Hot tub water heater

Hi guys.

Looking for some advise on the position of the “Baffle plate” in my water heater.

In the images below you can see the green baffle plate in two different positions.

Normal wood stoves have them open at the front (just above the door) but feel this is to bring the heat to the front of the stove, hence heating up the room.

As I want as much heat to stay inside my fire box, would moving through baffle opening to the back be better? Hopefully heating more of the steel that’s in contact with the water?

Also wanted to check if placing fire bricks on the door would help keep the heat inside the fire box?

Many thanks Morten.

Hi Morten....Welcome to Permies!

It has been my understanding that the baffle was often positioned so that the flame path would be directed to the front which helps to keep the glass clean during the burn and be able to see it better too for viewing pleasure.

Not sure if you are in the planning stages or actually have a stove built and putting on the final details, but thought I'd also mention that there are very efficient rocket hot water heaters that are being built by DIYers also. One of which is here: Walker boiler

Gerry Parent wrote:Hi Morten....Welcome to Permies!

It has been my understanding that the baffle was often positioned so that the flame path would be directed to the front which helps to keep the glass clean during the burn and be able to see it better too for viewing pleasure.

Not sure if you are in the planning stages or actually have a stove built and putting on the final details, but thought I'd also mention that there are very efficient rocket hot water heaters that are being built by DIYers also. One of which is here: Walker boiler

Hi. Thanks for the feedback and great forum. . This is going to be working as a thermosiphon system heater next to the hot tub, so kind of took the design from Chofu heaters and made it my own a little.
So it is going to be a home build. No window in the door, so I think I will set the baffle to open at the back of the burner and hopefully get some secondary burn going aswell.  

Cheers Morten.

Keep in mind that wood stoves use the front baffle opening as a place to introduce secondary combustion air AND then clean the glass on the door. Perhaps a rear baffle opening could be used to introduce secondary combustion air and then help clean the heat exchanger wall.??
Also, I’m not sure there’s much point having water under the stove?! I could be mistaken. Added volume? Thermosyphon?  

Jeremy Baker wrote:Keep in mind that wood stoves use the front baffle opening as a place to introduce secondary combustion air AND then clean the glass on the door. Perhaps a rear baffle opening could be used to introduce secondary combustion air and then help clean the heat exchanger wall.??
Also, I’m not sure there’s much point having water under the stove?! I could be mistaken. Added volume? Thermosyphon?  

Hi.

Added underneath as it’s still a warm area and would be wasted Heat exchange if exposed to the air :-)

Going to add fresh air to top of baffle with pipes to hopefully get some secondary burn. So holding thumbs.

Thanks for the feedback 🙏🏻

What others have said and if you have baffle closed by door you will be getting a houseful of smoke when you open the door.  My wood boiler had a firebricked box and the door had a metal reflector plate.  On top of the firebricked box it had a tank with vertical tubes that the smoke and heat passed through to heat the water in the tank.  What a pain in the butt it was to have to take the top cover off and clean those tubes that would want to creasote up when the smoke hit the water cooled tubes.  I built a 16" long drill bit to fit my electric drill.  I saw a wood boiler at a business that had a better design that had the tubes horizontal making it much easier to clean. The key to woodboilers is to have the biggest water tank possible. Use the woodboilers like a battery charger and the tank as the battery. The woodboilers can burn for the most part at a very high and efficient rate and with little to no smoke. It's operation should be almost separate from your heat load. A normal thermostat hooked through circuitry to circulator pump/s to piping and the storage tank gives good steady heat that is not what you get with wood stoves (including "all nighter air tight stoves).