Immersion Heater Question

[Rotax100uk]

Hi all, the immersion tank we have has two heater elements, one economy 7 at the bottom and booster at the top, both controlled by switch fused spurs on the wall etc...

We are getting alot of noise coming from the tank (LOUD banging sounds) the set temp of the stat is 60oC.

Firstly i have been told to check the thermostat, so i swapped over the top and bottom stats..... still no difference!!! (both set to 60oC)

We then got in touch with a local plumber who said "why is the stat set SO HIGH!!! it should be set to 40oC"

So i am understanding, the stat needs to be set to 60oC to stop bacteria growth.

By the way we are in a hard water area, with no water softners

Can anyone offer any better advice as its becoming hard to sleep with all this noise (Tank is in the main bedroom cubboard)

 

[BLOD]

Are both the immersions working ? Try them individually.

 

[AWheating]

top immersion should be 60, bottom could be set at 40-50. sounds like overheating or corrosion issues.

 

[stani]

top immersion should be 60, bottom could be set at 40-50. sounds like overheating or corrosion issues.

why do you want to set the bottom stat to 40-50? serious question AWH sorry if it sounds argumentative, it is'nt, just interested in your thoughts.

 

[AWheating]

the bottom stat assuming its in the bottom half of the cylinder should be set lower because if you heat the bottom to 60 then the top of the cylinder due to stratification (spelling?) will always be hotter and above 60. So seting the lower stat to a lower setting will give you a temp similar to the top stat set slightly higher.

if that makes sense 🙂


of course without knowing the size of the cylinder its just a suggestion on my part.

 

[Dannypipe]

Your stat could be knackered and boiling the water, regardless of whether it is top or bottom or set at 40 or 60. Do you know how to check it?

If not, get someone in. Boiling water in your cylinder is a serious matter and is potentially very dangerous.

 

[sparra1100]

yep sounds like its getting to hot and the tank is expanding hence the noise banging,get someone in to have a look cos the tank could go at the seams

 

[stani]

it certainly does and even the spellimg is good, cheers mate.

 

[Dannypipe]

Exactly, so you could set your stats for 40, but if one of them is knackered it could just keep going, like an element in a kettle, until the water is boiling.

Not unusual for this to happen, and you will find the cold water storage tank in the loft starting to get warm as the cylinder over heats and overflows via the open vent. If it goes on long enough, the plastic tank gets too hot, and splits. Then you have 40 gallons of boiling water raining through the ceiling.

Exactly this happened and tragically killed a baby a few years ago, hence why all new stats have a resetable thermal cutout.

 

[kirkgas]

the bottom stat assuming its in the bottom half of the cylinder should be set lower because if you heat the bottom to 60 then the top of the cylinder due to stratification (spelling?) will always be hotter and above 60. So seting the lower stat to a lower setting will give you a temp similar to the top stat set slightly higher.

if that makes sense 🙂


of course without knowing the size of the cylinder its just a suggestion on my part.

if you have 2 working stats, the lower set to 40-50 and you never need the top one then its stands to reason that the water in the cylinder will never reach 51 and will therefore be prone to bacterial growth, i appreciate it is unlikely in a domestic scenario but i have always believed stored water should be set to 60-65 to stop this, if you run out of hot water and use the top one set to 60 then the water will go to 60, but this cannot be the most economical use of the immersors as by storing it lower than 50 during the night you are likely to run out quicker and need the top up from the more expensive one more often, with the lower one set to 60 and heating the water to 60 how will the water at the top be heated to more than 60, as you say stratification causes circulation in the cylinder which will cause the hot to rise and the cold to drop allowing it all to get to 60 when the stat will turn off meaning an even temp of 60 throughout the tank with no chance of the top water being above 60
if that makes sense

 

[tamz]

Get the stats checked and replaced
I agree with Kirk. Set both to 60º. The temperature at the top will at most be a couple of degrees warmer plus as it is an economy 7 cylinder setting the lower stat to 40 is not a good use of cheap rate electric.

 

[Rotax100uk]

Well thanks for the replies, i do think now as a safety measure im going to replace the stats in both the heaters. they dont seem too expensive. so would 60 be the best temp setting for my tank? or should i turn it down. BTW i only use the bottom (Economy 7) heater too. Thanks again.

 

[tamz]

60º is best

 

[Rotax100uk]

Sorry TAMZ i didnt see you post as i replied, i will be taking your advice. thanks..