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[nd guy]

I've searched and did not come up with an answer (maybe wrong keywords) but I was wondering why woodmaster runs about 1/2 the water capacity then a comparable sized boiler (square footage wise)? What is the idea behind less water storage and is there any benefits or draw backs to doing this? I know they have some that run comparable capacity but I have seen alot that are less. Thanks

[Smokeless]

Less water means quicker recovery. But less available BTU if demand is high in a short time. Like three zones that come on at the same time. It may have a lag time, Like Base board needs 180deg F   
  If radiant floor heat is used. At say 95- 110 deg  that is less demand. And will give a smaller volume boiler enough leed time to catch up before it drops the temp down to far.
  You could also incorporate thermal storage. Kinda expensive.
 So  if you have radiant floor heat you should be fine. Does that boiler require a thermal protection valve?
 A lot of the smaller ones do.

[nd guy]

I would like to do radiant in the house and soon to be attached garage. Shop has propane boiler for floor heat and want to add wood into the system. What is a thermal protection valve? Is it needed to not shock a boiler with too cold of water? Still learning and looking for the right boiler. Thanks Smokeless.

[slimjim]

I know that the new clean fire is pressurized and small mass because they are looking to eliminate the plate exchanger as well as allow anti freezing the system inexpensively.

[Smokeless]

Yes nd guy that is exactly what it prevents. Keeping the boiler above a given temp. Prevent pyrolytic gas condensate from happening inside fire box. I think it is above 140degF.
  It circulates water in a loop threw the boiler,When boiler is cold.  Prevents it from going to the system. When the boiler is up to the set temp, It sends hot water to the system.
If the system return water is to cold it will mix hot water into the cold warming it up.
Some boilers eroded from cold return water directly hitting the fire Box.
 Internal water manifolds are a important component. 

[MattyNH]

my boiler only hold 59 gallons of water real quick recovery.. ya when all the zones are calling ya temp drop on the boiler.. but its a way faster recovery than a boiler that holds a 250 gallon boiler.. These days they have a tank less hot water heaters and boilers powered by propane/city gas .. What I've been told very efficient.....I see them more and more  for awhile now..

[slimjim]

Look at it as a thermostat on your pickup truck or car, when the vehicle is warming up in the yard the thermostat closes and the anti freeze stays in the engine, when the engine has warmed to its set point then it is allowed to mix with the system and be cooled by the radiator.
Small volume or large volume, each has its use, bottom line is to do as the manufacturer says, they designed it and will need to stand behind it if something goes wrong!

[E Yoder]

I agree with what's been said- water capacity is one factor among many in a particular model's design. The manufacturer should have that worked out during the development stage of the unit. I guess I don't see low or high volume as good or bad, just different. Kind of like a flywheel, sometimes you need inertia, sometimes you don't.
 I often get the "how many gallons does it hold" question at shows, especially from guys with high volume units. Some NC manufacturers near us went high volume to accommodate solar due to a state incentive. Now some see it as a measure of efficiency or btu output, which it isn't, just ability to store heat.
Generally speaking I would prefer quick recovery/low mass but some situations would do better with higher mass, like greenhouses or other big fluctuating loads. For most residential installs low mass works well.
Just my opinion.
 

[nd guy]

Thanks for all the replies. Great info but now I have more questions. LOL My plan is to run an older conventional boiler for two reasons lower startup costs and need to get rid of some old (punky) wood also have good wood. After a couple of years I may move up to a gasser and reduce my wood consumption. My "loads" are a well insulated shop 30x40x14 with water floor heat run by a propane boiler (approx 700-800 gals of propane a yr.), House 28x56 doublewide (propane forced air approx 700-800 gals a yr.) and within 2 yrs and attached garage at 900-1000 sq ft. with floor heat. DHW would be great also (easy to add I know). I would like to put radiant into the house by running staple up pex to the subfloor and leave the forced air alone (hence backup with central air). I know this is a loaded question but what are my best options for a boiler? Sorry for the long post, I've ben doing this for 7-8 months in my head! Thanks Guys

[mlappin]

If your talking best option for a used boiler I’d say whatever comes up for sale at a reasonable price, if you're talking new then it depends on who you ask and what they’re selling.

[nd guy]

If your talking best option for a used boiler I’d say whatever comes up for sale at a reasonable price, if you're talking new then it depends on who you ask and what they’re selling.

I agree 100 percent but when it comes to outdoor boilers, I'm a 16 yr old kid in a used car lot!! At 3X that age I do alot better in the used car lots!! LOL!! Like I said "it's a loaded question" just looking for any input that may be helpful. I learned alot by wandering the lots!! LOL!

[slimjim]

Are you able and willing to cut and weld, if so then a steel boiler, we have rebuilt several of the Seqouyah Paradise first generation gasser, they have proven to be a decent unit that burns about anything.

[E Yoder]

Are you located in ND ? I'm not sure what would be the most common used boilers in your area.
There are so many brands and models... Maybe look over Craigslist and post what you find. I would imagine there would be a lot of older Woodmaster, CB, Heatmaster, etc. units out there.

[Smokeless]

Heatmaster is coming out with a new economy model.
 It may be worth looking at that option. It is the GS series.

[nd guy]

Yes Richard I am able to cut and weld and steel is my first choice for that reason. I live in eastern ND smack dab in the middle of Heatmaster in Winkler, CB in Greenbush and Woodmaster in Red Lake Falls. Been searching Craigslist all winter. I have heard about the GS and waiting for them to release info June 1st I think. When we toured CB a month ago I learned that they are coming out with a new model this summer but didn't give any info. Waiting on that one too.