Practical Advice

[grainfedprairieboy]

Howdy folks. Long time lurker but finally taking the plunge here.

Over the past several years the information I have gleaned from the posters here has helped to convince me that a wood gasification unit is the way to go. Further, I am sold on the concept of running a short hot fire and utilising water storage.

I am currently renovating and building an addition to a rural home and will have a requirement for a boiler in the 300,000 BTU range. Wife is a city girl and demands a relatively fire and forget system for those occasions when I am not around so a natural gas backup of some sort is in order.

I have narrowed my options down to an AHS multifuel NG backup with add on heat storage and the Garn with a combination NG boiler.

My question is: what do you feel is the best way to combine a wood gasification boiler with natural gas back up and indirect thermal storage?

 

[Nofossil]

Howdy folks. Long time lurker but finally taking the plunge here.

Over the past several years the information I have gleaned from the posters here has helped to convince me that a wood gasification unit is the way to go. Further, I am sold on the concept of running a short hot fire and utilising water storage.

I am currently renovating and building an addition to a rural home and will have a requirement for a boiler in the 300,000 BTU range. Wife is a city girl and demands a relatively fire and forget system for those occasions when I am not around so a natural gas backup of some sort is in order.

I have narrowed my options down to an AHS multifuel NG backup with add on heat storage and the Garn with a combination NG boiler.

My question is: what do you feel is the best way to combine a wood gasification boiler with natural gas back up and indirect thermal storage?

Welcome to the forum and the boiler room.

Question: How did you arrive at 300,000 BTU/hr? That's a very high number. Oversizing your boiler hurts your efficiency.

I'm a fan of keeping the wood and fossil units completely independent, so that either or both can operate as needed without affecting or depending on the other.

 

[grainfedprairieboy]

I did a heat loss calculation. Might seem high but the house is close to 6000 square ft of heated area (includes basement) and has a small indoor swim in place pool to be heated 3 out of 4 seasons.

 

[Eric Johnson]

I too am a fan of having independent heating units, though in the case of mating a gasifier with a gas burner, there are fewer safety concerns since the gasifier isn't going to produce any creosote in the stack.

But, if you have a combo unit and it ever springs a leak or other major problem, you're stuck without a backup.

My approach, if I had to start from scratch, would be to put most of my money into the wood boiler and then buy a cheap gas boiler to use strictly for backup. And pipe them in parallel.

 

[grainfedprairieboy]

So then which in your opinion is best: integrating the indirect storage or separating?

One of the only things that appeals to me about the AHS is the multifuel option. Perhaps the Garn is the better choice? Both seem to be around the $18,000 mark.

 

[sdrobertson]

My approach, if I had to start from scratch, would be to put most of my money into the wood boiler and then buy a cheap gas boiler to use strictly for backup. And pipe them in parallel.

I'd echo Eric and with that heat load - I'd really think about the Garn. Building fresh, you could really make a nice boiler room.

 

[flyingcow]

Keep everyone posted of your decision. When you get it up and running, I'll grab the minivan and pick up a few of the hearth.com crew on the way out and see this 6000sq/ft with pool house. :coolsmile:

 

[Jim K in PA]

So then which in your opinion is best: integrating the indirect storage or separating?

One of the only things that appeals to me about the AHS is the multifuel option. Perhaps the Garn is the better choice? Both seem to be around the $18,000 mark.

GFPB - welcome to the Boiler Room.

I don't expect to use it as often as you might, but I am building toward a similar solution as you describe. I have a GARN WHS2000. I have piped it primary/secondary. I am incorporating a propane fired backup in a secondary loop that consists of an outdoor pool heater rated at 150k Btuh. It is big enough to meet my max loads, but you may need a bigger unit to meet yours. It will be automated to kick in at a low set point and operate independantly until the GARN is fired again. I have not completed the installation of it yet, so cannot offer direct experience with this solution.

I think integral storage is a big advantage in terms of efficiency and decreased complexity. However, the GARN is a BIG unit, and you need a big space to put it in. External storage gives you more options for configuration, but has more complex piping, pumping and control issues.

Do keep us posted on what you end up with.

 

[sdrobertson]

I think integral storage is a big advantage in terms of efficiency and decreased complexity. However, the GARN is a BIG unit, and you need a big space to put it in. External storage gives you more options for configuration, but has more complex piping, pumping and control issues.

Do keep us posted on what you end up with.

I'll echo this also but add that the space issue would be comparable. My 2000 gallons and boiler don't take up much more room than a Garn. If I didn't want to tinker and didn't have allot of the parts on hand, I would have gone with a Garn in a heartbeat.

 

[grainfedprairieboy]

Like I said, I`ve been lurking a long time and learned a lot from you boys over the years......certainly enough to incorporate a separate 20x24 concrete block room off the shop dedicated to what ever heat system is eventually installed. The door was also left wide enough that I can slide prit`near anything inside.

I also need the large thermal storage capacity because I want to incorporate solar vacuum tubes into the design and add 30-60 per year. Figure the older and weaker I get the added solar capacity will help pick up the slack.

Having said that, is a complete off the shelf unit (boiler and storage combined) better then a patchwork system under real world conditions?

 

[Nofossil]

Like I said, I`ve been lurking a long time and learned a lot from you boys over the years......certainly enough to incorporate a separate 20x24 concrete block room off the shop dedicated to what ever heat system is eventually installed. The door was also left wide enough that I can slide prit`near anything inside.

I also need the large thermal storage capacity because I want to incorporate solar vacuum tubes into the design and add 30-60 per year. Figure the older and weaker I get the added solar capacity will help pick up the slack.

Having said that, is a complete off the shelf unit (boiler and storage combined) better then a patchwork system under real world conditions?

Advantage of separate storage: You can optimize it in many ways - size, insulation, better stratification, multiple sections and/or taps, and so on. It also lends itself better to the 'intermittent short hot fire' approach because you get usable heat for the zones almost immediately. You can modify / upgrade / replace either the boiler or storage without affecting the other.

Disadvantages: More plumbing, floor space, and control complexity.