Coil length for domestic water heater?

[Butch(OH)]

I want to build a heat exchanger to help preheat heat my domestic water, already have one of the vertical tubes beside the water heater and it cant keep up. We use a sled load of hot water. I am thinking about a simple pot of X size with my OWB water going through it and adding a coil of copper tube with my domestic water going through it. My question is how long does the coil need to be?

 

[damifino]

water heater

I might not be on same page as you but what I want to do (when I get my wood stove) is take a old water heater and strip it down to a bare tank. Then put it next to the wood burner and pipe it into my domestic water system so the water gets pre-heated before it goes into my working water heater. The first tank gets heated just by being next to wood burner.
I don't know if you are thinking that simple or if you have higher tech ideas in mind.

Eric

 

[Sawmill]

Just buy a plate type exchanger that goes in the line from your outdoor stove, You will never run out of hot water and you will take some of the heat out of the water being pumped back to your furnace. They do not cost that much and work very well.

 

[blackdogon57]

Question

Just buy a plate type exchanger that goes in the line from your outdoor stove, You will never run out of hot water and you will take some of the heat out of the water being pumped back to your furnace. They do not cost that much and work very well.

I am having the same problem with my hot water set up. With the plate type exchanger do you replace the existing hot water tank and attach it to your existing hot water lines and just get hot water on demand or do you still use the tank ??

 

[Jkebxjunke]

I am having the same problem with my hot water set up. With the plate type exchanger do you replace the existing hot water tank and attach it to your existing hot water lines and just get hot water on demand or do you still use the tank ??

I saw on a site a way to use a plate exchanger and a circ pump on the HWH and for mounting a thermostat on the tank to control the circ pump.
the circ pump was hooked to one side flat plate exchanger and the boiler to the other side... I was thinking of using the side arm set up but I am wondering now if it is not going to be enough? and I would think using a flatplate and a side arm would be over kill ... unless... hmmmm maybe if you put the flat plate on the cold inlet and the side arm where it usually goes... the FP would heat the water coming in and the side arm would keep the tank hot hmmm

 

[Sawmill]

Get rid of the side arm. Here is how mine is hooked up. Inlet line come into the house goes to the furnace then thru the plate heater and back to the tank on the OWB it is all run using one pump and and no thermostat. You guys are making an easy system to complicated, I never run out of hot water and the pilot light is shut off on my water heater, I am using the tank as storage for hot water. One word of caution you may have to install a mixing valve as the water in the water heater is the same temp as the line temp. I wash all my equipment with a line hooked up outside and have yet to run out of hot water. I have used 140 degree water to wash grease and oil off and you can use higher temp if needed by turning your furnace temp higher, but be careful when you do. If you guys are getting your info from your dealer I would look for another dealer because he is trying to sell you stuff you don't need. Remember KEEP IT SIMPLE less electronics means less dollars put out by you and less headaches later down the line.

 

[Butch(OH)]

I saw on a site a way to use a plate exchanger and a circ pump on the HWH and for mounting a thermostat on the tank to control the circ pump.
the circ pump was hooked to one side flat plate exchanger and the boiler to the other side... I was thinking of using the side arm set up but I am wondering now if it is not going to be enough? and I would think using a flatplate and a side arm would be over kill ... unless... hmmmm maybe if you put the flat plate on the cold inlet and the side arm where it usually goes... the FP would heat the water coming in and the side arm would keep the tank hot hmmm

That is exactly what I am looking at, a way to pre-heat while we are using water and the side arm keeps the tank warm when not in use. I want to quit using gas when my OWB is running and I am not near that now. One thing they dont tell you when you buy a side arm is the thermosat for the water heater is located at the bottom where the cold water comes in and if you dont turn it down the heater will come on every time you use water and help the side arm, Turn the thermostat down or off and the side arm doesnt keep up and you run out of hit water. We have 5 takoing showers here and a clean freak wife, we usea LOT of hot water, maybe with two in the house it wouldnt be an issue. The knock my dealer put on a plate only system is that if you go all day and dont use any water the tank will lose heat and the water heater burner will run or if you have it turned off you will have luke warm water for bath time.

I just want all the hot water I need all the time under any circumstance without the gas burner lighting and there are comprimizes with a plate and a side arm system. Am open to any ideas.

 

[Butch(OH)]

I might not be on same page as you but what I want to do (when I get my wood stove) is take a old water heater and strip it down to a bare tank. Then put it next to the wood burner and pipe it into my domestic water system so the water gets pre-heated before it goes into my working water heater. The first tank gets heated just by being next to wood burner.
I don't know if you are thinking that simple or if you have higher tech ideas in mind.

Eric

No hi tech wanted simple is better. I have an outdoor boiler but basicaly want to do like you, pre heat what goes into the tank and let the side arm do the rest.

 

[Sawmill]

I can tell you that we have been gone for days at a time and the water in our water heater was still warm. The water heater has been shut off for over a year now. I would guess it all depends on where your water heater is located at and how well it is insulated.

 

[Jkebxjunke]

No hi tech wanted simple is better. I have an outdoor boiler but basicaly want to do like you, pre heat what goes into the tank and let the side arm do the rest.

how bout if you came out of the side arm and into a plate exchanger hooked to the cold inlet... the side arm keeps it warm and the flap plate heats the water entering the tank.. how would that work?

 

[rx7145]

I have a flat plate that heats the water that goes into the hotwater tank. I also have a sidearm that keeps the water hot. Never ever run out.

 

[itn]

sounds like maybe u just need more storage for your water. possibly another water heater that doesn't work just to store more hot water? or any sort of tank should work just insulate it.