As a result of system follow-up it was possible to visit the system and talk with some of the owners which lead to the detection of some problems:

Tenants refer to be happy with the general performance of the system since spring 2008 and to have no need to use the back up boiler for domestic hot water.

But there are some complaints regarding the information on how to correctly use the STS.

In some cases there is also high gas consumption for tenants that have the boiler regulated for higher consumption temperatures. We noticed that the reason comes from the fact that the three way valve that should prevent heat transfer in the wrong direction was not installed.

The lack of a maintenance contract has brought problems in the relation between the contractor and the owner of the installation, based on claims of violation of the terms of guarantee. This aspect is also affecting the actual dwelling owners because they will have to support now the costs of such contract, which is absolutely necessary and mandatory, nowadays, in accordance with the new building code.

In the process, a questionnaire was decided to do to the dwellings owners. The questionnaire focused the establishment of the consumption profile of the tenants (including number of people per apartment, usage schedule, central heating use, total gas consumption and gas fired utilities), to assess their satisfaction level and suggestions for improvement of systems performance.

Unfortunately most of them did not answer until the moment and because of that is not possible to present the results. Anyway this aspect is becoming more and more important and it should be taken into account, since the first beginning of the monitoring period, in order to have detailed qualitative information in parallel with the quantitative one.

1st International Congress on Heating, Cooling, and Buildings, 7th to 10th October, Lisbon — Portugal /

3. Conclusion

Although some problems are not satisfactorily solved, the solar thermal system has been delivering enough energy to have an interesting overall solar fraction which makes the dwelling owners happy with its performance since spring 2008. Some of them refer to have no need to use the boiler. This qualitative result matches with the 40% efficiency collection that we are measuring now.

Most of the problems found in this installation would have been avoided if the commissioning process of the total heating system had been executed by the same team, avoiding by this way the misunderstandings and problems between EPUL and installer, that occurred later and contributed to the delay on finding and executing the right decisions, proposed by INETI.

Another important source of problems was the bad solution implemented by the promoter related with the maintenance contract, which was not part of initial contract with the installer and it was supposed to be done between installer and the dwelling owners grouped in a condominium. This solution delayed the execution of such contract for system maintenance, contributing to the actual situation. So, the experience of this installation shows the importance of a warranty maintenance contract that the actual RCCTE code imposes in connection with the actual solar obligation.

References

[1] J. A. Duffie, W. A. Beckman (1980). Solar Engineering of Thermal Processes, John Wiley & Sons, New York.

[2] NetPlan (March 2007), Manual do Sistema Solar Termico, Empreendimento EPUL Telheiras XXI.

[3] INETI (January 2004), Estudo de Viabilidade Tecnico-Economica de Instalagao Solar Termica para produgao de Aguas Quentes Sanitarias em fracgoes autonomas de habitagao Lote 1 — Telheiras Norte III.

[4] RESOL DeltaSol® ES, Mounting, Connection, Handling, Fault localization, Examples.

[5] ServiceCenter Software Suite for controller configuration and visualization: Installation, Operation.

[6] RESOL Data logger DL1: Mounting, Connection, Operation, Fault localization.