Just before my furnace cuts in it starts this high pitched whistle sound that goes through the whole house. Once the furnace cuts in, it begins clunking/banging quite loudly.It is an oil hot water furnace with hot water coils in it. I have no problem with the hot water and have it regularly cleaned, repairman could not see a problem and the holding tank was drained, any suggestions ?

It is possible the gas line is causing the whistle, if your gas line is a flexible line and too small , it will whistle. The point at which a 1/2 " flexible line will whistle is when it serves a furnace or appliance larger then 100,000 BTU's
The banging may be caused by air in the water pipes, be sure your expansion tank has air in the top of it and is not water logged, if it has air in the pipes you can bleed the pipes at the highest point by losing a fitting and allowing the air to escape then retightening the fitting. Good luck, Mike

I guess that gives a new meaning to the old song of whistle while you work. LOL

As you are well aware there should be no whistle,clunk, or banging.

This could be caused by a oil burner pump,or burner motor that is starting under a load. Once started it goes on its merry way and that noise leaves. It could also be your water circulator pump especially if it is a Bell and Gossett or any pump with a coupling between the motor and the pump itself. If one of the coupling springs breaks it will make a clunking sound.

I suggest you have a good repair men look at your system and not the one that could not find the problem even with a the noise it was making when he was there. Obviously he is not a very good repairmen because anyone should be able to track that noise down while it is happening.

Just before my furnace cuts in it starts this high pitched whistle sound that goes through the whole house. Once the furnace cuts in, it begins clunking/banging quite loudly.It is an oil hot water furnace with hot water coils in it. I have no problem with the hot water and have it regularly cleaned, repairman could not see a problem and the holding tank was drained, any suggestions ?


ACETC

It is a oil hot water boiler. No gas line.