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[robreynolds]

I'm in the process of buying an outdoor wood furnace rated for 10,000 square feet, and I'm going to do the installation myself.  I get the impression that there are hundreds of ways to get the heat from the furnace to my living space, and I'm trying to narrow it down. 

I have a 2900 square foot steel building on a slab, of which 850 is our living area for now.  It's decently insulated.  The remainder of this building is a big workshop with a 15 foot ceiling and about an inch and a half of spray foam insulation. 

The other steel building is 1200 square feet, all one room, with three long pex loops in the slab.  They're in zones but it's one big room, so not a critical issue.  This building is insulated. 

For the larger building, it has been suggested to me that I can place a water to air heat exchanger in series with a 50 plate exchanger, in a loop from the furnace.  The air exchanger would be installed in an old furnace, which I have on hand, to heat the big shop. The three rooms of our living space would be heated with a secondary loop through the 50 plate exchanger.  It's pretty easy to keep this place comfortable currently with one small wood stove in the middle room, so I'm not going to use blowers.  Simple radiators should be plenty. 

For the other building with pipes in the floor, I was wondering what kind of regulation it needs.  I had assumed that I would install a plate exchanger and a secondary pump controlled by a thermostat.  But it has been suggested to me that I can supply these loops directly from the furnace.  In that case, I suppose a thermostat would control a valve to regulate the flow through the floor.

This is all the heating that I will be doing for now, but we plan to start construction this year of a greenhouse and a house.  The house is just going to be average size, and the greenhouse will be around 750 to 1000 square feet, earth contact on the north side, so not a huge demand in either case.  All options are open for these two future projects.

I'm not interested in spending trainloads of money on parts and materials.  I also understand that if I don't spend enough I will have to spend more later.  So what's an efficient and practical way to set it up?  It's an interesting situation because I'm going to have so many different types of spaces attached to the same furnace.  Fewer pumps in the entire system means less electrical consumption, which sounds good to me.  Incidentally, I don't mind trading decreased furnace efficiency for increased electrical efficiency because I have more wood than I know what to do with. 

Any thoughts on this?  Sorry for rambling.

Rob

[Smokeless]

Yes first go to a reputable plumbing supply store. With all the dimensions and your btu set up you have now. They can put that info in a computer cad design program. And figure it out for you. Every window that faces south compared to a North facing window. Is big difference in btu required at -15. F
 Most will do it for free.

[robreynolds]

The only heating I have now is a small wood stove in the area where we are living.  The big shop and the new building with pipes in the floor are not yet heated.  So I can't compare to existing equipment.

Good point about the windows.  Each of the existing buildings has only one north facing window, so no problem there. 

My main question is not so much about heating capacity.  It's more about the layout.  The two buildings are very different from each other in total volume as well as heating method and insulation value.  The big building has less insulation, big south facing windows, plus an apartment with more insulation and six big windows.  The small building has better insulation and four very small windows.  It will be used for finishing quilts and running a laser cutter, so it's a place where you don't want to suffer from cold hands. 

I went to the dealer's house and noticed that he has his house and his shop on one circulating pump.  If I do that for these two buildings I will have to regulate the heating via secondary loops with their own thermostats.  Should I pay any attention to the advice I got, suggesting that I can feed the floor loops directly from the furnace circulator?  In theory it sounds like it would work, but is it bad advice?

One other point, I'm about a hundred miles south of Kansas City, so I won't be dealing with Arctic weather.  It only gets down to the neighborhood of 0 degrees one or two nights each year, and this year is looking like it might not do that at all.

Mostly what I'm asking about is general principles rather than BTU values and such.  I need to know whether I'm better off with an extra pump or an additional heat exchanger, etc., and then I will do all the research to figure out which brand and how big.

[mlappin]

You need some kind of tempering device for your in slab radiant, at least I’ve always been told 180 degree water thru cement is a bad thing.

[robreynolds]

Interesting.  The dealer keeps his water temperature set at 125.  Maybe that's why he thought it was a good idea to feed it directly into the floor loops.

So if I set my water temperature hotter, I'm assuming that I'll get more heating done with less pumping, meaning a savings on my electric bill.  Then I would have to use a heat exchanger and a secondary loop to feed the floor pipes.  What kind of tempering device would be appropriate for this application?  If I just turn the flow down, the concrete nearest the heat exchanger would still be subjected to excessive heat.

[mlappin]

Need a tempering valve, one thing I can say about CB, they have some nice diagrams. Goto Central Boilers website and they have a diagram on plumbing a tempering valve into a radiant floor loop.

[robreynolds]

Thanks.  I'll go and take a look. 

[Bondo]

Interesting.  The dealer keeps his water temperature set at 125.

Ayuh,....    I can't comment on all yer questions, but a couple points anyways,...

Runnin' the boiler under 140° causes condensation, inside the firebox, which can lead to rustin' out,....

I run my home built unit 'tween 160°, 'n 175° / 180°,...
I tried up to 190°, 'n the pex just 8' or so from the boiler, right where is goes through a 4" long sweep plastic conduit, Blows out the side of the tubin',...
Replaced it twice in 2 seasons, have since lowered the boiler hi-temp,....

The other thing is,    Don't scrimp on the underground lines, I did, 'n regret it Badly,...
Research the twin insulated lines, 'n buy the Best,...

[robreynolds]

Clarification:  The dealer was here at my house a couple of days ago and he said his temperature is at 150 degrees.  I suppose I could be wrong, but I could swear he said 125 when I was there 2 weeks ago. 

At any rate, I've been looking more closely at the equipment and I'm pretty sure I understand it now.  I'll be using a mixing valve for the floor heat, and I've heard a few times not to cheap out on the insulated lines from the furnace to the house.  Thanks for all of the advice.