Wood-Stove Hot-Water system

[mountain]

The attached link is a draft of an article on Wood-Stove Hot-Water
http://mountainelectric.ca/AltEnergy...veHotWater.pdf

Unfortunately I could not add photos, as I have camera issues.

It works!
Is wood-heat Solar energy? I think so. Of course we are lucky to live in rural BC, with an endless & renewable supply of free firewood. But this article focuses on a system to reduce external (electric) energy for domestic hot-water. It uses a creative plumbing arrangement such that no special tank is required, just the existing un-modified tank. This approach is applicable to solar-thermal HWT as well.

[J.P.M.]

Click on it with a modern browser, it's a active link, i was just there:
excerpt: A cautionary tale from one of our correspondents.

"A co-worker of mine put a heat exchanger in his furnace firebox. Without proper controls he quickly made high pressure steam and soon solder joints were failing and the system came apart in what sounded like several small explosions. His solution? Weld the damn thing together the next time. It held together, but it back-fed steam all the way to his artesian well and he had a nice geyser out back. True story." Scott

Nothing wrong with copper as long as the rest of the system is properly designed for it. However, since most folks are not well versed in boiler design, and copper is rather expensive, welding and heavier components of st. stl. are probably preferable.

However, that does not change in any way the requirements for proper attention to safety. Simply because a design can withstand higher pressures/temperatures due to material properties, section thicknesses or "bigger" welds", does not mean that safety, particularly safety relieving devices (safety valves, rupture disks, etc.) can be avoided or ignored.

In the case cited, the well acted as the relieving device and while it may cause a chuckle, that was more fortunate than humorous and a good example of God protecting fools. It is a smoking gun pointing to the ignorance of a design that lacks relieving devices and who knows what else. More example of DIY ignorance causing harm.

Somewhat early in my engineering career, I saw the results of boiler failure and the steam explosion that followed. Fortunately (for me), it wasn't my design or equipment that failed, and more importantly no injuries, but it sure put the fear of the almighty in me next time I sat down for a design effort. Another true story. J.P.M.

[Mike90250]

Click on it with a modern browser, it's a active link, i was just there:
excerpt: A cautionary tale from one of our correspondents.

"A co-worker of mine put a heat exchanger in his furnace firebox. Without proper controls he quickly made high pressure steam and soon solder joints were failing and the system came apart in what sounded like several small explosions. His solution? Weld the damn thing together the next time. It held together, but it back-fed steam all the way to his artesian well and he had a nice geyser out back. True story." Scott

[thu292]

i can't open link

[Mike90250]

A copper coil in a wood stove is a time bomb, copper will work harden in the heat, and will fracture easily. Stainless Steel is the preferred material for a heat loop in a stove or heater.
http://www.woodheat.org/heating-wate...ood-stove.html

[Logan005]

When I was a kid we made and placed a copper coil inside the fire box of our wood stove, it pumped water through the coil and into pex tubing in our concrete floor. Even in the teens weather we could burn for four hours in the evening and sleep warm all night. home was earthen berm, super insulated.

[SunEagle]

The original link that mountain shared does not work for me. Is it still available?

That post made by mountain is over 5 years old so the link is probably long gone by now.

[gmanInPA]

The original link that mountain shared does not work for me. Is it still available?

[russ]

My system has been in operation for a few years. The pressure reliefs lift a few times every year. No problem so far.

It only counts if they function perfectly year after year - maybe they will and maybe they won't.

If it is a low pressure system and you can use a vent pipe it would be great.

[Grahamsurette]

I'm thinking of venting the top of the hw heater that way it would be a little safer I think.

[organic farmer]

Make sure that the relief valves are in a position where steam and hot water coming out will not cause risk to people or damage to the surroundings.

My system has been in operation for a few years. The pressure reliefs lift a few times every year. No problem so far.

[Grahamsurette]

Make sure that the relief valves are in a position where steam and hot water coming out will not cause risk to people or damage to the surroundings.

Thanks for that. No one want hot steam in their face

[inetdog]

No, not really. I have pressure-relief valves in the loops.

Make sure that the relief valves are in a position where steam and hot water coming out will not cause risk to people or damage to the surroundings.

[Grahamsurette]

Toss in a few check-valves to ensure the flow is always in the direction that you intend it to be.

When you have multiple loops with Y-connections, there is a possibility of water flowing in the opposite direction, without any check-valves.

I will do that. This is the second winter I've had my garage and I've been itching to see my infloor in action. Thanks for your input. If anyone has anything else to add I'm open for options

[organic farmer]

Alright I think I've figured it out.... Normal hot water tank, thermo siphon supply into the top of the tank with the return from my floor Y'ed Into it. Return going back to the stove exiting from the drain at the bottom of the hw heater with the suppy to the floor T'ed off somewhere in this area along with the circ pump. If it was designed correct I think it would work well and the suction from the circ would encourage the flow of natural convection. Thoughts?

Toss in a few check-valves to ensure the flow is always in the direction that you intend it to be.

When you have multiple loops with Y-connections, there is a possibility of water flowing in the opposite direction, without any check-valves.