Case Study

Twin ASHP Cascade system in Norfolk

Award Winning ASHP Project Heat pump installer of the year 2023

This award winning air source heat pump (ASHP) installation, where the customer contacted us before they purchased their property, as they were investigating the viability of installing a heat pump and the approximate costs of an installation, before they put in an offer on the property.

This property was a 200-year-old hard to heat period home in poor repair with an old oil heating system. There was no gas available at the property and the customer did not want to continue with oil heating, they were interested in installing a modern heating system which would be environmentally friendly.

The customer was doing many renovations to the home and due to delays in the supply of materials for their renovation the works took longer than planned. We completed the underfloor heating and installation of radiators first and the heat pump installation once it arrived, however this was also delayed due to supply issues.

We recommended a cascade system with 2 x NIBE F2040 12 kW air source heat pump, 300L cylinder & a 200L buffer vessel.

The house had a space heating requirement of 43,354 kWh per year and the hot water demand is 6,113 kWh per year, giving a National ACR & HP Domestic Air Source Project Winner 2023 total heat requirement of 49,467 kWh per year.

“We were impressed by R A Brown from our first visit to the showroom. We felt that we could trust the advice given by knowledgeable and experienced staff. We had a lot to learn about air source heating and the advice we received was very helpful. Through the process of planning and installation, we were confident that R A Brown was working with us to provide the best system for our needs. Our questions were answered quickly and we had several on-site meetings to work out the best way to solve problems which arose.”   Mrs W


Oil v’s ASHP CO2 emissions

The reduction of CO2 emissions on this project really sets it aside.

If the customer had installed another oil boiler heating system, it would have produced 14,741.16 kg CO2/kWh a year. Over an anticipated 15-year life span of an oil boiler, it would have produced 221,117.40 kg CO2/kWh.

The opportunity to drastically reduce the carbon produced would have been lost, had they not decided to make the change from oil and consider the environment.

Heating the property with Oil there would be estimated CO2 emissions of 14,741.66 kgCO2/kWh.

Heating the property with an ASHP there would be estimated C02 emissions of 1,907.94 kgCO2/kWh.

CO2 savings to be made with our recommended solution

The recommended solution of a cascade system with 2 12 kW Air Source Heat Pumps means the home now produces 1,907.94 kg CO2/kWh a year, giving an annual saving of 12,833 kgCO2/kWh per annum.

With the average mature tree absorbing 21kg CO2 a year the emissions the oil boiler would produce over 15 years would need 10,529 mature trees to absorb the CO2. In comparison the air source heat pump cascade system over 15 years would only need 1362 mature trees to absorb the CO2.

Find out more about air source heat pumps




“We were pleasantly surprised to find that air source heating was viable option for a period house, as it is usually associated with modern builds. Our house has large windows and high ceilings. Our first winter was very chilly, since the air source heating has been operating, the constant gentle heat has made the house feel welcoming and pleasantly warm, even though we are running the heating at a low level to reduce electricity costs“

Mrs W, Homeowner

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