Garn Jr. Sizing

[dlabrie]

I have spoken with Chris Holley, the Garn dealer in Maine about buying a Garn Jr. to replace my OWB. It would be in my garage, 85’ feet from the house connected to the FHW system via the already installed, underground, 1” insulated PEX lines. My concern is if the Jr. is big enough for my situation.

My home is 2700sf, the attic has a good R40+, and the walls are insulated 2X4 construction with double pane windows from the 70s. I have been heating it without a problem with an old Central boiler, CL4436 running at 180* through FHW baseboards. It has also taken care of my DHW. During a normal winter day I fill the OWB twice/day. When we have the occasional winter blast; windy and 0 to -30* I fill it 3 times/day.

I don’t mind the fill schedule mentioned above but I would not want to have to load any more frequently. This morning the outside temp was 10* and as a test, I set my OWB to its lowest setting: 140-150. The house is maintaining its setting of 68*. Now, it is 14* outside and I have raised the temp in the 2 main floor zones to 70* to see how long it takes to raise the house by 2*. It took 30 minutes.

When I play around with the Garn Sizing chart the 1000 doesn’t seem to be adequate. Are there any Garn Jr. users in a similar situation that could chime in? I can just afford the Garn Jr. but there is no way, I can afford a larger model.

Thanks

 

[TCaldwell]

Have you discussed your system with Chris in detail, he is pretty crafty when it comes to extracting heat from a garn. Why not try lowering your supply temp even lower, and find the threshold of your system that will still heat your house. Maybe you could afford to upgrade some of the emitters and get away with a Jr, to extend time between firings.

 

[maple1]

You could always (I think?) add more baseboard, or some cast iron rads in certain places, to get more out of lower temp water.

 

[leon]

As much as I hate forest eaters:

AS Bob has said "you can add cast iron radiators" to replace the baseboard(my words)
which would cost you less money and you can invest in the smallest Garn if desired but a
coal stoker boiler will accomplish the same thing for you for less money.

If you replace your baseboard with cast iron radiators you can reduce your water temperatures.

I can and will tell you by installing firebrick in my wood and coal boiler like I did I reduced my
coal and wood consumption too.

I filled my firebox half full of firebrick right up to the flue breech and created a huge amount of
thermal mass in the process.

I guess if it were me I would add back cast iron radiators and replace the baseboard and
fill the firebox half full of firebrick to reduce my wood use by running at lower temperatures and
by using the firebrick for additional thermal mass and in the process burn the fire hotter and cleaner.

Its an opportunity cost decision on your part and if you buy salvaged radiators and invest in square
tubing to eliminate pipe runs under the floors and under the doors you have a much less chance of leaks.



I would rather see you add a pallet of standard firebrick(not the half size!) to the firebox like I did
first before making any major investment decisions for a heating system.

Its your money and I am not trying to spend it just offering my past experience in this issue

 

[dlabrie]

Thanks for the replies.
I did talk to Chris and he also suggested seeing if my system could function at a lower temp. So I
did try lowering my OWB temp. from 175-185 to 140-150. I have setback thermostats on 3 zones; one is set back 3 degrees and the other two are set back 2 degrees at night. With the lower OWB temp. It took 3 hours for the heat to catch up this morning and about 15 minutes for the DHW to catch up after a shower. I really don't want to try retrofitting my base boards to accommodate lower temp water. If I were building new I would definitely go with low temp radiation.

Is it possible to have a wood gasifier with storage that will give me 180* temps to work with That I would only have to load 2 times a day?

 

[leon]

I have mentioned in the past the more storage you have the better; some folks on the arborist site forum are using retired insulated railcar tanks for water storage tanks and boiler firebox shells feeding them with skid steer loaders.

Having a huge thermal mass is to your advantage and will reduce your firing rate and in the process you will have a cleaner burn especially if you have firebrick in the firebox.

Using the above example an 8K insulated tank of water will hold lots of heat and thermal mass and if you load your forest eater with firebrick the fire will be hotter and cleaner and you will consume less wood.

You could install a small modern wood boiler in the garage and have the tank next to the garage as an option and that boiler will run hot and continue to push 180 degree water into the tank when it gets up to temperature or simply heat up water to a lower temperature and you will still have a huge thermal mass to bless your heating system with and if you install cast iron radiators the temps required will be even lower as you still have 8K in thermal mass in the same water to use.

Me-I would invest in a Keystoker KAA-2 or a more modern interior wood boiler and a surplus storage tank and simply have a heat exchanger and two pumps one for the heating load and a second for the keystoker to pump 4 GPM into the tank

The other thing is if you have 8,000 gallons of hot water at 140 degrees in this example you do not need that much energy to heat it to 160 degrees either so keep that in mind when looking at the big picture as the same can be accomplished with a Garn by insulating the shell too.

The newer gasser wood boilers need maintenance and "dry wood". A simple firebox filled half full of fire brick as was my case was something I wish I had done 33 years ago instead of 7 years ago.

If you simply lay firebrick in yours now and fill it half full to the breech I would imagine you will see quite difference even though most of the heating season is over. Stack the firebrick and make a running bond on the outside closest to the water jacket after you clean the boiler if you decide to go that route. All I can tell you is it worked for me and I had much less smoke and a hotter fire too.

 

[mike van]

diabrie, give me a call if you want, this is my 3rd winter on a Garn Jr. I talk better than I type. I'm happy with it. Tonight 6 PM i'll be here - eight six zero 927 308six

 

[flyingcow]

I ve got a jr in my truck garage. Not a huge heat load, but I am using a "modine" type unit to heat the garage. I love the simple operation of the Garn. Chris Holly was great to work with. It's freaking impressive how quick you can bring up the tank temp. The Garn water temp will be down to about 115/120, fire up 1 load of wood, 2 1/2 hours woods all gone, tanks at 175/180.(BTW, my Garn is still not insulated properly). Plus the unit heater is running that 2 1/2 hours. This unit heater will push over 80k btu's when it's running on 160ish water temp. This is plumbed up very simple. No mixing valve.

But I also have a Solo Innova -30 with 820 gals of storage,to heat my house. I've got the Innova next door in my unattached garage. Piped underground (50ft) to the basement of my house, where my 820 gals of storage is. I have a 1800sq/ft 2 story house on top of a hill in northern Maine. Plus a full(unheated) basement. R-19 walls in the house, the attic is close to R-60. But the R-60 upgrade was done just a yr ago. Might have been an R-25/30 before that. Innova was installed the winter of *08. Baseboard throughout the house. Plus our kitchen has staple up radiant, keeps the feets warm.

This am, 6f outside no wind. My 820 gals of storage was about 115/120f. Fired up Innova. Here's the nice part. In 45 mins Ive got 160f water flowing thru the baseboards. 15 mins later water temp is pushing 180f. Fire will burn out in about 3 1/2 hours. I might go out after the sun sets and start a small fire again. If its sub zero, especially if the winds blowing, I'll do two fires a day. BUT( the important part), I didn't spend a lot of time sizing my boiler and storage. I have a weil Mclain oil boiler that was 80k btu's. So I bought a 102k wood boiler. If I was to do it all over again? I'd go up a boiler size and put 1,000 gals of storage. And i should put a continuous circ on my baseboard with an outdoor reset.

I bought the Innova thru the guys in NH. Woodboilers.com I used their piping layout, and valves. A little pricey, but works great. But when I have any questions about hows its running, they've been great to deal with also.

Not sure if this helps. Sometimes comparing these two types of wood boilers is not easy for me. But both units work great and I've had great customer service from both companies.

One other option, look at the classifieds/ craigs list etc. With the dropping of oil prices, people are looking to sell the wood boilers. More work than some thought. You might find a 3 or 5 yr old unit for less than 1/2 price. And i have occasionally seen a Garn or two, but might be a ride to get it. I picked up a solo 50(7yrs old?)? a few yrs ago. Cant remember exactly, but I think I bought it for $950. I think I sold it just under 2k? Maybe $1800.

You got time to look around.

 

[dlabrie]

I have mentioned in the past the more storage you have the better; some folks on the arborist site forum are using retired insulated railcar tanks for water storage tanks and boiler firebox shells feeding them with skid steer loaders.

Having a huge thermal mass is to your advantage and will reduce your firing rate and in the process you will have a cleaner burn especially if you have firebrick in the firebox.

Using the above example an 8K insulated tank of water will hold lots of heat and thermal mass and if you load your forest eater with firebrick the fire will be hotter and cleaner and you will consume less wood.

You could install a small modern wood boiler in the garage and have the tank next to the garage as an option and that boiler will run hot and continue to push 180 degree water into the tank when it gets up to temperature or simply heat up water to a lower temperature and you will still have a huge thermal mass to bless your heating system with and if you install cast iron radiators the temps required will be even lower as you still have 8K in thermal mass in the same water to use.

Me-I would invest in a Keystoker KAA-2 or a more modern interior wood boiler and a surplus storage tank and simply have a heat exchanger and two pumps one for the heating load and a second for the keystoker to pump 4 GPM into the tank

The other thing is if you have 8,000 gallons of hot water at 140 degrees in this example you do not need that much energy to heat it to 160 degrees either so keep that in mind when looking at the big picture as the same can be accomplished with a Garn by insulating the shell too.

The newer gasser wood boilers need maintenance and "dry wood". A simple firebox filled half full of fire brick as was my case was something I wish I had done 33 years ago instead of 7 years ago.

If you simply lay firebrick in yours now and fill it half full to the breech I would imagine you will see quite difference even though most of the heating season is over. Stack the firebrick and make a running bond on the outside closest to the water jacket after you clean the boiler if you decide to go that route. All I can tell you is it worked for me and I had much less smoke and a hotter fire too.

Leon,
Thanks for the reply. A Keystoker KAA-2 would be great but for two things- 1, Coal isn't readily available here in Northern NH and an 18 wheeler can't access my property so I would be stuck buying bagged coal. 2, I have my own woodlot so wood is free.

The fire brick in the OWB sounds like a great idea, but it has already sprung one leak that i had to have welded and i want to replace it before I have another.

A modern interior wood boiler, in an outbuilding, and a surplus storage is the route I have been considering. But I kept running into the idea that they are used with lower temp (140*) water in more efficient radiant systems than I have, which seemed to be the issue with the Garn Jr.

 

[dlabrie]

But I also have a Solo Innova -30 with 820 gals of storage,to heat my house. I've got the Innova next door in my unattached garage. Piped underground (50ft) to the basement of my house, where my 820 gals of storage is. I have a 1800sq/ft 2 story house on top of a hill in northern Maine. Plus a full(unheated) basement. R-19 walls in the house, the attic is close to R-60. But the R-60 upgrade was done just a yr ago. Might have been an R-25/30 before that. Innova was installed the winter of *08. Baseboard throughout the house. Plus our kitchen has staple up radiant, keeps the feets warm.

This am, 6f outside no wind. My 820 gals of storage was about 115/120f. Fired up Innova. Here's the nice part. In 45 mins Ive got 160f water flowing thru the baseboards. 15 mins later water temp is pushing 180f. Fire will burn out in about 3 1/2 hours. I might go out after the sun sets and start a small fire again. If its sub zero, especially if the winds blowing, I'll do two fires a day. BUT( the important part), I didn't spend a lot of time sizing my boiler and storage. I have a weil Mclain oil boiler that was 80k btu's. So I bought a 102k wood boiler. If I was to do it all over again? I'd go up a boiler size and put 1,000 gals of storage. And i should put a continuous circ on my baseboard with an outdoor reset.

I bought the Innova thru the guys in NH. Woodboilers.com I used their piping layout, and valves. A little pricey, but works great. But when I have any questions about hows its running, they've been great to deal with also.

Not sure if this helps. Sometimes comparing these two types of wood boilers is not easy for me. But both units work great and I've had great customer service from both companies.

Flyingcow,
This is just what i had in mind. With an unpressurized storage tank, can you circulate the stored water through the wood boiler and through the radiators or are heat exchangers necessary? Can you give me an idea how yours works?
Thanks.

 

[leon]

Leon,
Thanks for the reply. A Keystoker KAA-2 would be great but for two things- 1, Coal isn't readily available here in Northern NH and an 18 wheeler can't access my property so I would be stuck buying bagged coal. 2, I have my own woodlot so wood is free.

The fire brick in the OWB sounds like a great idea, but it has already sprung one leak that i had to have welded and i want to replace it before I have another.

A modern interior wood boiler, in an outbuilding, and a surplus storage is the route I have been considering. But I kept running into the idea that they are used with lower temp (140*) water in more efficient radiant systems than I have, which seemed to be the issue with the Garn Jr.

=============================================================================================

You should also check with Gary Switzer in Dundee, New York about his hybrid wood boilers as he has built them for 33 plus years now-I bought the last wood and coal boiler he made in in 1983.

Gary and his son in law do very good work. I bought my wood and coal boiler from him and recently sold it to a gentleman that has one of his hybrids that he bought used and he is installing it in his garage to heat his log cabin.

They install each unit and stay until they are satisifed it is running properly.

I am sure he would build a firebox lined with fire brick for you to make it last even longer and heat better.

Garys boilers are pressurised and pressure tested and a simple steel expansion tank with an airtrol valve would be all you need for it if you use or need a heat exchanger.


Please tell him I said hello if you call him.


Garys shop is only about 20 miles from me and an easy trip from Ithaca or South from Geneva.

[email protected] 1-607-243-8689


Given enough notice I would be glad to go up there with you.

 

[flyingcow]

Flyingcow,
This is just what i had in mind. With an unpressurized storage tank, can you circulate the stored water through the wood boiler and through the radiators or are heat exchangers necessary? Can you give me an idea how yours works?
Thanks.

Others will explain better, but the hot water from the boiler goes in the standing tank of water, via a coil or heat exchanger. That same hx will pull heat back out of tank and heat you baseboard, once the wood boiler is off. Plus there is a dhw hx in the tank. That 820 gals of water just sits there, storing heat like a battery. Some refer to them as a heat bank.
There are a few different ways to use storage. Some use 1000 gal propane tanks, for pressurized storage.

But don't write off the garn yet. The price of the gar obviously includes your storage.

 

[maple1]

Is it possible to have a wood gasifier with storage that will give me 180* temps to work with That I would only have to load 2 times a day?

I think if you need 180 water all the time, you will be disappointed with storage performance no matter what kind of storage setup. I can go down to 125 or so on top before needing to refire (depending on the day), with my baseboard - but that goes in steps. If you start with 180, then all the water circulates leaving you with 160 at the top. (One lap). As things keep heating from storage, the supply temps step down in 20° increments (give or take - reducing a bit with each lap) with each lap. I think I get about 3 laps out of mine. About 2000 gallons worth of flow. If you really needed 180, you'd be looking to refire after one lap. That's with decent stratification - if stratification isn't good, you might be done sooner. I'm not sure, but I think the Garns may not do stratification as well as divorced boiler & storage - someone with a Garn please correct me on that if wrong.

You mentioned above testing the performance of your existing system by reducing boiler temp & seeing how the system responded. But I think you were trying to raise house temp. Recovering from setback requires more heat input than maintaining temps does. If you haven't, I would leave your house stats at a certain point (68? 70?), then cool your boiler, and see at what point the house starts to lose heat or it starts to feel like it's getting too cool. You might be surprised at what the boiler temp point is then. You might also find that only one spot of the house or zone gets to feeling cool - which might mean a couple more rads needed in only one place.

With mine I only burn once a day. For no more than 6 hours.

 

[flyingcow]

https://www.hearth.com/talk/threads...ent-for-sale-never-installed-or-fired.147623/

 

[flyingcow]

https://www.hearth.com/talk/threads/garn-whs2000h-used-3-seasons.146128/

 

[Wook660]

=============================================================================================

You should also check with Gary Switzer in Dundee, New York about his hybrid wood boilers as he has built them for 33 plus years now-I bought the last wood and coal boiler he made in in 1983.

Gary and his son in law do very good work. I bought my wood and coal boiler from him and recently sold it to a gentleman that has one of his hybrids that he bought used and he is installing it in his garage to heat his log cabin.

They install each unit and stay until they are satisifed it is running properly.

I am sure he would build a firebox lined with fire brick for you to make it last even longer and heat better.

Garys boilers are pressurised and pressure tested and a simple steel expansion tank with an airtrol valve would be all you need for it if you use or need a heat exchanger.


Please tell him I said hello if you call him.


Garys shop is only about 20 miles from me and an easy trip from Ithaca or South from Geneva.

[email protected] 1-607-243-8689


Given enough notice I would be glad to go up there with you.

Gary's the man! Him and Dave just finished installing my new boiler with oil back up 2 weeks ago. They drove almost 6 hrs, worked until 2am, crashed at my place and then worked most of the following day until it was up and running before heading home. His website is very limited, but we stopped by his shop on the way back from Ohio last year and he demonstrated the one in his shop. We were sold.

 

[dogwood]

Diabrie, I've a Tarm Solo Innova 50 with a thousand gallons of pressurized storage that easily heats my 3000 sq. ft home. Granted we're in Virginia, not New Hampshire, but even in the dead of winter with temps in the low teens I've not had to burn more than twice a day and only occasionally filling the chamber to the top. You should check out Tarm Biomass. They're located not far from you in Lyme, New Hampshire They sold and shipped us ours. They carry Froling too. Talk to Chris Hoskin there.

Mike

 

[dlabrie]

Mike,
Thanks for the info. I am currently leaning towards a Portage & Main EGR 250 but once "mud season" is over here in NH, I plan to take a ride on my Motorcycle over to Lyme to see what they have to offer.
David

 

[dogwood]

Diabre, FYI, I recieved this email from Tarm Biomass today:



We are Moving Soon to our
New Location

We will be moving March 24th and 25th and will be closed both days.

Our new address will be:
19 Archertown Road
Orford, NH 03777

Our phone number and mailing address will stay the same:
1-800-782-9927
1-800-Stay Warm
P.O. Box 285
Lyme, NH 03768

 

[Karl_northwind]

Mike,
Thanks for the info. I am currently leaning towards a Portage & Main EGR 250 but once "mud season" is over here in NH, I plan to take a ride on my Motorcycle over to Lyme to see what they have to offer.
David

looks like the heatmaster G-series.
I like storage, and I like GARNs, but in many applications (like replacing a dying forest eater) where the balance of system is in place, and you need high temperature water (like heating baseboard radiators, assuming they're sized "properly" for 160-180F water) something like the OWB gasifiers make sense for the budget-minded operator.

If all the other factors are in place, adding radiation to deliver peak heat load from lower water temps makes a lot of sense.

 

[dlabrie]

Diabre, FYI, I recieved this email from Tarm Biomass today:

View attachment 176843

We are Moving Soon to our
New Location

We will be moving March 24th and 25th and will be closed both days.

Our new address will be:
19 Archertown Road
Orford, NH 03777

Our phone number and mailing address will stay the same:
1-800-782-9927
1-800-Stay Warm
P.O. Box 285
Lyme, NH 03768

Thanks, Mike. I'll be heading out there once the mud dries up

 

[dlabrie]

looks like the heatmaster G-series.
I like storage, and I like GARNs, but in many applications (like replacing a dying forest eater) where the balance of system is in place, and you need high temperature water (like heating baseboard radiators, assuming they're sized "properly" for 160-180F water) something like the OWB gasifiers make sense for the budget-minded operator.

If all the other factors are in place, adding radiation to deliver peak heat load from lower water temps makes a lot of sense.

You hit the nail on the head. Either I go with an OWB gasifier or replace my slant fin baseboards with low temp emitters and go with the Garn. The OWB gasifier seems to be the least expensive and easiest to install.

 

[leon]

I realize its your money and your time but I would also call Gary Switzer and ask about his hybrid
boilers which are also a two pass smoke tube system. The boilers he builds are pressurized
hydronic heating boilers and you can keep your baseboard heat(as much as I hate mine).

You could very easily install a steel expansion tank with an airtrol valve above the Switzer boiler in the garage ceiling.
to maintain 12 PSI in your baseboard.

Gary and his son in law deliver the units he builds, they install them and make sure they are working right
while they are there long before they leave and I am sure your garage would work for this.
========================================================================================
Disclaimer: I have no financial or business affiliation with Gary Switzer.
========================================================================================

 

[Wook660]

I realize its your money and your time but I would also call Gary Switzer and ask about his hybrid
boilers which are also a two pass smoke tube system. The boilers he builds are pressurized
hydronic heating boilers and you can keep your baseboard heat(as much as I hate mine).

You could very easily install a steel expansion tank with an airtrol valve above the Switzer boiler in the garage ceiling.
to maintain 12 PSI in your baseboard.

Gary and his son in law deliver the units he builds, they install them and make sure they are working right
while they are there long before they leave and I am sure your garage would work for this.
========================================================================================
Disclaimer: I have no financial or business affiliation with Gary Switzer.
========================================================================================

Not to nit pick but they are 3 pass now.

 

[leon]

Not to nit pick but they are 3 pass now.

I am glad that Gary has improved them further as it will be even better for the homeowner as he or she will
use even less wood.