Where can I find diagrams for home heating systems ? Electrical and piping

Might help

A wiring diagram , look to see if these systems have anything in common , power supply , common ground point . Do you know how to do electrical testing , how to read a wiring diagram . Do you know anything of automotive electrical systems ? How to read an electrical diagram Lesson 1 The Trainer 29 Understanding How Electrical CIrcuits Work and How to Test...

Electric Testing Techniques You Need to Know

http://www.bbbind.com/free_tsb.html free wiring diagrams !

A wiring diagram is a simple visual representation of the physical connections and physical layout of an electrical system or circuit. It shows how the electrical wires are interconnected and can also show where fixtures and components may be connected to the system. Use wiring diagrams to assist in building or manufacturing the circuit or electronic device. They are also useful for making repairs. DIY enthusiasts use wiring diagrams but they are also common in home building and auto repair. For example, a home builder will want to confirm the physical location of electrical outlets and light fixtures using a wiring diagram to avoid costly mistakes and building code violations.
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A good ground is typically a cold water pipe. The cold water pipe is required to be grounded to the electrical service in nearly all buildings. Since cold water pipes are often in contact with hot water pipes in steel sinks, water heaters and furnaces, etc.; a hot water pipe - whether for heat or domestic use will also work. The same holds true for gas piping. Electric appliances fueled with gas have their pipes connected to ground via the electrical cord and electrical service. You could also obtain a "3 wire" cord cap from you hardware store, and connect an wire to the ground terminal of the cord cap, and plug it directly into a grounded electrical outlet to obtain a good ground. If you do not ground the wires, the noise will likely be worse than before at the wire acts like an antenna for other noise sources. You may also have luck connecting to the ground terminal on many of the older amplifiers - as many turntables required ground, too - and this was the method used.

Good luck!

does is sound like a train , when the noise starts ...... if so there is sludge in your system rads and pipes need flushing out

You have either air in the pipes or not enough support for the pipes. You will never be able to eliminate all noise because pipes expand and contract each cycle but more support and less air in the pipes may help.