Megaflo indirect cylinder thermal cut out.

[BurnageManc]

Turn the boiler off for a few hours so the pipes supplying heat from boiler to cylinder goes cold.

Now with DHW turned off fire up boiler for heating and check to see after a while if pipes to cylinder have also heated up.

If they have then the motorised valve is passing.

If they haven't heated up turn on DHW and check cylinder stat on Megaflow.

Checked that already Alan and the valve operates fine, i have come to the conclusion that the thermostat is faulty and isnt switching off when it reaches the set temperature.looks like new thermostat time.

 

[muggles]

Just because your zone valve moves doesn't mean it's not passing. I'd be testing that first - turn your entire heating system off and wait for the cylinder circuit to go cold. Now turn your heating on but leave your hot water off and see whether the coil warms up

 

[Taylortwocities]

That's possible, bujt (if you go back to the beginning) the OP said

My Megaflo is producing hotter water than usual .

The Megaflo does not heat water up on its own!
The primary source of heat will be the boiler. The Megaflo has a temperature control (aka "tank stat") within the indirect thermal controls assembly.

The other source of heat is the immersion. This theory has been discounted by the OP. I'm assuming the immersion -if fitted - is turned off.

 

[BurnageManc]

Just because your zone valve moves doesn't mean it's not passing. I'd be testing that first - turn your entire heating system off and wait for the cylinder circuit to go cold. Now turn your heating on but leave your hot water off and see whether the coil warms up

Thanks Andrew I have already done this and it definitely is not passing.

 

[BurnageManc]

That's possible, bujt (if you go back to the beginning) the OP said

My Megaflo is producing hotter water than usual .

The Megaflo does not heat water up on its own!
The primary source of heat will be the boiler. I do not think that the Megaflo has a temperature control (aka "tank stat") within the indirect thermal controls assembly.

The other source of heat is the immersion. This theory has been discounted by the OP. I'm assuming the immersion -if fitted - is turned off.

There is no immersion fitted so its not that. The boiler water within the primary coil can only be controlled by totally switching off the flow of water around the cylinder at the divertor valve . This is achieved by the programmer telling the valve to close,in our case this works perfectly.The other way of controlling the water around the coil is that the cylinder stat senses the temperature is at that set on its gauge and in turn closing the valve . If You draw off hot water the tank replenishes itself with cold water which the stat recognises and allows the valve to open and reheat the cylinder. In my case I am now 100% certain that the thermostat is faulty and although allowing the valve to open when cold does not sense that the required temperature has been reached and continues to heat the water over and above that temp required.

 

[muggles]

Just because your zone valve moves doesn't mean it's not passing. I'd be testing that first - turn your entire heating system off and wait for the cylinder circuit to go cold. Now turn your heating on but leave your hot water off and see whether the coil warms up

Thanks Andrew I have already done this and it definitely is not passing.

Sounds like a problem with the thermostat then. You should be G3 Qualified & Registered to work on unvented cylinder components

 

[ban-all-sheds]

So if I understand correctly, are you are saying you don't have an immersion heater fitted at all, and not that you have an immersion but without a thermostat

So doesn't that make it a Plumbing problem, not an Electrics one?

 

[BurnageManc]

So if I understand correctly, are you are saying you don't have an immersion heater fitted at all, and not that you have an immersion but without a thermostat

So doesn't that make it a Plumbing problem, not an Electrics one?

Bit Of both thats why i will get the guy who installed it back as he is qualified to do so.

 

[BurnageManc]

So if I understand correctly, are you are saying you don't have an immersion heater fitted at all, and not that you have an immersion but without a thermostat

So doesn't that make it a Plumbing problem, not an Electrics one?

Bit Of both thats why i will get the guy who installed it back as he is qualified to do so.

All sorted now replaced cylinder stat and all fine now.Thanks to all for your help.

 

[eveares]

Good that you got it sorted. Strange that you have no immersion heater as well?; I assume you only have one flex lead coming from your tank.

A heating engineer once turned the thermostat up on my mega-flow that I had at my old house, and I assume he forgot to lower it back down after testing.

 

[BurnageManc]

Good that you got it sorted. Strange that you have no immersion heater as well?; I assume you only have one flex lead coming from your tank.

A heating engineer once turned the thermostat up on my mega-flow that I had at my old house, and I assume he forgot to lower it back down after testing.

Yes only one flex lead as there are no immersions (Tank allows 2) if the gas goes down or boiler its cold shower time. Thanks anyway

 

[eveares]

if the gas goes down or boiler its cold shower time

That one of the main draw backs with combi boilers; you need gas, electricity and a working boiler to have a hot shower! (Ok my combi has a 14L HW storage, but that won't last long !)