We have a lake cottage in Ohio that we visit mostly on weekends, 1-2 weekends a month. We use it year round.

There is a New Yorker Boiler oil fired boiler, it's mounted outside on a concrete slab. Model is OS114 - rated for outdoor use. About 25-30 years old now. It has been a workhorse but is showing its age and I am planning on what to do next.

I am having trouble finding many outdoor boilers, this was all I could find. Any opinions on these?

http://www.thermodynamicsboiler.com/os_series.htm

Other boiler makers tell me to build a little shed adjacent to the cottage but I'm not convinced I can make it damp proof sufficiently that the mild steel parts won't start rusting immediately.

I really don't have the room to move the boiler indoors. The utility room is already overfilled with mechanicals. If I absolutely had to move it indoors, it would need to be a tankless model of some kind. I'd prefer a tankless electric boiler if such exists, because there is no flue available right now in the utility room.

I keep the thermostat set at about 46 when we are not there. I'd like to go lower but I of course worry that the water in the boiler will freeze. From the exterior wall, the pipes have about 2-3' of run before they enter the boiler. I have them wrapped of course. It has worked well up till now, the boiler is running often enough, so far no damage. With the cost of oil rising, I am tempted to add some antifreeze to the system and try to run it around 40 when not there - thoughts? (Would do this during boiler replacement.)

I have an internet thermostat and crank it from 46 to 70 a few hours before we leave home and its warm when we arrive.

It used to rise the temperature at 7 degrees per hour, last time the HVAC guy came out he said the boiler was set too hot and dialed it back and it now rises 5 degrees per hour, still fast enough for me.

Ideas and suggestions?

Brian