I have a RINNAI 26 INSTANT / tankless WATER HEATER. Works well but if I touch the shower tap while showering I get an electric shock like that of an electric fence. It is a pulsed signal and not continuous. There is no electric fence near (1000M away) It seems as if the ignition on the water heater is pulsing through the water. It only shocks when the water runs and the heater is on. We have installed a heavy copper earth wire (2.5mm Xsection) directly from the copper pipes to the main power feed earth. The whole plumbing system is copper and the drains are plastic. Problem still there. Any suggestions?
I assume by main power feed your talking about the breaker box? If so make sure the breaker box is actually grounded. Also check inside the heater and make sure the ground wire in there is connected and has a solid connection.
SOURCE: Tankless water heater not meeting the need
Yes the faucet could be a problem. Try changing for one which you know is ok.
The long run of pipework - each bend, elbow or joint all have a reducing effect on the flow, maybe enough to matter with a restricted outlet. none of this can be altered except by renewing with larger bore pipe - expensive!
Also there should be a dirt filter in the mains water input line/pipe. Try removing & cleaning. Try also removing , reconnecting and then the hot tap [faucet]
The boiler will have an actuator valve which fires it up when a certain flow of water is reached. If the flow is reduced AND the valve is worn, maybe a replacement. Not sure about it's USA construction but in the UK [it's called a diverter valve] many have a rubber diaphragm which is cheap to replace
Check also if it uses a flow sensor switch
Had a look at the Takagi web site and there are pdf's of manuals
takagi.com
Overall I am still thinking that the main prob is in the flow.
Hope I've helped - come back anytime
Rod.Davies
SOURCE: which circulating pumps works on tankless water heaters
Laing UCT-909-TANKLESS UltraCirc Tankless Water Recirculating Pump
This is designed to maintain the proper flow to fire the heater. Please be sure the pressure in the house is at least 5 psi over the minimum required for your unit.
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Yes the breaker box and it has a good ground. Also inside the heater we have double checked the grounding connection. Cleaned and re-done - This is why I am perplexed. I may need to run a grounding wire inside the drain pipe and then connect it outside to a good ground to get rid of the problem. - Not sure.
Another thing to check is use a VOM on an outlet and see if there is any voltage between common and ground. One leg should have 110 and the other should read zero. If there is voltage on the common leg there is an outlet or switch that is wired backwards and the shock is a result of a backfeed.
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