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Post in 'The Boiler Room - Wood Boilers and Furnaces' started by buddylee, Feb 6, 2013.
Would it be advantageous to add water storage to my Hardy H2. Anyone ever do it ?
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If you search for "benefits of storage" you'll probably find all sorts of posts. Whether or not it makes sense in your case depends entirely on what you're trying to accomplish with storage.
Looking to save wood. Can't justify a gasification. System as we don't have the cold winters in Georgia like folks up north do.
I would totally agree with you on that.
Stee said it best. Give us a couple scenarios on how you might think storage might help you and we will critique them.
My thinking is that when the Hardy gets a good burn going there is no smoke coming out he stack. No smoke means better efficiency. If I have an insulated storage tank I could heat longer off of it than the 100 gallons that's in the Hardy.
Sure adding storage would be a benefit. I connected a 1000 gallon dairy tank to a friends Hardy this winter. He put the Hardy and the old dairy tank inside a storage container. We pump the Hardy first to an Ergomax tank, this provides separation between the Hardy water and his pressurized, radiant slab tubing. He also put some pex coils inside the dairy tank for solar input. The additional tank allows long hot burns and a nice long "coast" for his small 900 sq ft apt radiant load.
Keeping the Hardy out of the smoldering mode is a big plus when you live in a hollow. The system behaves better and he breaths easier If you heat with an OWF may as well run it as clean ad hot as possible, cut down on the creasote formation Hardys are famous for.
He also spray foamed the inside of the container and that adds to the longer drawdown for the Hardy and storage. The container also housed his standby generator as he lives off-grid. and the whole package id lockable for tool storage.
Storage can reduce the amount of wood burned by a conventional boiler but it also can create a creosote problem inside the boiler. In the early 80s, I added 1000 gallons of storage to a small cast iron down drafting wood boiler. The hope was to get away from a creosote problem by making the boiler work harder charging storage. The creosote problem only got worst. Prior to adding storage, the boiler water would maintain a standby temperature of 170 degrees or better for DHW supply. With storage added return water would be as low as 100 degrees. Internal creosote buildup in the boiler and chimney became a huge problem. So plan on installing a boiler protection valve so boiler water temperatures can remain high - 160 to 170 degrees. The boiler, when storage was added, went from burning 16 to 10 cords per year. With a gasification boiler charging the same storage, annual wood consumption is now 4 - 4 1/2 cords per year.
Like you, we live in a area of milder temperatures and so far this winter, the draw from storage has not been much over 15,000 Btus per hour. We use the system year round so our storage is very well insulated and in the summer we can go 3 weeks between firings.
The original boiler was set up to charge the storage using gravity so the boiler only charged storage. There was no way of going direct to the load if storage temperatures were low. The storage is horizontal 54" by 112". A baffle was installed 8" from the top, down about 16" from the top of the storage and 40" inches from the charging end of the tank. Two copper heat exchanger coils rest on top of this baffle; one for DHW and the other for house heat. If storage temperatures are low, only a very small portion of storage needs to be heated to supply the coils.
This foil backed insulation was first wrapped around the storage tank reflective side in.
Three layers of compressed fiberglass insulation with joints staggered and held in place with aluminum banding was installed over the fiberglass backed foil.
We use the system year round and much of that time the BTU draw is low. For us, a well insulated storage allows BTUs only to be drawn from the tank when there is a demand.