Indirect on warm start boiler

How is it 'warm start'? If it’s an older triple aquastat you can turn the low limit all the way down or modify the control. If it’s a newer one, you can take care of it in the programming.

A boiler with an indirect really won’t go 'cold' in the summer, unless it’s shut off.

I agree with @mattmia2 about the standby-time savings. I previously had a Buderus indirect tank that was extremely well insulated. When no hot water was being used, the only heat loss was through the tank jacket into the living space under the stairs to the second floor. That area had no outside walls, so the heat stayed inside the house.

The tank would take more than 18 hours to drop just 10 degrees, which was the thermostat’s differential. That worked out to about four 10-minute oil-burner runs every three days while the house was unoccupied. The boiler itself would cool down to room temperature within five hours or less.

Running the boiler as a warm-start system would definitely waste fuel that isn’t necessary. There’s no exact way to calculate your savings, since your usage may be very different from the vacation home I’m describing, where the house was often unoccupied for five days at a time in both summer and winter.

If your home uses a lot of hot water, the savings may be smaller because you won’t see the same standby-loss reduction that I did. That said, the bottom line is simple: any boiler temperature maintained above the boiler room temperature is using fuel unnecessarily, and every bit of reduction helps.

So one tank will take 8 hours of standby before the boiler needs to restart and that is on a very small water content boiler, My experience was 18 hours of standby time and my boiler was a cast iron oil fired boiler that completely recharged the 10° drop in the tank temperature is about 9 minutes and 46 seconds on average. but your standby time could be different and that depends on the boiler and tank that you have.

The control on the boiler does not need to be replaced and you don't even need to tell them what you are doing if you don't want to. Just remove 2 wired from the Low Limit side of the control and wire nut them together. Viola! you have a cold start boiler. read this post: