Help please.boiling hot water in shower?

does this indicate the thermostat on the hot water cylinder is gone?. Last power bill was excessive too!

moodybleu, Jul 19, 10:01 am

if the thermostate has gone, you won't have hot water, are you sure its not the cold water can't get through << more clues needed from you

kids4ever, Jul 19, 10:14 am

hmm. I don't know if I have any other clues. its a really old low pressure system which I have looked at updating to mid pressure but just haven't done it as its quite expensive.

moodybleu, Jul 19, 10:48 am



you are wrong - when thermostats fail they generally fail 'on' , the contacts weld shut so the switch no longer operates to turn it off. So it does sound like the thermostat has failed. Or its a plumbing issue like a tempering valve.

ryanm2, Jul 19, 11:08 am

May even be the element - it has happened to me before too.
Thought it was Thermostat (exactly same symptoms) it turned out my element was failing.

neoslowmo, Jul 19, 11:08 am



I dont understand how a failing element would make your water boil ? That makes zero sense.

ryanm2, Jul 19, 11:10 am

I know - but it did - more than welcome to talk to the electrician that replaced it, and it stopped after, been fine since (2+ yrs)

neoslowmo, Jul 19, 11:13 am



Sounds beyond a tempering valve

golfaholic2, Jul 19, 11:28 am



Gosh that sounds like a really bad idea, safety-wise. A ticking time bomb!

astrophe, Jul 19, 11:37 am

my daughter thinks I should stop worrying and just call a plumber or sparky? she is almost always right so perhaps i'll just do that.

moodybleu, Jul 19, 12:09 pm

have you tried turning the temp down on the cylinder?

robyn35, Jul 19, 12:16 pm

that happened to us once too. We turned it down too, but it made no difference the water was still boiling. Had 2 enormous power bills before we put it all together too. Just something that needs fixing by someone who knows whats what

stillwaters, Jul 19, 12:20 pm

See what temp the cylinder is set to , then run the water hot from a tap and hold a thermometer in the water flow . if its hotter than the water setting you can probably bank on needing a new thermostat .

golfaholic2, Jul 19, 12:24 pm

Plumber hubby says, if the problem is just in the shower then possibly mixer faulty. If overly hot in all taps then points towards thermostat problem.

tmacc, Jul 19, 1:24 pm

Ha ha. this was actually written by my smart a. daughter! Anyway, I turned on the hot and cold taps on the bath and let them run for a while and then the shower water temp went back to normal. The cold water has always been slow but does seem to be worse noticeably when flushing loo and filling washing machine. So. maybe its just time to update the whole system. Thanks for all the advice. anyone know a good plumber?

moodybleu, Jul 19, 1:30 pm



'requardless of what another trader is saying, i still reckon the coldwater is the problem, not getting though correctly

kids4ever, Jul 19, 10:24 pm

It's thermostat in cylinder. Replace it. Element can't turn off if thermostat fails.
It's not the tempering valve because they fail to cold.
If cold water was restricted in shower water would be hot but not boiling hot.

kerry22, Jul 19, 10:57 pm

I agree, it will be thermostat failure and the heating element will be on all the time, thus the high power bill and boiling water out of the tap. Turn your hot water cylinder off at the wall right now.

We had a similar problem but with the oven, thermostat failed and element on 100% and burnt itself out and heated the whole kitchen cabinetry up, if we hadn't noticed could have started a fire probably.

lucky.gadgets, Jul 20, 12:33 am

we had this problem. replaced thermostat and all good

lindamae, Jul 20, 10:30 am



we always get ACTION PLUMBING

kids4ever, Jul 20, 7:50 pm


Definitely not the best at price, that,s for sure.

choccy2, Jul 20, 8:56 pm

If its a low pressure system does that mean you have a header tank in the ceiling? If so it will supply the cold water to the shower.its a safety feature to prevent scalding when someone else where in the house runs cold water. Even when my cylinder boils due to wet back we can always have a shower at the right temp. I would be checking your mixer out.

flopsie, Jul 21, 2:49 pm

we have found there charges are ok. never had a problem with them, would rather go with a well kbown company and get good service than a cheap dodgy outfit, just for the sake of saving a couple of dollars

kids4ever, Jul 22, 8:29 pm



Pretty funny! In my opinion some of the bigger companies are the worst. Just because someone's cheaper than . plumbing doesn't make them dodgy. If you only knew the stories I've heard about the company you've mentioned. Your hair would curl

kerry22, Nov 25, 2:38 am

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