Colored paper
Though central heating systems are the most reliable heating systems available, they can still have issues that reduce the heating quality. One problem is when a leak messes the heating system and you have a hard time locating its source.
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2. Do the same thing with the pipes that go into the water heater. If you locate a leak from fittings and soldered joints then you must drain the water system to replace the joint.
3. Check the temperature at the hot water feeder pipes. It should be the same everywhere. If an area is cooler than the others then this is a sign of a blockage that has to be fixed.
4. If you own a system that uses a heat exchanger and a heat connector verify them too for water leakages or moisture. You can also tell there is a leakage if the water has a musty odor. A problem with these systems can only be solved by a professional company.
Use colored paper
1. Leave a piece of colored paper underneath the water heater for 2 hours.
2. Go back after two hours and look at the paper. See if there are any droplets on it.
3. If there are droplets on it, try to identify the source of the leak and call someone to come fix it.