HI Folks.
This is my first post so apologies if it's in the wrong location.
I recently installed a 3kw Solar system with an iboost diverter which diverts electrical power to the dual elements (3kw and 2kw) on the water cylinder when there is an excess of power.
I recently discovered that a top mounted dual immersion (sink and bath type) will not fully heat the tank of water EVER. This is because of the thermostats location. ( I installed a set of 4 externally mounted Thermocouples on the outside of the tank to verify my readings).
My tank is 40 in high. My dual immersion has a 36in and 11in elements and the single thermostat is 18 long. I believe the thermostat averages the temp along it's length rather than at the tip like a thermocouple. This is a standard enough immersion. (Model Tesla TIH 467) Obviously enough the thermostat is not reading the temperature at any point below 18 in which isn't even half way down the tank. The effect of all this is that the sink element will heat the top 11in plus a bit and then once the second longer element kicks in it will start to heat the water (which will rise) and cause the thermostat to "make" once the top 18in of the tank are at temp leaving the bottom half at almost cold !!!! What is that all about.!!!! So I've ended up diverting my excess power to the grid when I haven't even heated the full tank!!!
Previously I used to heat my tank from the gas central heating which used a coil located at the bottom of my cylinder so I always had a full tank of hot water.
Considering I have a teenage son who plays sport 5 days a week and a 11 yr old daughter who likes 30min showers I need every drop of free solar hot water I can get.!!!
So.......I've been considering my options.
btw I don't have battery storage on my PV system as that adds a lot to the cost and I wanted to have as short a payback as possible.
OPtion 1. I have asked TPFAY for a quote for a Dual element DUAL Thermostat. The 36in element should have a thermostat somewhere near the 34in mark at least and the 11in element should have a thermostat up around that height. Does anyone know why this isn't already done? I know these are mechanical style actuated so maybe there's something in the 18in that is limiting. Anyone know if there is a company already doing this. I haven't seen anyone with a thermostat more than 18in and that's the main problem. My iboost allows for two output channels (heater 1 and heater 2 ) so I can use the two seperate thermostats to control the two elements
Option 2. Fit a cylinder stat, externally mounted on the side of the tank down at the 34" mark, bypassing the thermostat in the head of the dual immersion. Is there certification issues for the electrican in bypassing the immersions thermostat and linking this one in instead.
Option 3 . Cut a new hole for an element mounted at the bottom of the tank. This might be a problem as I already have a coil inside at the bottom for the gas heating loop which will be in use in the winter months.
OPtion 4. Fit a Willis heater.....this will trickle heat the whole tank and provide circulation thus evening out the temp of the cylinder. I'd really prefer not to do this as it's more cost, and plumbing.
Option 5. Replace tank for dual immersion top and bottom element.
I've spoken with Tesla technical and they agree this happens with top mounted dual elements and see it as a design issue but don't have a fix.
I think there's a lot of solar installations currently NOT optimised for this exact reason and a new element design might solve the problem.
All input will be very greatly received
Thanks in advance
Jamie
This is my first post so apologies if it's in the wrong location.
I recently installed a 3kw Solar system with an iboost diverter which diverts electrical power to the dual elements (3kw and 2kw) on the water cylinder when there is an excess of power.
I recently discovered that a top mounted dual immersion (sink and bath type) will not fully heat the tank of water EVER. This is because of the thermostats location. ( I installed a set of 4 externally mounted Thermocouples on the outside of the tank to verify my readings).
My tank is 40 in high. My dual immersion has a 36in and 11in elements and the single thermostat is 18 long. I believe the thermostat averages the temp along it's length rather than at the tip like a thermocouple. This is a standard enough immersion. (Model Tesla TIH 467) Obviously enough the thermostat is not reading the temperature at any point below 18 in which isn't even half way down the tank. The effect of all this is that the sink element will heat the top 11in plus a bit and then once the second longer element kicks in it will start to heat the water (which will rise) and cause the thermostat to "make" once the top 18in of the tank are at temp leaving the bottom half at almost cold !!!! What is that all about.!!!! So I've ended up diverting my excess power to the grid when I haven't even heated the full tank!!!
Previously I used to heat my tank from the gas central heating which used a coil located at the bottom of my cylinder so I always had a full tank of hot water.
Considering I have a teenage son who plays sport 5 days a week and a 11 yr old daughter who likes 30min showers I need every drop of free solar hot water I can get.!!!
So.......I've been considering my options.
btw I don't have battery storage on my PV system as that adds a lot to the cost and I wanted to have as short a payback as possible.
OPtion 1. I have asked TPFAY for a quote for a Dual element DUAL Thermostat. The 36in element should have a thermostat somewhere near the 34in mark at least and the 11in element should have a thermostat up around that height. Does anyone know why this isn't already done? I know these are mechanical style actuated so maybe there's something in the 18in that is limiting. Anyone know if there is a company already doing this. I haven't seen anyone with a thermostat more than 18in and that's the main problem. My iboost allows for two output channels (heater 1 and heater 2 ) so I can use the two seperate thermostats to control the two elements
Option 2. Fit a cylinder stat, externally mounted on the side of the tank down at the 34" mark, bypassing the thermostat in the head of the dual immersion. Is there certification issues for the electrican in bypassing the immersions thermostat and linking this one in instead.
Option 3 . Cut a new hole for an element mounted at the bottom of the tank. This might be a problem as I already have a coil inside at the bottom for the gas heating loop which will be in use in the winter months.
OPtion 4. Fit a Willis heater.....this will trickle heat the whole tank and provide circulation thus evening out the temp of the cylinder. I'd really prefer not to do this as it's more cost, and plumbing.
Option 5. Replace tank for dual immersion top and bottom element.
I've spoken with Tesla technical and they agree this happens with top mounted dual elements and see it as a design issue but don't have a fix.
I think there's a lot of solar installations currently NOT optimised for this exact reason and a new element design might solve the problem.
All input will be very greatly received
Thanks in advance
Jamie