Freeze Protection - Antifreeze may be my only option

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hartkem

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Jan 24, 2012
249
KC
I have my new EKO 40 outside in my dedicated boiler shack 130' from the house. My 490 gallon pressurized insulated storage tank that I bought from new horizons is located in my basement next to my forced air furnace. My wife and I have very inconsistent schedules so may not be able to avoid antifreeze for freeze projection. I know antifreeze should be the last choice but lets assume its the most reasonable option due to my situation. I am having a hard time swallowing the price of 250 gallons of antifreeze. I am contemplating on using a water to water plate exchanger to separate the inside storage tank from the boiler. I would then use antifreeze only on the outside boiler side which would probably less than 50 gallons of water. My concern is efficiency of the plate exchanger and the negative impact that this would have on the capability of my system.
 
If you go that way just size the heat exchanger for a very close approach temp. (approach temp = difference between side A and side B) You won't lose any efficiency so to speak, just a few degrees of available temperature. Let me know if you need help sizing.

The other thing to remember is that when you go away and let the boiler go "cold", the heat exchanger in your furnace will begin to transfer heat back into the wood boiler once water temp drops below the air temp in the plenum. You'll definitely lose some heat from the fossil fuel side of things due to the water circulating in the HX "robbing" a few btu's from the air stream but as long as you have circulation it won't freeze anything outside.
 
Insulated piping underground to and from a reasonably tight and insulated boiler shack, and the boiler shack itself should be very easy to protect from freezing.

All you should need is a small thermostatically controlled electric heater in the shack just in case, and then a timer to circulate a little water through the underground lines from time to time just to make sure some unexpectedly cool spot doesn't freeze.

The lines themselves can go for weeks without freezing most anywhere south of Yellow Knife, it's just the isolated cold spots you need to worry about.

--ewd
 
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I agree with ewd's approach. I have an insulated outside boiler room 70' from the house. I insulated the shed piping, bought a thermo-cube freeze protection plug, a small 1500W heater in the shed. It won't let the shed freeze. You would be amazed at the thermal mass in the boiler, it does not take much to keep warm. Having a freeze protection PID in the boiler room would be ideal - cycle the circulator when temp <x. The "heat" you take from storage will be more than made up by the saving from not buying a HX, not buying (and servicing) glycol, and no using a lower capacity transfer medium (glycol solution). You might even consider wiring a power feed to the circulator from a freeze protection cube. Simple, cheap. Hmmm, how to place two thermo-cubes; Stage 1 - the heater, Stage 2 - the boiler circulator. Just an idea.
 
Why not set it up when the wood boiler drops below a preset temp the pumps comes on to circulate from the tank to the wood boiler?
 
EWD's approach is good also. We've done it that way many times. They key is maintaining circulation.

I sure wouldn't recommend antifreeze unless absolutely required.
 
I'm doing something like henfruit's suggestion. using a UPS to back up the Laddomat circulator, boiler controls and using a diverting zone valve to bypass the laddomat boiler protection/ if the shed (or boiler?)temp should drop below 35F. it'll just flip the zone valve over so the boiler will receive water from the bottom of the tank and circulate back into the top of the tank.
if theboiler's firing when the power goes out, the boiler/pipe will be above 35 F,and the zone valve will be in the normal/run position anyway. protection for the price of a zone valve and aquastat. not too bad. The backup system will be in place anyway.
 
I see now after reading all your responses that it will be easy to control freeze protection. I like the idea of a small electric heater controlled by the thermocube. Doesn't the EKO have built in logic to turn the circ pump on when there is a risk of freezing? My boiler shack is 10x12 and I plan to insulate it well. I will bury the thermopex at 36" to help out.
 
yes the eko will turn the pump on when the temp gets to 40*f this will only circulate water around the boiler. You risk freezing at the pipes coming out of the ground.......easy fix you can use heat tape and insulation to get you buy. I used mine in my ploe barn for 2 years with no insulation. I just wrapped the pipes up real well with insulation and never froze anything.

Rob
 
I have a 1/8" hole drilled in my Danfoss plate - this allows trapped air to get through and also allow a little circulation when the boiler goes into freeze protection. I never see it freeze but I guess it is there. Early on, before the shed was insulated and I was an absolute newbie, I did freeze the pipes. Gets quite interesting! My shed is now insulated, the pipes are insulated, contrller freeze protection, AND a thermo cube. No problems.
 
yes the eko will turn the pump on when the temp gets to 40*f this will only circulate water around the boiler. You risk freezing at the pipes coming out of the ground.......easy fix you can use heat tape and insulation to get you buy. I used mine in my ploe barn for 2 years with no insulation. I just wrapped the pipes up real well with insulation and never froze anything.

Rob
Is this because the thermostat inside the danfoos will route the water back to boiler? So how do people circulate water through the entire primary loop for freeze protection? An additional pump or special piping layout?
 
That is one huge thermal mass you have there in the storage tank. It would seem to me that with a storage tank that size and a boiler that size, you will never freeze up your system if the Taco pump runs continuously, as they do in my open CB systems. I designed my boiler loops with flat plate Hx's for hydronic floor heating and DHW, and the efficiency does not drop much from using them (if they are sized right). Isolating the boiler loop with Hx has several advantages. I would not use antifreeze as it lowers the thermal transfer properties of water. Being able to reverse the heat flow would depend on the way that you set up the Hx on the storage tank. If you use a passive convection loop with a FP Hx on the storage tank low down on the loop, the convection flow will be cut off when cold water returns from the boiler. It will still absorb heat there though, but it is not as effective in reverse mode (which could be a good thing for freeze protection). My systems rob heat from the DHW when the fire goes out.
 
Insted of spending your money on glycol buy a battery backup or a generator. Then If the power goes out you can still run the boiler. An electric heater for the boiler room while on vacations.
 
To ease my mind and save some electricity I added a small pump into the boiler loop to use as an "antifreeze" pump when the boiler and "big" pump were shut down in cold weather. A small gas boiler was used if need to add a little heat. We don't normally get the bitter cold weather that some of you get, but it worked well.

pumps1.jpg



smpumps.jpg
 
Nice plumbing fuel farmer. I'll bet it's plenty warm in that room when the waters hot.
 
Hartkem,
How long will you be away from the boiler?

I have my boiler in an insulated building with 50ft of thermopex to house. My pex is just 1ft under grade in one spot, 4ft when enters house.I start a fire once a day in the deep of winter(sub zero at night) and then every 2 or 3 days in the easier days of winter. I was a little nervous at first about freezing, but it's been good. No problems. I live in northern Maine btw. Stay away from antifreeze, IMO.The circulator idea is more than adequate and cost effective.

Basically the colder it gets the more fires I have, keeps it comfy in there. My room is 12x8 with a 10ft ceiling. 6 inches of F/G in walls and ceiling. No additional heat needed. I did keep an electric heater in there the first part of the winter, but now it's gone.
 
I like the Surge milk tank. looks like a big one, at least 2500 gals? nice looking piping

The tank is 1000 gallons. I could us 2500 gal or more. Back when I was trying to figure pump flow rates I was able to use the milk measuring dip stick and charts to get really accurate measurements.
 
Is this because the thermostat inside the danfoos will route the water back to boiler? So how do people circulate water through the entire primary loop for freeze protection? An additional pump or special piping layout?

Yes the danfoss will only open when the return water is above 140*.........explain to us your what your schedule would be like for you to worry about freezing your boiler.

Rob
 
Yes the danfoss will only open when the return water is above 140*.........explain to us your what your schedule would be like for you to worry about freezing your boiler.

Rob
Well Its common for me to be gone 2 weeks a month. Possible 2 weeks at a time. My concern is the electricity going out while im gone.
 
Well Its common for me to be gone 2 weeks a month. Possible 2 weeks at a time. My concern is the electricity going out while im gone.

Add a 60W solar panel to a battery backup system for the circulator. You'll have everything you need for when you are home or away. I use backwoodssolar.com for my solar stuff. You could set up your boiler to run off inverter system from a battery, and the battery charged for AC voltage and/or a solar panel. While you are away, you are not running the boiler fans so all you need to run is the circualtor for freeze protection when needed.
 
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Ok then i would go with your plan with the antifreeze and flat plate HX. many ways to keep water flowing like a danfoss bypass like in my blog pics but if it is a power outage that your worried about i would go with plan 1.

Rob
 
Don't know your piping arrangement but if you have primary / secondary I would not be too concerned with constant circulation. You will not freeze 500 gallons of water that fast. I would only be concerned if it was for an extended period of time(Weeks).

Good luck
 
To ease my mind and save some electricity I added a small pump into the boiler loop to use as an "antifreeze" pump when the boiler and "big" pump were shut down in cold weather. A small gas boiler was used if need to add a little heat. We don't normally get the bitter cold weather that some of you get, but it worked well.



smpumps.jpg

That is one large fortune in copper there! Scrap copper is $4 a pound now. PEX would be a heck of a lot cheaper... I had a miniature version of that distribution syetm with my hydronic floor heating system, which was all PEX after a brass header.
 
That is one large fortune in copper there! Scrap copper is $4 a pound now. PEX would be a heck of a lot cheaper... I had a miniature version of that distribution syetm with my hydronic floor heating system, which was all PEX after a brass header.

When that was installed 10 years ago I priced CPVC and copper. There was not much difference in price. Yes today it would be pex.
 
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