Buderus R2107 Domestic Hot Water setting

Stelcom66

I had the annual cleaning done yesterday. The tech was the guy who has been coming out for years and knows the system and my particular setup well. I mentioned how in the middle of a hot summer day the furnace would be running for what I assumed was DHW production. He then set it to AUTO which if I understand correctly will just run in 'Day' mode. I noticed this morning the water was not as hot, but adequate. What i should have told him was, this time of year it's always in 'Night' mode. This I assume would mean with the DHW setting switched from 24 HRS to AUTO there would be no DHW heating. I just called the shop to confirm - someone will call me back.

If I have the furnace in Auto mode and the temperature all the way down - and the system is in Summer mode (an umbrella icon is illuminated) I assume the system would only run to heat the DHW during 'On' times, weekdays beginning around 6-7am, and for an interval late afternoon correct? During cold weather I use a wood stove a nights and weekends. I think Summer mode is 55º. I suppose I could reduce that a bit too. That could be a concern though with the clothes washer needing hot water. I wonder if I'd be saving much fuel overall in Auto mode.

Big Ed_4

I would set shut off the "day-night " for a single family home with thermostats …

You want to keep the control on "auto " … The setting for hot water is the Faucet button. Push it in and turn the knob to adjust ..The boiler temperature setting knob should be set to Auto…

Stelcom66

Since the end of April or so it's been in Night mode. When it's colder next month, I'll change it to Auto for a brief interval of heat in the morning. Due to always being in Night mode this time of year - as I suspected the DHW was not being heated, it got down to 85º. A callback from the tech confirmed DHW would in fact not be heated with my settings.

For now I set it back to 24hrs. I may review the Day/Night settings in consideration of DHW production. Which if I understand correctly, will only occur in Day mode. I certainly don't need any heat in the radiators now, so my plan is to set the living area control/thermostat to Auto, with the temperature all the way down. That, and Summer mode I believe should keep heat to the radiators off.

Big Ed_4

You have the room sensor , the knob adjusts the boiler temperature curve for the room set point .. There is a programed timed set back for the system to follow if used . The hot water production can be programed to follow or not …

Stelcom66

With DFW set to Auto, I assume it will follow the programmed timed setback. My concern was providing heat in the house, which at this point I don't need. With the knob at the minimum temperature and Summer mode I hope only hot water production will activate (heating) but not the circulator pump to provide heat in the house around 6am weekdays.

Big Ed_4

Down load the manual …

Stelcom66

I did when I got the furnace. A few different ones, including installation and service. I will run DHW in Auto.

Stelcom66

This seems like the way to go - setting DHW to Auto. I haven't heard the furnace run except for the 'On' times, which is in the morning late afternoon. That's enough to have hot water in the morning and evening. During warm seasons it's not heating the house, as the temperature control is all the way down and I lowered 'Summer Mode' to 50º.

I do think this will save fuel. I had the tank filled about a month ago, it was down to about a quarter tank. The last time before that was the day after Christmas 2023. It's just me here, and the wood stove helps. So even before this setting I don't use the typical household amount of heating oil. But not all the wood I use is free.