A hot water recirculation is arguably more efficient with a WrightChoice micro-pump but its manufacture is complicated and a number of customers struggle with air entrapment. Other customers get them to work brilliantly, think the fitting of the devices was easy, and sing the praises of hot water recirculation.

I want to sell a system that is so easy to fit that its a DIY job that can take under 30 minutes and there is never problems with air locks. Thats more happy customers and less hasle for me.

This post describes the WrightChoice cold water recirculation process.

Storing Surplus Energy (No Demand)
With the Micro Pump on, the flow rate is 1.5 litres minute.
With the 2.8 KW Immersion Heater on the heating rate is 1.5 litres a minute

Observations
Cold water drawn from the bottom and entering from the top enters the top 1/3rd of the cylinder at a flow rate equal to the heating rate. The rising air bubbles and heating creates eddie currents in the top of the cylinder only.  The temperature of the hot water zone remains constant and the hot zone descends at 1.5 litres a minute.
70 litres of hot water increases to 210 litres of hot water in 2 hours.
When there no cold water left in the cylinder, hot water recirculates, the immersion heater turns off.

Storing Surplus Energy (With Demand)
With the Micro Pump on the flow rate is 1.5 litres minute.
With the 2.8 KW Immersion Heater on the heating rate is 1.5 litres a minute
Observations
Cold water drawn from point A and delivered to point B.
If the temperature of the hot water zone is 60 degrees C and the cold water is 15 degrees C, the mixed water is 1/3rd cold to 2/3 hot (45 degrees C).
Reducing the pump flow rate to 1 litre a minute and the mixed water is 52.5 degrees C

The top third will reach the maximum set temperature and turn off.

Using Surplus Energy (With Demand)
With the Micro Pump off the flow rate is close to nil.
Even with the 2.8 KW Immersion Heater on the thermostat stops it heating.

Observations
For a ‘perfect shower’ , hot water at 60 degrees C and the cold water at 15 degrees C, mixes at a shower to give a shower at 45 degrees C (6 litres). A full 210 litre cylinder will empty of hot water in 50 minutes, that’s 6 showers lasting 8 minutes each.
The top third will reach the maximum set temperature and the immersion heater will turn off and remain off until all the hot water is used or surplus energy becomes available again when it starts storing energy again.