Heating and Plumbing Information

Boilers

The range of gas boilers available is currently vast but recent changes to the Building Regulations has meant that recently all boilers are required to be high efficiency boilers or Condensing Boilers. Condensing boilers basically employ a design so that more heat is recovered from the gas energy that is inputted into the heating system. Typically heat is recovered from the flue gases; the water vapour in the exhausts gases is cooled by the incoming air, thus causing the vapour to form into a liquid state, hence the term condensing. Condensing boilers tend to work at their highest efficiency at lower temperatures so boilers are often designed to feature fully modulating operation at low temperatures, ensuring the output matches very closely to the heat demand.

Combination boilers, usually referred to as 'Combis', are the most commonly found boilers in the UK. They operate in a similar way to a traditional 'gas geezer' whereby water is heated on demand and there is no heat storage facility. This means they are extremely compact and ideal for new housebuilds where space saving is often at a premium. In recent years hybrid versions of combination boilers have evolved whereby a small amount of water storage is provided within the casing of the boiler. These are known as storage combination boilers. Typical output capacities of combination boilers are 24kw, 28kw and 35kw but this varies with each boiler manufacturer. The efficiency of the boiler is reflected by the SEDBUK rating and ideally one should be seeking a SEDBUK, A or B rated boiler.

System boilers have all the benefits of combis but tend to provide a higher output capacity. They work on a sealed system basis and are predominantly for central heating. If domestic water heating or commercial water heating is required then a storage cylinder is provided in the traditional way.

Open vent boilers work in a traditional manner, whereby the heating circuit is presurrised using a high level cold water tank usually located in the loft. The open vented boilers, whilst being very traditional in the plumbing arrangement, are however usually wall-hung boilers which help to save large amounts of space.

Industrial and commercial boilers are also highly efficient but tend to have cast iron heat exchangers. They are often referred to as 'gas atmospheric boilers' and can produce outputs of 46Kw to in excess of 338Kw. A modern boiler would need to meet European Standards on emissions of Low Nox (Class 5) and Building Regulations Part L2A and Part L2B.

Most natural gas boilers are suitable for Propane LPG fuel options and require only a change of burner nozzle. Many boilers are now able to run in conjunction with solar panels where gas forms the secondary top up, heat source. Solar smart combi boilers are now being produced by many boiler manufacturers. Other new features available are economisers, or top box gas savers, where even more heat is recovered from flue gases by incorporation of a secondary heat exchanger.

Oil fired condensing boilers are available but due to high oil prices these tend to only be the boiler of choice where natural gas is unavailable. Oil fired boilers either have aluminium, cast iron or high molybdenum stainless steel heat exchangers.

Flues

Fluing technology has advanced significantly in recent years with telescopic and concentric flues, which have made the heating installer's life much easier. Many vertical flues tend to be open flues with most wall mounted boilers having horizontal room sealed flues. Flue fittings are available in many configurations for the differing circumstances of each boiler installation. Gases leave high efficiency boilers at lower temperatures, which can cause condensation problems on nearby windows for example. Plume management then becomes an issue and plume management kits and accessories are available.

Traditional solid fuel boilers tend to have twin wall fluing systems due to the extremely high temperature of the flue gases.

Storage Heaters

In recent years storage heaters have made great advances in efficiency and control technology. The principle of storage heater is that a heavy mass core is heated overnight using cheap rate electricity. This core is made of a high density Iron Oxide compound that gives up heat very gradually. During the day different levels of heat can be achieved by adjustment of the output controls. All heaters now have integral adjustable electronic room thermostats. More advanced intelligent controls now mean that heating a building using storage heaters, exceeds Part L of the building regulations for energy efficiency and controllability.

Extended tariff electricity and split daytime tariff electricity has improved the flexibility of the use of storage heaters, giving them a daytime 'boost' facility. Many storage heaters incorporate a crossflow fan which can take heat from the retained heat in the core or from a separate heating element.

Many new housebuilders currently install electric panel heaters often with digital electronic thermostats. These use more electricity than storage heaters but are very flexible often suiting occupants who are out at work. Electric heating often gains favour from housebuilders in circumstances where a gas boiler flue would be difficult to incorporate.

Underfloor Heating

Electric underfloor heating is extremely popular in modern apartment blocks where stone, tiled and limestone floors can be maintained at very comfortable temperature. The underfloor heating elements tend to be installed in the form of heat-mats whereby the mat forms a continuous heating element. The heat provided is a radiant heat and thus creates very few convection air currents or draughts. The whole electric underfloor heating system is controlled by room thermostats.

Wet underfloor heating systems are ideal for new build construction and ideally run at relatively low temperatures of about 40 degrees centigrade. This makes such systems extremely compatible for use with heat pumps as the main source of heat. The network of plastic tubes are run through the timber floor joists and a heat reflective tray directs heat upwards. A manifold valve enables different zones for each room to be created. Wet underfloor heating is invariably used in timber framed housing and volumetric construction where extremely high levels of thermal insulation means that lower temperature heat sources are effective in providing comfortable levels of heat. All underfloor heating is designed to give continuous heat and not to be operated as an 'on demand' style of system as one might use with conventional central heating.

Skirting Heating

Skirting Heating provides floor level central heating. The heaters replace normal skirting boards in a room providing all around heating and increased flexibility in furniture placement. The location of the heaters means they are easily accessible and easy to install on both new build and refurbishment projects.

Convective skirting heaters comprise finned pipes hidden behind a decorative panel. Like radiators they heat the air around them and rely on convection currents to warm the room. These units are typically larger than the skirting boards they replace.

Radiant skirting heaters are smaller and more closely resemble the profile of conventional skirting boards. The majority of heat is transmitted as radiant heat resulting in a more even temperature profile and improved thermal comfort relative to convective heaters. This improved comfort is similar to that realized with underfloor heating and translates into energy savings.

These systems can be either hot water heating or electric heating. Like radiators, skirting heaters are highly responsive warming up and cooling down quickly. The hot water based system plumbs directly into the normal central heating system piping and can be run off all types of heat source including condensing boilers and heat pumps.