Heat First, Power Second: The Secret to Right-Sizing EcoPrime microCHP

katieslaski
7 days ago
3 min read

When it comes to deploying a micro-combined heat and power (microCHP) system, sizing isn’t just a technical step, it’s the key to unlocking performance, efficiency, and return on investment. The EcoPrime™ microCHP from Axiom Energy is designed to deliver both heat and electricity simultaneously, but like any energy system, its success depends on matching the unit to the right application.

In this article, we’ll walk through how to properly size EcoPrime for real-world installations and why thermal demand, not electrical demand, is the driving factor.

Understanding How EcoPrime Works

EcoPrime is a heat-driven microCHP system, meaning it operates based on a building’s thermal demand. As it produces heat, it simultaneously generates electricity as a byproduct.

Each unit:

Produces 13,000–47,000 BTU/hr of thermal energy
Generates 1.2–4.4 kW of electricity
Achieves system efficiencies exceeding 90%

This fundamental relationship is critical: If the system isn’t running for heat, it isn’t producing electricity.

Step 1: Start with Thermal Load, Not Electrical Load

A common mistake is trying to size microCHP based on electrical demand. With EcoPrime, the correct approach is the opposite.

Why?

The system modulates based on heat demand
Electricity is generated only when the engine is running
Maximizing runtime = maximizing savings

Best-fit applications include:

Facilities with consistent hot water usage
Buildings with year-round thermal demand
Operations running 24/7 or long daily hours

Examples:

Multifamily housing
Hotels
Fitness centers (pools & showers)
Laundries
Restaurants

Step 2: Identify the “Base Thermal Load”

The ideal EcoPrime sizing target is the minimum continuous thermal demand, often called the base load.

This ensures the unit:

Runs as many hours as possible
Avoids short cycling
Maximizes ROI and energy savings

Rule of thumb: Size EcoPrime to meet the lowest consistent heating or hot water demand, not peak demand.

Peak loads should be handled by:

Existing boilers
Supplemental heating systems

In fact, EcoPrime is typically installed alongside a boiler to handle fluctuations and redundancy.

Step 3: Evaluate Load Profiles (Daily + Seasonal)

A proper sizing exercise looks beyond total energy use and focuses on when energy is used.

Key questions:

Is hot water demand steady throughout the day?
Does the building have off-season dips (e.g., schools, seasonal properties)?
Are there spikes that require backup heating?

Ideal load profile:

Flat, consistent demand curve
Minimal idle periods
Year-round usage

For example:

A hotel with continuous occupancy → excellent fit
An office building with no weekend load → less ideal

Step 4: Consider Runtime Optimization

MicroCHP economics improve dramatically with runtime. EcoPrime systems are designed for:

Continuous operation (24/7/365) when thermal demand exists
Long engine life (~40,000 hours)

Higher runtime means:

More electricity generated on-site
Greater utility savings
Faster payback

Step 5: Use Buffer Tanks to Stabilize Performance

A buffer tank plays a critical role in proper sizing and system stability. It acts as:

A thermal battery
A buffer between production and demand
A way to extend runtime during low-demand periods

Benefits include:

Reduced cycling
Improved efficiency
Better integration with HVAC systems

Step 6: Scale with Multiple Units When Needed

For larger applications, EcoPrime systems can be installed in parallel. Advantages of modular scaling:

Match larger thermal loads
Provide redundancy
Maintain efficiency at partial loads

Example:

Two units serving a pool facility can simultaneously provide heat and generate electricity while maintaining flexibility in operation

Step 7: Match the Application, Not Just the Building Size

Square footage alone doesn’t determine sizing, usage patterns do. Two buildings of the same size can have dramatically different suitability:

Building Type	Suitability
Apartment with high hot water usage	Excellent
Warehouse with minimal heating	Poor
Hotel with laundry + showers	Excellent
Office building (9–5)	Moderate

The key metric is: Thermal intensity per hour, not building size

Final Thoughts: Right-Sizing Drives ROI

The EcoPrime microCHP system is most effective when:

It is heat-led
It runs continuously
It serves consistent thermal demand

When sized correctly, EcoPrime can:

Reduce energy costs
Lower emissions by up to ~30%
Improve overall system efficiency beyond traditional grid and boiler setups

Want Help Sizing Your Project?

Every building is different. The best way to determine the right EcoPrime configuration is through a detailed load analysis. Axiom Energy can help evaluate: