Extended Shutdown Freeze Protection ?

If someone [me] gets to put a stoker boiler in a shop that is not used on a daily basis is there an alternative to hydronic anti freeze? I started to gather pricing and unfortunately this boiler alone has 53 gallons of water capacity.Talking with the anti freeze people,that will require over $600.worth of product.I would rather not run out there and build a new fire every time the temps go into the freeze damage zone,that could not only double my coal cost but would be a pain.Anyone out there have an idea for a way around the 600 bucks? They tell me RV anti freeze is only trouble in the making when used in a hydronic system.This whole idea of installation is not frozen yet ,but it is getting mighty slushy. Thanks Mike

If you are going to put an unfired boiler in an unheated building for and not use it at least every other day, then I would say antifreeze would be the only way to go. 30% solution of propylene glycol wholesales for about $4-5 a gallon in 55 gallon quanities. With 5 gallon pails it can jump to $15 a gallon due to handling and container costs. You will have to find someone to purchase the glycol through and expect to pay a markup, tax and possibly a delivery charge.

The chemical companies predilute the glycol for you to ensure no on site water impurities affect the solution. If you need more than 55 and less than 110 gallons, buy in a greater strength and dilute on site with distilled water or water that has gone through an reverse osmosis machine.

30% will freeze proof the system to 3 deg. F. and burst proof the system to -10 deg. F. Even if it is that temp outside, it will take days for the building and system to reach that temp.

Dow Corning and Interstate Chemical Co., Inc. are the two major players I know of in HVAC gylcol solutions.

Other options are:

1. Get a stoker furnace or stove in lieu of a boiler. No water to freeze.

2. Get a thermostat that allows you to set the building temperature at 40 deg. f. when you are not out there. It takes very little coal to keep the building at 40 on a yearly basis if it is somewhat sealed and insulated. I put over 100 gallons of glycol in my system thinking the same thing as you. I got tired of re-lighting the fire and wanted to leave the plumbing operational during the winter. The second year I left the thermostat at 45 degrees during the week. Most of the time, I was burning about 15 lbs a day just to keep the fire lite. Only in extremely cold weather did I burn coal to keep the building from freezing. I found I was burning just under two tons a year to keep my 2400 square foot workshop warm with only turning the thermostat up on weekends.

Glycol will keep your piping system clean as it is slighly agressive. Any leak that would normally self seal with plain water will continue leaking with glycol in the system. You must have perfect joints or leaks will be an issue. Also, the gylcol should be tested every year to make sure it has not lost the inhibitors and become corrosive.

Thanks steamup,the most helpful information usually comes from first hand experience.I have a better picture now. Mike

Yup, what Steamup said.. and don't forget that with antifreeze in the system you will not transfer as much heat in the same amount of time. It will take longer to bring the building up to temp when asked to do so as anti freeze does not transfer heat as quickly as water. If you have a borderline system....that is...if you have just barely enough baseboard or radiators to do the job, you may find that with anti freeze it will not do the job. If it is new construction add about 20% more baseboard. Now, don't get this confused with efficiency. It will not take more fuel to heat, it's just that the heat comes slower.

Thanks Freddy, you brought out one more factor that makes the anti freeze route a disagreeable way to go.With the yearly monitoring,ability to find the smallest piping imperfection and leak on us,the poor heat transfer,the disposal if it goes flat, and still the biggest "ouch" is the cost.The best I could do around here so far is $18.00/gallon.If I go ahead with this install [when and if I can get this boiler] it looks like I will need approx 30 or so gallons.I am starting to think that a big ol' fat furnace is starting to look pretty attractive to me. Mike

Just some clarifications and info-

If you use propylene glycol, it is non-toxic an disposal is not a problem. Ethyelene glycol is toxic and is a disposal problem.

At 30%, the Specific heat is .944 with an increase in viscosity. The lower specific heat can be compensated for by an increase in flow and/or temperature. The viscosity increase means you have to figure a little more head for the pump. Add about 10% and you should be ok.

Another trick to a boiler and plain water would be to turn the aquastat way down to the minium setting during unoccupied times. This would minimize coal consumption while keeping the system hot for freeze protection.