The installation of a Nibe ground source heat pump, underfloor heating and MVHR system
The project:
The clients were selling their house and moving to the countryside to build their dream home. Orangehouse Renewables were commissioned to design and install the heating and ventilation systems for the new home. Ground works started early in the project with boreholes being drilled for the ground heat collectors. As the house was being built, the MVHR system and underfloor heating were installed. Once the screed had been poured and dried, flooring was laid ahead of the heat pump plant being installed.
The challenge:
Ground source is the best and most efficient heating system but due to limited horizontal space a vertical borehole ground heat collector was needed. Due to the layout of the building plot the boreholes had to be drilled to the rear of the house before the footings were dug. If the foundations had been dug first, access would have been impossible. The header pipe work from the 3 boreholes back to the manifold chamber had to be installed at the same time as the ground work for the boreholes, and then extended through the footings and into the plant room as the house was built.
The ventilation ducting needed detailed design and planning to ensure efficient installation and performance.
The solution and benefits:
Following detailed design calculations, a Nibe ground source heat pump was specified, along with a buffer tank and hot water cylinder with integration into the solar PV system.
The system was set up so this would allow excess solar or cheap rate electricity to be stored as warm water, reducing the need to buy expensive electricity from the electricity supplier. The addition of a Tesla Power Wall led to payments from the electricity supplier.
What was involved?
The ground source heat pump system was installed in a dedicated plant cupboard at the back of the garage. The MVHR unit was sited in the loft and the roof vents fitted by the roofers during the build.
The ground floor underfloor heating was stapled to the floor insulation and screeded early on in the build programme to maximise drying time. A dry overlay screed board system was used on the first floor to provide thermal mass and efficient low temperature heating.
Client feedback:
“From our initial discussions with Orangehouse Renewables through to design, installation and commissioning, it is difficult to imagine that anything could have gone better. OHR understood that the ground source heating and MVHR systems would be crucial aspects of our self-build project and worked with us throughout to ensure that everything went smoothly. Their installation is nothing short of an engineering masterpiece and is constantly admired by all who see it, including the other engineering trades who share the same space.”
Common concerns about ground source heat pumps:
Freezing the ground
Proper design ensures that the ground performs as a rechargeable battery. If enough heat collector pipe is installed in a large enough area, heat can be collected when needed during cold weather and is then replenished by the sun and the rain – effectively recharging the heat source. Ground source collects surface energy, not geothermal energy from deep within the earth.
Warmth and comfort
There is a plentiful supply of hot water when required and there are no concerns about keeping the property warm during cold weather. The whole house MVHR system blows warm fresh air into the living rooms and bedrooms, and extracts stale air from the kitchen and bathrooms – the indoor air is like being outside, but warm!
Energy costs
Every unit of electricity consumed powering the heat pump generates 4.7 units of heat (470% efficient) – the 3.7 extra units of heat are harvested from the ground. The high quality Nibe heat pump has a 7-year warranty but should last around 20-25 years and the ground heat collector, although costly to install is energy infrastructure lasting 50 years plus. The solar PV array and batteries allow the house to combine smart tariffs and home generation to minimise running costs.
