nemo
New Member
Posts: 48
|
Post by nemo on Jul 6, 2015 14:04:55 GMT -8
Hello! I have seen a couple of water heater designs and all of them have the water heater separate(on top or next to) from the main body of the stove, i mean the heat riser and barrel. In the parts I live in, the country side, people have wood stoves that look like this and the fire and the heat riser is just in the middle of the water tank. All it needs now is a barrel on top instead of heat going directly out the chimney and you have a "pocket rocket" with horizontal feed. Why can't I put that kind of a water tank made of cast iron instead of the classical heat riser. Can't water be the insulator at the same time? When water gets hot it moves to a different insulated tank that it only for depositing. Water keeps cycling and cooling the riser and heating itself at he same time. ?
|
|
|
Post by satamax on Jul 7, 2015 1:11:56 GMT -8
Can't water be the insulator at the same time? Absolutely not.
|
|
|
Post by johndepew on Jul 7, 2015 11:57:20 GMT -8
Yeah, you can't expect the same material to function in opposite ways at the same time. I.e. water cannot insulate and be a thermal battery simultaneously.
|
|
|
Post by buckeyenut on Jul 8, 2015 15:52:55 GMT -8
I've only been reading on here for a few weeks. But if I'm understanding it correctly to function the riser must maintain very high temps. The water would strip the heat away and reducing those temps would make it just smoke and smolder
|
|
nemo
New Member
Posts: 48
|
Post by nemo on Jul 8, 2015 21:55:33 GMT -8
Yeah, I get what the trouble is. Same volume of water would keep equal temperatures in the riser and outside it, the outside should be the colder so it can push the heat down in the bench. Thing is , cob is also a poor insulator. It takes a few hours until it reaches same temp , after that the rmh is very slow. Sawdust in clay slurry or ash might hold longer. Know that vermiculite and perlite are best but also expensive and hard to find in Romania. But this is other discussion. Thanks!
|
|
|
Post by satamax on Jul 9, 2015 2:47:12 GMT -8
Rockwool is cheap!
|
|
|
Post by buckeyenut on Jul 9, 2015 13:59:04 GMT -8
Yeah cob is a poor insulator but world's better than water especially when you consider water will only reach boiling point and evaporate as steam which will strip heat away
|
|
|
Post by patamos on Jul 10, 2015 10:16:21 GMT -8
Plus water is the ultimate conductor of heat, to which all other materials are compared. It transfers/balances heat from the hot end of its mass to the cold end about 10 time faster than earth or low-fibre cob.
Perhaps your heat riser could be insulated, the tank set just above the top of the riser, and the flue become a jacket that surrounds the tank, then comes back together as a flue above that. So long as your tank is vented and readily refillable (like with a toilet float lever that activates the refilling)… you could get up to 100c in as much mass as you need.
just a thought…
p
|
|
|
Post by johndepew on Jul 24, 2015 17:17:37 GMT -8
This is what Pat is talking about, pretty much, only his idea skips the exchanger coil and pumps water straight from the tank. donkey32.proboards.com/thread/1096/hot-water?page=1&scrollTo=10245You could also probably keep the flue running through the middle of the tank, so long as it happened AFTER the insulated riser, although you'll probably be limited in how efficiently you can heat water due to gas velocity if the system is arranged vertically. Donkey's design in the link above seems very effective. Why reinvent the wheel?
|
|
|
Post by patamos on Jul 25, 2015 22:15:38 GMT -8
Thanks John for finding that link.
I'm terrible at sifting back like that.
And thanks Donkey for drumming up the idea and building one.
My thoughts come from that. Heated liquid could be drawn directly from the tank, or via exchanger coils. The important part is that the tank is vented and somehow refillable. So long as it is vented the temperature will not exceed 100c. steam pressure will not build. and explosions will not result… Even if you just detour your cold water line thru this set up before tying it into an existing hot water tank… you will be cutting down your electric/gas/other power consumption by preheating your HW and then storing it in the tank - the best place to do so for most cases...
|
|