Rayburn to MegaFlo System - Limited Hot Water

[endaxi]

You really shouldn’t be working at anything to do with your Megaflo, except doing the air gap.
The thermostats for immersion and for operating motorised valve (heat to coil from Rayburn) are part of the critical safety components of the unit.
Only a unvented G3 qualified person is supposed to work on those. Excess heat is highly dangerous on unvented units.

Check that no water is ever dripping into tundish, especially when cylinder is up to full heat, as this will lose you hot water and can be due to lack of air gap, or other faults.
Note that all unvented units need serviced once a year for safety and warranty, which is usually 25 years

Wise words and I'll always yield to a professional. In my Megaflo manual however there are Installation , Commissioning and User Instructions. In the User Instructions it details how to adjust both thermostats. These instructions are 15 years old and may now be outdated.

 

[endaxi]

...I will double check for a second cover tonight too...

Sorry, just for clarity, I was typing from memory. I had a look and I believe both thermostats are in the same housing. I have to work blind to get to the screw to open the cover and it's a bit of a faff so I haven't opened it to confirm. Looking at my manual the wires come in at the bottom right of the box and the indirect thermostat is quite hard to spot at the top right of the box.

That said, please bear in mind what ReJect has posted. I only adjusted mine as my User Instructions told me how and I certainly wouldn't advise anyone to do anything that is dangerous or contravenes the rules. There are live wires in the box so maybe best to get a professional in.

Sorry if I've muddied the waters.

 

[ianmcd]

what is the thermostat on your Rayburn set to ?