Immersion heater

Hi,

I currently have a boiler with immersion heaters to boil. However, I am having trouble with them. I have set the thermostat to the highest but sometimes they still turn off. I don't understand what's happening. I've even taken off the cut off switch to allow it to keep going but then the heater won't actually work. Can anybody advise or tell me of a manufacturer of immersion heater that will allow me to boil consistently without issues.

It's effecting my beer making to say the least.

Thanks

How much volume are you trying to boil?

Hi.

Around about 200 litres

That's a lot of wort.

Goals:
Get the wort to 101 btu/kg in reasonable time (15 minutes)
Maintain a minimum of 10 l/hr boiloff (5%)

Assumptions:
Steel Kettle
Liquid Dimensions: 50 cm wide, 101 cm tall
Wort starting Temperature: 70oC
Wort Starting volume 200 l

It takes 4 btu's to raise 1 liter 1 C

You need to add 31 degrees to 200 liters of water. This totals to 24,800 btu/hr. So, 4x that to ramp up in 15 minutes or 99,200 btu.

Once at 100oC, you need only to maintain that temperature and calculating the loss from surface area and metal, it's about 15,000 btu/hr in a 20oC room.

Boiloff requires 2068 btu/kg of steam. At 5%/hr, you'll need 20,680 btu. plus the maintenance heat of 15,000 btu.

Results:
Max btu: 99,200
Min btu: 35,680

3.41 btu = 1 watt. I'd add at least 20% more wattage to have headroom.

Max Watt: 35,000
Min Watt: 12,600

Thanks for that information, any ideas why my existing heaters would be cutting out though. I don't want to modify it if I don't have to I just need to make it work. When it does work (which is sporadically) it works well.

Anyone electrically minded that could pose a theory?

Lots of reasons.

Cracked insulation on the heating element. I'ts designed to gently transfer heat, but if you hit the hot element with cold water, it can crack. Same with vigorous scrubbing.

Turning on the heating element with a dry kettle will usually cause failure. Often in seconds.

If the element grounds out to the kettle, but the kettle isn't grounded, then the unit is burning out between the two hot feeds. If it only has a single hot feed, then you'll feel a shock.

If it's designed for a hot water heater, then the unit is designed for less than 101 C. This means the high limit switch is breaking the current. Get a heat unit designed for boiling.

Burned out thermostat, again related to it being for a hot water heater and not a boil.

There are a lot more, but I suspect that your heater is under powered.