owb

[coxy]

ok had some issues today with my stove i was on my way to the logrite open house and my daughter call and said a pipe broke to my stove and the temp was 290  so i made i mad dash home it warped the inside good but is what it is hope it didn't crack it but will find out  :  the question i have is I'm going to put a new hot air oil furnace in so i have another heat source i want to know if i can run a loop of copper tubing around the pot in the oil furnace so if i go away in the winter the water in my owb don't freeze  if it will only maintain the water at 50 it should be fine just enough so it don't freeze   and don't have to worry about it doing what it did   my house is part baseboard hot water and the other part is hot air i don't want it all hot water heat its an old house and don't think it will be good enough with out the hot air   hope you can understand what I'm trying to say :laugh:  thank for the help 

[PAmizerman]

My dad has two furnaces hooked together.  One is in the house and the other outside. (to heat his outbuildding). He doesn't heat the building all the time so he ran boiler antifreeze in the outdoor system. Since he wanted to heat with the indoor furnace but not have to run antifreeze inside he put a heat exchanger in. I was surprised how efficient the heat exchanger is. If this is something you may be interested in send me a PM 

[coxy]

the way your dads is set up wont work for me his oil furnace has water so it an oil fired boiler mine is just hot air like a trailer furnace  so the water to water exchanger wont work for me   

[trapper]

when we go on vacation the heat exchanger from the outdoor furnace that is inside the plenum  
of the gas furnace keeps the water in the outdoor furnace at 40 degrees.  We leave the pump on the outdoor furnace run when er go away.

[coxy]

that's the way mine use to be but i built a box and put the rad and blower together away from the old oil furnace because i had planed on putting in a new oil furnace 3 years ago so i guess ill have to do it now  

[mike_belben]

I have done a good bit of fooling with home made heat loops.  

When you say copper loop around the pot, what exactly do you mean?  The copper loop will have your OWB water pumped through it, and the loop will be where, inside the furnace getting hit by the burner flame?

[coxy]

ya the loop  will be on the out side of the pot/heat exchanger on the oil furnace then run back to the owb  hoping just enough heat so it don't freeze the owb

[mike_belben]

Look up thermal siphon if you dont know what i mean.  You dont want to orient the loops vertical like a ferris wheel or roller coaster loop.  You want the loop to be a corkscrew like a coil spring standing on a table.  This way even if your pump fails, the heat will create a pretty decent flow and boiling wont occur.  Trapped water in the pipe that boils is pretty violent.

 So the bottom leg is cold inlet to the loop and top leg is hot outlet from the loop.  Id also incorporate a one way check valve in the bottom cold leg below the coil so that heat cant force flow backward against the traffic.  

Google "sidearm heat exchanger" and youll get some pretty good pics.  I had a thermal siphon coil from my water heater drain spigot, through a copper coil packed against the woodstove and then teed back into the hot discharge line.  I also had my cold ground water input line go down into 30ft of coiled copper that was submerged in a lobster pot ontop the stove before it entered the water heat.  In winter id look like a lobster after 40 minutes in the shower.  God I love hot showers.

[coxy]

mike  i was thinking the same thing ill give it a try the worst thing that happens is it don't work and wouldn't be the first time my cob job failed  :D :D