The project has begun: Harman Mark III heating coil install

I know in domestic water piping, it's not a good idea to connect copper and galvanized pipe and fittings together due to electrolysis. Does the same thing apply to hydronic distribution pipes? You doing such a good job, I'd hate to see corrsion and leaks pop up down the road at these dissimilar metal connections.

I have installed quite a lot of coils in Harman stoves, I use a Lenox hole saw with no lubricant or coolent. The saw I am currently using has drilled dozens of holes in stoves and well casings for well hookup. Lenox makes a great hole saw

Smitty,
I see you put the gaskets for the coil on the outside of the stove. I just bought my coil yesterday and the dealer told me to put them on the inside. Does it really matter? The coil I got is an "L" so it wont be directly over the fire, it will run along the side wall. He says that the temp inside the firebox will still be more than enough to heat the water. I'm only using it to heat DHW for 2 adults and a 5 yr. old. I use shower at 11:30pm, wife in the am and the boy takes his bath in the evening. Should be lots of tiome for recovery.

Jeff

I put the gaskets on the outside because I figured they'd disintegrate being in the firebox -- I'm not sure if their designed to withstand that kind of heat. I didn't want to have to take everything apart just to replace a gasket -- I'm sure you won't want that either . I'm curious as to how long the nuts holding the coil on the inside will last after a season of being less than a foot away from a 1800* coal fire! You also don't want any of the threads in the firebox, because that will be the thinnest metal -- you don't really want that in a hot & corrosive environment.

I used anti-seize on all the threads -- I don't want to be cutting the coils out just to upgrade (many, MANY years from now) or move the stove.

Yeah you should be set with hot water production with just the 3 of you . Judging from the amount of heat it takes my oil furnace to heat just DHW (for 2 adults), a coal fire won't have any problem -- even with a small coil.

coalkirk wrote:I know in domestic water piping, it's not a good idea to connect copper and galvanized pipe and fittings together due to electrolysis. Does the same thing apply to hydronic distribution pipes? You doing such a good job, I'd hate to see corrsion and leaks pop up down the road at these dissimilar metal connections.

That was something I never thought of. I'll have to keep an eye on that. I think I just grabbed whatever was in the bin in front of me @ Home Depot (as long as it wasn't plastic ) without really thinking about it. Thanks for the heads-up!

pa coal cracker wrote:.... your posts are helping me out I hope you won't mind a few questions along the way.

No problem --that's why I'm taking pics & posting my progress.

ablumny wrote:WOW is all I can say. I havent fired up my new Harmon DVC-500 yet but was already thinking about something like this.

Does anyone know if there would be issues adding this type of coil to a DVC-500?

Should be no different than in a hand-fired, except that you may not have as much space as I do, due to the stoker assembly being in there. In the (VERY DISTANT! ) future, I'd like to go with a stoker boiler in parallel with my oil furnace.

But I've had enough with plumbing to last me a few years!

Thanks Smitty. Another option would be to use some high temp stove paint to kind of encase the inside nut, maybe even two or three coats to help with the corrosion.

Jeff

I've heard of coils leaking. Also, make sure you have PRV where needed. If the water stops circulating and the water in the pipe turns to steam it could rupture the pipe. With the correct safety measures I think it will be OK. I have a coil myself so I hope it will last a long time. Make sure to clean the coils well when you clean the stove. The coil I installed is one of the best investments I made. It heats my entire basement. I have about 40 + ft of 316 ss coil.

Would painting the coil in high temp paint help to increase it's life span or would it just slow down the process of the water heating up?

Hmmm. I don't think high temp paint would insulate the pipe at all. It didn't occur to me to paint the coil. I'm using 316 SS which is suppose to be corossive resistant but the flyash can eat through SS as evidence by my SS flue pipe that had many little holes in it when I took it apart for cleaning. I'm not sure if it should be painted or not. You have me thinking.

I was leaning more toward painting the nut itself and maybe remaining threads just so you would't have as much buildup on the nut in case you wanted to break it loose sometime in the future. I would think the paint would just break apart if you tried to turn the nut and it would work free because the paint would prevent the nut and threads from getting corrosion build up.

Jeff

Good idea.

Smitty
I'm going to tell you something you may or may not want to hear.I THINK you will be making to much hot water with them coils.If you have 7 teenage daughters you'll be ok.

I built a coil from 1/2" copper that was about 10.5' long in a wood stove and it would heat up a 30 gal tank in about 45 mins(170F).

Thoes things are going to make a LOT of hot water.

Good luck they look like good quality coils,should last for years.
DON

Sorry,
Just read your post about dumping heat into the boiler and heating system.With a good fire in the middle of the winter I wouldn't doubt thoes coils will absorb 15 or 20K btu's of heat.No science behind the numbers just the seat of my pants.
DON

If you use any paint inside the firebox, it will just flake off -- even the highest temp paint is no match for a coal fire. On the outside, it's no problem. But inside is pretty hot

BIG BEAM wrote:Sorry,
Just read your post about dumping heat into the boiler and heating system.With a good fire in the middle of the winter I wouldn't doubt thoes coils will absorb 15 or 20K btu's of heat.No science behind the numbers just the seat of my pants.
DON

I hope they make that much -- I'll have some warm rooms!

It's all done & NO LEAKERS!



I'll put the firebrick, grates, doors & chimney connector in when it gets closer to the cold weather -- I've had enough of my basement!

After I finished the leak repair, I decided I'd better do some maintenance on the oil boiler.



Made a difference in stack temps. Last night when I ran the boiler after refilling, the stack got up over 300* -- almost to 350*-- after running for 16 minutes straight (heating 55* well water to 180*). This time it never got over 250*, but it took 4 minutes longer to heat up -- I was thinking that doesn't make sense -- then I realized I forgot & left a zone valve open after bleeding air out of all the zones!! So not only did it heat the boiler water, the 41 gallons of water in the indirect-fired tank, & the new lines going to the coils, but it was heating my TV room on a 75* day & 92% humidity!!