wood fired pool heater/treating rust

[forgeblast]

HI folks just bought a second hand wood fired pool heater a wws-80 (warm water solutions). The previous owner said that there was a melt when he did not keep the water circulating
though the pipes (1 1/2' pvc) and water went everywhere. To move the beast (its very well made) I had to remove the fire brick. I am glad I did. A lot of rust inside.
The collar to the chimney will have to be replaced.
My though is that when the chlorine pool water hit the stove he just kept firing it and it created a lot of corrosion.
I want to fix it right, before I set it up.
I have emails out to different places about rust inhibitors/encaplsators. My fear is that the heat will degrade them.
There willl be a layer of firebrick over everything but I am concerned that If i do not
treat the rust that it will be a bigger issue.
Anyone do something similar: an outdoor wood burner, or old wood stove that you fixed up.
Any help would be appreciated.
thanks!!

 

[ponytug]

More details would help, as would photos. I am imaging a water leak over the exterior of the firebox, but there are a few unknowns.

Where do you have rust? What is the metal that you have rust on? How thick is it? How far has the rust gone in? How extensive is the rust? Do you have rust in the heat exchanger?

All the best,

Peter

 

[forgeblast]

More details would help, as would photos. I am imaging a water leak over the exterior of the firebox, but there are a few unknowns.

Where do you have rust? What is the metal that you have rust on? How thick is it? How far has the rust gone in? How extensive is the rust? Do you have rust in the heat exchanger?

All the best,

Peter

Sorry folks had to type quick and head to an inservice. The Only USA Made Wood Fired Burning Swimming Pool Water Heaters - The BEST Wood Pool Heater available with longest reputation shows the model 80. it has a stainless steel heat exchanger. The rust was inside the fire box as the flue was open when it happened. Which then trapped mosture under/behind the firebrick. as most were cracked I was glad i started taking them apart. I think i might need to neutralize any chlorine water that is still in there, and then grind to see what kind of metal i have. I was hoping there would be a product that would help me out but it looks like a lot of hand work will be needed.
out of the stainless steel heat exchanger is where the pvc is connected back into the pool fiter loop. when you burn it with out water running though it the heat exchanger will dump hot air into the pipe melting it. which is what happened to the original owner. causing water to get into the firebox because the flue was open. Rust is all over the inside, the collar that connects the chimney to the unit is rotted. but the inside is not supper bad there is some flaking of the metal, and outside the unit there is some paint blister.

 

[ponytug]

Thanks for the details.

Just so the scenario is clear; is this right? The prior owner had the flow blocked for some reason (e.g. pump turned off, went into filter wash....), but left the fire burning, at which point the stainless steel heat exchanger boiled dry, heated up and melted the PVC pipes. Did the overheating also melt the stainless pipes? Then at some point the water came back on and got things wet? Or was this an over heat condition that generated a water leak for awhile?

Is the rust that you are worried about the inside wall of the firebox, I.e. behind the firebrick?

If the fire brick got wet with water, especially if it was a salt water pool, the fire brick is toast. It will have lost much of its insulation abilities, and the salt will vaporize when the brick gets hot, which corrode the living daylights out of any metal in the area. I would be tempted to start completely over on the firebrick.

For an in ground pool, I think that this might be short a few safety devices, and for an above ground pool (with a flooded return line) I would be thinking of an extra overheat valve on the intake side.

All the best,

Peter

 

[forgeblast]

Thanks for the details.

Just so the scenario is clear; is this right? The prior owner had the flow blocked for some reason (e.g. pump turned off, went into filter wash....), but left the fire burning, at which point the stainless steel heat exchanger boiled dry, heated up and melted the PVC pipes. Did the overheating also melt the stainless pipes? Then at some point the water came back on and got things wet? Or was this an over heat condition that generated a water leak for awhile?

Yes, he turned off the filter or had a power outage, and the fire was kept burning....
The stainless steel is fine and holds water under pressure. When the water came back on it leaked and everything got wet.

Is the rust that you are worried about the inside wall of the firebox, I.e. behind the firebrick?

If the fire brick got wet with water, especially if it was a salt water pool, the fire brick is toast. It will have lost much of its insulation abilities, and the salt will vaporize when the brick gets hot, which corrode the living daylights out of any metal in the area. I would be tempted to start completely over on the firebrick.

Yes! I pulled every firebrick out because all were cracked. When I pulled them that is when I saw the moisture and the rust/corrosion. I will start with 100% fresh firebrick. I just want to stop any corrosion that was started.

For an in ground pool, I think that this might be short a few safety devices, and for an above ground pool (with a flooded return line) I would be thinking of an extra overheat valve on the intake side.

I plan on making a bypass, and extra tees to drain it completely when needed. I have been sketching it out to make sure this doesnt happen again . I will also be adding the water inlet before the chlorination to keep chlorine out of the stainless as much as possible.

All the best,

Peter

Thank you appreciate it.

 

[ponytug]

If you can, I would sand blast the inside (if not, I have had good success with the textured sanding disks) and use medium temperature paint, or stove black, not the 3000F material, which won't get hot enough to set.

You should be good with that. There is always going to be ash around, so the trick is to keep the interior dry.

FWIW: the manufacturer recommends that the chlorination happen after the heater, which is what you are planning, right?

All the best,

Peter

 

[forgeblast]

If you can, I would sand blast the inside (if not, I have had good success with the textured sanding disks) and use medium temperature paint, or stove black, not the 3000F material, which won't get hot enough to set.

You should be good with that. There is always going to be ash around, so the trick is to keep the interior dry.

FWIW: the manufacturer recommends that the chlorination happen after the heater, which is what you are planning, right?

All the best,

Peter

I ordered a dechlorinator that i plan on spraying in first to get rid of any chlorine residue , then I will tackle clean up. Thanks for the tip about the stove black I was looking at the higher temp paint. I plan on putting the chlorination unit after the stove. I am just working out where it needs to be in relation to the filter etc... I dont think I can can blast it, but I should be able to get in there and sand disk it. thank you!!!!

 

[forgeblast]

Just an update. I pulled off the top, and spend about 6 with a hours wire wheel knocking the thicker rust off. We think they had a salt water pool with the corrosion we saw. Then I pressure tested the stainless steal manifold (two pvc caps 1 1/2'' and a schrader valve on one. Put it in a dunk tank after i added air and no leaks. brushed on jenolite rust converter and will spray with high temp spray paint as soon as that is done. The company is making me a new roof and chimney collar and sending me the fiber insulation for the stove. Just need some fire brick and the parts and we are good to go.