long term owb shut down

[luap]

This was our last winter burning wood due to declining health. Now it will just be propane furnace. I would like to keep the owb ready to use for a backup but need to look at anti freeze etc and what it would take to put it in long term mothball but still ready to use if needed. It is a Hardy stainless steel stove and has been trouble free. I think it holds 175 gal but would have to double check that. * edit , just checked and it is 100gal. The coldest temps I have seen in my life time here has been -50 F but it seems the last decade it's only been in the -20's F. I would welcome any suggestions.  

[gspren]

I use boiler antifreeze but it's expensive and if your system is that big not worth it. How easy or difficult would it be to drain the system? If you could drain the boiler and blow air through the outdoor lines that would be best. If your circ pump will prime with only a few gallons then you could get a 5 gallon bucket of antifreeze add a few gallons of water and use that to exercise the pump twice a year.

[luap]

The system is easy to drain. Takes a little more to fill it though. I want the stove to be easy to startup if needed. so  I haven't looked at the exact cost for antifreeze but at 100 gal capacity I wouldn't have to have it filled completely. For a 60% solution rate of antifreeze that would be 40 gal. Menards is $60 for 5 gal so approx  8 - 5 gal pails at  so looking at approx. $500.00  I may just have to bite the bullet for the peace of mind for protection. I have had this stove since 2008 and to replace it would be lots more. I appreciate the thoughts though as I also heat my shop with it and those lines could be drained. 

[gspren]

The past two years with oil being cheaper, me being older, and we aren't hurting for money and since we retired we often go away for a week or two every month I only burn the OWB to heat a small out building when I'm here. The antifreeze works well for our off and on operation. I still like cutting some wood so this works OK for me plus it's a good backup. With this extended "self quarantining" I'm actually further ahead on wood than I've been in a few years so next winter I may heat the house some again.

[E Yoder]

If you do drain it remember that just opening the drain valve doesn't empty out the pump. I replaced a pump yesterday for a customer who "drained" the OWB and went to Florida. Came home and started heating the pool, except the pump had split open.
Hot air coils are notoriously difficult to blow out with air, much easier to pump antifreeze through.
You've probably thought of these things, just putting it out there.