Central Boiler FORGE 3500 Outdoor Coal Boiler

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lsayre
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Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75
Location: N/E Ohio, between Medina and Wadsworth

Post By: lsayre » Wed. Dec. 05, 2018 9:16 pm

Olllotj wrote:
Wed. Dec. 05, 2018 9:12 pm
On top of more radiation and circulator he needs some distribution work. Zoning!
I agree fully. If he had 2 separate zones instead of 1 zone his Grundfos 15-58 would likely be totally adequate to move 70,000+ BTUH, and his friction head demand would go down noticeably, and concerns for velocity noise would go away also.


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McGiever
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Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: RICE,PEA,NUT,STOVE /ANTHRACITE and EGG / BIT
Other Heating: Ground Source Heat Pump and some Solar
Location: Junction of PA-OH-WV

Post By: McGiever » Wed. Dec. 05, 2018 9:22 pm

Olllotj wrote:
Wed. Dec. 05, 2018 9:12 pm
On top of more radiation and circulator he needs some distribution work. Zoning!
Zoning addition will change all the math due to much improved performance...best to figure what direction this will go...unless we're just looking to a "band-aid fix" for now.

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lsayre
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Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75
Location: N/E Ohio, between Medina and Wadsworth

Post By: lsayre » Wed. Dec. 05, 2018 9:37 pm

If he needs 70,000 BTUH, and his baseboards average 500 BTUH across a drop of 22 degrees for the case of 180 degree water departing the boiler, he needs at least 140 feet of baseboards.

70,000 BTUH / 500 BTUH/Ft. = 140 Ft.

If it was my house, and given its location and HDD's and sq-ft combined with uncertainty as to his heat loss, achieving 156 feet of installed HW baseboards would be my goal. That would ideally require at least 3 zones to retain confidence that Delta-T per zone would stay around the neighborhood of 20 degrees, and not likely wander to more than about 25 degrees max.
Last edited by lsayre on Thu. Dec. 06, 2018 1:18 pm, edited 1 time in total.

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Lightning
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Hand Fed Coal Furnace: Overmodified/Bored out Clayton 1537
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Post By: Lightning » Wed. Dec. 05, 2018 10:15 pm

McGiever wrote:
Wed. Dec. 05, 2018 9:22 pm
Zoning addition will change all the math due to much improved performance...best to figure what direction this will go...unless we're just looking to a "band-aid fix" for now.
What would give him the best results, economically for short term? Would it be possible to "T" off of the current zone to split up and add more radiators?

CapeCoaler
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Post By: CapeCoaler » Wed. Dec. 05, 2018 11:02 pm

Primary secondary loop...
Constant circulation on primary...
Secondary circulators...
Run pex in attic...
Cut in zones and return piping to a closet...
If water is not circulating what about freeze protection...

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McGiever
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Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
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Coal Size/Type: RICE,PEA,NUT,STOVE /ANTHRACITE and EGG / BIT
Other Heating: Ground Source Heat Pump and some Solar
Location: Junction of PA-OH-WV

Post By: McGiever » Thu. Dec. 06, 2018 12:35 am

Lightning wrote:
Wed. Dec. 05, 2018 10:15 pm
What would give him the best results, economically for short term?
Build a multi-zone header...split the existing zone into two and add yet a third zone to handle new additional rads.
With an outdoor boiler one assumes there is already a buried PEX bundle in the ground...hopefully it is sized favorably and can deliver the full load required.



Would it be possible to "T" off of the current zone to split up and add more radiators?
That is what *CC* mentioned above with the Primary/Secondary
Lee, Where are your hydronics books? ;) Holohan and Seigenthaler

CapeCoaler
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Stoker Coal Boiler: want AA130
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Location: Cape Cod, MA

Post By: CapeCoaler » Thu. Dec. 06, 2018 12:42 am

How much room in the attic...
Walking room or crawling room...
How do they make DHW now...
Add the zone for indirect...

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lsayre
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Stoker Coal Boiler: AHS S130 Coal Gun
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Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75
Location: N/E Ohio, between Medina and Wadsworth

Post By: lsayre » Thu. Dec. 06, 2018 7:00 am

I'd likely settle on 4 zones, with 3 zones for home heat, each "ideally" consisting of 52 ft of standard HWB, and 1 zone for an indirect domestic HWT.

On an individual rooms basis this should come right close to 15.5 sq.-ft. of interior floor space for each ft. of installed HWB. Add hallway and closet sq-ft to rooms with open access to them.

This might be overkill, but allowing for a slab home with cinder block construction and zero insulation, and ballparking ~7,500 HDD's, it might not be.

52 ft x 3 zones = 156 ft. of HWB

156 x 500 = 78,000 BTUH.


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lsayre
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Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75
Location: N/E Ohio, between Medina and Wadsworth

Post By: lsayre » Thu. Dec. 06, 2018 7:21 am

I presume that generally outdoor boilers operate unpressurized and transfer their heat to a home via a water to water heat exchanger that is on a continually operating circulator loop. On the home heating side of the water to water exchanger, you can install supply and return manifolds with either a single circulator and zone valves, or with individual circulators for each zone. This arrangement would make for a primary/secondary type install.

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lsayre
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Stoker Coal Boiler: AHS S130 Coal Gun
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Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75
Location: N/E Ohio, between Medina and Wadsworth

Post By: lsayre » Thu. Dec. 06, 2018 8:38 am

As to what can be done very quick and dirty:

Replace the Grundfos 15-58 circulator with a Taco 2400-20 circulator (1/6 HP) if the boiler is pressurized, or a Taco 2400-20-WB circulator if the boiler is unpressurized. Install a bypass leg (if one does not already exist) to regulate flow and mitigate velocity noise in the house. Activate the 2400-20 via the homes T-Stat and a relay, provided that the loop will not freeze anywhere. Abandon this plan if the pipe may potentially freeze anywhere along the line while idle.

Unfortunately the 2400-20 is not inexpensive.

The 2400-20 circulator delivers 10.5 GPM into 26 ft of friction head, 8 GPM into 28 ft of friction head, and 7 GPM into 30 ft of friction head. In this single zone application I would think it will yield somewhere around a real-world 6.5 GPM wherein the current situation is around 4.5 GPM. At 6.5 GPM and allowing for 30 degrees of Delta-T it is delivering ~97,500 BTUH. For the existing case of 22 degrees of Delta-T it is delivering ~71,500 BTUH.

Disclaimer: In the end this plan may be nothing more than throwing good money after bad. It should appreciably bump up the GPM's, but it does not address what appears to be inadequate radiation, as well as poor distribution due to the single zone. If the radiators can't actually extract 71,500 BTUH, the Delta-T will drop accordingly, and less heat will go into the house. If all that happens is that the Delta-T drops to ~14 degrees, the 2400-20 circulator will be delivering the same BTUH as for the 15-58 circulator.

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McGiever
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Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: RICE,PEA,NUT,STOVE /ANTHRACITE and EGG / BIT
Other Heating: Ground Source Heat Pump and some Solar
Location: Junction of PA-OH-WV

Post By: McGiever » Thu. Dec. 06, 2018 11:23 am

There have been tales of users that laid a second PEX insulated bundle over top of the ground temporarily to get their required heat for the season...and to then bury it later at another better time.

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Post By: Rob R. » Thu. Dec. 06, 2018 1:06 pm

It is nuts to have the underground piping in series with the zone piping. Most outside boilers are installed with a heat exchanger, so the house side can remain a closed system - this also allows you to control the zones separately from the zone circulator(s).

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lsayre
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Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75
Location: N/E Ohio, between Medina and Wadsworth

Post By: lsayre » Thu. Dec. 06, 2018 1:22 pm

Rob R. wrote:
Thu. Dec. 06, 2018 1:06 pm
It is nuts to have the underground piping in series with the zone piping. Most outside boilers are installed with a heat exchanger, so the house side can remain a closed system - this also allows you to control the zones separately from the zone circulator(s).
I fully agree, but sadly this (everything in one long train, and a potentially unpressurized one at that) appears to be how the system presently operates. A heat exchanger should be a top priority.

Lee, do you know if the system is pressurized to the typical ~12 PSI? Did you see an expansion tank? Some of these outdoor boilers can't be pressurized. But I believe that one made to burn coal should be.

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Lightning
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Post By: Lightning » Thu. Dec. 06, 2018 2:51 pm

Nope, this is an open system, no pressure. There isn't a heat exchanger either. It's just out of the boiler, thru the monster loop and back into the boiler under constant circulation.

My primary concern was to get more heat away from the boiler, because it's barely idling. He wants to add more radiators, but like you guys suggest the loop needs to be split up into zones, at least two zones for now.

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Post By: Qtown1835 » Thu. Dec. 06, 2018 2:53 pm

Maybe throw a 85kbtu modine in the garage just for good measure and would make for a good dump zone.


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