Electric hot water cylinder noise

[MARIA OLIVIERO]

For the past few months my hot water cylinder has been making a boiling, gurgling type noise for about 1 minute every 5 minutes or so. The thermostat was replaced a month ago, but it didnt make a difference. I have called over 20 different plumbers and electricians and they have no idea what it could be. I was advised to get a thermometre to check the water temperature to see if it was at the same temperature as on the thermostat – which it was – 60 degrees celsius. So why would it be making a boiling type noise if the water is not at boiling temperature? Also the copper pipe leading from the top of the hot water cylinder is too hot to touch. Our overflow pipe on the roof is leaking excessively as well and at one stage i saw water shooting from it. The water in New Zealand is soft, not hard, so it isnt sediment. Could it be that the Temperature pressure relief valve is not working and therefore the tank is more or less continuously filling and when the cold incoming water hits the hot element it makes a noise? i have no idea! any clues?

[Retired plbg1Participant]

Sounds like heater is full of lime.

Art Reired Plumber

[denny25Participant]

what do i need to do to fix it? flush the system?

[Retired plbg1Participant]

If it isel. shut off power and water and take out bottom el.and suck out lime with wet vac. use small piece of water hose taped in vac.

[denny25Participant]

thanks. Fingers crossed that is the problem because i was under the impression that soft water areas (such as Auckland where i live) dont get the lime build up?

[SelgasParticipant]

If you have water running out of the “expansion pipe” on your roof then one of three things must be happening, 1. the pressure reducing valve seat is failing allowing excessive water pressure to built up and travel up the expansion pipe to discharge on the roof, 2. The thermostat although new may be faulty in so far as it’s tollerances are concerned – it may reach max set temp switch off the power but not allow the temperature to drop sufficiently before reactivating itself again causing the water in the top of the tank to build up with latient heat and account for the very hot outlet pipe temperature. Before I attempt #3 I would like to know if the cylinder is mains or reduced pressure for certain – please advise.

[denny25Participant]

it is a low pressure system

[SelgasParticipant]

Given you have a low pressure system and I am asuming the pressure to your cylinder is controlled by a pressure reducing valve ( ajax or equivalent ) that being the case I would suspect that the PR Valve seat is faulty allowing water to continually overflow onto the roof and in doing so will introduce cold water at the base of the cylinder causing the thermostat to cut in and out which in turn will turn your element on via the thermostat. This faulty valve or exssive pressure will by allowing hot water to de discharged onto your roof, run your energy bill ski high if you do not have it attended to real quick.

Have your Plumber check or better still replace the pressure reducing valve and readjust the pressure settings when he fit the new one.

[denny25Participant]

thanks we have a plumber coming to replace the valve or at least check it out on thursday. I assume also the ‘boiling’ noise is the cold water against the hot element?

[denny25Participant]

Ok we’ve just had a plumber look at the hot water cylinder and basically the whole thing needs replacing – it is leaking slightly, the valves are not working properly and the element is corroded right back (hence the boiling noise). He also things the house is not earthed because he said when elements get to the stage ours is at they normally trip the electrical switch, but as ours is not earthed its not (he also had a look under the house and couldnt see an elecrical earth). I thought earthing was simply to prevent electrical shock and nothing to do with tripping switches? now im just confused!

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