Thermometer replaced in hot water tank but water much colder
Anonymous user 28/02/2024 - 2.57 PM
My hot water stopped working and I have had the thermometer in my hot water tank replaced at the top and bottom by a plumber, however the plumber told me that the bottom one did not have any electricity going to it. Since the plumber replaced the thermometers the water is much colder (it is set on max temperature though) and there is also less hot water. In the meantime I had the electricity for the bottom heating element repaired, but this is turned off, however as this never worked this should not make a difference? Is there anything the plumber could have done wrong?
Are you a tradesperson and able to answer this question?
So your plumber carried out diagnostic checks to your immersion heaters and found the fault to be the thermostats? (not thermometer)
If your are still not receiving hot water then the fault is clearly the immersion heater elements and not the thermostats. To determine if an immersion heater element has failed we use a Multimeter to check resistance, a good reading will be 18-20 ohms any less or Open Line means the element has failed, ask your plumber if he carried out these tests and if he did, what resistance reading did he get?
Testing a thermostat is slightly different - here we are looking for continuity the same as your room thermostat. When the desired temperature is reached the thermostat switches to open thus breaking the circuit/power to your immersion heater until the temperature drops and the thermostat detects that temperature drop and closes the circuit allowing power to get to your immersion heater again, the cycle begins once more.
3kw Immersiom heater - the maths:
P=IV
V=IR
3000/230 = 13.04A
230/13.04 = 17.64 Ohms
Hi. Just a note here to add to the above. You need to be very careful with things like this as it reminds me of a problem I encountered a few years ago. It was on an off peak immersion heater where the customer was complaining the water was only luke warm. Upon checking I found the element to be completely open circuit as well as a low reading to earth. Upon removal I could see the heater core physically broken & in direct contact with the water. The alarming thing was that I would have expected the fuse to have blown but it didn't as the wire was completely disconnected in the fuse box. This installation was lethal & but for the fact it was live after the customer went to bed then she could have been electrocuted by the hot tap. Do make sure that the earthing is ok. In normal use they do not do very much & make no difference to the way things run. However earths are the most important wires you have in the house as they stop you being electrocuted when a fault arises. The latter case is a classic example of a potentially tragic scenario. From what you describe it sounds to me like you may have a similar issue. Please Please Please have your earthing properly checked out.
