What do I do with my indirect water heater when I go on vacation?

SAMB

My indirect water heater runs off an oil-fired boiler. It's pretty efficient, but of course even when there's no demand it still loses enough to kick on the burner every so often. If I'm going to be away for a week or two, I'd like it not to kick on at all, except to keep the house at a minimum temperature. I'd be happy to have to wait a bit for hot water when I return if I can save some oil while I'm gone.

So other than lowering the temperature on the water heater, which is something of a pain, what else can I do?

The system has a shut-off valve for the feed to the water heater. What happens if I close that valve?

Any wisdom offered will be greatly appreciated.

Hot_water_fan

If you don’t want to lower the temp, I’d just leave it be: yes there will be some standby losses but it’s unlikely you’ll feel them. When I’m home, the max therms I use a month for DHW is ~20, with a ~60% efficient heater. If we’re talking about the summer, it’s about half that. So if 10% of that is standby and you’re only away for a week or two, we’re talking 2.5%-5% of a small amount if you completely zeroed out standby losses. 

Steamhead

You could wire a switch in series with the tank's thermostat, and turn it off when you go away.

hot_rod

If you turn it down or off, I would run it up above 140 for 1/2 hour when you turn it on again. Just to be sure and potential bacteria growth i dealt with. Let some run out of the shower also, as non use is when legionella takes over in the piping.

pecmsg

hot_rod said:

If you turn it down or off, I would run it up above 140 for 1/2 hour when you turn it on again. Just to be sure and potential bacteria growth i dealt with. Let some run out of the shower also, as non use is when legionella takes over in the piping.

ASHRAE Recommends 140* F for 1 hour to kill the bacteria. 

STEVEusaPA

I usually only get to vacation in warmer weather. I shut everything off, turn off water coming into the house.
When I get I turn the water back on and fire up boiler/indirect.
Been doing it 20+ years without an issue.
As a side note laundry is usually the first hot water usage.

flat_twin

"So other than lowering the temperature on the water heater, which is something of a pain, what else can I do?

The system has a shut-off valve for the feed to the water heater. What happens if I close that valve?"



If turning down the aquastat is a PIA, then you probably don't want to take Steamhead's advice and install a switch to disable the aquastat (Good suggestion). You could also just disconnect one wire of the aquastat. Loosen screw, lift wire.


Turning off the water supply to the water heater doesn't stop the boiler from firing when the indirect temperature falls.

SAMB

Upon reflection and consideration of what's been put forth here, I think the best I can do is to let it be. Can't be all that much oil that'll be lost. Thanks to all.