I have gas water heater and boiler. I'm not too familar with hoe these work. I know the heating system is forced hot water through baseboards. if I go on vacation and turn the water heater off, this won't affect the boiler will it? The water being circulated around the baseboard is not from the water heater is it? probably a stupid question but I would very much appreciate some feedback
Your domestic hotwater shouldn't co-mingle with your heating hot water, and you should be able to turn down the water heater without problems.
Also you should not have to worry about lines freezing by turning down the water heater any more than if you were to leave the temperature up. The heat doesn't migrate to the far ends of the hot water supply without water flow. Now if you were to turn down the hot water heat too low, and have poor water line placement that could cause a freeze and possible burst.