Non-motoring > Why no limescale ? Miscellaneous
Thread Author: hawkeye Replies: 9

 Why no limescale ? - hawkeye
During the 12 years I was doing handyman work around the Richmond, Yorkshire area, I had plenty of light plumbing work to do caused by the hard water here. Ballcock and shower head replacement, toilet fill systems, tap washers and seat cutting were common. I did a couple of electric shower boiler replacements where the elements were too covered in scale to work properly or had burned out. Our kettle at home needs descaling every year for which I use citric acid.
Now we come to the holiday accomodation next door. It has no limescale prevention device and had a Triton electric shower installed about 23 years ago which has had regular use and no maintenance. I imagined it would be pretty much ready for some attention by now, so in this current interval between bookings I decided to use an endoscope to peep inside the shower boiler as a prelude to removal for descaling or replacement. There wasn't a crumb of limescale anywhere. I was astounded. To keep out of Mrs H's way for a bit, I removed the boiler anyway. The elements had a matt copper colour and looked in good condition; possibly fit for another 20 years.
My questions; why isn't it silted up? Where is the limescale? Is there some magic at work here?
 Why no limescale ? - Duncan
>>
>> My questions; why isn't it silted up? Where is the limescale? Is there some magic
>> at work here?
>>

Indirect system?

The same water being heated over and over again. It heats the water used in the shower through a coil?
 Why no limescale ? - CGNorwich
Yes it’s a closed system so once the limited amount of carbonate in the system has precipitated that’s it. Combi boilers supplying hot water directly from the mains are much more prone to scaling however.
 Why no limescale ? - hawkeye

>>
>> Indirect system?
>>
>> The same water being heated over and over again. It heats the water used in
>> the shower through a coil?
>>

No, like many electric showers, the mains water enters the shower boiler and is heated by 1 or 2 coils in a plastic chamber on its way to the shower head.

The water comes from the same main that causes the kettles to fur up in both houses.
 Why no limescale ? - Zero
Is it the same water? being next door is no guarantee its the same source.
 Why no limescale ? - Dog
>>My questions; why isn't it silted up?

Private water supply?
 Why no limescale ? - Bromptonaut
OP refers to a Triton electric shower so presumably fed from the rising main.

EDIT cross posted with OP
Last edited by: Bromptonaut on Thu 8 Oct 20 at 14:12
 Why no limescale ? - T junction
We have a Triton, when you switch off the heater goes off but the water continues to run for a few seconds. this has the effect of the incoming cold water cooling the element rather than the hot water remaining in the chamber and boiling so depositing scale. Never looked in ours but nice to know that, if yours is the same, the system works.
Last edited by: T junction on Thu 8 Oct 20 at 16:10
 Why no limescale ? - CGNorwich
Ah I didn't notice it was an electric shower.

As T juncion says the water in a shower does not reach particularly high temperatures unlike a kettle. Calcium carbonate does not precicitate from water until it reaches somewhere around 35 to 40 degrees C and precipitation does not become significant until a temperature of 60C is reached.

Thus a shower heater which probably does not exceed 35C in use will not be subject to scalng whilst a kettle boiling the same water will be.
 Why no limescale ? - hawkeye
Thank you for the replies. I phoned the Triton helpline this afternoon in search of some insight but got none; the agent's script must have said said something like, "don't descale or damage will result" or some such. No expression of surprise that the equipment should still be running after 20-odd years.

The shower does run on for a few seconds after switching off until the water runs cold so I'm ready to accept CGN's explanation. I wish I could remember the makes of the showers that had suffered with scale.

Now then, a 200-year-old house with a bunch of unruly guests expected at the end of the month (lockdowns permitting); what else can possibly go wrong?
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