The Ultimate Guide to Buying a Diesel Generator and Securing a Maintenance Contract
Why Diesel Generators Still Matter
In today's fast-paced world, uninterrupted power supply is more critical than ever. Whether you're protecting a commercial facility, powering remote operations, or securing backup for critical infrastructure, diesel generators remain the most reliable and scalable power solution available.
At Blackwell Generators, we specialise in supplying robust, high-performance diesel generators tailored for businesses, agricultural operations, construction sites, and backup power systems across the UK and beyond.
This comprehensive guide is designed to help you make informed decisions on purchasing the right generator for your needs and why having a maintenance contract in place from the start is essential to avoid costly failures or downtime when you need power the most.
Understanding Your Power Requirements
1.1 Calculate Your Load
Before selecting a diesel generator, it is essential to evaluate your site's power requirements. Begin by creating an inventory of all equipment that needs to be powered, along with their individual kW or kVA ratings. Consider both running and starting loads, as some devices (like compressors or HVAC units) have higher starting demands.
A qualified electrical engineer or generator supplier, such as Blackwell Generators, can assist you in this process.
1.2 Prime vs Standby Power
Generators are typically rated for two kinds of power outputs:
Prime Power: For sites where the generator is the primary source of electricity.
Standby Power: For use during emergencies or power cuts.
Make sure you understand the difference. For instance, a generator rated at 100 kVA prime may offer 110 kVA standby.
1.3 Single-Phase or Three-Phase?
Most UK homes require single-phase (230V) generators, while commercial, industrial, and agricultural sites usually need three-phase (400V) power. Check your utility connection before purchasing.
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Chapter 2: Choosing the Right Generator Model
2.1 Generator Size Matters
Avoid under-sizing (which can overload the generator) and over-sizing (which leads to poor fuel efficiency and higher costs). Once you have your load calculated, choose a generator with at least 10% headroom.
2.2 Recommended Brands
At Blackwell Generators, we stock a curated range of trusted brands:
Perkins: British-engineered, reliable, and globally supported
Cummins: Excellent performance, parts availability, and long lifespan
Baudouin: A premium European choice offering excellent value
Volvo Penta, Deutz, Doosan: Great options for high-performance requirements
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2.3 Enclosures & Sound Attenuation
Diesel generators can be supplied in various formats:
Open Type: Ideal for indoor or plant-room installations
Acoustic / Weatherproof Canopy: Reduces noise and protects from the elements
Containerised Units: Secure, portable, and ideal for large installations or rentals
We offer super-silent enclosures and fully bunded options.
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Chapter 3: Runtime, Fuel & Tank Options
3.1 Integrated vs Extended Fuel Tanks
If you're looking for long runtime (e.g. remote construction sites, telecom towers), ensure your generator is equipped with:
A bunded base tank
Or an external bulk tank connection
Our standard fuel tank options vary from 8 to 24 hours of runtime under 75% load.
3.2 Fuel Efficiency and Cost
Diesel remains the most cost-effective fuel source for medium to large generators. Our Perkins and Baudouin models are optimised for fuel efficiency.
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Chapter 4: Key Generator Features to Consider
4.1 Control Panels
Look for sets fitted with:
DSE controllers (e.g. DSE6120): Intuitive, programmable, and industry standard
Auto Start and Auto Transfer (ATS) functionality
Alarm displays and data logging
4.2 Circuit Breakers & Safety
We recommend sets fitted with:
ABB or Schneider circuit breakers
Emergency stop push buttons
Overcurrent protection
4.3 Monitoring & Remote Access
Optional upgrades include:
GSM-based remote monitoring
Web-based control platforms
Alert systems via SMS or email
We install and configure these on request.
Chapter 5: Compliance & Installation
5.1 UKCA Certification
All our UK-assembled generators come fully UKCA marked and compliant with British safety and emissions standards.
5.2 Site Surveys & Installation Support
We provide full site assessments, logistics, and installation support. Whether your generator is installed in a basement, on a rooftop, or in a secure container, we ensure it’s done professionally.
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Chapter 6: The Critical Role of Maintenance Contracts
6.1 Why Generators Fail
The most common causes of generator failure during an emergency are:
Battery failure
Fuel contamination
Lack of oil/coolant
Control panel malfunction
Blocked air filters
Most of these issues are preventable with scheduled maintenance.
6.2 What a Maintenance Contract Includes
At Blackwell Generators, our maintenance agreements typically include:
Quarterly or bi-annual inspections
Oil and filter changes
Battery and coolant checks
Load testing (resistive or reactive)
24/7 breakdown support (optional upgrade)
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6.3 Compliance & Record-Keeping
Our engineers maintain detailed reports and service logs which help meet Health & Safety and insurance audit requirements.
Chapter 7: Cost Considerations
7.1 Upfront Costs
Generator prices vary depending on:
Brand and model
Power rating
Features (ATS, silent canopy, bulk tank)
Typical costs:
20 kVA Perkins Generator: ~£5,000 - £8,000
100 kVA Baudouin Set: ~£8,000 - £13,000
500 kVA Cummins: ~£20,000 - £35,000
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7.2 Maintenance Costs
Maintenance plans start from as low as £250/year for light-use standby sets. Larger units or 24/7 prime power applications require more frequent servicing.
Our team will advise the most suitable plan based on:
Load profile
Runtime hours
Site conditions
Chapter 8: Delivery, Commissioning & Aftercare
8.1 Delivery & Logistics
We deliver across the UK and internationally. All units are:
Fully tested and inspected before dispatch
Supplied with operation manuals and documentation
Generator Delivery Information
8.2 Commissioning
Our engineers offer full commissioning services including:
Electrical termination
Load bank testing
User training
8.3 After-Sales Support
We stand behind every unit we sell. You’ll benefit from:
Access to genuine spare parts
Technical support
Warranty claim assistance (where applicable)
Chapter 9: Avoiding Common Mistakes
9.1 Buying the Wrong Size
Undersized units cause tripping and wear. Oversized units suffer from wet stacking and inefficiency. Always size your generator based on actual and peak loads.
9.2 Ignoring Maintenance
Skipping oil changes or fuel checks can lead to catastrophic engine failure. A maintenance contract pays for itself.
9.3 Using the Wrong Fuel
Ensure the diesel you use complies with EN590 standards. Consider fuel polishing services for long-term storage.
9.4 Poor Location Selection
Install your generator on a level, ventilated surface with easy access for maintenance. Avoid low-lying areas prone to flooding.
Chapter 10: Conclusion & Next Steps
Choosing the right diesel generator is an investment in operational resilience. But purchasing the right unit is only part of the equation — ensuring it performs when needed is just as important. A maintenance contract should never be an afterthought.
At Blackwell Generators, we’re here to guide you through every step — from sizing and sourcing the right equipment to commissioning and maintaining your generator for years to come.
Ready to discuss your project? Visit our Contact Page or call our team directly to get started.
Your power. Our priority.
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