Piggyback wood boiler with no storage tank

[cbova]

Is anyone running a wood boiler tied into a propane FHW system with no storage tank?

I have a newly build 2000 (finished) sqft Colonial with a propane forced hot water system. I'd like to tie in a wood boiler but I don't have the room/money for water storage tanks. Will I have a problem with overheating? I would love to add a heating zone to the basement/garage (2 car under garage) but it's obvioulsy not insulated as well as the rest of the house with 2 concrete walls and one studded wall (insulated) and 2 10' garage doors. So there's another 1000 sqft that I can use as a dump zone. A warm garage/basement would be a bonus since I am down there 3-5 nights a week working on something or another. I also have ~500 sqft in the attic that may get finished in the future.

I was looking at the Harman SF-160 or SF-260. My ultimate goal would be to have the boiler fired most of the time and controlled by the thermostats on the main and second floor and have the garage/basement either on demand or as a dump zone. In the event that I didn't fire the wood boiler the propane would take over seamlessly

Am I dreaming?

Thanks

 

[Boil&Toil]

Storage is really worthwhile; you should plan for the eventuality that you manage to "afford" it and you'll end up saving money in the long run (if you're not looking at the long run, none of it really pays off.) If you're going to use the garage as a dump zone in lieu of storage, I'd suggest putting that on a heat-exchanged anti-freeze loop so you can let it freeze if you're not dumping. You should also have a "real" dump zone for power outages (a thermo-syphon loop that opens up when the power goes out so the boiler does not overheat if a fire is lit.)

Depending on how your FHW system is designed, it can be more or less frustrating to use a wood boiler effectively - if the radiators are sized on the assumption that the FHW will be at 180F from the furnace, it's a narrow window where the wood is up to temp but not overheated. If you have radiant floors, wood works much better since a wider range of water temperature is effective for heating, and there'a range of options in between (such as adding more radiator area.)

 

[mike van]

I ran a Harman SF 260 for 16 years with no storage. I hold the unofficial record here for the most un-reported un-responded to chimney fires in town. If I had to borrow money for storage from a loan shark, I'd do it.