Water or antifreeze in OWB?

[PAmizerman]

Did you fill your outdoor furnace with water or antifreeze?

[thecfarm]

Water, but we have good water. Wife use to have a cooking license and had to have a mandated water test for the state. The water has to be tested above a home owner water test.

[Gary_C]

It depends on your system and how you want to run it. Water is the cheapest and better of the two for heat transfer than antifreeze but water in a closed loop system must be treated to avoid problems. What can cause problems in a water system is iron content, mineral content like calcium plus acidity.

Central Boiler sells a water testing kit plus a treatment chemical that will work in any closed loop system and I'm not sure about other OWB sellers.

Automotive antifreeze is not recommended because of poorer heat transfer abilities but many people use it in systems that are subject to freezing like outdoor concrete slab heating systems. There is a commercial antifreeze that is recommended for closed loop heating but it's not cheap. 

[gspren]

It depends on how you use your OWB. If it will be fired all winter use water, if like me you plan weeks away use the special antifreeze, only downside I've seen is cost. The talk about heat transfer is usually misunderstood, the mixture is still half water and the water being circulated takes care of any other SLIGHT difference in transfer, remember stainless steel has one of the worst thermal transfer properties of all common metals but they still work because of the liquid, I've run mine both ways and can't tell the difference but as I type this we are at our DE home and the OWB in PA is cold, tomorrow afternoon it will get fired up after an 8 day shut down. JMHO

[woody_88]

Water, but we have good water.

+1 on the good water. I am in process of a new warranteed out central boiler, my suspicions is our salty-high iron well water eating a hole in the water jacket. Only 1 year

[DR Buck]

It depends on your system and how you want to run it. Water is the cheapest and better of the two for heat transfer than antifreeze but water in a closed loop system must be treated to avoid problems. What can cause problems in a water system is iron content, mineral content like calcium plus acidity.

Central Boiler sells a water testing kit plus a treatment chemical that will work in any closed loop system and I'm not sure about other OWB sellers.

Automotive antifreeze is not recommended because of poorer heat transfer abilities but many people use it in systems that are subject to freezing like outdoor concrete slab heating systems. There is a commercial antifreeze that is recommended for closed loop heating but it's not cheap.

I ran my Central Boiler for over 10 years on just water.  In fact other than a topping off once after a couple years it was the exact same water.   I had zero problems.    I did the recommended water test quite a bit when I first got it up and running and had no reason to add anything to the water.   After a few years I got to where I only checked it once before I fired it up for the season.  I never used any anti-freeze and kept mine burning all winter. 
I found that if I was going to be away for any period of time in the winter if I loaded it to the max wood I could get in, and lowered my water temp to 75º - 80º  it would be fine for 4 to 5 days even when outside temperatures were below freezing.   I'd also set the inside thermostat down to around 60º so the air circulation fan would not run as much,reducing the amount of heat taken from the OWB water as it passed through the heat exchanger.  

[Al_Smith]

It's not for me to say only perhaps mention hard water .I have same ,iron which the softener takes care of most of it .However if on  the occasion I need to top off or completely  change the coolants in my automobiles I use distilled water .It's relatively inexpensive at the most only requiring two gallons per vehicle at 99 cents a gallon .
I have no idea what an outside burner would require or  if it would be cost prohibitive in such an application .I do know certain water conditions at work that required a lot of water utilized gigantic RO filters to assure water purity .

[doctorb]

A coupe of these posts have mentioned cost.  If you use the available environment-friendly antifreeze, and have a large capacity water jacket, you are talking about a very large expense to protect your furnace and pipes.  I do agree that if you use your OWB intermittently and are not around the remainder of the time, you probably need to protect the system.

On the other hand, as has been discussed on the Forum before, by just constantly running the pump, my system gets no lower than 53 degrees.  There is always some heat transfer to the system from inside your basement and the underground pipes.  Now, if the pump dies or the electricity is off for a prolonged period, things will get dicey.  But, in my experience, I am not concerned about pipe or furnace freeze as long as the pumps are running.  I can easily check whether the pumps are running from my basement, and I do so 3-4 times a week under normal winter conditions, and daily when we get to single digit temperatures.

Secondary to some recent back surgery, I am taking this winter completely off from using my OWB, and I have no antifreeze in my system.  It's a bit unsettling in the beginning, just letting the system sit with only the pump running as the temperature stays below freezing, but, after years of looking at this, I am quite confident that my system will not freeze if there's water moving through it.  So the antifreeze question is not really a question for me any longer.

Here's the thread with daily data on my OWB winter shutdown and how the temps fared with just the pump running.

https://forestryforum.com/board/index.php?topic=55740.msg807380#msg807380

[Gary_C]

  I can easily check whether the pumps are running from my basement, and I do so 3-4 times a week under normal winter conditions, and daily when we get to single digit temperatures.

How do you know from your basement if the pumps are running? 

[thecfarm]

Copper at 180° you can not hang onto, PEV at 180° you can. I don't check mine,unless I feel something is not right, but the above is true. The guy that installed my OWB told me this.

[Gearbox]

Water only . Mine is tied into my gas boiler in the house . If the OWB goes  out the gas in the house keeps the OWB about 120 .

[E Yoder]

We rarely use antifreeze anymore. Due to expense and issues it causes if it turns acidic.
If I leave I let the pump run. No issues for 12 years.

[doctorb]

Gary C-

I have temp sensors on the intake and outflow pipes entering my basement.  If the pump wasn't running, the pipes would have a temp close to, but maybe a little below, the ambient temperature of my basement (which is, when I'm using the oil furnace, a minimum of 68 degrees).  When I see the temp in the OWB lines is in the 50's, I know the water is circulating.

The other way I can check is by closing and opening a valve.  I have a return loop in my system that permits me to shut off the water to the heat exchangers and just send it directly back to the OWB.  That's how it is set up when I am not using the OWB.  If the water from the OWB is not circulating, you hear nothing when you close the valve as there is no flow to stop.  If you close the valve while the water is circulating, you can hear the change in water flow as you close the valve.


Neither method is probably full proof, but it beats a trip to the stove.  Thoughts?

[Gary_C]

I was just wondering as this winter as well as some times in past winters I have let my Classic go out at times and I did not have the foresight to put temp gauges in the basement. So my only good means of checking anything is by feel.

My system is very simple as the entering hot water goes thru a sidearm heat exchanger on the hot water heater and then thru a coil in the oil fired forced air furnace. I do have a three way valve for the furnace coil that allows me to bypass that coil but I rarely put that on bypass.

When I let my OWB go out, the temperature does not go below about 86 out at the wood stove and I'm sure both the sidearm and the furnace coil are adding heat to the water. Last winter when I let the OWB go out for a longer period, I also pulled the fuse on the door damper so the draft would not pull air thru the stack and the temperature of the water did not go below about 104. When the OWB was off, I did not see any significant increase in either oil consumption or electrical usage.

I hope your back recovery is going well. My excuse for not running the OWB is being a caregiver for my wife (Alzheimer's) and dealing with closing up my sister's estate this past year which has left my cut and split wood supply at near zero. I have a bunch of real old logs laying around that I cut up as I have time but it's very poor quality wood and burns fast. It's nice to just keep oil in the tank and not worry about the OWB at times.

[doctorb]

Gary C -

I also found my OWB system was being heated by my oil furnace, when I didn't have the return loop that separates the heat exchangers from the OWB.  I just decided that I would use that to my advantage, if needed.  Haven't needed to do that and, with a 9 year history behind me, I don't foresee ever having to do so.  Just saving a bit of fuel oil rather than warming the OWB.

When my OWB was set up, I have a switch to allow just the pump to run, keeping any blowers and solenoids completely off.  So its easy for me to just circulate the water while the rest of the electronics are dormant.

We both have used or OWB's for quite a few years.  I like the activity of maintaining it, I guess some would call that crazy, but I do.   Not sure if I'll get back to it in the future or not.  Life has its priorities and they change with time, like everything else.