gasifier storage and efficiency

[Nofossil]

There's been a lot of discussion on this topic, and I've been something of a skeptic. I finally got off the couch, put down the beer, and did the calculations.

During my first season, I ran a short season without storage. Second season, I had storage. Here's the bottom line:

2005-2006, no storage: 3.2 cords, 4350 degree days - .74 cords per 1000 degree days

2006-2007, with storage: 4.5 cords, 6177 degree days - .73 cords per 1000 degree days

A whopping 1% reduction in wood consumption!

The WAF was way better with storage, though. The house temperature was even and warm all the time, and we never ran out of hot water. We also have far fewer situations when we have to build a fire at an inconvenient time.

In my world, WAF outranks efficiency any day.

 

[ISeeDeadBTUs]

Obviously the WAF is WAY up there if she brought you a beer on the couch

 

[Eric Johnson]

We'll probably have this discussion until we're gray old men, nofossil, but I think a typical user with a big boiler will see greater gains--in some cases approaching the 40% claimed by Zenon for the EKO. Let's face it, you're not a typical user and--I hate to bring this up in a public forum--you don't have a very big boiler.

You're atypical in that you are into details and making detailed measurements, and you have the motivation, knowledge and ability to operate the thing at something approaching maximum efficiency.

Most of us fall somewhat shy of that.

Here's my take on it:

An undersized boiler is going to be more efficient than an oversized one, if for no other reason than it will idle less. You can fill an undersized boiler up to the gills and let 'er rip, for the duration of the load, which is the most efficient way to burn. With an oversized boiler, you're making small fires and tending the boiler more frequently. This introduces a lot of cold air into the boiler itself on a regular basis, and doesn't allow it to reach full efficiency, since there isn't enough wood in the firebox to get it there and keep it there. You run a bunch of smaller cycles, instead of fewer big ones. You're also tempted to dump heat with a big boiler. I'd rather crank my house stat up to 80 than see the boiler go into idle mode. So that's another big loss right there.

But with a tank, these issues all disappear once you learn how to time everything.

In fact, on my way to work this morning, nofossil, I was trying to figure out a good way to document these claims when I eventually get my tank going. It won't look anything like the charts you produce, but I bet I can come up with some empirical means of calculating the difference--perhaps wood usage over a specified time and under similar weather conditions.

And I must say, tank or no tank, with an ambient temp in the house between 75 and 80 at all times, my WAF has never been better.

 

[ISeeDeadBTUs]

And I must say, tank or no tank, with an ambient temp in the house between 75 and 80 at all times, my WAF has never been better.

All I can say is . . .I hope there's no website for 'Gasifier Babes', cause if my wife finds out your wives are livin in 80 degrees . . . . :bug:
Hell, my stats have never seen 70!!

 

[Eric Johnson]

That's one of the upsides of having an oversized boiler. Another one will be tonight, when it gets down around zero and I won't have to get up at 4:00 a.m. to stoke the damn thing. That was one of the bad things about my old Royall--sometimes I'd sleep on the couch when it was way below zero so that I could go out every few hours and jam more wood into the firebox. That gets old real quick.

 

[Nofossil]

We'll probably have this discussion until we're gray old men, nofossil, but I think a typical user with a big boiler will see greater gains--in some cases approaching the 40% claimed by Zenon for the EKO. Let's face it, you're not a typical user and--I hate to bring this up in a public forum--you don't have a very big boiler.

It's not the size, it's how well you use it. WAF is a good guideline.

You're atypical in that you are into details and making detailed measurements, and you have the motivation, knowledge and ability to operate the thing at something approaching maximum efficiency.

Most of us fall somewhat shy of that.

Here's my take on it:

An undersized boiler is going to be more efficient than an oversized one, if for no other reason than it will idle less. You can fill an undersized boiler up to the gills and let 'er rip, for the duration of the load, which is the most efficient way to burn. With an oversized boiler, you're making small fires and tending the boiler more frequently. This introduces a lot of cold air into the boiler itself on a regular basis, and doesn't allow it to reach full efficiency, since there isn't enough wood in the firebox to get it there and keep it there. You run a bunch of smaller cycles, instead of fewer big ones. You're also tempted to dump heat with a big boiler. I'd rather crank my house stat up to 80 than see the boiler go into idle mode. So that's another big loss right there.

But with a tank, these issues all disappear once you learn how to time everything.

In fact, on my way to work this morning, nofossil, I was trying to figure out a good way to document these claims when I eventually get my tank going. It won't look anything like the charts you produce, but I bet I can come up with some empirical means of calculating the difference--perhaps wood usage over a specified time and under similar weather conditions.

And I must say, tank or no tank, with an ambient temp in the house between 75 and 80 at all times, my WAF has never been better.

This may come as something of a shock, but I actually agree with you. My reason for posting this was to bring a dose of reality to the discussion. I doubt that anyone will see numbers anywhere near the 40% that I've heard, and I'd hate to see anyone go through the work and expense if that was the benefit that they were expecting. I also think that the cost and expense might turn people away if they think that a gasifier without storage would be that much worse.

I think that we're on the brink of having the ten commandments of gasification:

1) Dry wood
2) Smallest boiler that meets your needs
3) Adequate outside air supply
4) Adequate draft
5) Inlet temperature protection
6) Storage if you can do it
7) If storage, at least one radiant zone if you can do it
8) Turbulators
9) Optimize secondary air
10) Hearth.com boiler room membership

Still a work in progress, but what do you think as a first draft?

 

[Eric Johnson]

I tried, but couldn't think of anything to add. So I'd say you pretty much nailed it. I'd put the hearth.com membership somewhere closer to the top of the list, however.

 

[kuribo]

from an efficiency standpoint, I think it is true that you gain little with storage with a properly sized gasification boiler. Someone with a typical OWB though, may gain a great deal.

Again, the main benefit to storage may be the ability to fire on a more convenient schedule, i.e., less often, having a heat reserve, etc....

 

[brad068]

The most important thing that I think storage offers, is when you are in the transition periods- spring and fall. This is where boilers loose efficiency. Storage allows boilers to operate at full output during these times. Like my boiler, it never idles. Its wide open or out. The only thing that changed since it got colder is that I fire once every 24-36hrs. In the fall I was firing every 3-4 days. My boiler works the same if it -10F or 60F. Just longer periods between firings that all.

 

[EricV]

Another plus for storage is summer time DHW. I plan to use mine for my DHW year round. At least a good tempering tank in the summer.

I think the oil truck driver flipped me the bird the other day driving by, hahaha. because he didn't stop at my house.

 

[barnartist]

sorry for the delay Nofossil, thought it posted.
My scanner took a crap, so I had to tak a pic of my drawing.
anyone chime in, keep in mind I'd like to add 2 more tanks, and you need a couple of photo's, Once again, go to www.barnartist.com click on W.S.

 

[TCaldwell]

to keep the garn religion going, i burn all year, for dwh, 750,gal hot tub and a 20,000gal pool when not house heating, because of storage, saved in pool propane $2600 in one season, took about 5 cords wood , once you get the rythm it is more flexible with storage, but i will say that even with storage ,most want to size based on heat demand, once or twice a day firings, however you still need a high enough btu boiler output so you dont have to baby sit , as without storage. adding storage after the boiler purchase is fine but should be thought of when thinking what boiler to buy, you should know what your requirements are beforehand

 

[brad068]

to keep the garn religion going, i burn all year, for dwh, 750,gal hot tub and a 20,000gal pool when not house heating, because of storage, saved in pool propane $2600 in one season, took about 5 cords wood , once you get the rythm it is more flexible with storage, but i will say that even with storage ,most want to size based on heat demand, once or twice a day firings, however you still need a high enough btu boiler output so you dont have to baby sit , as without storage. adding storage after the boiler purchase is fine but should be thought of when thinking what boiler to buy, you should know what your requirements are beforehand

AMEN Tom,

I think we are fortunate to have Garn boilers. Thats the problem with knowing your heat load base on a 24hr period especially in spring and fall. Storage allows flexibility in these times. I plan on burning my boiler year round when I get it to its final instal location. I also have solar panels that I'm tieing in.

 

[Nofossil]

to keep the garn religion going, i burn all year, for dwh, 750,gal hot tub and a 20,000gal pool when not house heating, because of storage, saved in pool propane $2600 in one season, took about 5 cords wood , once you get the rythm it is more flexible with storage, but i will say that even with storage ,most want to size based on heat demand, once or twice a day firings, however you still need a high enough btu boiler output so you dont have to baby sit , as without storage. adding storage after the boiler purchase is fine but should be thought of when thinking what boiler to buy, you should know what your requirements are beforehand

5 cords per year for house, DHW, hot tub, and $2600 equivalent in pool heating? I'm quite impressed, unless you live in Hawaii. If I burned 24/7, I'd go through 5 cords in 60 days.

 

[TCaldwell]

garnification, i am interested in intigrating solar panels to the garn, do you know anyone who has installed yet
thanks tom

 

[brad068]

garnification, i am interested in intigrating solar panels to the garn, do you know anyone who has installed yet
thanks tom

No. But I think it will work. I was questioning how hot of water I could get out of these panels and nofossil said I could achieve 175F. I hope the panels can carry me through the summer and help out in the other seasons as well.

 

[TCaldwell]

nofossil, to clarify that 5 cords replaced the propane for the pool, hot tub and dwh for non house heating season, i am a flatlander, live in ct.,and prefer wine. with respect to the solar panels tied to garn what sort of rise could you expect with 140deg entering water and with what gpm, what preference of collector type? thanks your garn conscience

 

[Nofossil]

nofossil, to clarify that 5 cords replaced the propane for the pool, hot tub and dwh for non house heating season, i am a flatlander, live in ct.,and prefer wine. with respect to the solar panels tied to garn what sort of rise could you expect with 140deg entering water and with what gpm, what preference of collector type? thanks your garn conscience

My site (link is in signature below) has a section on solar panel performance. Flow rate is tough to calculate because mine is set up to circulate via convection only. I calculated the flow rate at about 1/2 gpm, but it varies with sun intensity and tank temperatures. On a good summer day, I get 50,000 BTU over and above hot water usage, which is probably around 60,000 BTU per day.

I use a combination of an above-ground solar pool heater from eBay and a set of three glazed copper panels. The glazed panels are necessary to get temperatures above about 135, but if you have to buy them, the pool heater may give better performance per dollar.

 

[mikeyny]

One thing is for sure, the more experience you get running each individual wood boiler, not matter what style size or brand the less wood you will burn. Over 4yrs I have cut my wood consumption in half. I have an older undersized boiler and have learned how to optimize its efficiency over time. I have an old house, high ,ceilings limited insulation and a hand full of kids constantly opening the door to go out sleigh riding, (how do you figure that into your heat loss calcs ??) I have 7 heating zones and programmable stats throughout the house. Basically, it a juggling act. The boiler runs flat out, stats never call for heat at the same time and it all seams to work pretty well.

 

[Eric Johnson]

I agree with your assesment of gaining efficiency through experience. I can't quite explain why it is, but it seems to be true.

 

[Bartman]

Now I'm totally confused. While trying to figure out the best equation for burning efficiently, I threw in the WAF factor, and that knocked the calculations out of the park. One minute she's cold, next she's too damn hot, all the while I'm maintaining 70F! Guess it's time for a younger one.............. :grrr:

 

[Eric Johnson]

The WAF is based on a series of complicated, arcane and absolutely top secret algorithms that roughly half the population is genetically incapable of deciphering, and wouldn't be able to understand even if they could decipher them. The algorithms allow the WAF user to collect and store information which can be (and often is) used decades later as a defensive/offensive mechanism--way beyond the point of normal data obsolescence, and often with no prior warning.

The only thing I know for sure about the WAF is that, like heating with wood, it works by momentum; if it's working to your advantage, you want to do what you can to keep it going that way. You don't want it working against you.

 

[Bartman]

Well said.

 

[barnartist]

somebody want to update me on WAF. I have a sniff about it, but would like the Websters-boiler rooms definition.

 

[Bartman]

I've been married to mine for almost 28 yrs.