Wood/Vitodens combo

Glen

I am receiving more and more interest in combining outside wood fired boilers with vitodens/radiant installations. Preheating the DHW is also a consideration. I am thinking that the two systems can be separated/combined via a flat plate heat exchanger on the LLH supply side, with a large buffer tank to store the hot water from the wood boiler, related controls etc. Disabling the vitodens shouldn't be a problem (eg when the water in the buffer tank reaches a usable temp). Should I pipe the supply side from the buffer tank through a three way to control the heat to the LLH? Have any of the folks on the Wall combined these systems that may want to pass on a few suggestions?

Unknown

wood boilers

Glen,

You can not combine this through the low loss header. A wood boiler needs to have a place to "throw off" excess heat or the fire regulating door will close off your combustion air. Add to that the fact that if you "low fire" a wood boiler all the time you will creosote the crap out of it. You would need to set this up as secondary circulation on the SYSTEM side of the LLH with a "dump" zone.

It's all do-able. I would want to check into the electronics on the Vitodens200. It is made to constant flow between the boiler and low loss header maintaining a supply temp according to outside temp. It then "feels" the rate of rise and fall and adjusts it's burner accoridingly. I wonder what the "brain" would think on a 50F day and your throwing 180F water from the wood boiler through the pipes :-)

In my own feable mind I thing it would be like eating something so cold it is smoking with the thought htat it was really smoking from being too hot.

wheels

hr

I have a MZ and wood boiler

in my shop. Fairly easy to do with a primary secondary loop. Mine fires a low temperature radiant, and has a 165 gallon (used LP) tank as a buffer and dump zone.

I am going to do some upgrades this fall and add a Grundfos MixiMiser VS to build a boiler return protection for my wood boiler. See the link below for a simple and effictive return protection method.

I'd like to up my storage to 500 gallons also. Currently I use a VS to inject from the buffer tank (180°) into the circle primary loop to get my radiant temperature.


http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,128051,00.html


Check into the Aqua Therm outside burners as they are pressurized and eliminate the need for a HX to isolate.

I'm also looking at some European wood boilers, gasification units that burn a bit more efficiently. typical outdoor burners run 40-50%. The Euros claim close to 80% with the gasification boilers. Half the fuel and a cleaner emissions.

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Unknown

mvc-008F.jpg

Hey HR,

I love the primary loop. Very cool. Very artistic.

Is that (mvc008)the cad drawing that you had to feed into the computer to have the automatic tube bender and plasma cutter do their job in the assembly room for you? :-)

wheels

hr

thanks wheelie!

I am still noodling the final piping. A loop and buffer like I propose would also lend itself to a solar tie in with plenty of buffer capacity.

My biggest challange is a control package to make it all stage and communicate properly.

Could be a good exercise for the Caleffi team. Be nice to be able to dial up the system for a status when I am out of town

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Glen

I am thinking about a 250 gal buffer forming a large primary loop with the wood boiler. Most wood boilers here are open affairs so I could then separate the two systems with the heat exchanger. Once the buffer is up to temp a disable signal can be sent to the Vitodens which would also start the secondary pumps suppying a mixed temp to the low loss header. At that point all flow through the Vitodens would stop and the wood boiler would then be primary heat source. Another secondary loop would supply another heat eschanger to heat domestic. Customer is not using a Viessmann indirect but choosing a large electric unit. Your drawing is close to what I have in mind - the secondary loop essentially doing the same job as the low loss header.

Unknown

which terminals...

exactly which terminals on a Vitodens 200 actually call the boiler?

wheels

hr

Got drawing?

If I read you right you are considering the buffer within the primary loop?

I don't think this would be the best arrangement. That large capacity could keep the boiler running cold return for an extended time. This does effect even wood fired boilers by lowering efficiencies and encouraging creasote formation. Keep in mind most outdoor wood furnaces have large water contents and need some time to rev up. Adding more buffer volumne to a furnace that holds 150- 200 gallon or more will really slow down your response.

With the buffer as a secondary you get useable hot water quicker for your load, directly from the primary, and sip off to the buffer as the loads are satisfied, or maybe not at all if the boiler and load match exactly on design, or below design days.

Also you could buffer the Viessmann with the same tank, via the primary loop, to extend it's run time and give you the ability to handle micro zones that may be below the low modulating rate.

Or the Viessman could feed directly into the loop.

The independant primary loop gives you lots of options, sort of like an 18 speed transmission on a large truck. It allows you to adjust the heat generator(s) in various combos. One at a time, both together or staged as demand requires.

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Glen

4.1 and 4.2 can disable the boiler and then there is at least 2 if not 3 programming addresses that would need to be set. HR - if you send me your fax # I can send you my initial design.

hr

This article may help

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,4498,00.html

Siggy has promised to get us an updated wood boiler article. I'd like to see his latest ideas with new components that were not available when he wrote this first column.

I did get to see the "mother of all buffer tanks" at Siggys home a few years back. He had a welder build a tank about 12" wide, about 20 feet long and two stories tall in his home. It started in the basement behind a wood stove and went up to the rafters. Painted with a mural on one level. It was both a buffer tank and a huge panel radiator. I believe he charged it with solar and wood.

He now runs an oil fired Buderus as primary heat source. Guess we all tire of the wood ritual at some point What a clever idea to make the interior wall of your home a buffer tank/ panel radiator. Had a nice ring to it, when you bumped against it, also

Fax me at 417-753-3685, like to see your design.

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Unknown

ahhhhhhhhhhhhhh

I see it now, x4.1 and x4.2, coding changes 011 & 027 and look at 0A2. THANKS!!!!

I see a note about operating curves in reference to 027. You know anything on that one?

wheels

Mi39ke_2

Garned Again

Interesting stuff, all this additional buffer tank information.

If you burn a lot of wood, why not have the boiler itself have all the water?

I've been looking at the Garn unit as a viable alternative.

American made and designed. The engineer said he was surprised when he did a patent search, as all the other competitors were trying to control the fire. He doesn't.

He doesn't control the fire. Did I say that? He burns at extreme efficiency with no-smoke and absorbs the energy. Two moving parts on the boiler. The door. The fan. Side vented. Fan submerged. No losses.

Granted, it is expensive and for bona-fide wood people only.

He claims to have done the first Wirsbo installation, many years ago. I'm inclined to believe him as he seems to have integrity and ethics.

At his seminar, within a couple hours, I learned more about wood burning than I had in years of messing around. Example: Smoke equals very low efficiency. How basic is that??

Would love to hear experienced users of this machine give opinions. It's been around a long time. Lots of R&D already accomplished. Good references and project examples of units saving extreme amounts of wood (and labor!).

Brought the Garn info to the Siggy show and forgot to get it to him (Siggy).

Speak to Martin Lunde, PE at Garn.

www.garn.com

Michael Ward--not a Garn employee

hr

Hey Mike

nice to hear you are still seeking and learning, atta boy.

That's quite a boiler, the smallest size weighs 15,000 lbs! 71/2 ton is the right! with a 1500 gallon water capacity. Wonder how you move that thing or what happens if it springs a leak while you are out of town

Certainly it makes some sense to store the heat within the boiler IF it's located inside. Not the case as you know with outdoor open system wood furnaces. To me it makes more sense to pump the water and store it inside with that type.

I'm not quite clear on the test results. Using the smallest unit 1500 gallons is it possible to raise the temperature the indicated delta t with the indicated 70 lbs of wood?


If the claimed numbers are true that's some serious performance. The independant test I have heard of for the typical "wood furnace" indicates mid 40% best efficiency.

Thanks for the link, I'd like to hear his spiel. Was this at your local energy fair?

Do they deliver and haul it down the stairs into the basement?


Seems an energy progressive state like Wisconsin that prohibits residential snowmelts due to energy waste would be one of the first to clamp down on the less efficient, smoldering 40%ers. Any rumor of this?

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Mi39ke_2

Glleepp Glloopp Yupp, I think [g]

Hey HR,

Glad you are still prodding and analyzing!

Yes, it's only a boiler for the serious wood people. Outdoor only. Comes with directions to insulate and build a building for it. Big, big, big.

You and Siggy can tell us if it makes sense once you analyze the machine, mass, typical application, etc.

This sucker is built to last. Practically crawled inside it at the meeting. Serious welding. A Northern dealer held a seminar and we jumped at the opportunity to hear Martin Lunde speak.

Since the engineer has serious "chops" I would venture it is something to look at for installations beyond the typical home.

The best installation for a Garn would be a an outbuilding, home, and maybe another office on the same boiler. Serious woodburning only, I'm afraid.

Martin says he turns away people who want to heat merely a small home with his unit.

Don't know about the clampdown. I like the Clash song, though. [g]

Martin is very accessible and could speak for hours on the efficiencies of wood burning. I can put you in touch if you don't reach him through the site. Let me know what you think, as I value your input. Tell him you spoke to me, as I have been prodding him to be a little more vocal. He has some serious customers on the East Coast who will buy no other machine after attempting some of those inefficient units.

Michael Ward

Mi39ke_2

Also...

He had a lot to say on welding, metals and the construction of the competition's boilers. Water quality too! Have I caught your attention! I thought so.

Regards,

Mike

hr

Kudos to Martin

for considering all the important aspects. Emissions, welding, water quality, and proper application. Owner/ operator training is also a big plus

So what about Wisconsin's take on emissions. Sounds like the wood furnace manufactures have "committed up" to address the upcoming EPA tier 2 emission standards.

As I research wood burners the gasifiaction process, seen in Martins and most Euros like Tarm, etc. holds the key to greatly decreased emissions and an almost doubling of efficiency (wood used) Looks like plenty of independant labs here and across the pond have tested and confirmed this.
The wood burning marketing is heating up around here with uncertin fuel prices, I'd like to sell and install only the best most efficient units. Still searching.

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Mi39ke_2

Wisco

My particular market is made up mainly of manufacturers selling to the DIYer crowd. As there are not many hydronic contractors making waves, I can see why they might want to work with homeowners rather than inexperienced contractors who can muck up the sale.

We too have seen an increase in woodburning inquiries. I guess the Tarm unit is currently top choice for tiny systems and the Garn for larger projects. I haven't installed either of these. I like to see some history with these machines, of course. We've used Aquatherm on previous projects.

Wisconsin...what a wacky place. Minnesota...what a wacky place. We have more lakes, but they promote the lakes better, I think. [chuckle] If there are some emmission standards to be met, we will certainly consider them...after Minnesota does, probably. [g] Minnesota is a real progressive HVAC state, IMO. But heck, what do I know? I only sit and listen a bit...lurk a bit...wander a bit.

Thanks for teaching and pushing, hr. Let me know if you find the perfect machine.

Mike