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[offshell]

So, I'm pretty new to the boiler setup and have some general questions.

There's an Aqua-Therm 345 attached to the back of a shop with an small insulated setup with lines running underground and into a utility room and then a valve system inside that can be switched back and forth between an 18kw electric boiler. The previous owner left maybe a cord of cut wood and a cord of uncut wood. The temps at the beginning of January were about -18F at night around here in Minnesota. The home has about 2600 square feet of radiant slab heating with a couple hundred being a single car attached garage. For the first week I burned through pretty much all of the wood that was cut. There's a valve inside that adjusts how much water circulates directly back to the boiler and was used to adjust the temperature in the house but there was no thermostat tie in for the home when using the outdoor wood boiler so there's no real control over what temperature water goes into the slab other than the aquastat on the OWB. There's no mixing anywhere. Since I was basically running out of wood, I switched the system over to the electric boiler which now with the temps being up between 20F to 35F I've been hovering at about $45 a week in electric which so far as I can tell is less than I would spend on wood right now. When the electric boiler kicks on it usually stays on for about 10 hours before it kicks off and then the house usually overshoots by about 2 degrees and doesn't kick back on again for over 24 hours. With the electric on I'm still feeding the OWB a bit to keep it alive.

I guess I'm not 100% sure what I want out of the system but after reading around a bit I feel like there's a few pieces missing and I'm curious how other people have set up or would set up a similar system. With no antifreeze in the system, I can't really leave for any period of time. I'm stuck debating whether it makes more sense to try to get antifreeze into the OWB or to have some setup where the electric boiler could feed some warm water back to the wood boiler to keep it from freezing. At the same time I feel like I burn through more wood than I would if the house was capable of controlling circulation into the floors. Right now when I load up the OWB there is an aquastat but the boiler continues to pump through the house whether the house needs it or not. I would fill it at 6am and by 5pm I'd be lighting a new fire and the house would usually be warmer than I really needed it.

Would you tie both systems together so that the electrical system would be capable of backing up the wood system? Should I be looking for something to control the temperature and flow of water into the floors?

At the same time I'm planning to put in a heatpump a/c and furnace this summer and I'm not sure if it would be better to tie the systems to it instead in terms of emergency back up. I also ran into an issue with the thermostat one night where I tried to use the indoor wood stove and confused the entire system. Is it worth looking into getting a temperature sensor in the slab itself?

[aarmga]

I would advise against using anti-freeze in the system, it can be very corrosive. I use water from my furnace to feed back into my owb to keep it from freezing.

[slimjim]

You need to get a professional whom you can trust to help with those decisions, it sure sounds to me like a major home owner hack job to me!

[offshell]

I would advise against using anti-freeze in the system, it can be very corrosive. I use water from my furnace to feed back into my owb to keep it from freezing.

Would using an electric boiler to do the same thing make any sense here? Ideally id not want to continue to heat the entire loop but rather just feed some warm water back to the boiler to keep it from freezing vs keeping the entire loop at temp. I am planning on having a few different groups out to look and give me some quotes on what they would recommend. I'm just trying to get a few ideas ahead of time about how this type of system would be managed. Neither the inspection or appraisal raised any red flags about the setup but I guess we'll see when I have some experts out. I know I'll be stacking wood this spring though!

[mlappin]

If you use the proper glycol it will work much better, never substitute RV antifreeze for the proper stuff.

[aarmga]

I agree completely.  On the other hand that stuff is expensive.  The best thing to do is keep that loop moving. When it's very cold my furnace will keep my owb at 110 degrees from back feeding.  It does however use a little more propane but hardly noticeable.  I won't do this all winter but when it's in the 40s-50s daytime and just dips below freezing at night I just run the furnace and don't burn wood anymore.  Never had any problems yet doing it this way. Much cheaper than spending mucho money on antifreeze that you need to replace every 3-5 years.

[kommandokenny]

I like the antifreeze option here.
Do you want to jeopardize 10k for the sake of a few hundred dollars of antifreeze [spread out over 3-5 years]
It's -40 c/f here in the winter sometimes,,  and i  don't trust pump failure or back feeding from my fan forced furnace.
Hard to enjoy the Keys, if your worried about coming home to a potential nightmare.

Thats what I would do anyway,,I'm no expert ..

[aarmga]

I guess if u look at it that way plus added money from antifreeze plus the cost of the stove plus upkeep on the antifreeze you might as well just heat with oil or propane or even better nature's best, natural gas. Seems like the savings light at the end of the tunnel just gets out of reach that way.

[kommandokenny]

It's expensive saving money

[aarmga]

It can be!  In my case yes it is lol.  My furnace is too small for my house it will only heat my house to 65 degrees on the 0 degree nights and when the wind blows I'm lucky to see 62.  The furnace fan is great the heat exchanger is too small but it's fine because I heat my house with my boiler and it actually cost me more now than just having a properly sized furnace.  I needed the most expensive saw I could get plus I needed a very expensive brand new tractor to haul wood plus a nice dump trailer and a new truck and a shed around the wood stove to keep it out of the weather.  So what a 5000 dollar furnace upgrade turned into a 100,000 dollar investment to keep my house warm.  I understand what you're saying but hobbies come with cost plus I get fun new toys the wife thinks I need to keep her house 72 degrees all winter

On that note I know where it can get expensive and where you can save money.  Running antifreeze to me is like throwing away a brand new chainsaw

[kommandokenny]

Well I did not invest that much,,would be nice though.
You will break even when your dead ,,,no maybe not even then.

I Had the saws and atv/wagon and 100 acres of bush.
Bought the splitter and boiler 10 k.
Paid for itself first 3 years,, saving $2800 in propane cost/year
Could keep the house at 80f ,,no problem, burning 6 bush cords.a year
Will save 50k over the next 18 years,,, so 300 in anti freeze a month would not bother me.

If you can afford to go to fla. you can afford some antifreeze.
Everyones situation is different,, but for me, here,, with this potential cold,, antifreeze works.

[aarmga]

10-4 sir.  I see your point and I understand now that with traveling a lot that would make sense to do.