iBoost and my immersion heater

ely_ellis

Having just had my Solar PV system installed including iBoost, I have a question about the immersion heater itself.
The manual for the iBoost says that when it reaches temperature the iBoost will say "Water Tank Hot".
But how will it know?
I assume that at some point the current to the immersion heater will be cut off by a thermostat, but what happens if there is no thermostat fitted or connected in line, will the iBoost continue to heat the water?
There appears to be a thermostat fitted on my tank, but the wiring suggests that it is connected to the central heating boiler which would obviously turn the boiler off when the correct temperature is reached, but the immersion heater appears to be connected directly to the MCB in the consumer unit.
Do immersion heaters have internal thermostats or at least a cut out and if so, is there a default temperature they cut out at.
I expected there would have been a terminal on the iBoost for a thermostat connection, but doesn't appear to be the case.
Cheers

pinnks

The iboost is just an intelligent switch. it turns on and delivers its proportionate load and will detect open circuit when the immersion thermostat reaches temp. the immersion thermostat is integral to the immersion heater and not part of the central heating system.

EricMears

ely_ellis wrote: »

Having just had my Solar PV system installed including iBoost, I have a question about the immersion heater itself.
The manual for the iBoost says that when it reaches temperature the iBoost will say "Water Tank Hot".
But how will it know?
I assume that at some point the current to the immersion heater will be cut off by a thermostat, but what happens if there is no thermostat fitted or connected in line, will the iBoost continue to heat the water?
There appears to be a thermostat fitted on my tank, but the wiring suggests that it is connected to the central heating boiler which would obviously turn the boiler off when the correct temperature is reached, but the immersion heater appears to be connected directly to the MCB in the consumer unit.
Do immersion heaters have internal thermostats or at least a cut out and if so, is there a default temperature they cut out at.
I expected there would have been a terminal on the iBoost for a thermostat connection, but doesn't appear to be the case.
Cheers

Your iBoost won't "know" that the water is hot enough - but it will detect that the immersion heater has gone open circuit and that that must mean tank is hot enough.

Immersion heaters do indeed have internal thermostats and it's usually possible to change the one provided for one with a higher cut out temperature (or even one with a variable cut out temp).

ely_ellis

Ah, so the thermostat on the side of the tank has nothing to do with it then.
I will have to have a closer look at the immersion heater, see if there is a cut off temperature on it.
I remember when I was a kid, if we forgot to turn off the immersion heater we could here the pipes banging and the overflow spitting out hot water!
The system we have now is a closed system but we do have an expansion bottle on the top of the tank.

DREKLY

My immersion element has a removeable cover, held on by a small nut & washer, and inside is an adjustable thermostat with
markings in degrees, so you can set it with a small screwdriver in a slot to the desired temperature, in this case, it's about 55 -60 c - hope that's of some help !
maybe pop the cover off with it switched off, and have a peep!

ely_ellis

Spot on !
Small finger-tight nut in centre of lid, removed and can see thermostat setting (55 deg).
Also, just noticed a small piece of paper on the floor next to the tank and guess what!, it is the wiring instruction for the immersion heater with diagram showing the thermostat... haha
Only bought the house 2 months ago and its just over 10 years old, so what are the chances...!
Anyway, query fully answered, thanks guys.

EricMears

ely_ellis wrote: »

Ah, so the thermostat on the side of the tank has nothing to do with it then.

That thermostat is probably part of the (gas?) central heating system.

If you want to use the iBoost effectively, make sure that the immersion thermostat is set at a higher temperature than that on side of tank. But note that neither will be very accurate and may indeed be in completely different places so you need to do a bit of 'dial wiggling' to ensure you've still got a few degrees of immersion heating left when the CH system has switched off.

Kernel_Sanders

ely_ellis wrote: »

I remember when I was a kid, if we forgot to turn off the immersion heater we could here the pipes banging and the overflow spitting out hot water!

That reminds me of the distressing case in 2006 of a baby being scalded to death by the rupture of this header tank above her cot. http://news.bbc.co.uk/1/hi/england/somerset/7179092.stm
RIP Rhianna Hardie

ely_ellis

Kernel_Sanders wrote: »

That reminds me of the distressing case in 2006 of a baby being scalded to death by the rupture of this header tank above her cot. http://news.bbc.co.uk/1/hi/england/somerset/7179092.stm
RIP Rhianna Hardie

That is terrible. I vaguely remember that too.

Got a full tank of hot water yesterday and already again today.
Doesn't take long to get the water hot and the message 'water hot' on the iBoost.

We don't have the central heating boiler (Oil fired boiler) on a timer at all. Generally if we want showers/baths we just put the boiler on boost for 1 hour. Usually the water stays hot for a couple of days depending upon usage.

oldskoo1

Hi Ely

For max use of hot water heating via solar you may want to turn up the immersion stat, higher than the dhw stat. I have mine immersion stat set to 70.

Watch your overflow pipe, if it leaks a little you may need to recharge the air gap in your cyclinder. The most obvious sign is high pressure when you turn on the taps after heating the tank.

You may also want to turn off the boiler timer in the mornings. The extra hear via solar with mixer taps easily lasts for evening and morning hot water usage and if the solar cannot refill the tank the boiler kicks in by tea time.

So far the boiler had never needed to come on, even on dull days.

Ectophile

Modern immersion heaters should have two thermostats. One is adjustable to set the water temperature. The second is a safety cut-out to shut off the power should the first one stick closed. The cut-out was added to prevent the water in the hot water cylinder ever boiling.