Thermosiphon Question for Coil

I do know of a few people whom just plumb the coal boiler in series with the elec. hot water heater. Coal boiler first, outlet of coal to inlet of elec. Has been working good for over 30 years on both setups, original water heaters too, though they both expect the water heaters to die one of these years. Drain the water heater once a year and change the anode if needed. There are ball valves on the coal for bypass for when it gets shut down and cleaned once a year. I'm pretty sure that is how i am going to plumb my AA-130 once installed.

Trader,

I like the diagram, how would you draw it up if you had the water from main going into the tank first?

Why would you send it through the the tank first? That really defeats the purpose of the hot water coal.

I think it may just be easier to use a bronze pump and call it a day. I know that son of a gun will keep the water moving.

Richard S. wrote:Why would you send it through the the tank first? That really defeats the purpose of the hot water coal.

Because the system is already in place and from reading how it's setup on page three figure two http://www.meyermfg.com/domesticcoil-install.pdf one would only need to connect to the drain valve and slice into where the pressure relief valve is. That would seem like the easiest way to set it up, unless I'm mistaken?

The first pic in the PDF link is my original diagram. The relief valve is higher but I just wonder how fast the water would actually circulate. WOuld it dribble out of would it be a nice siphon.

Adamiscold wrote:Because the system is already in place and from reading how it's setup on page three figure two http://www.meyermfg.com/domesticcoil-install.pdf

Might be easier but I don't see the point of putting cold water into a external hot water heater when you can preheat it. The coal is on 24/7, you're still heating water even when it's idling. There isn't any reason to utilize it to the fullest. The lager coils on the bigger furnaces can supply enough hot water on their own, you don't even need the tank. The tank is just a convenience because it supplies hot water if you turn the furnace off and with it going through the coil first you have a endless supply of hot water. In fact its actually a small safety measure because the initial water coming out of the coil is hot enough to scald.

If you're looking for simplicity I'd suggest you'd be better off simply running the cold water through the coil first and then into the hot water tank without a loop. That would be the absolute simplest method.

If you're looking for simplicity I'd suggest you'd be better off simply running the cold water through the coil first and then into the hot water tank without a loop. That would be the absolute simplest method.

That would be the simplest way, but the water would always be stagnant until something called for hot water. Wouldn't the water just boil to the point where it wanted to exploded or melt the pipe? It would seem that a pressure relief valve would always be letting off steam or allowing water to pour right out of it.

The relief valve is higher but I just wonder how fast the water would actually circulate. WOuld it dribble out of would it be a nice siphon.

Trader that's a big concern for me, how would you know if you were getting the most out of that type of setup? It seems that a pump would be the best way to know you are getting the most out of your system.

My coil is 1/2" so I don't want to run my main water through that and take a chance of a pressure drop and be assured that the water is circulating between the coil and the tank.

In the winter the water coming into my house is ice cold. Given the diagram above, would this ice cold water bother the stainless steel coil inside my furnace?

Is there a way of using the aquastat in my elect. water heater to control a bronze pump? So instead of the elect elements it would control a pump that would cicul. water through my coal boiler coil

I am trying to understand the process of getting heated water out of my Keystoker Koker furnace. I can install the coil and the valves and run the lines. That doesn't appear to be a problem. What I don't understand is what prevents the water from overheating and frequently blowing the relief valve? Do I need to install an aquastat connected to a heater to dissapate excessive heat into the basement? I guess I'm asking how all of you produce hot water without overheating your system and ending up with too much heat going into the water.
A little backgroud: My wife and I are "empty nesters" so demands on our water system/hot water are not very high. Our source of water is our well. Our heating system is forced air, with the Koker connected to our propane furnace. My neighbor is a plumber and would be willing to help me fix any mistakes I make.
-Len

It may blow the relief valve. It all depends on the size of the coil and how much hot water you use. The water should always be circulating through the coil. You don't want the water to sit in the coil and then turn to steam - also once relief valves start opening it's a good chance they will fail and start to leak. I had two go on me this weekend. One was a snap to replace and the other was a pita to get to. There are a few threads on this.

Hello Clairdon, yes you can get your DHW tank too hot, and this will result in a PRV opening.

It isn't too difficult to rig up a water circuit that would take the hot water and run it through a lenght of baseboard finned tubing, or a 'toe-kick' heater.. or a similar place to 'dump' excess heat.

The good thing about doing the above is the 'excess heat' is still going into your home.. If your basement is usually cool or cold, you could run some baseboard to heat it, or augement heat in some other part of the house.

You can use a 'strap on' aquastat that makes contact on temperature rise, to trigger a circulator pump, this would run the heat through the 'heat dump' circuit, then when the aquastat reads that the temp has dropped below it's set point, then the circulator will turn off.. not too difficult and will keep the PRV from venting.

Hope this helps.. Greg L

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