Domestic Hot Water Priority
- Rob R.
- Site Moderator
- Posts: 18004
- Joined: Fri. Dec. 28, 2007 4:26 pm
- Location: Chazy, NY
- Stoker Coal Boiler: EFM 520
- Hand Fed Coal Stove: Chubby Jr
In that case, I suggest skipping the DHW priority altogether. The last thing you want when it is -20F is for the circulator to not run for a period of time due to high DHW demand. The fancy zone controls do offer a "timeout" that will allow the other zones to run after a certainly length DHW priority, but even an hour with no circulation on an outside loop is risky in severe weather.
An alterative would be to drop only the zone for the main house if the boiler temperature drops below setpoint. This is less likely to cause freezing issues and you would notice it quickly.