Heat Exchanger Help

[LadyTang2]

I'm unclear how heat exchangers work exactly. I know what broadly what it is but what is setting the water temp? Is it just a dedicated tankless water heater? Do they have fine temperature controls and how reliable/accurate are they? (if that fails everything dies) I could see setting one temp on the heating unit but it looks like some people have this communicating with their aquarium and using cold water if it gets too hot. How does this communication happen and how does the cold water connect? Again do folks simply use tankless water heaters?

I guess I am looking for a list of equipment needed for the different solutions and how it ties together.

@KenO @ca1ore @Dr. Dendrostein

Thanks!

 

[ca1ore]

A heat exchanger is simply a container that allows two water streams to exchange temperature across a conducting membrane. In the case of our tanks, this is usually a titanium or PVC shell with a titanium heat exchange element inside. Tank water is pumped through the shell; hot or cold water is independently pumped thought the exchange coil to either heat or cool the tank water. The two streams do not intermingle. The actual heat exchanger is a passive device, you also need some way to pump water through it and to control the pumping based on a temperature controller. Broadly you will need:

• The actual heat exchange unit
• A pump to circulate the hot water through the heating coil.
• Perhaps a solenoid or two for safety
• Plumbing for both the hot water side and the aquarium side
• Depending upon your setup, you may need a circulation pump to move tank water through the exchange unit.
• Some kind of temperature controller (maybe two).

The advantage is that you can use oil/gas heated water from your house to replace the electric heaters, which for most will result in an energy saving.

 

[LadyTang2]

What is heating the water, is it usually a dedicated tankless unit? How would you control the temp if it was not dedicated?

How would the temperature be communicated to the exchanger? It's these details that really confuse me, I am sure it can be done many ways but how do you do it?

If you have some idea of the ideal set up, let me know what that is

 

[Dr. Dendrostein]

I'm unclear how heat exchangers work exactly. I know what broadly what it is but what is setting the water temp? Is it just a dedicated tankless water heater? Do they have fine temperature controls and how reliable/accurate are they? (if that fails everything dies) I could see setting one temp on the heating unit but it looks like some people have this communicating with their aquarium and using cold water if it gets too hot. How does this communication happen and how does the cold water connect? Again do folks simply use tankless water heaters?

I guess I am looking for a list of equipment needed for the different solutions and how it ties together.

@KenO @ca1ore @Dr. Dendrostein

Thanks!

heat exchanger is only possible because of the laws of thermodynamics. One law says heat is attracted to cold if it wasn't for this law, we wouldn't have air conditioning or heat exchangers

 

[LadyTang2]

heat exchanger is only possible because of the laws of thermodynamics. One law says heat is attracted to cold if it wasn't for this law, we wouldn't have air conditioning or heat exchangers

Thanks! I'm also wondering exactly what equipment is involved and how people get things talking to eachother. Do you have one,what is the flow path of water, do you leave the pumps on?

 

[ca1ore]

What is heating the water, is it usually a dedicated tankless unit? How would you control the temp if it was not dedicated?

You could use a dedicated tankless heater, but most folks who do this use a loop from their existing hot water tank. Since the loop does not have differential pressure, a pump in that loop is used to move hot water through the exchanger as needed.

How would the temperature be communicated to the exchanger?

A standard temp controller like an apex or ranco is used to trigger the pump in the hot water loop. when the tank temp drops below the low set point, pump comes on and pushes hot water through the exchanger. When tank temp rises above the high set point pump is turned off.

 

[Dr. Dendrostein]

Thanks! I'm also wondering exactly what equipment is involved and how people get things talking to eachother. Do you have one,what is the flow path of water, do you leave the pumps on?

I dont have one, youtube has ideas on htexchgr for aquariums.

 

[Blue Spot Octopus]

https://www.reef2reef.com/posts/6790827/ Check tis thread out.