Air source heat pumps… an absorbing proposition

Air source heat pumps absorb heat from the outside air. This heat can subsequently be used to warm radiators, air convectors and water, or in other heating systems. The process lowers fuel bills, cuts carbon emissions, and requires minimal maintenance.

The way it works is, ambient heat is absorbed at low temperatures into a fluid that passes through a compressor and generates higher-temperature heat, which is channelled through the heating circuit.

A great introduction to ground and water source heat pumps

Ground and water source heat pumps (GSHP) are easy to run once installed and provide low-carbon heating or cooling. Average reduction in CO2 emissions are reported to be from 25 % to 70%. These reductions depend on the use of GSHP - either for cooling, heating, or both. These systems offer the benefits of reduced running and maintenance costs, and overall energy bills, which offsets the up-front capital investment that is often higher than for conventional systems.

Insulating the pipework and valves of a hot-water and heating systems could help cut heat loss or heat gain by up to 90 %. In one or two years, the investment could be recovered, and savings made.

Take an office working on a single-shift system, for example. Fitting insulation to 100 mm pipework would cost around € 23 (£ 20) a metre but save € 23 (£ 20) a metre, assuming a gas price of € 0.03 (2.5 pence) per kWh. That means a payback period of just one year.

Biomass heating is a proven technology which most commonly uses virgin wood, certain energy crops, industrial wood residues and certain agricultural residues to produce heat. Biomass is considered a low-carbon technology if the feed material is derived from sustainable sources. Significant carbon and operational cost savings, as well as reduced fuel price volatility, are achieved with the use of biomass heating. Using certain biomass resources as fuels can also help divert by-products from landfilling and reduce costs associated with waste management.

Flash steam released from hot condensate can be recovered and applied elsewhere in the plant to maximise overall efficiency. Recovery systems reduce steam-raising costs, utility bills and CO2 emissions, and help achieve significant savings in fuel, water and feed-water chemicals. The return on investment is quick (around 3.4 years with the assumptions taken here). Jacketed vessels, flash-steam recovery vessels, and several other tools are available to operate flash steam recovery.

Some conditions need to be satisfied for successful flash-steam application:

The return of the condensate

Steam condensate is a well-known by-product of many industries. What is less well known is that it can be a powerful source of heat that can be reused.

Using this end-of-pipe steam to improve efficiency makes economic and environmental sense. A plant’s energy load and water consumption can also be cut by insulating pipework and preventing steam and condensate losses.

There are two main types of condensate recovery systems:

Economisers are gas-to-water heat exchangers located within a purpose-built flue section. They are used to recover heat from flue gasses for shell and water-tube boilers.

The main use of economisers is to pre-heat boiler feed water. An economiser can potentially be retro-fitted to most steam and high-temperature hot-water boilers, and there are also opportunities to fit economisers to conventional, non-condensing heating boilers.

On a daily or weekly basis, steam boilers blow down hot water from the boiler to avoid the formation of sludge.

Blowdown heat systems can recover much of this waste heat and reuse it. The system is made up of a flash vessel and a heat exchanger. It works best when blowdown is carried out continuously when boilers are operating over longer periods and levels of condensation recovery are relatively low.

Case for dual burners

Installation of dual fuel burners to replace heavy oil burners, with the aim of increasing fuel-heat effectiveness and avoiding radiation heat loss, among others.

Steam and high-temperature hot water (HTHW) boilers is a category of technologies commonly used in industrial sectors and in some applications in public and commercial organisations. HTHW boilers are very energy intensive and therefore offer many opportunities for energy and cost savings.

According to the Carbon Trust, heating can account for as much as 60 % of total energy use, yet a large proportion of the energy consumed by heating is likely to be wasted due to incorrect control settings. Notably, lowering heating temperatures by just 1º C can save 8 % on fuel consumption, and heating costs can increase by 15 % or more if boilers are poorly operated or maintained. Optimum heating systems can lead to significant cost savings