Solar i boost taking out thermal cutout

[bigspark17]

Hi all. Has anybody experience solar iboost creating problems with immersion heater safety cut out? Does the iboost somehow heat the tank higher than the thermostat or does it have something to do with the iboost heating via DC.

 

[freddo]

The iboost doesn't bypass the element control stat, it's likely that the stat is faulty. The iboost uses triac controlled AC not DC

 

[davesparks]

No, the iboost cannot magically bypass the thermostat unless it has been physically bypassed.

 

[bigspark17]

The iboost doesn't bypass the element control stat, it's likely that the stat is faulty. The iboost uses triac controlled AC not DC

Triac controlled ac? Can you expand on that? I was under the impresion it was DC thats how it could regulate the input of a resistive load?

No, the iboost cannot magically bypass the thermostat unless it has been physically bypassed.

Yes i get that, its been happening on a brand new double immersion unvented cylinder, the iboost was connected to the bottom element and top element was connected to ec10 supply, fine during summer as plenty of free hot water from the 4kw system but come winter not enough excess electric so when relying on ec10 noted that the thermal overload had triggered. It then kept happening on good “sun” days. My diagnosis was faulty thermostat was looking for any other possibility.

 

[freddo]

Triac controlled ac? Can you expand on that? I was under the impresion it was DC thats how it could regulate the input of a resistive load?

It's just a microprocessor controlled dimmer switch that happens to have a heating element connected to it rather than a filament lamp. The triac just switches rapidly on and off.

 

[davesparks]

Yes i get that, its been happening on a brand new double immersion unvented cylinder, the iboost was connected to the bottom element and top element was connected to ec10 supply, fine during summer as plenty of free hot water from the 4kw system but come winter not enough excess electric so when relying on ec10 noted that the thermal overload had triggered. It then kept happening on good “sun” days. My diagnosis was faulty thermostat was looking for any other possibility.

Ah, that's a bit different to the way your previous post read.

I've seen it plenty of times where a bottom element causes the top element overheat stat to trip.

The top of the tank naturally ends up hotter than the bottom as the hot water rises to the top. So when the bottom element gets to its set temperature the top of the tank is actually quite a bit hotter. So if the bottom element is set high enough it will heat the top thermostat enough to cause the overheat trip to operate.

My soloution in the past has been to turn the bottom element down a little but.