Solvärme till Östersunds Rehabcentrums terapibad
Förstudie av förutsättningar för, - och lönsamhet med, solfångare för att värma terapibadet
This report treats whether it is viable to invest in solar heating to heat the therapy pool at Östersunds Rehabcentrum. The rehab center is owned by the county council of Jämtland and is located on Solliden in Östersund city. The solar heating where supposed to be a complement to the district heating that was heating the pool in the current situation. Later, it however showed that this was not the case. The pool is currently being heated by a radiator circuit that is being heated by the district heating. The temperature in this circuit is however controlled by the outside temperature. If the outside temperature is increased sufficiently, there is no need to heat the building with the radiators. What happens then is that the temperature in the circuit might fall so it no longer can heat the pool. When this happens, an electric heater of 15 kW kicks in to heat the pool instead. Studies of the control signal to this electrical heater show that it heats the pool approximately from the middle of April until the beginning of October. Calculations show that the electrical heating stands for 72 % of the annual cost to heat the pool, even though it heats the pool during half of its running time.Because of this, three options for investment where calculated based on the wishes of the client. One option is to connect the pool directly to the heat source, which is district heating, to eliminate the electric heating. The second option is to install solar heating after the pool has been connected directly to the heat source. The third option is to keep the current connection of the pool and only install solar heating. The last option is investigated to compare the viability in solar heating depending on current heat source. The solar heating systems have been dimensioned to cover the pools energy demand during optimum conditions, with a working temperature in the solar collectors of 50°C. This is to avoid problems with not having use of the energy from the solar collectors during optimum conditions. Four different solar collectors are compared, two flat plated and two collectors with vacuum pipes.To determine the viability of the investments their pay-back time and present value have been calculated. The life-span of the solar collectors is approximated to 40 years and the cost of capital is 4 %. The annual increase in energy cost for electricity and district heating is calculated to 4 and 3 %, respectively. There is a possibility to receive financial support for some investments, this has however not been taken into account in the calculations.The results show that the most viable investment is to connect the pool directly to the district heating. The pay-back time is only one year and the annual cost for heating the pool becomes less than half of what it is today. The profit after 40 years becomes 1,6 million kr. Investing in solar heating that replaces the district heating proves not viable during the 40 years period. If the connection to the radiator circuit is retained, all of the solar collectors become viable. Most viable in this case is the solar collector 24-ST, with a pay-back time of 16 years and a profit of 1,3 million kr during the calculation time.