What is the Renewable Heat Incentive?

The Domestic Renewable Heat Incentive (RHI) is a government financial incentive that promotes the use of renewable technologies, such as heat pumps or solar thermal. Eligible applicants receive quarterly payments for seven years based on the amount of clean, green renewable heat their system produces.

Since its launch in April 2014, more than 25,000 renewable heating systems have been successfully installed. And it’s estimated that 1366kT of CO₂ will be saved across the lifetime of the scheme by those accredited in the first 10 months. That’s the equivalent of 6807 journeys to the moon and back!

The scheme is specifically targeted at, but not limited to, homes off the gas grid, as these are the properties that have the potential to benefit the most from renewables.

In a property with no access to the gas grid the savings are obvious. A property with an electric boiler feeding radiators would cost approximately double the amount to run each year than a heat pump with a typical Coefficient of Performance (CoP)*. The heat pump also needs electricity to run but far less than a radiator system as its efficiency is much greater.

Heat pumps and the RHI

Heat pumps are ideal off-grid solutions that are eligible for the RHI and offer decent payback tariffs. There are two main types of heat pump, ground source (GSHP) and air source (ASHP), with a wide range of options available in terms of heat output:

  • ASHPs are an affordable option and suitable for properties with less outside space. The unit sits outside the property with the cylinder, buffer tank and associated control equipment fitted inside.
  • GSHPs, on the other hand, are fitted indoors with the ground loops or boreholes placed in the ground outside. GSHPs need more space both for the unit inside the property and for the ground loops externally and they are also more expensive to purchase and install, given the groundwork requirement, but the RHI tariff level is set at a higher level to reflect this.

 

RHI PAYMENTS
GROUND SOURCE
AIR SOURCE
SOLAR THERMAL
RHI Tariff payment
pence / kWh
19.1
7.42
19.51
Possible RHI payments over 7 years using Nu‑Heat renewable technologies*
£14,154
£4,907
£1,540
An average two-bedroomed house, using 15,000kWh of heating per year with a SPF of 3.4 on GSHP and 2.7 on ASHP.
Solar thermal based on average 3-bedroomed, 4-person household using 49,640 litres of hot water p.a.
May 2014.

 

Installation and the RHI

In order to be eligible for payments, the chosen renewable system and the installer/commissioning engineer must be MCS approved – which is something that Nu-Heat can help both homeowners and installers with. The legislation aims to ensure that all renewables systems are installed to the highest standard and operate efficiently.

*CoP – Coefficiency of Performance: the measure used to display heat pump efficiency
In a well-insulated property every single kilowatt of electricity used to power the heat pump can provide up to three kilowatts of free energy. This ratio is known as the CoP.

For more information on heat pumps and the RHI give us a call on 01404 540650.

A closer look at… buffer tanks

A buffer tank is a vessel that is used in a heating system to contain a volume of heating system (primary) water.

It is a particularly important component of a heat pump system, reducing the number of starts and stops that the heat pump has to make in order to meet the property’s heat load, in turn helping to increase the life-span of the heat pump.

Nu-Heat BufferBox100

What is a buffer tank for?

A buffer tank has two main functions:

  1. To increase volume

    A heat pump system is designed to work continuously, adding just enough heat to keep the building up to temperature. This is fine during the depths of the heating season when the building heat loss is close to the design condition and the heat pump needs to tick over. However, in spring and autumn when the property’s heat loss is lower, the heat pump does not need to keep continuously adding heat.

    In these warmer months, the additional volume that a buffer tank provides gives an extra load for the heat pump to work on. Once it has satisfied this load, meeting the demand, it will switch off but the buffer tank will continue supplying heat to the property. This means that there will be a longer period of time before the heat pump will not need to switch back on.

  2. Hydraulic separation

    In most heat pump systems there are two main circuits: one around the heat pump, and one around the heat emitter (most likely underfloor heating). There are different design requirements between these two circuits (the water temperature difference and hence flow rate), and yet they have to interface.

    The buffer tank allows the two circuits to be designed independently, allowing an installer to think of each circuit as its own entity, with a different flow rate for each, and yet the heat gets from one to the other.

Does every heat pump require a buffer tank?

Every heat pump system designed and supplied by Nu-Heat includes a buffer tank, whether it’s our space-saving buffer box that can accommodate a cylinder sat on top, a wall hung option or a floor-standing tank.

The choice of buffer tank is sized according to the heat pump capacity and model requirements during the system design.

Find out more…
See more about heat pumps from Nu-Heat on our website
Click here to view more information on Nu-Heat’s BufferBox100
View our EnergyMaster HP information sheet

How it works:
Air source heat pumps

Thanks to the Domestic RHI, air source heat pumps (ASHPs) are becoming increasingly popular.  The scheme is a great incentive for homeowners, encouraging them to opt for renewable technologies.  It’s also good news for installers who can expect more renewables business.

So, what exactly is an ASHP and how does it work?

 

IMAGE NIBE F2040 8KW

 

How an ASHP works

ASHPs, sometimes known as air-to-water systems, work by using warmth extracted from the air.  This low temperature warmth is absorbed by a fluid held in the ASHP which passes through a compressor where its temperature is increased before being made available for the heating and domestic hot water circuits of the property.

An ASHP can operate in temperatures as low as -20˚C.

How it saves on heating bills

An ASHP essentially offers ‘free’ energy.  It delivers more heat energy than the electrical energy it takes to operate.

As a comparison, if an electric fire uses 1 kWh of electricity, it delivers 1 kWh of heat, meaning its ‘Coefficient of Performance’, or CoP, is 1.  This means that the electric fire is 100% efficient.

If 1 kWh of electricity is put into an ASHP, it could deliver 3 kWh of heat, giving it a CoP of 3.  The heat pump has extracted an extra 2 kWh of ‘free’ heat from the air and delivered it for use in heating and domestic hot water.

It’s this ‘free’ energy that makes an ASHP attractive, especially to anyone who cannot access gas as they have the most to gain.

ASHPs and underfloor heating

An ASHP reaches its highest levels of efficiency when producing low flow temperatures.  It’s the lower flow temperatures required by underfloor heating that make it the perfect partner for ASHPs.  By integrating the two systems together, both technologies play to their strength and maximum efficiency can be achieved without compromising comfort.

ASHPs  and the Domestic RHI

The Government recognises that ASHPs have a part to play in making UK housing more energy-efficient and reducing energy bills, which is why they have been included in the RHI.

To help offset the cost of installing an ASHP, a homeowner can expect a tariff rate of 7.3p/kWh.  A typical home using around 20,000kWh per annum of heating requirement could get around £7000 in payments over a seven year period – a considerable amount to go alongside the savings on energy bills.  Visit Ofgem to find out more.

Who can install an ASHP?

The majority of heating engineers could install an ASHP with a clear manual to follow.

It’s important to remember that in order to qualify for the Domestic RHI, both the system and the installer has to be MCS approved.  Nu-Heat offers support packages to both MCS and non-MCS installers – give us a call for more info.