Coalgun S130 square footage question

Hi all, I'm currently heating my 2 story, 2000 sq ft old poorly insulated farmhouse house with a Hitzer 354 hand fired stove with blower. I live in northwest NJ in Warren County near Phillipsburg NJ.

My other "heat system" in this house is electric baseboard, which if run for primary heat is over $700 a month in electric bills to keep the house about 60 degrees if you're lucky.

I also have a 3 story workshop and outbuilding that is approx 45 feet to the side and uphill from the house. The outbuilding has a "walk out" ground level basement, then a 1st and 2nd story above that, that are somewhat insulated. So I'd be heating the 2nd and 3rd floor of the outbuilding, each floor is 600 square feet, for 1200 square feet total of heated outbuilding plus the 2000 sq foot main house for a total of approx 3200 square feet.

I plan on using slant fin baseboard in the house and outbuilding. I want to install a coal boiler in the bottom floor (basement) area of the outbuilding, then pipe up to the fintube to heat the 2nd and 3rd floor of the outbuilding. Probably looking at about 100 linear feet of fin tube total in outbuilding. I'd also build a masonry chimney with chimney block and clay flue liner etc.

For the house, I'd probably have about also about 100 lineal feet of baseboard, maybe split into zones or plumbed "home run" style off a manifold. I'd use 1.25 inch dual thermopex for the feed and return lines underground from the outbuilding to the house, probably rent a trencher and come into the house via the basement wall. (I can't put the boiler inside the house basement because the basement ceiling is only 5'6 in height, whereas the outbuilding's "basement" ceiling is almost 9 feet high.)

Would the S130 coal gun handle this approx. 3200 square foot heating project? Also would I need a huge circ. pump since the return would be flowing uphill back to the boiler? I really like the idea of a boiler to keep the coal mess in the outbuilding and to not have to lug coal into my living room to feed the Hitzer hand fired anymore. Plus the chance to heat the outbuilding and house together all with one boiler would rock.

I;m pretty handy and have a buddy who's a plumber/HVAC guy, although he has never installed a coal boiler or OWB. But the idea is labor costs would be down since we could probably do most of the work ourselves. Any thoughts are much appreciated, thanks.

what is the elevation difference between the house basement to the location of the boiler...

CapeCoaler wrote: ↑

Sat. Jan. 26, 2019 5:03 pm

what is the elevation difference between the house basement to the location of the boiler...

Hard to say, but I would guess it might be anywhere from 7 to 10 feet.

3800 sq ft, 3 floors on the outbuilding. No?

Elevation is irrelevant. Closed loop systems do not have height head to contend with. Only friction head exists within a closed loop.

I'd be more inclined to look at an S-260 for heating all of that. Particularly if you also want to heat DWH.

I feel like the S 260 is overkill, I wish there was a Coalgun model in between these two sizes.

Maybe a Keystoker KB 8 would be a better choice for this setup?

Another question I have for you boiler guys is:

Does the circ. pump just run nonstop and pump water thru the entire system 24/7 during heating season ? I know the outdoor wood boilers run the circ. pump 24/7, so I assume for coal boilers it's the same?

If not, what keeps the boiler water from just boiling over and blowing out the PRV as steam? My thought is that if the cicrc. pump isn't running, the water "trapped" in the boiler would overheat and turn to steam fairly quickly. It's not like an oil or gas boiler where the fire shuts down between cycles, so how exactly does a coal boiler work without exploding?

Also, if it is pumping water through all the time, how does the water ever "stay" in the boiler long enough to be reheated? Is there some sort of valve that keeps water trapped in the boiler until it heats to 180 degrees and then lets it be pumped back out to the lines and thru baseboards etc? Sorry if these questions sound stupid but most of the info online seems aimed at people who are already very familiar with heating systems and HVAC in general.

The water inside my boiler just sits there and does no movement until needed by a zone and when called for by a T-Stat. But I don't have an underground leg that needs to keep moving to keep it from freezing. At the end of a firing cycle and the start of a period of idling it generally overshoots a bit (usually to about 205-210 degrees) and then it settles down and slowly cools down until it fires and heats itself up again. There is noticeably less heat being produced at idle than is required to sustain, let alone raise boiler internal temperature.

Whatever the current temp in the boiler is, that is what goes out to the users (baseboards or whatever) on a heat call. There is no magic need to hold water within the boiler until it is at 180 degrees. Mine can be anywhere from about 215 degrees down to about 150 degrees. Above 215 degrees my dump zone (my basement loop) opens and runs the boilers heat down to about 195.

My boilers internal pressure is 12 PSI at cold filling, and never rises above 15 PSI. That's what expansion tanks are for.

If your circulator on the primary loop runs 24/7, it is not circulating water throughout the entire house 24/7.

At 12 PSI water boils at somewhere right near 244 degrees. And at 15 PSI it boils at several degrees above that. So I could most likely get by without ever even having a dump zone. I certainly don't have one in the case of a power failure.

I guess you are plumbed with all copper, since I understand that PEX can't handle more than 200 degrees?

Also how exactly does a "dump zone" work? What kind of valve opens to dump the water when it gets too hot ?

I'm all copper. A zone valve opens and the circulator turns on at 215 degrees. An aquastat regulates this. I can't speak for the temperature capabilities of PEX.

I believe a keystoker KB-8 delivers more BTUH than an AHS S-130. It is probably much larger physically also.

Thanks for the info, I wonder if it would make more sense to avoid PEX altogether and run black iron pipe in a trench (with spray foam insulation in the trench) from the outbuilding to the house, then all copper pipe inside the house.

scottybk wrote: ↑

Sat. Jan. 26, 2019 9:25 pm

Thanks for the info, I wonder if it would make more sense to avoid PEX altogether and run black iron pipe in a trench (with spray foam insulation in the trench) from the outbuilding to the house, then all copper pipe inside the house.

I certainly wouldn't think so. Perhaps others will chime in here.

Elevation is irrelevant. Closed loop systems do not have height head to contend with. Only friction head exists within a closed loop.

Only relevant to the fact that the pressure in the heating system will be higher in the house basement...
If the boiler is set in the walkout of the shop...
And system is set for 12 psi at the boiler...
The house basement will have the head pressure of the elevation difference...
Shouldn't matter much unless there is an expansion tank in the house basement...

scottybk wrote: ↑

Sat. Jan. 26, 2019 9:25 pm

Thanks for the info, I wonder if it would make more sense to avoid PEX altogether and run black iron pipe in a trench (with spray foam insulation in the trench) from the outbuilding to the house, then all copper pipe inside the house.

PEX gets buried all the time for boilers.
PEX should however be avoided being used for any near boiler piping. Dump zone doesn't have to be set to a high of 230*F.

I went from a OWB to coal and still use my 200' of buried pex for 7 years with OWB and on my 4th season with coal....no issues with pex