# Outdoor Boiler Install



## MELOC (Sep 26, 2005)

Howdy folks. It's been a while since my last visit and the order and number of boards has changed. I hope my questions are appropriate for this forum. I know the mental power and experience can be found here, though. 

I'm trying my best to get a brand new Central Boiler 6048 installed before it gets banned next year. I will probably have several questions, but for now I my question is electrical. While the boiler will probably sit @60-70 feet from my home, the electrical run will probably be 100+...perhaps up to 125 feet. I think the boiler is fine with 15 amp service and my question is wire size for the run. I think I am at the limit of 12 gauge. 12 gauge is cheaper than 10 gauge in two ways for me... if the run turns out to be 100 feet or less, 100 foot rolls are available. I think the 10 gauge rolls are 250 feet at my local store, so anything less is sold by the foot. Looking to bury the cable.

Another thought is to provide service to my garage which is another 60 feet or so from the boiler. I wanted to run 220 to the garage to power some wood working equipment. I thought about running the 220 to the boiler pad, eventually it will be a small pole shed...open with no walls, but this will probably make everything a lot more complicated. The boiler is absolutely the priority right now and I can stop with the 110 15 amp circuit for now. I hate to spend the money twice for the long run, however. So I am considering one big run.

I'll be dumping a ton of money into this project. I am freaking at the cost of the thermopex...$11-$12 per foot for a @75 foot run...as well as the $9300 cost of the boiler after taxes. It should pay for itself in 4 years as I have loads of spruce and pine to burn on top of the normal good hardwoods. There is no time to shop for used boilers and time is of the essence. I need a safe, wood powered heat source outside of my home as my chimneys are shot and I have had 2 close calls with chimney fires in two years. The health of a family member makes burning wood indoors unhealthy and dangerous. I have existing hot water radiators and I should be able to tie the boiler in with the current system with only a few repairs to a leak or two.

any thoughts?


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## TnAndy (Sep 15, 2005)

#12 wire would be fine for 15amp at 125'. As far as any wire goes, if you go to any decent electrical supply house, or Lowes, or Home Depot for that matter, you can get most any type/size wire cut by the foot. You'd need to compare price to a roll, as you may find a roll cheaper if you get close to it in length.


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## MNBobcat (Feb 4, 2011)

Since you're going to have to trench to bury the thermopex, you may as well trench the additional 60 feet to the garage. If I was you I'd run 100 amp to the garage and put in a sub panel and then run wire from that sub panel back to the boiler. And since you're trenching to the garage, you can run a second thermopex to it and use the boiler to heat the garage, too.

Also, consider mounting the pump for the boiler inside your house instead of at the boiler. That way if a pump fails you can replace it in the warmth of your house instead of standing out in the cold.


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## MELOC (Sep 26, 2005)

I like the idea of running to the garage and running back to the boiler. I really cannot afford the extra thermopex right now. The dealer quoted a cost of $11-$12 per foot.


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## mike554 (Jun 9, 2012)

I used pex from Lowes and insulated it myself. I put all the lines in 4" pvc.


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## kycrawler (Sep 18, 2011)

I have a hardy outdoor boiler it pulls 2.1 amps at max draw I also used oxygen barrier 3/4 PeX pipe and insulated it and pulled it was through 4 inch black drainage pipe I ran 2 Romex wires and 2 strands of telephone wire in the pipe also the extra romex and phone wires were in case I had problems the new wires were already ran also the phone wire is heavier gauge than thermostat wire and less likely to break


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## EDinTN (Sep 8, 2014)

I've worked on large boilers for nearly 50 years.... I wonder how much wood it will take per week (in the freezing cold) to keep that rig happy? I grew up with a fireplace and it took lots of wood to keep it going.


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## mike554 (Jun 9, 2012)

I only have to load my Hardy twice a day in very cold weather and once in milder weather.


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## MNBobcat (Feb 4, 2011)

You guys that used regular pex and insulated it...do you notice the snow melting off the ground right where your pex tubes run? If you do, all that heat going into the ground means a lot more wood to burn. I didn't want to take any chances. The central boiler thermopex is expensive but its also the best you can get. I figured it would pay for itself in wood savings.

EdinTN - last winter was extremely cold (-35 )and I burned about 26 cords. But I have a large house and a pole building.

The cost of the loggers cords is half what I would have paid for propane. I used to go out in the woods and cut the wood myself but haven't had time of late. Even buying the wood I save a ton of money. My boiler paid for itself a long time ago.


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## EDinTN (Sep 8, 2014)

Good news...


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## mike554 (Jun 9, 2012)

I've never noticed any snow melting where my line is buried. I also don't worry too much about how much wood I burn. I have probably a couple years worth of slabs that I'm burning and making more all the time.


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## MELOC (Sep 26, 2005)

water infiltration is the biggest enemy, from what I have read. I can't think of a practical way to insulate so much pipe and keep it water proof. I thought about trying to build pipe with 8 foot sections and either spray insulation or fiberglass, but things move and seals break. water needs no help finding a way in...that is what water does.

the salesman told me that he has seen the pipe in operation laying on top of the snow with no melt. I think that is too easy...heat can escape to the air with no signs in the snow, but when it is buried, it is easy to see the melt that occurs when all of the heat is contained in the ground. that said, I still feel that thermopex, or a good equivalent, is the best way to go. the only insulated pipe I saw online was some hokey looking pipe wrapped in foam sheets like people use for shipping material. I guess I will bite the bullet.

I would like to run heat to my garage, but I don't think I can justify the cost right now, I was considering an "as needed" run with plain pex, but I feel it would need to be some sort of drainable system. I wouldn't want that run wasting so much heat and I am not comfortable leaving it "non-circulated". 

I like the idea of the extra wiring. I am not 100% sure how the system will work...still waiting on the final word for financing before I get absorbed into the project (hopefully this week). I will be hooking it in with an existing boiler in my basement that feeds hot water radiators. my understanding is that the outdoor unit will circulate 180-185 degree water to the indoor boiler...which will distribute it via the existing thermostat...as needed. I was guessing the damper will be controlled by the outdoor boiler temp or the return water temp. at the outdoor unit itself.

I am not sure I like the diagram for hooking it in with the hot water heater. it wants to circulate the water from the furnace via a heat exchanger, the physical design I like (a pipe in a pipe from the bottom of the water heater to the top like someone else on this forum had years ago) however, it wants to maintain 180-185 degree water in the water heater and mix it with cold water for usage.


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## MELOC (Sep 26, 2005)

concerning wood usage...I have lots of spruce and pine that goes to waste. my needs in the past have been for clean/prime oak and other hardwoods. that gets hard to find when you cut your own. I will now be free to use the wasted wood. burning as much pine indoors as I would need to gets scary for me. that stuff gets out of control quickly. I don't know how you left coasters do it.


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## EDinTN (Sep 8, 2014)

Hope it works out well for you... I'm just to old to haul wood anymore.


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## MNBobcat (Feb 4, 2011)

MELOC said:


> water infiltration is the biggest enemy, from what I have read. I can't think of a practical way to insulate so much pipe and keep it water proof. I thought about trying to build pipe with 8 foot sections and either spray insulation or fiberglass, but things move and seals break. water needs no help finding a way in...that is what water does.
> 
> the salesman told me that he has seen the pipe in operation laying on top of the snow with no melt. I think that is too easy...heat can escape to the air with no signs in the snow, but when it is buried, it is easy to see the melt that occurs when all of the heat is contained in the ground. that said, I still feel that thermopex, or a good equivalent, is the best way to go. the only insulated pipe I saw online was some hokey looking pipe wrapped in foam sheets like people use for shipping material. I guess I will bite the bullet.
> 
> ...


Mine uses a plate heat exchanger for the hot water heater. It makes hot water fast enough that I have hot water on demand. The water heaters are only storage. I turn off the electric to the hot water heaters and then hook wires to the thermostat on the bottom of the first hot water heater. I have a pump hooked to the drain line. When it calls for heat it pumps water through the heat exchanger and then into the bottom of the hot water heater. Another pump circulates the water to a second hot water heater and equalizes the temperature between the two tanks. So I have 160 gallons of hot water all the time. If I didn't have the off-peak electric on the hot water heaters, I wouldn't have two heaters but as it turns out it works super good with the way I plumbed it to the boiler.

I've measured heat loss between the boiler and the house. The pex runs about 225 feet to the boiler. Heat loss is less than 5 degrees. So the thermopex works very well. Also, I buried it 4 feet deep.

The other consideration with pex is spacing between the two lines. You don't want heat transfer between the source and return lines. The thermopex maintains perfect spacing the length of the run. The outer shell that encases the pex and spray foam is really, really durable. You won't get any water infiltration in the thermopex. Its expensive, no doubt, but a good investment.


Your boiler probably has a primary/secondary plumbing where you have small pumps for each heat zone. They will use a water to water plate heat exchanger. Make sure they put the valves on the plate heat exchanger that gives you a bypass and a fitting for hooking up a hose. That way you can circulate a cleaner through it every few years to clean the exchanger.


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## MNBobcat (Feb 4, 2011)

mike554 said:


> I've never noticed any snow melting where my line is buried. I also don't worry too much about how much wood I burn. I have probably a couple years worth of slabs that I'm burning and making more all the time.


You're in a different situation if you're not living where it gets to be -25F.  Wood usage goes up dramatically when its below zero versus anything above zero. We get brutal cold here. I have to load the boiler with double the wood to get a 12 hour burn in that kind of cold.


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## kycrawler (Sep 18, 2011)

My pipes are buried 3 ft deep never had snow melted over the top


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## kycrawler (Sep 18, 2011)

The pictures above are of the install for the new house I only insulated the hot water to the house and the domestic hot water the cold supply and return are not insulated the pipes were taped together then the rope as used to pull them through the 4 inch solid black pipe


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## MNBobcat (Feb 4, 2011)

kycrawler said:


> The pictures above are of the install for the new house I only insulated the hot water to the house and the domestic hot water the cold supply and return are not insulated the pipes were taped together then the rope as used to pull them through the 4 inch solid black pipe


If you measure the water temperature at the boiler and also at the house before it goes through any heat exchangers, what is the temperature difference? I'm curious how many degrees you lose to the ground between the boiler and the house.


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## kycrawler (Sep 18, 2011)

With an ir thermometer it measures about 2-3 degrees difference


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## MELOC (Sep 26, 2005)

Thanks for the input, guys. Both the dealer and my nephew, the installation help, are trying to talk me into a plate exchanger for the hot water. I have not decided yet, or will improve as the budget allows. I have just finished financing the boiler...I have yet to come up with the $1200 + for the install. The Thermopex is just soooo expensive. I have already compromised the location so that it is 25 feet closer...and that means a smaller pad for now as space there is limited. 

The boiler will hopefully (if all goes well) heat the original in-basement oil/wood boiler. I am hoping to use the existing pump, thermostat and distribution system as-is. So if the outdoor boiler can maintain 185ish in the basement boiler, then the current distribution system should work as it always has in the past. The basement boiler already has a coil for hot water inside it's water jacket. if it is in good condition after sitting for several years, I would like to use it to heat the domestic hot water. I like the idea of the water jacket/hot water tank heat exchanger. Central Boiler's plans, from the website, have the water heater tank maintaining 185 F with a mixing valve that tempers the water to usage temperature. I am not a fan of this idea. I would rather use a small pump hooked to a thermostat, like another poster suggested, to maintain the existing water heater tank temperature to ...let's say 120-125 F via an exterior heat exchanger pipe. 

one of the problems I foresee is my existing water pressure. I use a 100 year old spring-fed, gravity powered water system that has gained too many users and has partially failed. I don't have much pressure. I know how it works now, and if I heat the hot water tank with an exterior heat exchanger, nothing should change and everything should work like it always has. if I rely on the basement boiler coil directly, or a new plate exchanger, I fear I will not have anything more than a trickle of hot water. I briefly tried using the coil a few years back and the pressure did drop. I fear I might have to find some sort of tank to use as a reservoir/cistern and add a pump in the basement. if I do that, lol, my pvc pipes will start flying apart with the new pressure as they are getting some age now. The current budget does not allow for new plumbing...as much as I need it. 

One other question/issue I have, and I am sure the dealer will answer it for me, is how to maintain the water level in the outdoor boiler. He told me it can be done simply by hooking up a water supply in the basement to the return line to the boiler. Once again, I fear my low pressure system may not be sufficient...I have no clue how this works just yet.


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## bigtuna (Aug 8, 2014)

How is this project going???


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## Ross (May 9, 2002)

Sorry i missed this one! Hope it's going well!


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