Hot Water Coil Project Questions

Hot Water Coil Project Questions

PostBy: traderfjp On: Wed Jul 25, 2007 10:07 pm

OK. I'm finally ready to tackle this project and could use some advice. I want to put a coil in my stoker and run it into my hot water heater. My stove is on the 2nd floor and the hot water tank is in the basement in a small room directly under the stove. It's proably a 12' run and 24' for the complete loop. I'm wondering if I will need a pump to circulate the water through the system?

If I do need a pump I'm worried that the electricity might go off and then there would be a build up of steam in the pipe. Would a relief valve keep my family safe?

Should I use galvanized threaded pipe and can I use copper at some point?

Thanks in advance.
traderfjp
 
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing 3

PostBy: ktm rider On: Thu Jul 26, 2007 1:53 am

I did it a little differently than this. My boiler is outside in my garage and I didn't want to run a supply and return line all the way out there. So, i got a water to water heat exchanger and "T" off my main hot water supply to my air handler and put the exchanger right beside my hot water tank. Saved me a fortune in piping AND burying the pipe and the headache that always comes with that.

Not sure how your set up is but this might be another option for you..
ktm rider
 
Stove/Furnace Make: AHS Multifuel
Stove/Furnace Model: CO 55 with oil backup

PostBy: coaledsweat On: Thu Jul 26, 2007 8:22 am

Because your heat source is much higher than your water tank it is unlikely it will thermosiphon well if at all, it most likely will need a pump. I would not use galvanized or threaded pipe. You should use copper tubing and sweat it. You must use a relief valve at or near the stove. Be careful where it dumps.
coaledsweat
 
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea


PostBy: traderfjp On: Thu Jul 26, 2007 9:13 am

I would prefer copper so that is a good thing. The relief valve needs to be by the stove. Are you saing that it's not as safe if I put it by the hot water heater. Astetically it would look better in the basement. Also, can I pipe the coil through the back of my stove through the hopper or would the pipes sweat and keep the coil from dumping onto the grate. Thanks.
traderfjp
 
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing 3

PostBy: Yanche On: Thu Jul 26, 2007 10:38 am

Lets try to understand the fundamentals. A water heater safety relief valve is temperature activated. It's on top of the water tank with the temperature probe in the water. That's where the water is the hottest. In your installation the hottest water is two stories up. That's where you need a safety device. When water is heated it expands. That increase in volume must go somewhere or the pressure will go up. Constrain the expanding water and with sufficient pressure build up something will break. It usually breaks where the hottest water is. This is almost always dangerous. In many installations the expanding water backs up into the public water supply line. In well installations it backs up into the bladder type water storage tank. EXCEPT if there is a check valve. Public water meters sometimes have an internal check valve. Sometimes there is a code requirement to have a supply check valve. Private well systems have check valves in deep well pumps. What do you have? Think through your design in your unique situation.

Perhaps your water coil will extract so little heat there little potential for a problem. On the other hand you may have some failure mode that causes a problem. You are trying to use a thermo siphon stove heating coil in a way it was not intended to be used. Thermo siphon systems tend to be self limiting and since the water tank is above the heating coil. The stove coil is always filled with water, negating a situation in which a small amount of water in the stove coil can flash to steam. Get some on site professional design help.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

PostBy: traderfjp On: Thu Jul 26, 2007 11:32 am

Yanche: It just me trying to figure this all out. The so called pros are like finding a needle in a haystack. My dad was a plumber and I use to work with him so I have a fair understanding. Anyway, I can easily add a relief valve off the coil loop. That is not a problem. I'm worried about safety and steam buildup in the pipes and the relief vavle would take care of that. The stove co. seels a coil kit so I'm not sure why you say: Quote"Thermo siphon systems tend to be self limiting and since the water tank is above the heating coil. The stove coil is always filled with water, negating a situation in which a small amount of water in the stove coil can flash to steam. "
traderfjp
 
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing 3

PostBy: coaledsweat On: Thu Jul 26, 2007 12:17 pm

A cup of water that flashes to steam is 16,000 cups of steam, you can see that this is a potentially dangerous situation. With your setup having the tank well below the heat source, it could be prone to failure. The project has issues that must be dealt with in a safe fashion or it isn't going to be very rewarding.
coaledsweat
 
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

PostBy: dll On: Thu Jul 26, 2007 12:40 pm

This link may help it has diagrams for both pump circulation and thermosyphon systems showing the recommended valves and their locations.


http://mha-net.org/msb/docs/dhw2.PDF
This link is broken, either the page no longer exists or there is some other issue like a typo.
dll
 
Hand Fed Coal Stove: Harman MKII
Coal Size/Type: Nut/anthracite

PostBy: traderfjp On: Thu Jul 26, 2007 12:43 pm

Thanks. I printed out the diagram. It's not rocket science but I want to make sure I have it all together before I start drilling my stove. ANy advice is appreciated.
traderfjp
 
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing 3

PostBy: Richard S. On: Thu Jul 26, 2007 1:50 pm

You may want to read this thread: http://nepacrossroads.com/viewtopic.php?t=1227

There's a few others, one even with pictures but I can't find it.
Richard S.
 
Stoker Coal Boiler: Van Wert VA1200
Coal Size/Type: Buckwheat/Anthracite

PostBy: Yanche On: Thu Jul 26, 2007 1:58 pm

dll wrote:This link may help it has diagrams for both pump circulation and thermosyphon systems showing the recommended valves and their locations.


http://mha-net.org/msb/docs/dhw2.PDF
This link is broken, either the page no longer exists or there is some other issue like a typo.
It looks like the referenced document covers all the safety issues.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

PostBy: cheapheat On: Thu Jul 26, 2007 3:42 pm

Hey trader, I wouldeventually like to do the same thingyou are andam curious what kind of coil you bought? I dont think the money will be there for me to do it this season but I am still curious. thanks jim
cheapheat
 
Stove/Furnace Make: Alaska Channing 3
Stove/Furnace Model: Bagging my own rice coal

PostBy: e.alleg On: Sun Jul 29, 2007 3:25 am

I am getting ready to hook up my hot water coil, I was thinking of hooking it separate from my existing HW heater and isolating the 2 separate heaters with simple ball valves. It appears that I can just T off of the fill line into the boiler and plumb that cold incoming well water to one side of the coil, then the other side will get hooked to the hot water pipe that goes to the shower. I 'm not sure what will prevent the boiler from heating the cold tap water and warming up all the pipes in the house...maybe I'll need a one-way valve on the inlet side? BTW how do I post pictures? I am aching to show you folks my new toy :)
e.alleg
 
Stove/Furnace Make: EFM
Stove/Furnace Model: 520

PostBy: Richard S. On: Sun Jul 29, 2007 6:26 am

e.alleg wrote:BTW how do I post pictures? I am aching to show you folks my new toy :)


For a single image click the browse button below the posting panel and select your image. It can have a filesize no larger than 300K. More info here : http://nepacrossroads.com/viewtopic.php?p=192
Richard S.
 
Stoker Coal Boiler: Van Wert VA1200
Coal Size/Type: Buckwheat/Anthracite

PostBy: gaw On: Sun Jul 29, 2007 8:18 pm

e.alleg wrote:I am getting ready to hook up my hot water coil, I was thinking of hooking it separate from my existing HW heater and isolating the 2 separate heaters with simple ball valves. It appears that I can just T off of the fill line into the boiler and plumb that cold incoming well water to one side of the coil, then the other side will get hooked to the hot water pipe that goes to the shower. I 'm not sure what will prevent the boiler from heating the cold tap water and warming up all the pipes in the house...maybe I'll need a one-way valve on the inlet side?


Yes, T off of the supply line from your well to the boiler. I just ran a ½ in. copper line into the hot water coil and the other end of the coil to all hot water faucets. You may want to put a valve between the T and coil. Between the T and boiler you will install either an automatic fill valve or a gate valve if you wish to fill and maintain boiler pressure manually. Your boiler should always be at a lower pressure than the domestic water and the valves filling the boiler are almost always closed so getting water from the boiler into your domestic hot is highly unlikely. If you are paranoid about it you could put in a check valve between the T and boiler fill valve. An auto-fill boiler valve may have a check valve built into it but I do not know if they do.

You only loose heat in the pipes that heat the house if your water temperature drops below the low limit of the aquastat. The circulator stops until the set temperature is satisfied. Only on rare occasions will you ever have such a demand on the boiler that you lose domestic hot water temperature. Check with EFM’s web site to see what their coils are rated for, I think you can find the info there somewhere. You may have to download the owner’s manual for the 520.
gaw
 
Stoker Coal Boiler: Keystoker KA-6
Coal Size/Type: Rice from Schuylkill County