Over the last couple of weeks, at various spare opportunities during our work around the house, is to deal with our Hot Water tank. We wanted to test it for leaks, run the water right up to maximum temperature and see how long the heat stays in.
One of the first steps to do before we proceeded to test the tank, is to put on our cement lid on to a rim of silicone, to create a seal. We put a line of parcel tape on the underside of the cement board so it didn’t stick to the wet silicone sealant, and just patted and laid the heavy lid down on top.
We did put on four layers of PU foam board on top, creating a insulation layer of 160mm thick.
We filled up the Hot Water tank that we previously installed a few weeks ago. Then, using spare solar energy from our roof panels, we heated up the water a few hours each day (when it was bright with sun) and eventually, got to 80°C. There were no leaks! Yippee!
We also tested the tank for any hot spots by using our Infra-Red camera sensor that gives a calibrated picture, showing actual temperatures and everything. We noticed that the back edge had a bloom of rising heat drifting up and we realised that it seems to be hot water vapour that is escaping the lid and the seal.
The temperature seems to be dropping at about an 1°C per hour, which is mostly because we still have two large uninsulated sections where the pipes and electric cables comes out the tank. Our calculations suggest that if we had a solid insulation of at least 100mm thickness, without any missing chunks, the temperature should last much longer at about 6hours for each 1°C drop.
Once the hot water cooled down to ambient surrounding levels, we inspected the lid and internals. We noticed that the lid has very slightly coiled up in the heat, and also the under side (exposed to the steam), had sprouted some limescale deposits of some kind. We hadn’t sealed the cement material against water so it looks like that the steam had managed to penetrate the substance and caused this side-effect. We cleaned it off using a piece of sand paper and decided to find some roofing rubber membrane we had left-over from doing the Garage roof. This will withstand the steam and protect the lid. We also installed ten captive nuts and bolts around the edge of the lid so we could flatten the lid back down on to the silicone seal again.
We will do another test soon, but after we had constructed the air ventilation that is situated next to the tank.