Greenstar 24ri - large temperature drop before re-fire

[desktop987456]

nearest tap was ~61C and even at 6:00pm this evening was still sufficient water at ~55C.

Interesting. You could teach me a few tricks as I am in the process of putting a HW cylinder.
When you at 6p.m water was at 55C; after how much time did you get the reading at 6p.m?
Depending on your usage, how much are you spending on gas in a day if it is reheated twice; once in the morning and at night? It would use more gas when you fire it first time in the morning but would use less during the day as water replenshises in the cylinder.
Does the boiler re ignite once the temperature falls below the cylinder stat?
Thanks

 

[Johntheo5]

You are not far away from getting the boiler to reheat the cylinder in one go, the burner is tripping at 73C which means the boiler SP is, 73-5, 68C, its refiring at 57C ish so, SP-11C, might be worth just increasing the the boiler SP to say 70/72C because its running at minimum output from ~ min12 to min 26, after which the cylinder coil is not able to absorb the boiler minimum output, that few extra degrees might allow it to run until the cylinder stat is satisfied.

When the HW (or CH) demand is satisfied then the zone valve(s) will close with the circ pump overrunning for another 3 minutes, is there a automatic bypass valve, ABV, installed somewhere?.