Case Study: High Efficiency Heat Pump Design in Lincoln
Overview:
A full heat loss led design and staged installation is underway at a large 303m² residential property in Harmston, Lincoln, replacing an ageing and inefficient heating system with a 16kW Samsung R290 air source heat pump. The property was originally built around 2000.
The project demonstrates how correct design principles, not property size, determine heat pump performance, delivering a future proof, efficient system tailored to the home’s exact heat demand of 13.65kW.
Complete Re-Pipe & Air Source Heat Pump installation
We’re currently mid-way through a major upgrade with Glow Heating, and we wanted to share our positive experience so far.
The team has just completed a full copper repipe of our house along with the installation of an air source heat pump, and the level of effort and professionalism has been outstanding. Paul and Ben have led the work on site with an exceptional team, all of whom have been tactful, hardworking, communicative, and clearly committed to doing the job right.
Glow’s Team For This Project
Heating System Designer: Jack McGovern
Lead Installers: Paul Clinton & Ben Kaszar
Support Team: Cody, Shaun, Max, Harry, Steve, Jack, Matt
Key Specifications:
Air Source Heat Pump: Samsung Mono R290 Integrated 16kW
Total Heat Loss: 13.65kW
Floor Area: 303m²
Design Flow Temperature: 45°C
SCOP 45°C: approximately 4.0
Heat Distribution:
139.8m² underfloor heating ground floor, installation scheduled May
Column style radiators on first floor
Future Proofing Provision: First fix underfloor manifold and pipework installed for future bathroom upgrades
This allows wet underfloor heating to be added in bathroom areas, ensuring sufficient heat output where wall space is limited and decorative radiators are typically used. The system can be extended room by room using a wet underfloor chipboard system as floors are upgraded.
Hot Water Cylinder: 300L unvented cylinder
System Design: Low temperature system with buffer vessel, mixed emitters, and zoned control
The Challenge System Limitations and Performance Issues
The existing system presented several long term issues:
- Non barrier plastic pipework allowing oxygen ingress and ongoing system degradation
- Gas boiler providing space heating
- Two vented hot water cylinders running on direct electric
- High running costs and inconsistent comfort, with some areas struggling to maintain temperature due to inadequate emitter performance
These combined factors led to growing concerns around the long term reliability and overall performance of the system.
Design Philosophy Performance Through Precision
Heat Loss Led Engineering
The system was designed using a full room by room heat loss calculation, resulting in a total design load of 13.65kW.
This enabled:
- Accurate heat pump sizing
- Correct emitter selection
- Elimination of oversizing and inefficient cycling
Low Temperature System Design
The system is designed to operate at a 45°C flow temperature, allowing:
- Higher seasonal efficiency
- Reduced running costs
- Stable and consistent heating output
Underfloor heating circuits will operate at approximately 30°C and are controlled via an ESBE mixing valve, improving both comfort and system efficiency.
Further updates will be shared as the underfloor heating installation progresses, as this phase forms a key part of the overall system design.
Mixed Emitter Strategy
To suit the layout of the property:
- Ground floor full underfloor heating scheduled for installation in May
- First floor column style designer radiators
Column radiators were selected to:
- Provide higher output at lower flow temperatures
- Maintain compatibility with low temperature heat pump operation
- Complement the aesthetic of the property
Example performance matching:
Kitchen UFH: 1301W demand to 1497W output 115 percent
Bedroom radiator: 1200W demand to 1320W output 110 percent
Hydraulic Design Buffer Vessel and Backup Heater Integration
A buffer vessel was installed to meet both system performance and manufacturer requirements.
This includes:
- Minimum 50 litres of system volume in line with Samsung requirements
- Integrated 3kW backup heater to comply with manufacturer guidance
- The system uses water with freeze protection primarily provided by anti freeze valves, rather than relying on glycol.
The backup heater also serves a critical operational role. Samsung specify its inclusion to assist in raising water temperature during certain operating conditions. This helps:
- Reduce strain on the compressor during cold starts
- Improve system stability in low ambient conditions, particularly below the system design point not expected to be required until approximately minus 5°C in this case, subject to commissioning and performance review
- Enhance long term reliability of the refrigerant circuit
This manufacturer led approach provides an additional layer of protection and supports system longevity.
The buffer also ensures the internal circulation pump within the outdoor unit can overcome system resistance and maintain nominal flow rates of approximately 45 litres per minute.
Why We Avoid Glycol
Instead of using glycol based antifreeze, this system relies on anti freeze valves and backup heater protection.
This approach:
- Maintains better heat transfer efficiency
- Avoids increased system viscosity
- Reduces long term maintenance requirements
This results in a more efficient and responsive system while still maintaining appropriate frost protection.
System Balancing Flow Regulation Strategy
Flow regulating radiator valves were installed across the radiator circuits to allow precise system balancing.
This enables:
- Accurate flow rates through each emitter
- Improved heat distribution
- Enhanced system efficiency
This also allows pump speeds on the secondary circuit post buffer to be reduced, helping to:
- Minimise noise within the airing cupboard
- Improve system stability
- Reduce electrical consumption
System Optimisation Mixing Valve Strategy
A dedicated ESBE mixing valve has been installed for the ground floor underfloor heating system to:
- Reduce flow temperature to UFH circuits
- Improve comfort control
- Increase overall system efficiency
The mixing valve will be commissioned alongside the underfloor heating installation phase in May.
Control Strategy Zoned Without Over Complication
Samsung thermostats were installed to control the ground floor and first floor independently.
This enables practical setback strategies such as:
- Reducing temperatures upstairs during the day
- Reducing ground floor temperatures overnight
This approach:
- Improves efficiency
- Reduces unnecessary energy use
- Maintains comfort where needed
The system avoids excessive zoning, delivering control without compromising performance.
Integration with Samsung SmartThings allows the client to:
- Adjust schedules remotely
- Fine tune heating patterns
- Optimise system performance
Installation Detail Electrical and Infrastructure
A dedicated 6mm supply cable was installed from the consumer unit to the heat pump, involving a challenging 36 metre run.
This ensures:
- Correct electrical capacity
- Compliance with system requirements
- Long term reliability
An additional 6mm cable was installed for a future hot tub connection. While not part of the original specification, this was incorporated during the project following discussions with the client.
By installing this cable alongside the main supply run, the client avoids future disruption and significant additional labour costs. This approach demonstrates a flexible, client focused mindset, delivering long term value by taking advantage of works already underway.
Installation Detail Floor Access and Pipework
To accommodate the pipework and wiring installation, first floor chipboard flooring was lifted throughout the property to allow for new pipework and cable runs.
As part of reinstatement:
- All flooring was relaid
- Additional structural supports were installed
The client noted:
“The floors are now less squeaky than before.”
An added benefit of the works, improving both the heating system and the overall feel of the property in the process.
Installation Approach Phased Delivery
The project is being delivered in stages:
- Heat pump and hot water system installation complete
- First floor radiator upgrades complete
- Underfloor heating installation scheduled for May
- This approach minimises disruption and allows for proper commissioning.
Running Costs
Previous system approximately £2,923 per year
New system £2,127 to £2,657 per year
Potential savings up to £796 annually
The client is planning to install solar PV, which will further improve savings.
Performance and Expected Results
Efficiency
Designed SCOP approximately 4.0 at 45°C
Weather compensated operation
Carbon Reduction
Previous 9.7 tonnes CO₂
New system 1.4 tonnes CO₂
Reduction approximately 86 percent
Key Takeaway
High performance heat pump systems are achieved through correct design, not assumptions.
With:
- Accurate heat loss calculations
- Correct emitter sizing
- Proper hydraulic design and control
Even large homes can achieve efficient, reliable, low temperature heating.
Considering a Heat Pump in Lincolnshire?
If you are based in Harmston, Lincoln or surrounding areas, the most important step is:
Getting the design right from the start.