Heat network in a small town in Vizcaya

The growing awareness in terms of energy efficiency, together with a clear desire to take advantage of fuels from biomass and solar energy, led the town of Ispaster, located in the Lea-Artibai region (Vizcaya), to decide on the installation of a district heating (DH) and DHW network with Rauvitherm pre-insulated pipes from Rehau, and executed and operated by the energy efficiency and resources cooperative Barrizar.

A solution was sought that would optimize energy management in the town, to serve different consumption points. Finally, a heat distribution network was chosen with the Rauvitherm system based on an efficiency proposal and microgrid with biomass and solar, and thus make use of the residual biomass with sustainable forest management.

The installation consists of a 90 kW biomass boiler, with the possibility of expanding it to several parallel boilers in cascade, in the event of an increase in the number of users to be connected. Said boiler works on an accumulation tank of 5,000 at 80ºC, from which, by means of 2 circulator pumps in parallel, hot water is pumped to the district network, with a thermal difference of 20.

Thermal exchange plants have been installed in each building, in which the transfer and sale of heat will be carried out to each user, for the generation of DHW and heating.

Regarding the work, it should be noted that the distribution of pipes was designed with a ring distribution, compared to the DH with branched distributions. The installation was carried out in two phases, a first phase of installing heating and DHW in the Ispaster school, and a second, more extensive phase in different consumption points such as the town hall, the play center, the nursery, the Church, municipal restaurants and leisure spaces, with which the ring was closed.

For the heat distribution network, pre-insulated DUO cross-linked polyethylene pipes with a diameter of 63 mm were installed in which hot water circulates at 80ºC and returns at 60ºC. DUO pipes are distinguished by carrying both the flow and return pipes within the same pre-insulated pipe, creating a more efficient system against heat losses in its distribution.