Vaillant Unistor 310 —reduce capacity?

See my post #3 above. By moving the sensor higher in a vertical cylinder, all you are doing is effectively reducing the temperature at the bottom of the cylinder. This still does not overcome the legionella issue, unless you ensure the whole cylinder is heated to 65+ at least once a week.

The Unistor is an unvented cylinder, so there is no access to fit additional thermostats, and no facility to move the existing one, which is a key component of the safety devices.

oldbuffer said:

The Unistor is an unvented cylinder, so there is no access to fit additional thermostats, and no facility to move the existing one, which is a key component of the safety devices.

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I understood from reading the VR10 installation instructions for the Unistor, that you push the sensor down the pocket, to the bottom. That suggests the sensor could be not pushed all the way down, to at least reduce the amount of full temperature HW to the upper levels, though I am not sure how well stratification might work, with the coil located much lower.

If the cylinder is taking over 30mins to reheat, you must be using the 300L or close to it. That’s a lot of hot water! If not, some settings are not right. Have you got both heating and HW temperatures set to maximum at the boiler, and the HW set to 50C on the 470? You can also set the max time the cylinder will be loaded before the system returns to heating at D.75. Factory default is 45mins. Also make sure your heating load is set correctly in D.0 and the curve on the 470 is set to 2.6 for radiators.