Ground Source Heat Pump

ground source heat pump

Ground Source Heat Pumps – Their Cost, Their Installation and Their Efficiency

Heating accounts for a significant portion of a household’s energy demand and a ground source heat pump system can provide a cost-effective and sustainable way to warm a home. The pump uses a small amount of electricity to transfer naturally occurring heat from the adjacent ground into the house.  As the temperature just a couple of metres below the surface remains more or less constant at 11°C to 12°C, it is possible to design a very efficient heat transfer system.

How does it work?

A sealed loop of fluid-filled pipe is buried in the garden or driveway. The length required depends on the size of the home and the amount of heat required. An average system for a family dwelling will typically require pipework up to 100m long.  Vertically drilled boreholes and deeper pipes can be used in more confined spaces. Once installed, the ground is restored to its original condition and the system becomes invisible.

The ground source heat pump circulates water and antifreeze around this loop. The fluid absorbs heat from the ground before it passes through a heat exchanger.  Energy is then transferred to the heating and hot water circuits of the home. The cooled fluid flows back into the ground loop in a continuous process for as long as the heating is required. Some systems can also be designed to meet cooling needs in summer.

While there are some minor residual energy and carbon costs, hooking the pump up to a home renewable technology such as a solar panel can increase its sustainability credentials even further.

What properties are suitable?

Ground source heat pump systems are not suited to every type of property. In general, they work most efficiently in well insulated homes with a relatively even and low heat demand. They produce heat at a lower temperature than more conventional central heating so a larger area is required for heat distribution. Underfloor heating is the ideal partner, though large heat pump system radiators are available. The system also requires sufficient outside space for installation. While minimal on-going maintenance is required, there can be considerable disruption during installation, and the system tends to be more attractive for new-build or as part of a wider home improvement project.

A typical domestic ground source pump is the size of a large upright fridge freezer. To save indoor space they can be installed in an outbuilding or basement.  They just need to be as close as possible to the end of the ground loop pipe. With a typical noise level of a little over 40dB at one metre away, they are as quiet as a fridge.  That’s considerably quieter than a typical gas or oil central heating boiler.

What do they cost and how much will I save?

Costs and savings will be dependant on the size of the pump, the length and depth of loop installation, the energy efficiency of the property, the sort of heating system that is being replaced and whether any additional work is required on the wider home heating system.  A typical domestic installation costs £12,000 to £15,000, with annual running costs of £600 to £700. At current prices, the payback from a ground source heat pumps is unlikely to represent an attractive alternative to an established mains gas central heating system. However, installers claim energy savings of nearly £1,500 annually for a typical four-bedroom house when compared with standard electric heating, or around £600 when compared to oil-fired central heating. That represents a saving of nearly 5,000kg of CO2 emissions each year.  Government Renewable Heat Incentive grants are currently available for installation.

Their installation will also greatly improve your energy efficiency score on your EPC.

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If you’d like to book an EPC for your home, simply contact us by phone or email, or fill in our contact form.

 

Hot Water Cylinder Insulation

EPC

Is your Hot Water Cylinder  insulation below standard?

An hot water cylinder heater is rather like a large kettle. It is an electric resistance loop that is inserted into a cylinder to heat stored water. Immersions are not the most efficient way of heating water in the home, but they do have the advantage of flexibility and ease of use, and they can be used on an economy night tariff electricity supply via a timer.

Homes without boilers generally rely on hot water cylinders with an immersion heater for their primary hot water supply. Many other houses with central systems have an immersion as a back up to provide hot water in case of boiler failure. 

A typical immersion heater uses 3kW of electricity an hour, and costs around £1 for two hours’ use on an average standard tariff, or perhaps a half of this on an Economy 7 tariff. This will generally provide the daily basic hot water needs for a small, one or two person household.

A large tank of expensively heated hot water will lose heat very quickly if not used immediately. Insulation is critical to energy efficiency, financial savings and minimising carbon emissions. It also makes for a more convenient system, as hot water will be instantly available without waiting for the tank to heat up again.

Modern cylinders are factory-fitted with insulation, generally in the form of a 50mm foam coating.  While this is usually sufficient, even relatively new tanks may have an out-dated coating of 38mm or less, as insulation standards have increased substantially over recent decades.  The thickness can be measured where the foam is cut away to allow the insertion of the immersion heater assembly. Any sign of copper means that there is an easy escape route for the heat.

An older hot water cylinder without foam or with a substandard layer can be insulated with a purpose-made jacket. These are widely available from DIY stores. It is worth paying a little extra for a thick jacket if there is room around the tank to accommodate it. The best cylinder jackets have a 75mm or 80mm glass fibre filling and a flame-retardant cover, and these can be bought for as little as £15. DIY fitting is straightforward, but remember not to cover the top of the immersion heater and its thermostatic cut-out.

Adding one of these jackets to an un-insulated tank can save around £80 a year on electricity bills, so the investment will pay for itself within three months. It will also reduce your annual household carbon emissions by 420kg. Using a jacket to top up a cylinder with 25mm of foam will save approximately £20 per year, with payback over nine or ten months.

It is also worth lagging the exposed hot water pipes in the immersion cupboard. These take the water from the top of the tank to the shower and taps. The sections closest to the tank can lose a lot of stored heat, and they can be very easily insulated with split foam tube that simply slips over the pipe and closes around it. This is a £20 DIY job that will save another £10 to £20 a year.

The Biomass Boiler Alternative

Biomass Boiler

An Introduction to Biomass

Households that are not keen on modern renewable energy technologies might prefer a more traditional wood burner or biomass boiler. Man has been burning wood to provide heat since he first harnessed the power of fire in his cave, but a modern biomass boiler offers a more sophisticated solution to home heating.

Simple wood burning stoves provide heat and a focal point for the main room and can include a back boiler to run small-scale central heating and hot water systems. A biomass boiler works like a normal gas or oil boiler but they burn renewable biomass instead. New generation systems are easy to use and deliver greater than 75% energy efficiency using pellets or properly dried wood.

Systems are available for a range of fuels, including logs, wood chips, sawdust, grass-derived biomass pellets or even peat. The choice of fuel will be dictated by the availability and price of a reliable local supply and the type of storage available. The greatest savings are made when buying in bulk so to get the best deal a significant amount of storage space is required.

Pellets are much easier to transport and store than logs, and provide a more controllable heat. Pellet-fuelled biomass boilers are available with automatic fuel feeders and they can be programmed in much the same way as conventional gas boilers. Log-burning stoves and boilers involve considerably more work and are less controllable.

The installed cost of a wood burning stove will be around £2,500 to £7,500, depending on the model and the availability of a flue. The price of a full biomass boiler system is greater than that of a comparable gas boiler at between £10,000 and £20,000, depending on model, size and ease of installation.

After the initial outlay, the system should reduce energy bills over time, with some studies suggesting that a biomass boiler can save the average household up to £800 a year when compared with standard electric heating, or up to £210 a year compared with an old G-rated gas boiler. However, at typical 2018 prices, running a biomass boiler is likely to cost more than a modern condensing gas boiler.

To maintain efficiency, the flue will need to be cleaned annually at a cost of around £50. Another downside is the need to remove and dispose of ash. Some biomass boiler systems have automatic ash removal and compression systems that make the job easier.

Government support is available for the installation of a biomass boiler or biomass stoves with a back boiler through the Renewable Heat Incentive scheme. The income depends on the system and the amount of energy it produces but the payment for a biomass boiler in a four-bedroom, detached house may be nearly £2,000 per annum. To be eligible, the property must have a compliant EPC that is less than two years old.  There is a calculator and information on the BEIS website here.

Six Common Energy Efficiency Myths

Energy Efficiency

Energy Efficiency Myths

Myth One

If I turn up the thermostat the room will get warm much more quickly.

This is not the case. A thermostat simply controls the maximum temperature, so turning it up will not alter how long the heating takes to achieve that room temperature.

Myth Two

It is more efficient to keep the heating on low all the time than to keep turning it on and off.

This means that your house is heated when you are not there and that it may be cold when you are home. It is far better, in terms of energy efficiency, to use a timer to heat the rooms that you are using while you are there. On a regular daily cycle, it is not necessary to have the heating on constantly to keep the fabric of the house warm. If you are away in winter, use a timer and thermostat to avoid frost damage to pipes. You can use radiator valves to restrict the heating to the rooms that you are using. Most people find 18°C to 21°C comfortable in an occupied room, and radiators can be turned down to 14°C or lower in other rooms.

Myth Three

When it is cold outside I need to turn the thermostat up to keep the house warm.

A thermostat maintains a desired temperature in the house no matter what the weather is doing outside.  Once you have selected your comfortable temperature, it can remain at that setting which improves your home’s energy efficiency.

Myth Four

Energy saving light bulbs take a long time to get bright, and they are very expensive.

There have been improvements in lighting technology in the last few years, especially with light emitting diode (LED) bulbs. They reach full brightness immediately, have reduced in price, typically last for over 20 years and their running costs are approximately a third of those of a comparable traditional halogen bulb.  

LED bulbs are now the best choice in terms of practicality and energy efficiency.

Myth Five

An appliance in standby mode does not use much energy..

Appliances on standby still use electricity. For an average household, turning them all off completely when they are not in use could save nearly £50 a year.

Myth Six

My vital appliances are responsible for much of the energy I use, so there is nothing I can do to reduce consumption.

Large appliances are responsible for about 15% of the energy bill for an average home, so dealing with the energy efficiency of heating is a greater priority. Nevertheless, choosing energy efficient appliances can also make a real reduction in consumption and bills. Compare energy labels on appliances before buying. Choosing an A+++ tumble dryer rather than a C-rated model can save approximately £50 per year.  A new A+++ electric oven will use some 60% less energy than a B-rated equivalent. 

Careful planning of how you use your appliances could also help. Dishwashers are very energy hungry, and can cost an average household nearly £50 a year to run. Consider whether you really need to use it to wash a few plates and make sure you wait for a full load before turning it on.

Buying a better gas boiler

Gas Boiler

Heating and hot water accounts for well over half of the total energy use in the home, so if you have an old gas boiler, changing to a more efficient model will save you money and give you a higher score on your EPC.

Boiler efficiency

Boiler efficiency is defined as a percentage, with gas boiler installation now restricted by regulations to those with a score of 88% or better. The energy efficiency is rated from A to G, with modern condensing boilers getting an ‘A’ rating.

Boilers more than 15 years old are likely to be inefficient due to hot gases escaping up the flue. Modern condensing boilers have larger heat exchangers that recover more heat.

If your boiler has a plastic flue and a second pipe coming out of the bottom to drain condensate outdoors it is a condensing type. If it does not have one of these, it is worth considering an upgrade.

What is available?

If you have a mains gas supply, a gas boiler is likely to be the cheapest option. There are two main types.  Regular (or conventional) boiler systems heat the water and store it in a cylinder.  Combination (combi) boilers heat the water on demand without the need for a cylinder. A third type, system boilers, are typically used in large houses with a substantial hot water demand.

Regular boiler systems take up quite a lot of space, but provide the highest hot water flow rate. However, they do lose some heat from hot water stored in the cylinder. They are generally a good choice for homes with more than one bathroom and a predictable hot water demand.

Combination boilers are the most popular choice as they are cheaper to install, more compact, and they cannot run out of hot water. They are less efficient than regular boilers when heating small quantities. They are suited to homes with limited space and no existing hot water tank, and those with a less predictable hot water demand. 

A new boiler is a big investment, and the technology can be complex, so check with a qualified installer what would be best for your home.

What if I don’t have gas?

Gas boilers are available that run on liquefied petroleum gas (LPG) from a tank, if there is outdoor space for one.  Oil-fired heating is a popular alternative, though heating oil prices can be volatile. With Government support schemes, low-carbon alternatives such as heat pumps or biomass boilers may present a cheaper option.

How much can I save?

A smaller, cheaper gas boiler may suffice in a well insulated home, so make sure you do that first.  New boiler prices range from approximately £500 to £2,500. Installation costs vary, so getting at least three quotes is recommended.

Your annual savings will depend on how inefficient your old boiler was. As an example, replacing a G-rated gas boiler with an A-rated condensing boiler could save up to £325 in a detached house, or £200 in an average semi-detached house.  An £1,800 gas boiler bought to replace a 60% efficiency boiler will pay for itself in seven and a half years.