# Outdoor wood boiler question??



## roselle (Oct 20, 2013)

I have an outdoor wood boiler, that heats my house and my hot water. How would I be able to keep my house plumbing from freezing if I went away during below freezing temps? There is no other heat. Also...Would the boiler itself freeze and crack? Is there anything I can do to protect it?

Good grief! My life is so complicated!


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## Caribou (Aug 18, 2012)

Yes, you can add propylene glycol to your boiler. Freezing can rupture your boiler. I hope you are not pulling the domestic hot water directly from the boiler. A side arm water heater is fairly common but it is old school and could be problematic in your situation due to freezing potential. A better answer would be an indirect domestic water heater run as a separate zone on your system. 

A bit more info about your system would allow me to give better advice. Also what is the record low temperature in the area?


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## roselle (Oct 20, 2013)

Caribou said:


> Yes, you can add propylene glycol to your boiler. Freezing can rupture your boiler. I hope you are not pulling the domestic hot water directly from the boiler. A side arm water heater is fairly common but it is old school and could be problematic in your situation due to freezing potential. A better answer would be an indirect domestic water heater run as a separate zone on your system.
> 
> A bit more info about your system would allow me to give better advice. Also what is the record low temperature in the area?


My boiler runs the hot water to my electric water heater, that is inside my basement. The water heater, is one of those heat pump/hybrid things and keeps the water hot until we need it. My boiler has a 300 gallon water jacket.

I just put in 2 gallons of "Control," which is the anti-corrosive we use.

Our average low temps here, for Dec.-Feb. are 25-29 degrees, although we are already getting into some lower than that. The record low was -20.

Thank you!


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## hiwall (Jun 15, 2012)

All the regular house plumbing would have to be drained and the lines blown out. Drains would need some anti freeze put in them. Your boiler would have to be mostly drained and antifreeze put in and then the pump run to send it through all the lines. The whole job would take awhile and just blowing out water lines is sometimes iffy. You might want to add RV anti freeze after you blow them out.


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## cowboyhermit (Nov 10, 2012)

This is why most outdoor wood boilers up here in Canada come with a backup, typically nat. gas but also propane or coal. It might be worth it to have someone look after the place while you are gone. 

The person who installed the boiler should be able to tell you how to protect it from freezing, household plumbing is another matter.


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## roselle (Oct 20, 2013)

cowboyhermit said:


> This is why most outdoor wood boilers up here in Canada come with a backup, typically nat. gas but also propane or coal. It might be worth it to have someone look after the place while you are gone.
> 
> The person who installed the boiler should be able to tell you how to protect it from freezing, household plumbing is another matter.


I visited him today and he had no clue what to do. No one to babysit it.


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## cowboyhermit (Nov 10, 2012)

That's too bad, those things aren't cheap to install, would expect better service:dunno: 
The advice others gave is good though. Only other solution I can think of is using electric heaters temporarily, but that isn't always the easiest/cheapest/safest.


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## Caribou (Aug 18, 2012)

Propylene glycol for boiler is typically sold in 60% solution and 95%. Depending on the brand there will be from 2% to 6% of anti foaming and anti rusting agents. 

I would guess that you will wind up with about 25-30% glycol in your system. Get yourself a hydrometer and titrate your glycol to freeze protect the system to about -10 to -20F. You want to be prepared for the worse case scenario. there will probably be a chart on the container so you know the percentage of glycol for the temperature you want to protect for.

You will need to figure out how much coolant is in your system. The boiler paperwork will tell you the boiler capacity. Measuring the total length of the piping will give you an approximation of the total volume. Once I figure out how much glycol I want to put in the system I take about twice that much fluid out. For example if I want to add five gallons of 95% glycol I remove ten gallons of water from the system. I then mix the glycol and an equal amount of water and I pump this mixture into the system. Let this mixture circulate for two or three days then test the concentration.

This is all based on having a clean boiler. A new boiler is dirty due to the manufacturing and the oil placed on them to keep them from rusting.


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## roselle (Oct 20, 2013)

Caribou said:


> Propylene glycol for boiler is typically sold in 60% solution and 95%. Depending on the brand there will be from 2% to 6% of anti foaming and anti rusting agents.
> 
> I would guess that you will wind up with about 25-30% glycol in your system. Get yourself a hydrometer and titrate your glycol to freeze protect the system to about -10 to -20F. You want to be prepared for the worse case scenario. there will probably be a chart on the container so you know the percentage of glycol for the temperature you want to protect for.
> 
> ...


Oh my! This just overwhelms me! My boiler was custom made. It has a 300 gallon water jacket, and it is about 20 ft. from the house, then the pex tie into the old furnace, to blow the heat into the house. (That furnace/heat pump doesn't work, except for the fan) The pex for the hot water, then runs another approx. 20 ft., and lays on top of visquene(sp), in my crawl space, and runs into my water heater. The pex is insulated.

I see this trip getting cancelled.....The plus is we would go soon, before it gets too cold, and the lows are only supposed to be in the 20's, but my kids have done without heat, and I don't ever want them to be cold again. Another plus is everything at my home is a learning experience.

It's been suggested I leave the pump circulating and that would prevent the furnace from freezing or just pack the firebox with wood, and set both the inside and the furnace thermostat to 40 degrees...


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## roselle (Oct 20, 2013)

cowboyhermit said:


> That's too bad, those things aren't cheap to install, would expect better service:dunno:
> The advice others gave is good though. Only other solution I can think of is using electric heaters temporarily, but that isn't always the easiest/cheapest/safest.


This guy is actually very nice and honest and he built the stove well...But he just decided to build these things and that is all he does. He is a welder, but he hasn't moved on to the next steps, such as using radiant heat with them etc....I asked for the electrical schematic, and he had no idea.


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## Tirediron (Jul 12, 2010)

Depending on the system design, IE does it need an pump to circulate or does it have enough elevation change to thermo syphon if the pump fails, you should be able to add a propane or natural gas fired hot water heater to the loop to keep things from freezing. If you need a pump to circulate then you need a glycol solution in the loop at least to the tempering tank , depending again on the system design (closed or open tempering loop)

A friend of mine has designed a system that uses solar hot water (glycol mix) panels, a large very well insulated heat battery tank , and a outdoor boiler.

With this system he plans to heat the battery tank to close to boiling by the solar panels in summer, and as they use up the heat, sometime in January the solar system won't be able to keep up, just before this he will fire up the outdoor boiler and run it full blast until the battery tank is near boiling again. 

A battery tank might be a possible solution to you concern as well as a way to gain a lot more efficiency from your boiler, because higher temps mean higher btu conversion.


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## roselle (Oct 20, 2013)

Tirediron said:


> Depending on the system design, IE does it need an pump to circulate or does it have enough elevation change to thermo syphon if the pump fails, you should be able to add a propane or natural gas fired hot water heater to the loop to keep things from freezing. If you need a pump to circulate then you need a glycol solution in the loop at least to the tempering tank , depending again on the system design (closed or open tempering loop)
> 
> A friend of mine has designed a system that uses solar hot water (glycol mix) panels, a large very well insulated heat battery tank , and a outdoor boiler.
> 
> ...


Mine needs a pump to circulate....A friend is coming tomorrow and going to rewire the pump, so the water will continuously circulate. I posted on another thread that my kids and I want to build solar panels to run the boiler, so we won't need to use electricity to heat with wood. However I don't know how to do this and the guy that built the boiler, doesn't know what the electrical schematic is...Thanks for your help!


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## Caribou (Aug 18, 2012)

Boilers are not rocket surgery. The difficulty is that the breadth of information can be daunting. Learn a little bit at a time, stick with it, and you will have it beat in no time. 

Has the boiler been cleaned after it was installed? By this I mean has the boiler water been cleaned? The flux and oils in a new system can eat up the boiler over the years as well as causing other aggravations. In a boiler that size I'd probably dissolve a couple pounds of TSP (trisodium phosphate), pump it into the system, and let it circulate for a good week before I flushed the system with clean water.


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## roselle (Oct 20, 2013)

Caribou said:


> Boilers are not rocket surgery. The difficulty is that the breadth of information can be daunting. Learn a little bit at a time, stick with it, and you will have it beat in no time.
> 
> Has the boiler been cleaned after it was installed? By this I mean has the boiler water been cleaned? The flux and oils in a new system can eat up the boiler over the years as well as causing other aggravations. In a boiler that size I'd probably dissolve a couple pounds of TSP (trisodium phosphate), pump it into the system, and let it circulate for a good week before I flushed the system with clean water.


I don't know if it was cleaned, but I know they tried it out, before they brought it here and installed it. We have only used it one winter, and did add 3 gallons of "Control," last year.The builder said to add 2 more gallons of "Control" each year, which I did last week. I surely don't want to have something happen to "Cinder." We love her! One thing about going without heat, for a long time...You certainly appreciate the warmth! Every day one of these kids says "I love having a warm house." If they hadn't done without, maybe they wouldn't appreciate something, that may be taken for granted...


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## Caribou (Aug 18, 2012)

Okay, they filled the boiler with water and fired it up at the factory the obviously drained it to transport. You mentioned that you used Pex for your plumbing so there would be very few soldered joints. With little oil or soldering paste in the system it is probably clean enough. I have made plenty of money fixing the problems caused by dirty boilers. I'm glad we talked this out.

Assuming that the 300 gallons is correct for the volume of one boiler I am going to guess that you will need between fifty and one hundred gallons of glycol depending on whether you want to protect for temperatures that you normally see or whether you want to go for the worse case scenario.

I see the weak spot being the utility corridor. It is outside and has no heat source of its own. Putting in a full time circulator, as you mentioned, should take care of that situation. I had a call where the heat had gone off. I got the boiler started before there was damage to the boiler. The antifreeze protected the boiler and baseboards from bursting. Unfortunately, the glycol mixture had turned to slush. The circulators on boilers are not designed to push a snow cone. Though the boiler was hot we could not distribute the heat due to the slush. We had to bring in a herman nelson to warm the house till the glycol mixture returned to a fully liquid state. The heating system came through the ordeal just fine. The rest of the plumbing did not fare as well.


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## roselle (Oct 20, 2013)

Caribou said:


> Okay, they filled the boiler with water and fired it up at the factory the obviously drained it to transport. You mentioned that you used Pex for your plumbing so there would be very few soldered joints. With little oil or soldering paste in the system it is probably clean enough. I have made plenty of money fixing the problems caused by dirty boilers. I'm glad we talked this out.
> 
> Assuming that the 300 gallons is correct for the volume of one boiler I am going to guess that you will need between fifty and one hundred gallons of glycol depending on whether you want to protect for temperatures that you normally see or whether you want to go for the worse case scenario.
> 
> I see the weak spot being the utility corridor. It is outside and has no heat source of its own. Putting in a full time circulator, as you mentioned, should take care of that situation. I had a call where the heat had gone off. I got the boiler started before there was damage to the boiler. The antifreeze protected the boiler and baseboards from bursting. Unfortunately, the glycol mixture had turned to slush. The circulators on boilers are not designed to push a snow cone. Though the boiler was hot we could not distribute the heat due to the slush. We had to bring in a herman nelson to warm the house till the glycol mixture returned to a fully liquid state. The heating system came through the ordeal just fine. The rest of the plumbing did not fare as well.


So I need all that glycol, even if the circulator runs 24/7? My boiler works off forced air, not baseboard....Don't know if that matters or not. Would I just add the glycol to the boiler, or do I drain all the water off and just add the glycol? Or do I just drain off the amount of water, that would be replaced with glycol....By the way...Where would I get that and how much is it? Is it just anti-freeze? I see this trip either getting cancelled or putting me in the poor house....Thanks for your help!


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## Caribou (Aug 18, 2012)

roselle said:


> So I need all that glycol, even if the circulator runs 24/7? My boiler works off forced air, not baseboard....Don't know if that matters or not. Would I just add the glycol to the boiler, or do I drain all the water off and just add the glycol? Or do I just drain off the amount of water, that would be replaced with glycol....By the way...Where would I get that and how much is it? Is it just anti-freeze? I see this trip either getting cancelled or putting me in the poor house....Thanks for your help!


The forced air V. baseboard matters in that there will be less water in the system. There are other pluses and minuses but I will not go into that now.

I already described the process so you can reread that post above. The quantity you require will set you back a bit. It will cost more than a trip to Costco but less than a new boiler.

I will not tell you whether or not to put glycol in your system. I will try to give you the information to make an informed decision.

In the +20's you have little threat as long as the boiler stays above freezing and the circulator does not go off. The boiler will take days to freeze. The Pex will freeze sooner due to the smaller mass. Power outages can be covered with a generator. A battery and an inverter will keep the circulator going but the flower for your forced air might require a generator to get enough power. A spare circulator might be a great prep.


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## roselle (Oct 20, 2013)

Caribou said:


> The forced air V. baseboard matters in that there will be less water in the system. There are other pluses and minuses but I will not go into that now.
> 
> I already described the process so you can reread that post above. The quantity you require will set you back a bit. It will cost more than a trip to Costco but less than a new boiler.
> 
> ...


The temp will be above freezing most of the time, during the day. I hope that helps. I have two extra circulators on the boiler, that are unused, just there for a future greenhouse/barn. I wonder if they could be wired, to kick in, if the one fails?

Would it help to put some of that insulation board around the boiler?

Thanks so much for helping!


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## redhorse (Dec 27, 2012)

Ours circulates constantly, but runs to a heat exchanger on the existing fuel oil furnace. If we go anywhere, we just drain the boiler, then crack the tubing for it in the basement and drain the lines. We have two thermostats in the house. One for the heat exchanger and one for the regular furnace. We just turn the furnace thermostat up and the house is still kept warm while we are gone.


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## ZoomZoom (Dec 18, 2009)

If you have a circulator running, couldn't you just install a piece of pipe heater and let the water heat a little while passing through that?

IIRC, Pex pipe expands so it "should" not have a problem if the water freezes. The issue is getting the flow going again if the pipes are full of ice.

Flowing water has a hard time freezing.


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## Caribou (Aug 18, 2012)

roselle said:


> The temp will be above freezing most of the time, during the day. I hope that helps. I have two extra circulators on the boiler, that are unused, just there for a future greenhouse/barn. I wonder if they could be wired, to kick in, if the one fails?
> 
> Would it help to put some of that insulation board around the boiler?
> 
> Thanks so much for helping!


Sorry, I forgot your extra circulators. While I have never seen a system where one circulator takes over automatically, it would be quiet easy to plumb a system that would allow you to close the valves on a dead circulator, open the valves on the good circulator, and flip the switches on each.

Added insulation around the boiler will increase its protection from freezing but it will also reduce the amount of heat loss thereby making it more efficient.


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## roselle (Oct 20, 2013)

Well...The best I could come up with...My neighbors offered to come every few days and load the boiler. I am going to set the thermostat on the boiler and inside to 40 degrees...We are going to "bank" the boiler in the morning.

I want to turn the water off, at the main line. Would that cause a problem? I do use the boiler for my hot water...


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