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Anyone add storage to a OWB ? I have a Hardy H2 and I'm wondering if storage would be advantageous. Would it help burn less wood ? When my Hardy gets up to temp, it produces no visible smoke. I have a coil inline with my central Ac ductwork.
If you do a quick search you'll find that this topic comes up with some regularity. I can summarize: most OWB operators don't like the idea of starting a fire every day from scratch. There are performance and freeze considerations to take into account when an OWB shuts down for a certain amount of time during peak heating season. OWB's in general put out a huge amounts of BTU compared to our indoor units. You'll need big lines, big flow, to get that heat into tanks efficiently to avoid idle.
The goal of storage is to eliminate idle (which is where the efficiency bump comes from) but primarily it's for convenience for us inside guys. And unfortunately (perhaps someone will correct me if I'm wrong) most OWB's were designed to idle....for long long periods of time...and then idle some more. If OWB's were not designed for near constant idle you'd rarely see a 200k btu unit behind a residential property. Very, very few of us will ever own a house big enough to come even CLOSE to the load the average OWB can output. Their outputs are a result of their massive fireboxes (designed to idle all day) and not a reflection of realword effecient demand loads generated by most homes.
For what it's worth - most of our inside boilers are oversized for homes too. That's the first thing I would say if I read my post above (your IWB is oversized too!). But IWB's were designed around the idea of thermal storage (at least in Europe) so they have a purpose...and even then they are still a fraction of the size of the OWB's in terms of firebox and output.
I have heard the Hardy boilers hold significant volume of water, like a few hundred gallons? I would think storage would help if your boiler is idling a lot. Also, I understand Hardy's are open systems, so open storage would work.
The less volume in the boiler, generally, the more storage will benefit I think. Lots of folks around MO have those type of boilers and like them. Gotta do the water volume and quality monitoring I understand as they are open systems