Hot Water Tank RFI

[Roy K8VWX]

      I have been attempting to submit  the following to the Rheem Corp. but so far have not been able to get through to them. Has anyone out there had this RFI problem from a mobile home hot water tank  73 / Roy

   In March 2015 my neighbor installed a new Rheem hot water tank in his mobile home. I am a amateur radio operator licensee extra class (K8VWX) and am having severe RFI (Radio Interference) in the 80 meter band.It has been traced to one of your 240 VAC electric hot water tanks. I'm guessing that you may be using a solid state thermostat  or dual ( SS stats ) if a upper and lower is required. The RFI is very unstable drifting up and down in frequency and has a rather constant repetitive BLEEP or pulse a few Khz down from the fundamental frequency. (It does have several harmonics also).

        

[VE3AJM]

Hi Roy

I've been helping a buddy of mine in his HVAC business, and from what hes told me, he can't think of any of the commonly available/installed hot water heaters that we install here that use solid state thermostats. They all use the common bi-metal type. Maybe there are others though.

What sort of circuit breaker did they use at the panel? Those GFI units etc have been known to create noise. Hopefully your neighbour will let you check it out.

Al VE3AJM

[Roy K8VWX]

      Thanks Al
I have done some checking into hot water tanks also Al and could not find any using SS stats. A good possibility as you surmised would be the 240 AC circuit breaker. This was a fire damaged mobile home that was started from a defective propane hot water tank. We do not have load demand meters or use hot water systems here  that transmit  or are controlled by the power company. Who knows since it was insured that the  installer may have  pawned off one of that type just to get rid of it. I'm going slow at this not to aggravate him Al but will do more investigation as time goes by. 73/Roy

[W3GMS]

Hi Roy,

This is the first time I have heard of an RFI issue with a conventional hot water heater.  I can understand if it was one of the newer heat pump hot water heaters which are becoming more popular around here.

Basically you have the upper and lower bi metallic thermostats and two heating elements.  Other than arcing of the contacts, I can't see anything else producing noise.  Also if the contacts arc, they won't arc for long due to the amount of current going through them. 

Are you sure the noise is coming from the HW heater?  The way you describe the noise your hearing sounds like its something else.  Of coarse if its one of the newer heat pump units then that's a different story.

73,
Joe-W3GMS   

[Roy K8VWX]

      Hi Joe
       
      No Joe from what I understand it is just a typical mobile home hot water tank. The RFI sounds like a poorly designed switching power supply from China. He claims that nothing else is on the 240 VAC breaker. I will wait a week or two and call him to see if he knows the electrician who done his work. Talking to him may be helpful and if it costs me a service call to get him out to the home to find the problem - so be it. Also Liability would rest on his shoulders.

       From what I've been told some of the newer breakers ( especially GFIs ) are pretty fast and have more SS crap in them  ( probably Chinese ) then you can imagine. Another thing I would like to know if the tank is grounded.  Thanks Joe / Roy