Boiler plumbing primary/secondary vs single loop. pro's and cons

Post Reply
 
Frank F
Member
Posts: 208
Joined: Sat. Apr. 07, 2018 8:48 pm

Post by Frank F » Wed. Jul. 11, 2018 6:36 pm

Hello all,
I getting ready to install my AA220 boiler. I have gotten alot of information. Everyone seems to have a different idea. So I'm asking you all.

I have 3 heat exchangers to feed. 2 water to air for my plenum. And 2 water to water for my hot water tank.

I had planned to run a primary/ secondary with three zones.

The last shop I spoke with said I should run one single loop through all three heat exchangers. This will save me initial cost but I'm not sure it's the right way to go.

Please let me know your thoughts, pros and cons. Thank you all in advance.


 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Wed. Jul. 11, 2018 9:21 pm

Frank, running a single loop through all three is certainly cheap and easy, but it will also have the worst performance and control.

If it were mine, I would use a variable speed circulator and 3 zone valves.

 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Thu. Jul. 12, 2018 5:56 am


 
Frank F
Member
Posts: 208
Joined: Sat. Apr. 07, 2018 8:48 pm

Post by Frank F » Thu. Jul. 12, 2018 6:45 am

Rob R. wrote:
Thu. Jul. 12, 2018 5:56 am
Residential Coal Boiler / Hot Water Design.
Thank you. That's what I assumed.

I have an additional question. I am installing the boiler in my pole barn and have to run about 100 ft to the house. Going to build a boiler room. I know this has been discussed alot on here but I have to keep it out of home environment ...my kid has breathing issues. So to make a long story longer my intention was to run 1.25" thermopex. I cannot find a local dealer that sells anything other than 1" and they all swear it's enough. They state it can yield 270 BTU. What are your thoughts?

Again thank you!

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Thu. Jul. 12, 2018 8:03 am

I believe that due to the new information of a 100 foot run, primary/secondary with 24/7 circulation is a given. This approach typically entails that you apply a circulator to each loop (or zone), in addition to the 24/7 primary loop.

 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Thu. Jul. 12, 2018 8:29 am

Frank, do you know what the heat load of the house is? 1" may be plenty, depending on what you need.

70,000 BTUs per hr is a reasonable expectation for 1" pex.

What are you going to use to product domestic hot water?

 
Frank F
Member
Posts: 208
Joined: Sat. Apr. 07, 2018 8:48 pm

Post by Frank F » Thu. Jul. 12, 2018 8:54 am

I know my house is currently heated by a 90k BTU propane. It has no issues heating. I haven't completed the heat load calc yet.


For the hot water.. im not sure yet. The guy im buying boiler from uses one and loves it.


 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Thu. Jul. 12, 2018 10:11 am

How do you produce hot water currently?

 
lzaharis
Member
Posts: 2366
Joined: Sun. Mar. 25, 2007 8:41 pm
Location: Ithaca, New York
Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Hand Fed Coal Boiler: former switzer CWW100-sold
Coal Size/Type: rice
Other Heating: kerosene for dual fuel Keystoker/unused

Post by lzaharis » Thu. Jul. 12, 2018 10:19 am

As far as the piping run from the barn to the home do not buy anything less than the $15.00+ per foot foamed pex insulation if you are burying it at a shallow depth as you will only lose about 1 degree in temperature for the piping run.

So if you buy pipe for both the heating loop and the domestic loops you will spend a bit more than $3,000.00 plus tax for both the heating loop and domestic loop foam closed cell foam insulated pex piping.
Plan on buying at least 10 feet more for both the entry and exit ends of the Pex loops for working room to connect both ends of the pex loops.

As Rob said what are you going to produce your hot water with?? you can bury a second Pex run with the same $15.00 insulated pex pipe for your domestic hot water and bury it in the same trench.

The un foamed wrapped Pex that is pulled through the solid ADS piping has a history of failing by allowing water to enter the ADS piping either from a perforation in the ADS pipe or by condensation.

Trench preparation is paramount in laying this pex pipe and making sure it is bedded in gravel sand and covered by gravel sand
after the pex piping has been connected to the system and pressure tested for 12-24 hours to check for leaks by examining the pipe run or using a mechanics stethescope to listen for leaks.

 
Frank F
Member
Posts: 208
Joined: Sat. Apr. 07, 2018 8:48 pm

Post by Frank F » Thu. Jul. 12, 2018 11:38 am

Rob R. wrote:
Thu. Jul. 12, 2018 10:11 am
How do you produce hot water currently?
Propane. So I was going to add a water to water heat exchanger. So I don't have to run a second set of lines.

 
Frank F
Member
Posts: 208
Joined: Sat. Apr. 07, 2018 8:48 pm

Post by Frank F » Thu. Jul. 12, 2018 11:40 am

lzaharis wrote:
Thu. Jul. 12, 2018 10:19 am
As far as the piping run from the barn to the home do not buy anything less than the $15.00+ per foot foamed pex insulation if you are burying it at a shallow depth as you will only lose about 1 degree in temperature for the piping run.

So if you buy pipe for both the heating loop and the domestic loops you will spend a bit more than $3,000.00 plus tax for both the heating loop and domestic loop foam closed cell foam insulated pex piping.
Plan on buying at least 10 feet more for both the entry and exit ends of the Pex loops for working room to connect both ends of the pex loops.

As Rob said what are you going to produce your hot water with?? you can bury a second Pex run with the same $15.00 insulated pex pipe for your domestic hot water and bury it in the same trench.

The un foamed wrapped Pex that is pulled through the solid ADS piping has a history of failing by allowing water to enter the ADS piping either from a perforation in the ADS pipe or by condensation.

Trench preparation is paramount in laying this pex pipe and making sure it is bedded in gravel sand and covered by gravel sand
after the pex piping has been connected to the system and pressure tested for 12-24 hours to check for leaks by examining the pipe run or using a mechanics stethescope to listen for leaks.
I intend on using thermopex. But having hard time finding the right length of 1.25. I can get either100' or 300' not specific lenght. But the 1 inch I can get exactly what I need.

 
lzaharis
Member
Posts: 2366
Joined: Sun. Mar. 25, 2007 8:41 pm
Location: Ithaca, New York
Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Hand Fed Coal Boiler: former switzer CWW100-sold
Coal Size/Type: rice
Other Heating: kerosene for dual fuel Keystoker/unused

Post by lzaharis » Thu. Jul. 12, 2018 12:48 pm

Will the Leisure Line dealer be installing the boiler for you?

For your own sanity I am going to suggest that you purchase 2 paper back books;

"Classic Hydronics" and "Pumping Away" which were written by Dan Holohan and they are worth every penny you will spend on them. you can purchase them directly from the authors home page at www.heatinghelp.com

Are you planning on mixing rice buckwheat coal or using just rice or buckwheat for fuel?

Is you house loop going to be the dump zone or are you planning on using the shed for the dump zone using a garage water to air heater?

Do you have a chimney to use already or are you going to be using a power vent draft inducer?

If you leave the boiler water temperature at summer temperatures of 140 low 160 high with 180 for the dump temperature you will be able to maintain a constant boiler temperature and have much less potential for shocking the boiler with water that is lower than 140 degrees.

One of our members has an AA220 and he installed it himself and he went through a to install it in his barn to heat his home and the barn where he had the boiler.
He uses only one of the twin stokers most of the time the boiler is operating. He has since moved his boiler into the addition that he had built on his home and he was in the process of having an estimate for a chimney the last time I chatted with him.

Once you have a good plumber you can work with and or buy the two paper backs I mentioned above you will learn a lot about hydronic heating.

I went through a lot with my installation of a Keystoker KAA-4-1 dual fuel unit with bad plumbers and no help from the dealer I bought it from and 2 sets of bad Hydrostat controls and installing a Honeywell L8124L1011 horizontal triple aquastat and a Bull Dog RB-122 low water cut off solved all the problems I had as the hydrostat 3250 plus have had a bad habit of failing and in my case it almost boiled the boiler dry and explode.

If and when you need to call Matt at Leisure Line he is very helpful with any problem you may have with your boiler.

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Thu. Jul. 12, 2018 1:02 pm

Most homes have a whole lot less actual heat load demand than they have available "existing" furnace BTUH's. And this is particularly more true for older homes, from back when many furnaces (oil, propane, or NG) had efficiencies of 45-50%. Using an existing furnace or boiler to size a new unit is generally a bad idea.

"On Demand" domestic hot water 'demands' a lot more BTU's than does home heating. Just look at any of the combination boilers such as those from Navien. The DHW side always packs way more BTUH punch than does the home heating side.

To heat a steady 3 GPM flow of water from 52 degrees (a typical well temperature) to 120 degrees for 1 continuous hour requires the following:

3 gpm x 60 min/hour x 68 degrees of rise x 8.33 Lbs./gallon = ~102,000 BTUH (BTU's/hour as output, not as input)

If you have a lot of people taking back to back showers, or even two people trying to shower at the same time, then DHW heat demand can be tremendous. Home heating demand is rarely as tremendous. Thankfully most people take showers at between 105 and 115 degrees. The 'average' requirement for which (if your shower head delivers at 3 GPM) is only 87,000 BTUH. I can (and did, for 10 straight years) heat my house (1,680 sq-ft, plus a finished walk-out basement of 840 sq-ft) on just a tad more than half of that. In fact, my back-up resistance boilers 13.5 KW equates to 46,062 BTUH. And even at better than -10F outside it did OK.
Last edited by lsayre on Thu. Jul. 12, 2018 1:35 pm, edited 4 times in total.

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Thu. Jul. 12, 2018 1:19 pm

All of that said, 'solid fuel' hot water boilers are sized with a 1.15 "pick-up factor", so if your homes heat loss calculation comes to 45,000 BTUH, and you do not intend to heat DHW "on demand", then your boiler should absolutely not be sized lower than 45,000 x 1.15 = 51,750 BTUH of output. Beware that many heating appliances are rated on the input side, and at a "real world" 70% efficiency, 51,750 output BTUH requires 51,750/0.70 = ~74,000 as the input BTUH rating. About the rating of a Keystoker Kaa-2 (from memory).

If I had a hot water storage tank (as opposed to my current situation of heating DHW "on demand"), I could properly heat my house with a Kaa-2. My Coal Gun S-130 is large enough to heat 2 houses like mine. And I live in an area with about 6,500 HDD's (heating degree days).

 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Thu. Jul. 12, 2018 2:10 pm

Frank F wrote:
Thu. Jul. 12, 2018 11:38 am
Propane. So I was going to add a water to water heat exchanger. So I don't have to run a second set of lines.
There is another member on here that did a very similar install, check out his thread below. I agree that a heat exchanger would work well. Let the loop circulate through the heat exchanger all the time, and run the two air handlers off zone valves.

Eshland S 260 Rebuild


Post Reply

Return to “Stoker Coal Boilers Using Anthracite (Hydronic & Steam)”