How is pre-insulated pipe used to form district heating networks?

A district heating network has a heat source supplying heating water and / or domestic hot water to two or more separate buildings on the site. This central heat source will then be connected to the various buildings in the scheme via an underground pipe network designed to maintain the water temperature when in transit (avoiding heat losses to improve energy efficiency). In this short article we look at how pre-insulated pipe is used and touch on the various options around the design of the network.

Here at Mibec we supply a wide range of pre-insulated pipe products from leading district heating pipe manufacturers like Rehau, Microflex or our own Mibec DHP pipe. Our range has pipe options available for both heating water and potable water applications and we are pleased to have recently launched Microflex Quadro, which can fulfil both applications in a single pipe thanks to its 4-core design – this can reduce the excavation depth of trenches saving time and cost. Pipes are available in a wide range of sizes to suit the project requirements and new products are introduced all the time – for example Rehau Rauvitherm and Rauthermex are now available in 160mm diameter.

How is pre-insulated pipe installed?

Pre-insulated pipes are extremely flexible and lightweight allowing for rapid installation and the ability to easily navigate over or around obstacles (such as trees and existing buildings) on site. Due to the flexibility of the pipe they are supplied in coils (up to 250 metres for some sizes) allowing for easy transport, delivery and storage on site. The pipe is also easy to handle; the installers can roll out the pipe straight into the pre-prepared trench directly from the coil (either by hand for smaller sizes or using a de-coiler). The ability to keep the pipe in a single long flexible piece has many advantages in terms of limiting the number of joints and connections required which saves on time, costs and reduces the likelihood of any future leaks. A reduction in joints will also mean less pipe cutting and less fittings to individually insulate to maintain the heat loss performance. Pre-insulated pipes are also very easy to cut (needing only a normal hand saw) and because the pipes have such a high degree of flexibility it easy to make the building connections – the installer will have a high degree of movement with the pipes to make any final adjustments.

Designing the pipe network

farm layoutThis agricultural project is a good example of a district heating pipe network with the central heat source (Anaerobic Digester in this case utilising wastage from the farm processes) supplying a combination of residential properties on the site, perhaps a few small business units, along with buildings that need heating for agricultural processes (drying gain etc). The owner of the heat source will be able to take advantage of the RHI incentive and being classed as a commercial project will receive the financial benefits for 20 years.

 

There are various methods for connecting properties to the heat network, at Mibec, we offer a full free of charge specification service covering the whole of the UK, designed to support architects, specifiers or contractors, helping you to select the optimum piping solution to meet your needs. The examples below show two of the options commonly used:

Branch – offers a flexible design, easy installation and is easy to extend at a later date.

Branch – offers a flexible design, easy installation and is easy to extend at a later date.

Building to building (or chain) – Is less flexible in design but has the advantage of fewer ‘Tee’ connections in the ground.

Building to building (or chain) – Is less flexible in design but has the advantage of fewer ‘Tee’ connections in the ground.

 

Please feel free to email or call our Mibec support department on 01948 661639 where one of our trained advisers will be more than happy to help you with your next project.