Site Built OWB vs ZC insert vs outdoor furnace

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Status
Not open for further replies.

phishheadmi

New Member
Oct 1, 2008
59
Northern MI
Hi again all...

Been inactive in the forums for a while, but just bought a new(er) house and am looking to heat mainly with wood. With much help from these forums I purchased a used VC Encore last fall, re-built it, built a slate hearth and installed everything...we absolutely loved it, reduced our heating bills by 80% or more and (I'm convinced) was one of the main factors in obtaining a sale in such a lousy real estate market.

The new house is a high-efficiency LP forced air setup...located in the back corner of the finished basement. There is a zero clearance fireplace on the main floor that I assume is inefficient as a heat producer. I'm looking at a few different options and I hope to get a little feedback from the experts. I initially started out looking for something to put in the existing FP to boost efficiency, but have stumbled across a few options.

Option #1...Install a Quadrafire 4100 insert in the existing ZC fireplace. I've measured for fit and determined (according to the mfr and stove shop guy) that the insert will work safely in the existing box. There's a stove shop two hours from my house that's going out of business and has the 4100 with cast iron trim kit for $2,000. I expect I'll have close to another $1,000 in chimney liner, flashing, extra parts, etc. I have a friend who was a chimney installer for years out west who'll help me to the install so labor will be cheap to free. Not a bad option, I think if I go with something inside the house it will be this, but I'd really like to heat the finished bsmt as well...which brings us to...

Option #2...While looking through the above mentioned stove shop's sale items, I noticed a "Bryan Furnace" which is an outdoor forced air furnace. I seem to notice the outdoor air furnaces aren't well thought-of in these forums...is that mainly due to inefficiency? This seems like quite a good deal... list price of $4,800 on sale for $3K, but would be a tricky install as my furnace room is in the far back corner of the bsmt, which is actually the front corner on the garage side of the house. I don't want to have the unit in the front yard, so I'd have to duct it into the basement, through the rec/home theatre room and into the furnace room. I'm thinking that run of 25' or so might be a bit much. The more I think about having an outdoor unit, the more I like the idea...no mess, smoke or risk of fire...plus we'd still have the ZC FP upstairs for ambiance. After reading some negative posts re the outdoor furnaces, I started looking around for OWB's and stumbled across...

Option #3...A guy I found on Craig's List who makes site built concrete OWB's. Basically it sounds like a boiler unit encased in concrete...there's much more to it than that of course, from the way he's describing them, it sounds like a very good deal. Apparently, he's been building them for 10 years and not had any problems...he has a patent on the unit and has offered to show me several he's done (though it's about a three hour drive for me). He claims they're very efficient with a secondary burn chamber, but obviously on a custom unit there's no lab testing or anything. On the surface, it sounds like exactly what I'm looking for...cost will be about $2,500 including the boiler unit, pump, 50' insulated piping, heat exchanger and all labor...I have the pad ready for him and the ditch dug, he builds the unit, hooks everything up and runs the line up to my furnace plenum (but will not install the heat exchanger, which is no problem as I have another buddy who's an hvac guy). Any immediate pitfalls, warning signs or things to watch out for come to mind? I love the idea of an OWB but really can't afford the usual $6-7K they cost...hoping this might be a viable alternative.

Thanks in advance for your help on this topic AND all the guidance in the past...what a great community!!

Matt
 
I also saw the "concrete" OWB builder. I emailed him but no response so I just sort of lost interest. I was looking to see if he had a steel firebox or if it had a firebox made of firebrick or refractory panels (similar to a Seton). Did he give any indication of how it was built? It would be interesting to see if it was a Hahsa type design - filled with sand or something for insulation.

I would be surprised if the entire firebox was cast in only concrete....every thing that I've read says concrete is a big no-no in furnaces because of the explosion potential.
My biggest question is how to service the thing.... what happens if it springs a leak? is the firebox surrounded by water? or does it have a manifold system like a seton.....

Wouldn't be fun to tear apart concrete and then have to re-pour the whole structure...
 
Another question to ask, especially on any outdoor options is whether your state or local gov'ts have any restrictions on OWB's and the like... You certainly don't want to put a bunch of money into installing a system and then get told you can't use it... (It is worth noting that a custom built unit, even if it is a good clean design, won't meet any certification requirements...)

Gooserider
 
Thank you both...very good thoughts. I'm meeting him tomorrow morning to look at a couple of units he's done. I'll be able to tell you more after, but I'm pretty certain it's a steel firebox.
 
Any news or pics?
 
No, unfortunately due to differing schedules (really we just left home two hours late) I wasn't able to meet with him. I'll be down that way again in a few weeks so I hope to check it out then...I'll let you know what I learn.
 
Status
Not open for further replies.