Craggs Energy’s industrial heating oil product. Developed specifically for commercial heating applications, it’s engineered to deliver a strong and stable heat output while reducing operating costs and minimising system stress. And, thanks to its winter-grade formulation, it’s engineered to stay free flowing in low temperatures and resist degradation in storage, giving you dependable, year-round performance with no need for equipment alterations.
Where can Flame 35 be used?
Flame 35 is compatible with a wide range of industrial oil heating systems and high-capacity heating setups across agriculture and industry. It’s particularly valuable for organisations that rely on reliable round-the-clock heat to protect crops, livestock, temperature-sensitive goods, or working environments. Typical applications include:
- Grain dryers
- Livestock sheds and poultry housing
- Greenhouses
- Commercial workshops and garages
- Industrial units and storage facilities
- Large buildings and production areas
- Hospitals
- Schools
- Hotels
- Distilleries
As long as the equipment is strictly heating only, most operators can use Flame 35 without issue – and without any internal burner modifications.
Where Flame 35 cannot be used
Because Flame 35 is formulated purely for heat generation, it doesn’t contain the performance additives, ignition properties, or combustion profile required for engines or equipment that produce mechanical power or propulsion. Using Flame 35 in these systems can cause incomplete combustion, injector and pump damage, excessive wear, and non-compliance with fuel duty regulations. Prohibited usage includes:
- Road vehicles
- Off-road machinery
- Boats or sea-going vessels
- Mobile plants
- Generators
- Combined heat and power (CHP) units
Using the correct fuel is essential for compliance and avoiding costly damage or downtime. If you need support identifying the right product for your equipment, Craggs Energy can advise on compliant alternatives for your business or farm.
Why choose Flame 35? Key benefits for farms and commercial sites
Switching fuels is never a small decision, but for many farms and commercial sites, Flame 35 delivers tangible day-to-day gains. From lower heating costs to cleaner combustion and reduced maintenance, here are the benefits that stack up quickly:
Significant cost savings compared to gas oil and diesel
Switching to Flame 35 is one of the quickest ways to lower heating costs for high-demand operations. Because industrial heating oil is manufactured specifically for heating – not propulsion – its price point is typically much lower than gas oil, diesel, and red diesel. For energy-intensive commercial and industrial environments, these savings can have a measurable impact on operating margins – particularly across large buildings, multiple sites, or prolonged heating periods.
No burner modifications required
Unlike some alternative fuels, Flame 35 is drop-in ready for many industrial oil-fired boilers and heating systems. Most operators can transition without installing new components, adjusting burner settings, or upgrading existing equipment – reducing downtime and eliminating costly engineering work. This makes the switch simple, quick, and low risk.
Consistent and high-quality heat output
Flame 35 is formulated to mirror the performance characteristics of gas oil. This ensures a strong and reliable heat output even during peak seasonal demand. For agriculture, where temperature control underpins crop quality and animal welfare, this stability is essential.
Year-round winter-grade stability
Weather volatility makes fuel resilience crucial. Flame 35 is supplied as a winter-grade product all year, protecting against cold weather gelling and maintaining steady flow in low temperatures. Operators can enter the colder months confident that their industrial oil heating systems will remain protected.
Cleaner combustion and reduced contamination risk
Industrial heating oil is refined to burn cleaner than conventional gas oil, which in turn reduces soot and residue build-up, lowers the likelihood of boiler fouling, and helps prevent contamination inside tanks and fuel lines. With fewer deposits accumulating in the system, operators typically experience less frequent servicing requirements and more consistent efficiency over time. This cleaner combustion supports reliability, protects long-term cost control, and helps maintain steady heat output – even during periods of heavy use.
Fewer acidic emissions
Flame 35 produces fewer acidic byproducts during combustion, helping to reduce corrosion inside industrial oil-fired boilers. Over time, this can extend component life and minimise operational interruptions, which is important for farms and commercial sites that rely on continuous heat.
Strong performance across varied applications
From grain drying to heating large industrial spaces, operators report comparable performance to gas oil at a fraction of the cost. With Flame 35 providing stable heat and a familiar burn profile, most businesses see no operational compromise when switching. For many, the fuel functions exactly the same – just far more economically.
How switching to industrial heating oil reduces downtime
Fuel-related breakdowns often stem from contamination, temperature issues, or incomplete combustion. Because Flame 35 is engineered specifically to minimise these problems, operators typically experience smoother boiler performance, fewer emergency callouts, and far less need for tank cleaning.
Over time, this cleaner, more stable burn also supports greater system longevity, helping industrial oil heating systems run consistently, no matter the requirement. For farms in particular – whether during harvest or winter housing – this reliability protects production schedules and reduces the risk of costly mid-season failures, keeping unplanned spend to a minimum in an already challenging financial climate.
Is Flame 35 right for your operation?
If your equipment is used purely for heat generation and not for propulsion or power output, Flame 35 is likely a suitable and cost-effective choice. Many farms and commercial sites make the switch to reduce fuel costs, lower their maintenance burden, and maintain reliable heating performance throughout the year. For operators managing demanding seasonal cycles, Flame 35 is the peace-of-mind solution.
Craggs Energy can provide tailored advice based on your equipment, heating demand, and operational profile. If you’re considering a switch or want to confirm suitability for your equipment, our employee-owned team is here to help – get in touch.
