PTC geyser elements?

[hxc87x]

Hi all,

Decided to pull the trigger on a solar system. I'm going for a 5kw sunsynk and plan to use the aux port and excess pv in the day to run my geyser.
I'm going to replace my geyser element with a 2kw element, but came across PTC elements which claim to be a bit more efficient than normal immersion heaters and therefore save costs:

2200 W PTC AC Element – Geyserwise

It's a nice idea but they cost ~R2k vs normal element ~R300... and I'm not sure I believe/understand the claims of it saving on costs

Anyone have some first hand experience and can confirm?

 

[EnT@nGleD]

I am also interested to find out.

Heat Up Test

This test determines the percentage energy saved when using an XTEND PTC Ceramic element compared to a standard resistive spiral element..

xtendelements.co.za

 

[hxc87x]

I am also interested to find out.

Heat Up Test

This test determines the percentage energy saved when using an XTEND PTC Ceramic element compared to a standard resistive spiral element..

xtendelements.co.za

That's interesting!
and this specifically is interesting

 

[Xtend]

That's interesting!
and this specifically is interesting

View attachment 1187012

Hi. The Xtend energy savings have been tested and confirmed on Kwikot test bench. Xtend is authorised for installation without affecting warranty.
The energy savings are a result of lower heat losses. Xtend operates at a lower temperature and has a larger surface area. This plus other design features reduce losses. This is why a 2kw Xtend heats at about the same rate as the 3kw spiral.
The reason the stat must be set lower is that the stat is positioned below the element with Xtend and in the middle of the element for a standard element. As the stat is lower with Xtend you need a lower stat set point to achieve the same thermal energy in the geyser. Around 10c in Kwikot. To be adjusted until hot water temp as desired.
We know there is scepticism. We have thousands installed. We are doing more tests with certified people and banks. There are many variables at play. The main questions to answer are:
Does Xtend give me the same water quality and do I save money. Lab tests won't do this, even though their results are most accurate as they are controlled.
Please let me know any other questions or concerns.

 

[Timber_MG]

Why not take two 150l kwikot geysers with the two different elements and measure a true power metered input up to some temperature, switch off the elements and measure the outflow temperature?

How much does the element resistance change between water at 25C and say 60C?

 

[noxibox]

Hi all,

Decided to pull the trigger on a solar system. I'm going for a 5kw sunsynk and plan to use the aux port and excess pv in the day to run my geyser.
I'm going to replace my geyser element with a 2kw element, but came across PTC elements which claim to be a bit more efficient than normal immersion heaters and therefore save costs:

2200 W PTC AC Element – Geyserwise

It's a nice idea but they cost ~R2k vs normal element ~R300... and I'm not sure I believe/understand the claims of it saving on costs

Anyone have some first hand experience and can confirm?

There have been debates about this on Power Forum (e.g. https://powerforum.co.za/topic/12851-geyser-ptc-elements/) and on international sites. But essentially the claims of increased efficiency for PTC elements are extremely suspect regardless any alleged independent testing.

 

[soulie]

ptc heaters only work well if they never get too hot and too cold .you fill a geyser in the middle of winter with ice cold water in gauteng that ptc is gonna kak to heat it to 40c and above .so if you turn the geyser off and fill it and yhe temp drops to say 17c its gonna suffer .

 

[DavidKinnes]

ptc heaters only work well if they never get too hot and too cold .you fill a geyser in the middle of winter with ice cold water in gauteng that ptc is gonna kak to heat it to 40c and above .so if you turn the geyser off and fill it and yhe temp drops to say 17c its gonna suffer .

Do you have any literature for this claim?

 

[Stonemason]

I use a Geyserwise system and it works extremely well. It is a dual element setup which uses DC directly from two solar panels and if necessary an AC element heats up the water if there is not enough sun.

Even with the rain and the clouds in Gauteng I have never had a problem with hot water and only needed AC power once for about 20 minutes (according to my Sunsynk inverter's graphs).

Just a warning to anyone replacing their geyser elements - Kwikot / Electrolux will drop your warranty like a hot potato if you don't use their branded elements. I don't know if they do DC elements at all.

Kwikhot has their own PV based solution which also uses a dual element.

 

[soulie]

Do you have any literature for this claim?

you may find something on google .we tried ptc heaters in spray booths for heating .in winter overnight they didnt work too well .if you keep the temp up they are fine .if i remember under 25 deg was an issue .for constant temp conditions like tropical fishtanks its great .i believe some are using dual elements .standard and ptc .for a 6 month warranty at a price .versus a standard element dont know .try it .

 

[Tim_vb]

you may find something on google .we tried ptc heaters in spray booths for heating .in winter overnight they didnt work too well .if you keep the temp up they are fine .if i remember under 25 deg was an issue .for constant temp conditions like tropical fishtanks its great .i believe some are using dual elements .standard and ptc .for a 6 month warranty at a price .versus a standard element dont know .try it .

Rather bump up the temp to 55C or you may well get all sorts of bacteria including the one that causes Legionnaires' disease

 

[soulie]

Rather bump up the temp to 55C or you may well get all sorts of bacteria including the one that causes Legionnaires' disease

LD is found in many places most wouldnt even think about .besides most geysers in sa are so kak they dont last long enought to gather anything .but yes a geyser should be at 55.incoming flak from all the plumbers

 

[wingnut771]

LD is found in many places most wouldnt even think about .besides most geysers in sa are so kak they dont last long enought to gather anything .but yes a geyser should be at 55.incoming flak from all the plumbers

What flak?

 

[soulie]

What flak?

everyone wants to set the geyser at higher temps .ptc elements you set a minimum of 10 deg lower than a normal thermo .max temp at any point in a hot water install shouldnt exceed 65 deg c , so says I .

 

[wingnut771]

everyone wants to set the geyser at higher temps .ptc elements you set a minimum of 10 deg lower than a normal thermo .max temp at any point in a hot water install shouldnt exceed 65 deg c , so says I .

What happens to a ptc element when it gets to 55?

 

[soulie]

nothing ptc is actually happier at higher temps ,ive been told the curve is different and the water heats quicker than what a standard thermo can react to so temps overshoot the set point rapidly .a normal geyser the upper water is much hotter than at the thermo but apparently with ptc even more so .that is on a horizontal geyser.vertical are much more efficient but not sure about accuracy there .im fitting a new geyser soon and may go for ptc but electric geyser hardly gets used so undecided.