how much more efficient is a lambda boiler when run w/o storage?

[TCaldwell]

I wouldn't take that to the bank. Far too many variables in play to count on an exact number.
Karl brings up a very salient point with the mass in the secondary chamber. It can make a huge difference in the amount of time needed to get the secondary chamber up to temp.
It coincides with what Tom is saying about the flue gas having to reach a certain temp or a set amount of time being reached before the control even starts to regulate what is going on.

In other words, even if you have a lambda controlled boiler, you may seldom reap any benefit from it if the boiler is experiences a lot of short cycling.

Even the EPA is wising up to this (and that is saying something!) from what I can see of their new proposal. Basically, you will have to have storage to reach emissions levels with any gasifier, lambda or not.
Seriously, storage is the answer to a greater degree than lambda, at least in my humble opinion.

Based on Tcaldwells input above - I would not count on that. I think he observed maximum Lambda benefit on the latter stage of the burn, and with a cycling boiler I don't think you would get to that stage as often. And, the lambda circuit is bypassed in the very early burn stage - which would be happening a lot more with cycling.

But I have no lambda experience, so I could be wrong.

This becomes evident when you are able to monitor o2, temp on a trend chart, combined with the relatively low btu outputs these boilers are capable of, becomes a question of splitting hairs. This is a good thread!

 

[Chris Hoskin]

I will be running w/o storage for the foreseeable future. If I am likely to cut my wood consumption by 15-20% with a lambda unit, that's huge.

Does anyone offer a Lambda boiler that does not "require" thermal storage?

 

[tjvt]

Does anyone offer a Lambda boiler that does not "require" thermal storage?

Vigas does.

Is storage more important for a Lambda unit? If so, why?

 

[hobbyheater]

Storage allows the boiler to fire at maximum efficiency for the entire burn cycle. In most set ups for domestic heating most boilers are very much over sized .A small boiler with a output capacity of 120,000 btu's per hour is going to idle a lot with a 60,000 btu's per hour load , and at 25,000 btu's per hour or less creosote build up inside the boiler very much starts to become a problem in many ways .

 

[tjvt]

Storage allows the boiler to fire at maximum efficiency for the entire burn cycle. In most set ups for domestic heating most boilers are very much over sized .A small boiler with a output capacity of 120,000 btu's per hour is going to idle a lot with a 60,000 btu's per hour load , and at 25,000 btu's per hour or less creosote build up inside the boiler very much starts to become a problem in many ways .

But this applies to all boilers. Storage maximizes efficiency, minimizes creosote buildup (assuming dry wood), etc., etc..

Why is storage more important for a Lambda boiler vs. a non-Lambda? That's the concept I'm not grasping.

 

[hobbyheater]

The old Jetstream is not Lambda, but I will try to explain from 30 years of observations.

The Jetstream has only primary forced draft .With very dry wood 7% and under moisture content the large refractory component heats up to 2,000* F ,more smoke is created than can be burned cleanly although not visible by watching the chimney .The only way that the excess smoke can be reduced is by reducing the wood available for combustion. If I try and burn a full charge of super dry wood efficiency can drop by as much as 20% to 25 %.( this number achieved by weighing the wood) . Possibly the Lambda unit could suffer in efficiency every the time the fire cycles as it loses its advantage in the time the fire temperatures takes to get back up to the gasification range of 1,350* F where the Lambda controls can work. The Lambda adjusts the air available for combustion.

 

[TCaldwell]

The effiency gained by lambda is outweighed by a lack of storage. All batch burn wood fires do much better when they can burn undisturbed to the end. I'm not talking about just the loss due to ideling, but the lack of effiency in bringing the fire back up to gasification and then to stabilize. Repeated cycling is a wood waster! If storage is not in the cards, get the smallest output boiler feasable, make smaller fires in a larger boiler and add storage later or burn pellets.

 

[TCaldwell]

tjvt, the answer is that storage is important for any boiler and without it the benefits a lambda boiler brings are pretty much lost. I would be surprised if there was a noticeable wood savings. Todays advanced boiler controls with modulating draft inducers that reduce boiler output when close to water target temp would have more impact than lambda without storage.