[paulbennett]

I mentioned this on the previous HN topic, the way the heating temperature is being controlled doesn't look correct to me. In all the boilers I've used the dial the servo is turning adjusts the temperature of the water being sent through the heating loop (to a blower or radiators) - this is not the heating thermostat. Generally you set this once and don't need to adjust it again, the thermostat does the work of turning the boiler on and off depending on when heat is required.

Similarly the dial above adjusts the domestic hot water temperature, while the system is running. Again, you rarely need to change it once its set to a temperature you are happy with.

Maybe I'm not understanding how this boiler works?

[radiowave]

There are circumstances where varying the closed-loop temperature might be useful. (Of course I have no idea whether this applies to the article.) In my system you get better efficiency by operating at lower temperatures (more of the heat in the flue gas can be extracted), but this (along with radiator surface area) limits the total rate at which heat can be transfered into the rooms. If you're allowing the house to get cold during the day when no one's in, having the water temperature at its most efficient setting might mean it takes several hours to warm the house back up. So it might be preferable to briefly run the system at a higher water temperature to more rapidly bring the room temperature up, then back off the water temperature to allow more efficient operation.

[kachurovskiy]

Talked to the heating technician this week. Here in Germany heaters are set to 55-60 degree by default and it's advised to not increase the temperature or the minerals buildup will ruin the system very quickly.

Water hardness here is high, around 20 degrees, so your mileage may vary.

[bluGill]

Are you mistaking different for correct? Generally the thermostat just turns the pump on, but is there actually anything wrong with leaving the pump on and changing the temperature?

[roel_v]

Yes: efficiency and keepimg temperature stable at a certain point (ie, with a small hysteresis).

Ad 1: the gist is that it takes less fuel to heat a liter of water from 30 to 31 degrees, than it does to heat it from 60 to 61 degrees.

Ad 2: with a lower temperature, it becomes easier to control your overshoot. Actually this is related to 1, but what you want in the end is to have a system that runs at as low a temperature as possible, all of the time.

[paulbennett]

I'm not entirely sure, however running the pump without actually heating the water seems like a waste of energy. Maybe that's how this boiler works though, I'd be interested to know more from the OP.