Heatrae Megaflo type with 2 heater elements and 2 separate programmers. After a thunderstorm (coincidence?) last week the megaflo water heater stopped working. The circuit breaker did not trip out but the light has gone out on the 20A water heater switch. However the lights are on on both of the programmers. I tried putting the programmers to boost but not working. Could you please suggest what I should check first? I am a careful DIY'er and am particularly cautious around electricity! Many thanks.
Megaflo water heater not working
- Thread starter timdaw
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- heatrae sadia megaflo
Yes I do! I haven't started investigating yet as it's in my wife's studio.
I'm also aware that you need a certificate to work on the guts of these sealed systems, but I thought I could investigate around it. If I need to replace the immersions then I will call someone in. But, both heaters are not working so I suspect it's something else.
The first thing to check with a Megaflo is that the thermal trip in the thermostat head hasn't activated.
You need to turn off the juice, remove the cover and see if a small pin is sticking out of the thermostat. If it is, reset and turn the temp knob down slightly.
Failing that you need to measure the impedance of each immersion element, across the spade connections, with the power disconnected. You should be looking for around 20 Ohms. If it is greatly higher or lower, you will need a new element. Often one element goes open circuit, and it is not noticed until No2 goes. The bottom one is normally on the cheap tariff.
There are no safety implications providing you work safely and change like for like. Getting wet or electrocuting yourself are the main concerns.
You need to turn off the juice, remove the cover and see if a small pin is sticking out of the thermostat. If it is, reset and turn the temp knob down slightly.
Failing that you need to measure the impedance of each immersion element, across the spade connections, with the power disconnected. You should be looking for around 20 Ohms. If it is greatly higher or lower, you will need a new element. Often one element goes open circuit, and it is not noticed until No2 goes. The bottom one is normally on the cheap tariff.
There are no safety implications providing you work safely and change like for like. Getting wet or electrocuting yourself are the main concerns.
Many thanks for that. I'll check those things first... with the power off!
I hadn't come across this Megaflo system before. I was puzzled about the two immersions, but I see that the lower one is supposed to be for the economy tariff, and the top one as a sort of booster? As my wife is only there during the day and only uses hot water for washing hands and washing up lunch dishes, I suppose the top one is not necessary to be on, and is a waste of electricity?
I hadn't come across this Megaflo system before. I was puzzled about the two immersions, but I see that the lower one is supposed to be for the economy tariff, and the top one as a sort of booster? As my wife is only there during the day and only uses hot water for washing hands and washing up lunch dishes, I suppose the top one is not necessary to be on, and is a waste of electricity?
The top one is only to give hot water if all the cylinder full, which was heated up over night, has been used.
So turn it off. Its only for intermittent manual use anyway. Some installations put a one hour run back times on it to avoid it being left on.
Tony
So turn it off. Its only for intermittent manual use anyway. Some installations put a one hour run back times on it to avoid it being left on.
Tony
The norm would be off peak electricity heats full cylinder and upper element used as a boost if water runs cold and off peak power is not active.
If both connected to standard tariff, no reason why you could not use both elements to heat the water faster.
If both connected to standard tariff, no reason why you could not use both elements to heat the water faster.
Thanks to everyone for helpful advice. Update - I finally got to check the system. There is power at the switch and to both controllers. The thermal cut out had popped on the top thermostat. I pushed it in and lowered the thermostat a bit as suggested. The body of the thermostat got hot, as did the wiring to the timer, but the immersion was not working/heating water. Checked both immersions and they both measure about 19 ohms across the terminals. It seems both thermostats are defective. When I put both on boost, there was no water heating from either immersion. I presume I should change both thermostats.
Incidentally the two timers are wired from separate switches. I turned the contact breaker marked 'immersion' off, but that only turned off one of the immersions! Good job I checked supply with the multimeter! Just shows how careful you have to be with electricity!!!
Incidentally the two timers are wired from separate switches. I turned the contact breaker marked 'immersion' off, but that only turned off one of the immersions! Good job I checked supply with the multimeter! Just shows how careful you have to be with electricity!!!
HELP!!! Problems still...
The supplier only sent one thermostat instead of two. I fitted it to the lower immersion. Water did not heat. I noticed that the wiring from the fused switch to the immersion was warm. Half an hour later the switch was almost too hot to touch. I checked the wiring inside the switch and that all looked good, no loose connections or signs of hot spots. So I've left it with the circuit breaker switched off.
Tested immersion heater impedance and it was 19 ohms, to both immersions.
Additionally there is a small leak from the shut off valve stem on the top of the cylinder. When I turned the handle to shut the valve off, water started pouring out of it! It goes from bad to worse!
Any suggestions, apart from getting a plumber in?
The supplier only sent one thermostat instead of two. I fitted it to the lower immersion. Water did not heat. I noticed that the wiring from the fused switch to the immersion was warm. Half an hour later the switch was almost too hot to touch. I checked the wiring inside the switch and that all looked good, no loose connections or signs of hot spots. So I've left it with the circuit breaker switched off.
Tested immersion heater impedance and it was 19 ohms, to both immersions.
Additionally there is a small leak from the shut off valve stem on the top of the cylinder. When I turned the handle to shut the valve off, water started pouring out of it! It goes from bad to worse!
Any suggestions, apart from getting a plumber in?
I don't see how the cable can get warm/hot if there is no current.
Did you measure voltage on the immersion element? Did you press in the little overheat reset button?
Did you wait long enough for the cylinder to heat up? That can be up to three hours from cold!
Tony
Did you measure voltage on the immersion element? Did you press in the little overheat reset button?
Did you wait long enough for the cylinder to heat up? That can be up to three hours from cold!
Tony
If the switch is getting hot it will need to be replaced, whether it is the cause of the fault or not. Any heat damaged copper will need to be cut off as well.
There is 240 volts at the immersion but it doesn't seem to be working. The thermostat is the new one, and the button is in. I couldn't wait any longer for the element to heat as the switch was very hot after just half an hour!
The end of the live cable at the thermostat end was heat damaged, so I cut that bit off before connecting it up. There was no sign of heat damage in the switch, and all connections were tight inside the switch.
The only way the switch can be getting that hot is if either the contacts have had it or the wiring connections are loose/not properly made.
Conclusion: Had to get a Megaflo engineer in. Both thermostats were faulty and the immersion elements were heavily scaled. Once they were de-scaled they worked properly and no more over-heating of the wiring. Incidentally the cables to the switches were replaced with silicon cabling which apparently is what should be fitted to these units.
We used megaflo-service.co.uk for the repair. They were very professional, civil and reliable, with transparent charging. I would be happy to recommend them.
Thanks to all for help and advice. Hope this helps someone else.
We used megaflo-service.co.uk for the repair. They were very professional, civil and reliable, with transparent charging. I would be happy to recommend them.
Thanks to all for help and advice. Hope this helps someone else.