Newbie Needs Help with OWB selection!

[ewdudley]

The advantage that Garn has over a normal gasifier in an application using temps <140* is that condensation and/or cold shocking the boiler is not an issue. A person can start a fire in a Garn at 110-120* and just let it run with no tempering valve or other protection. This is definitely not the case with other wood boilers.

Hardly a point worth making, I don't see how a $150 valve could sway the argument one way or another.

 

[maple1]

The Garn I believe has addressed this issue for higher temperature needs of over 150 degrees , with its larger storage capacity units of 1,500 and 2,000 gallons! You still have ample time between firings .
With the Jetstream when just heating DHW in the summer I let the storage drop to 120 and then take it back up to 195 , there is marked higher efficiency at these lower temperatures .
But the need for boiler protection I believe takes away this advantage for its newer cousins .

What do you use for heat exchanging to heat your DHW?

(Sorry for the slight derail.)

 

[Floydian]

But the need for boiler protection I believe takes away this advantage for its newer cousins .

Allen, I don't get it. Can you elaborate on this? I routinely run my storage down to 100, always start fires with a "cold" boiler and my loading unit works exactly as it is supposed to. I can verify this with a quick glance at the temp gauges on the unit. I just don't see how this lowers efficiency in any way. Sure the Garn and Jetsream don't require RWP and that is nice and all but really its just another trade off when it comes to choosing a system.

Noah

 

[hobbyheater]

Hardly a point worth making, I don't see how a $150 valve could sway the argument one way or another.

The Jetstream in my setup does not use boiler projection. The temperature rise rate of the storage is much more rapid in the 120 F to the 140 F range and this includes getting a 1,400 lb refractory from 55 F to 60 F after sitting for anywhere from 10 to 20 days to over gasification temperatures. The boiler with protection does not have this lower water temperature advantage for more efficient heat transfer.

 

[ewdudley]

The Jetstream in my setup does not use boiler projection. The temperature rise rate of the storage is much more rapid in the 120 to the 140 range, and this includes getting a 1,400 lbs refractory from 55 to 60 F after sitting for anywhere from 10 to 20 days to over gasification temperatures. The boiler with protection does not have this lower water temperature advantage for more efficient heat .

Again, efficiency is measured by how much heat goes up the flue relative to how much heat goes to storage. A modern gasification boiler that maintains optimum flue gas temperature throughout the burn cycle while insuring complete combustion is the most efficient. Return temperature protection does not affect flue gas temperature or combustion efficiency adversely when combustion is properly controlled.

 

[hobbyheater]

Allen, I don't get it. Can you elaborate on this? I routinely run my storage down to 100, always start fires with a "cold" boiler and my loading unit works exactly as it is supposed to. I can this with a quick glance at the temp gauges on the unit. I just don't see how this lowers efficiency in any way. Sure the Garn and Jetsream don't require RWP and that is nice and all but really its just another trade off when it comes to choosing a system.
Noah

The water coming to the boiler from storage is uniform in temperature and can be 100 /105 degrees making for very efficient heat transfer at this temperature .
I believe your loading unit makes the water in your boilers heat exchanger rise to 140 f before the water can circulate to storage .If this is the case your boilers heat transfer takes place at 140F not 100F.

 

[heaterman]

The efficiency discussion regarding boiler protection and minimum return temp vs not, is kind of off topic for the OP.
Suffice to say that any boiler will enjoy an increase in thermal efficiency if it is capable of firing into 120 degree water as compared to a higher temp such as 140-150* common to systems using a device to elevate return temps.
That difference is maybe 3-5% in a boiler that fires directly into storage so not enough in my book to be a determining factor in a purchase. (A Garn will routinely crowd or even hit an honest 90% when working from 110-120*).
The additional device and associated plumbing could however have some bearing in the overall scheme of things for a homeowner.

 

[heaterman]

Allen, I don't get it. Can you elaborate on this? I routinely run my storage down to 100, always start fires with a "cold" boiler and my loading unit works exactly as it is supposed to. I can verify this with a quick glance at the temp gauges on the unit. I just don't see how this lowers efficiency in any way. Sure the Garn and Jetsream don't require RWP and that is nice and all but really its just another trade off when it comes to choosing a system.

Noah

The issue is not so much the temp of your storage....which could be 80* for that matter. It is rather, that the boiler can burn into that water temp directly without any elevation of the return water temperature.
Minimum water temps in the tank of a Garn should be kept above 110* or it will turn into a condensing boiler with all the associated problems that brings to the table.

 

[hobbyheater]

Again, efficiency is measured by how much heat goes up the flue relative to how much heat goes to storage. A modern gasification boiler that maintains optimum flue gas temperature throughout the burn cycle while insuring complete combustion is the most efficient. Return temperature protection does not affect flue gas temperature or combustion efficiency adversely when combustion is properly controlled.

The point that I am trying to make , heat transfer rate between the boiler walls and heat produced by the burning wood is greatest at lower water temperatures .
I measure the efficiency by the number of available btu's in a lb of wood end up in the storage,and this value is greater in the lower temperature range and has been consistent for 30+ years.

This has to be my favorite picture.
With the Jetstream at full output the air is just hot enough to be uncomfortable to breath and the air smells no different than the air that comes out of a hot air register.
Being retired or retarded just do not have the money to buy the expensive testing equipment , but I am satisfied that there is efficiency here .

 

[hobbyheater]

What do you use for heat exchanging to heat your DHW?

Two copper coils inside the storage; one for DHW and the second for heating with No efficiency loss in the exchange.

 

[woodsmaster]

One advantage to return protection is I can have a 1,000 gallons of luke warm water, start a fire and have 170 degree water supplying demands in a half hour or less.

 

[Coal Reaper]

One advantage to return protection is I can have a 1,000 gallons of luke warm water, start a fire and have 170 degree water supplying demands in a half hour or less.

Theres something a garn cant do.

 

[Fred61]

Theres something a garn cant do.

And my set up can't either given that I only heat from storage but I don't care. Unless the sun in shining in, my living space is a constant 70 degrees all winter. Although everyone knows that lower temperatures = higher heat transfer rates it is a moot point to me since there is such a short duration of time before the return temperature reaches 140 even if it starts at 100. The efficiency difference would be difficult to calculate.

 

[Tennman]

Allan, that has to be my favorite picture of you also. A true wood boiler junkie sniffing fumes and steaming yer glasses. No comment on your retarded point. Natasha...this is not necessary to operate a wood boiler.

 

[heaterman]

Theres something a garn cant do.

I'll grant you that. It is pretty surprising to most folks though, just how fast even a 2000 will hike the tank temp up from 130 to 160-70. The firing rate of a Garn delivers a wee bit more punch than most residential sized units. Even the Jr is rated at 180,000 net.

 

[hobbyheater]

Allan, that has to be my favorite picture of you also. A true wood boiler junkie sniffing fumes and steaming yer glasses. No comment on your retarded point. Natasha...this is not necessary to operate a wood boiler.

Natasha ! Absolutely TRUE the whole wood burning experience to me is just plain fun ! From the first pieces of sawdust from the powersaw cut into the log ,I definitely do not want to miss out on that last fume leaving the chimney .
This wood burning thing can really GET INTO YOUR BLOOD ! SO beware !



IT is definitely is an ADDICTION and can just spiral out of control !


This is a recent picture of Self with my Bride of 41 years . She kindheartedly supports my addiction , with exception to the Fume Thing !

All the best in your decision !

 

[Floydian]

Allen, are those Bear bells in the last pic?

Noah

 

[Floydian]

I will get more info on my heating usage and get back to you! Thanks again!

Natasha, when you get us this info we'll get your thread back on track.Promise

Noah

 

[hobbyheater]

Allen, are those Bear bells in the last pic?
Noah

Yup ! It's hunting season AND we don't want to become the accidental trophy.