Educated opinions solicited

[ISeeDeadBTUs]

Life is great, I just would like to make it a bit 'better' this summer. Now that the Dog is dead and gone, shortly thereafter followed by my Mother being dead and gone, followed immediately by +3 weeks of influenza and 75 degrees in MARCH!! Well, neither of them liked it warm anymore than I, so maybe they knew what they were doing checking out before now. Anyway . . .back to the reason for my post . . .

My wood fired hydronic is about 75' from the house. It has no on-board storage. My indoor oil boiler is I think about 20 gal, and the DHW is 50. I think I'd like to put non-pressurized storage out next to the GW. The goal would be to do a full-throttle fire say every other day. I know NoFo has suggested in the past that there are inefficiencies inherent in this set up (the introduction of at least one more HX, standby losses into the atmosphere)but this setup would keep the standby losses from heating up my basement in the summer, and would mean I could fire the beast and walk away, knowing I would have hot water for a few days.

Any reason a 275 gal fuel tank (well insulated, of course) wouldn't work for this??

Jimbo

 

[Nofossil]

Fuel tanks are hard to clean, and 275 gallons is too small to be very useful. A set of four wouldn't be bad if you could get them new or figure out how the get the sludge out of them.

I have unpressurized outdoor storage.

 

[Gooserider]

Are you talking in terms of a full bore fire every couple days as a summer time only routine, or year round? Either way, judging by what I'm seeing other people here talking about, it doesn't sound like a 275 gallon tank would be big enough. Seems like most folks are running closer to 1kgal...

Gooserider

 

[WoodNotOil]

So long as the storage tank is well insulated, your basement should not pick up any heat from it. When I light a fire once a week the Tarm in the basement heats things up a little, but with your boiler 75' away that shouldn't be an issue for you. There are lots of ways to do un-pressurized storage. Check out some of the links at my web site. You will need to size it to your boiler so 275 will probably be too small.

 

[peakbagger]

A lot of the Dumont and Madawaska wood boiler installations back 25 years ago used 275 gallon oil tanks for unpressurized storage. Unfortunately, the tanks tended to fail long before the boilers did leading to a lot of free boilers availlable. For some reason folks just didnt want to go to the hassle of replacing the tanks after finding 275 gallons of dark smelly water on their basement floor.

 

[leaddog]

One of the problems with oil tanks are they are thin metal and because they must be in an open system they can rust thru quick. If you use one make sure you use chem. and check often. Also if you use a used one it might already close to being rusted thru as water settles to the bottem of oil tanks and even with oil in them they rust out in the bottem. Had a neighbor that lost 275gals of fuel oil thru a pin hole. He couldn't figure out where it went until he saw the TINY brown stain in the snow. Tank looked and felt solid and like new. Also don't even think of pressureizing as they will exspand and burst.
leaddog

 

[sdrobertson]

http://americansolartechnics.com/

Those are nice looking tanks. I wonder what they run.

 

[sparke]

That tank is made by a hearth.com member. I am sure he will chime in soon. : - )

 

[flyingcow]

http://americansolartechnics.com/

I got the 820 gal unit, like it. Insulated very well. HX's seem to perform well. All around good set up.

 

[pybyr]

That tank is made by a hearth.com member. I am sure he will chime in soon. : - )

He (Tom in Maine) is actually pretty circumspect at pitching his product, except insofar as answering specific questions put to him, or offering ideas to others doing DIY tanks.

Of the off-the-shelf unpressurized options I've seen, his impresses me most.

 

[sdrobertson]

That tank is made by a hearth.com member. I am sure he will chime in soon. : - )

He (Tom in Maine) is actually pretty circumspect at pitching his product, except insofar as answering specific questions put to him, or offering ideas to others doing DIY tanks.

Of the off-the-shelf unpressurized options I've seen, his impresses me most.

After I posted, I wondered if that was his. It defiantly looks good.

 

[jebatty]

I started my system with 3 - 275 gallon used fuel oil tanks for water storage. These tanks were quite "clean" and I ignored the issue of any residual volatiles circulating through the system, thinking that because the system was open, they eventually would boil off, and I used a high temp water filter to trap any nasties in solid or semi-solid form.

Two major issues. First has been mentioned, and that is that these are thin steel, very subject to rust, and you need careful pH and 02 control. My filter was trapping lots, and I mean lots, of rust slim. My pH was lower than it should have been, and this may have been the cause. Live and learn.

The second issue, which I never completely solved (because I moved to pressurized storage due to dissatisfaction with the open storage fuel oil tanks) is controlling vapor expansion in each tank. I started with a serial setup, hot water to top of one tank, bottom output to top of second, etc. Vapor would build up in first, and then second tank, etc. You need an auto venting system for each tank. I did not do that. I then tried a serial setup and parallel overflow, but obviously did not do it right and I still had the vapor expansion issue. I'm sure the vapor expansion issue can be solved, I just didn't succeed. Vapor expansion in each tank reduces hot water capacity, which quickly leads to overflow in the last tank.

I went 2/3 heating season with the fuel oil tank x 3 open storage, and now 1-1/3 seasons with pressurized 1000 gal LP tank. Hate to say it, but the pressurized storage has been absolutely problem free (well, almost) and I wish I had done that from the start. The "almost" relates to need for an hx setup with an open boiler, and hx is less efficient than feeding storage directly from the boiler. I started with a plate hx because I had antifreeze in the boiler, now have went to a 100% water and no hx. Very significant improvement in performance. I'm sure the 5 x 12 x 30 plate hx was undersized for my boiler output. Live and learn again. Still, I would avoid an hx setup if possible.