Investigation of the viability of a solar water heating system when used as a replacement of an instant electrical water heating system
This study focused on investigating the viability of replacing an electric instant shower system at a hotel located in Thika with a passive solar water heating system. The study involved quantifying the average daily hot shower water consumption per room at the hotel in order to choose an appropriate size of solar water heater. To quantify the shower water, a flow meter was installed on the shower line just before the instant shower head in the hotel room. At the same time, an electricity meter was installed on the same shower to quantify the consumption of electricity for every shower session. A digital thermometer was then fixed at the shower head to monitor the temperature of the exiting water. Measurements from this set up were recorded for a period of 30 days from 1st February 2015 to 2nd March 2015. The study found the average shower water consumption per room per day to be 47.17 liters and the average water temperature from the instant electric shower to be 39.8ºC. Further, the average electricity consumption per shower was found to be 0.75kWh per room per day. Thereafter, a solar water heating system was installed at the roof top of the hotel and connected to the hotel room. The instant shower unit was then isolated and the use of the solar water heater commenced. Digital thermometers were then used to measure the temperatures of the hot water from the solar water heater at V the roof tank storage and at the exit of the shower head at the following intervals 0900hrs, 1200hrs, 1500hrs and 1800hrs for a period of 30 days from 11th March 2015 to 9th April 2015. The average water temperatures from the Solar Water Heater (SWH) at the roof tank storage at 0900hrs, 1200hrs, 1500hrs and 1800hrs were 28.1ºC, 44.1ºC, 49.2ºC and 32.6ºC respectively. On the other hand, the average water temperatures from the SWH at the showerhead of the hotel room at 0900hrs, 1200hrs, 1500hrs and 1800hrs were 26.9ºC, 42.2ºC, 47.1ºC and 31.2ºC respectively. Supplemental heating would thus be required for the shower water at 0900hrs and 1800hrs. The average supplementary heating required at 0900hrs would have been 0.71kWh per room per day while at 1800hrs it would have been 0.47kWh per room per day. The calculated payback period for the use of the SWH in heating shower water was 6.5years.