Using a Heat Exchanger for BOTH Heating and Cooling a Large Aquarium

[ca1ore]

Had a few issues ….. plus a lot of business travel. Hoping to get the cooling side up and running this weekend.

 

[Biglurr54]

This is my fall project. My sump is in my basement and its a dry laid stone foundation. Needless to say its drafty and the temp is tough to maintain over the winter months (Upstate NY). I heat my house with an outdoor boiler so I have all the 180 degree water I could ever use.

On the cooling side, you do not want to reuse the cold water. Once it gets heated, you run the risk of Legionella (Grows in water temps 77-108). If you circulated cold water to cool the tank, you would end up with a tank of domestic water close to the legionella temps. Not worth the risk. Luckily our water heaters will keep the hot water tanks above 108 which will kill the bacteria.

Another thing to keep in mind on a build like this is the circulator pumps used on the domestic side. Most circulator pumps are designed for closed systems. that means that water is added to the system and then sealed off. The small amount of oxygen is used up quickly and then the water is absent of oxygen so corrosion does not occur. On our domestic water supply, it is considered an open system (Meaning new oxygenated water from the well is constantly added to the system.) This oxygen will corrode the pump quickly causing a failure. They make stainless steel and bronze circulator pumps for use in open systems. They cost a lot more money but they will not corrode and fail prematurely due to corrosion. When shopping for the circulator make sure you find one that states that it is compatible with an open system. (A lot say they work with water heaters and stuff that eludes to our purpose but they are for closed loop systems.)

I am going with a complete DIY build with a titanium tube ans shell exchanger. I will eventually do a build but i am following along on this one.

 

[ca1ore]

On the cooling side, you do not want to reuse the cold water. Once it gets heated, you run the risk of Legionella (Grows in water temps 77-108). If you circulated cold water to cool the tank, you would end up with a tank of domestic water close to the legionella temps. Not worth the risk. Luckily our water heaters will keep the hot water tanks above 108 which will kill the bacteria.

Maybe. My cold water comes it at around 55 degrees. I've not run it yet, but I'd be surprised if said cold water on the output side got anywhere close to 77 degrees. Depends, I suppose on how slowly or quickly one runs the cold through the heat exchanger. I was also thinking about using the waste cooling water as feed for my RODI system (RODI does better with warmer water). We shall see.

Another thing to keep in mind on a build like this is the circulator pumps used on the domestic side. Most circulator pumps are designed for closed systems. that means that water is added to the system and then sealed off. The small amount of oxygen is used up quickly and then the water is absent of oxygen so corrosion does not occur. On our domestic water supply, it is considered an open system (Meaning new oxygenated water from the well is constantly added to the system.) This oxygen will corrode the pump quickly causing a failure. They make stainless steel and bronze circulator pumps for use in open systems. They cost a lot more money but they will not corrode and fail prematurely due to corrosion.

Good point!

 

[Biglurr54]

Maybe. My cold water comes it at around 55 degrees. I've not run it yet, but I'd be surprised if said cold water on the output side got anywhere close to 77 degrees. Depends, I suppose on how slowly or quickly one runs the cold through the heat exchanger. I was also thinking about using the waste cooling water as feed for my RODI system (RODI does better with warmer water). We shall see.



Good point!

If you ran the domestic water through your well tank (like you are running through your water heater) eventually the heat in the well tank would raise potentially to 77+ degrees. Typical well tanks are around 40 gallons so with a large system, that water would quickly warm up. if you run the water from the well tank and then down the drain, the water wouldnt warm up. I like the idea of feeding an RODI. My plan is to not use the system for cooling and only heating as the cooling is difficult to achieve without being more wasteful than a chiller or well placed air conditioning unit.

 

[link81]

i would just waste the cold water to a french drain i think. it will make its way back into the well eventually.

I'm not sure if a circulator would even be needed on the the DCW side. Just use the pressure to push the water.
on the DHW side it wouldn't be an issue because that loop would remain closed. But i do like the idea of a small stand alone on demand heater. might even be able to use it for house water also during low demand times, then kick on the boiler when there is a higher hot water demand. (heating season)

 

[ca1ore]

A recirculatory pump is not needed on the cold side. Since it is an 'open' circuit, the pressure from the well pump will suffice.

 

[ca1ore]

Connected the cooling side of this thing this past Friday. Still playing around with cold water flow, but I am a bit underwhelmed. It’s not clear to me that this will allow me to dispense with the chiller - we shall see next Summer. Cannot connect the heating side because there appears to be a malfunctioning solenoid on that side of the control board. I’m supposed to have received a replacement solenoid from AE .... just crickets. Of course, haven’t needed heat on my system yet; though that will change as we get towards the end of Sept.

If I don’t get the replacement solenoid soon, I’ll just get one of amazon. AE makes top quality equipment, but dealing with them requires the patience of a saint ....

 

[Biglurr54]

That's too bad about the cooling side of things. I was worried it would take an ton of well water to chill the tank and something about a well pump running all day doesn't see efficient.

Heating side is another story.

I ordered my parts for the diy cheaper version for heat only. It will be a bit before I install it as I have alot of house projects going on and that seems like a great winter project!

 

[ca1ore]

Yeah, I think the cooling side may end up being live-and-learn. The other issue is that even running relatively low flow out of the well means sweating pipes in my basement sump room ... unless I crank the dehumidifier. Which doesn’t help the energy savings.

 

[ca1ore]

That's too bad about the cooling side of things. I was worried it would take an ton of well water to chill the tank and something about a well pump running all day doesn't see efficient.

Heating side is another story.

I ordered my parts for the diy cheaper version for heat only. It will be a bit before I install it as I have alot of house projects going on and that seems like a great winter project!

Are you buying the actual heat exchanger or going with some kind of drop in coil?

 

[mrpizzaface]

Really curious about this. Was planning on buying one of these for an upcoming build. I am concerned about your observations regarding the cooling. I don't think it would be worth it if I couldn't use it for both heating and cooling.

 

[Biglurr54]

I am using 55k btu titanium tube and shell heat exchanger designed for mariculture. It has 1in ports for the Hot water side and 1.5in for the tank water side. It will go inline on my main return line. I have a back up return with a separate line so if something fails, The APEX can shut off the return with the heat exchanger and run the back up return pump. ($175.00 off ebay)

For circulation, Im using a Taco 006-b4 (bronze) circ pump. ($109 off ebay) I'm using a generic solenoid which im going to double up on (One on either side of the exchanger) for redundancy purposes. This will also be used to stop the flow of well water if the heat exchanger gets an internal leak. ($35.00/ea of Ebay)

Lastly, I am going to use an Ink Bird Wifi temp controller ITC-308 plugged into the APEX to control the circ pump and solenoids. This will give me two temp readings, and two sources of alarms if things go out of range. The APEX will be the back up (typically always on) and the InkBird will do the cycling. Both will send alarms if things go outside of the limits. ($50.00 off amazon) This temp controller would work well with the cooling side as well. It would just require a couple of solenoids to make it work with cooling.

Over the winter I will cut into the plumbing and sweat everything together. I hate using pex but this application will work better with pex and the cost will be a lot lower with pex vs copper runs. That said, I'm still going to sweat copper fittings in!.

I'm at $400 in parts now and haven't bought the plumbing/pex stuff. So I'm looking at $500 all said and done. There's a very long return on investment on this one, but I get unlimited hot water from my outdoor wood boiler for next to nothing and there is cool factor of heating the tank with wood!

 

[Breadman03]

Yeah, I think the cooling side may end up being live-and-learn. The other issue is that even running relatively low flow out of the well means sweating pipes in my basement sump room ... unless I crank the dehumidifier. Which doesn’t help the energy savings.

Foam pipe insulation would help with that.

 

[ca1ore]

I am using 55k btu titanium tube and shell heat exchanger designed for mariculture. It has 1in ports for the Hot water side and 1.5in for the tank water side. It will go inline on my main return line. I have a back up return with a separate line so if something fails, The APEX can shut off the return with the heat exchanger and run the back up return pump. ($175.00 off ebay)

For circulation, Im using a Taco 006-b4 (bronze) circ pump. ($109 off ebay) I'm using a generic solenoid which im going to double up on (One on either side of the exchanger) for redundancy purposes. This will also be used to stop the flow of well water if the heat exchanger gets an internal leak. ($35.00/ea of Ebay)

Lastly, I am going to use an Ink Bird Wifi temp controller ITC-308 plugged into the APEX to control the circ pump and solenoids. This will give me two temp readings, and two sources of alarms if things go out of range. The APEX will be the back up (typically always on) and the InkBird will do the cycling. Both will send alarms if things go outside of the limits. ($50.00 off amazon) This temp controller would work well with the cooling side as well. It would just require a couple of solenoids to make it work with cooling.

Over the winter I will cut into the plumbing and sweat everything together. I hate using pex but this application will work better with pex and the cost will be a lot lower with pex vs copper runs. That said, I'm still going to sweat copper fittings in!.

I'm at $400 in parts now and haven't bought the plumbing/pex stuff. So I'm looking at $500 all said and done. There's a very long return on investment on this one, but I get unlimited hot water from my outdoor wood boiler for next to nothing and there is cool factor of heating the tank with wood!

Sounds like a good plan, though I am not personally a fan of the StinkBird .... I much prefer the Ranco. It's a bit more expensive, but not eggregiously so.

 

[ca1ore]

Foam pipe insulation would help with that.

Yes. I have most of the pipes insulated; helps but does not prevent sweating.

 

[Biglurr54]

The Ranco does not have wifi capabilities so you dont get the redundant alerts and monitoring but it comes at the cost of a cheaper relay. I have inkbirds running a number of things including tanks in the past and have never had one fail so I feel comfortable with them but i have heard the Ranco's are slightly more accurate and reliable.

 

[ca1ore]

Really curious about this. Was planning on buying one of these for an upcoming build. I am concerned about your observations regarding the cooling. I don't think it would be worth it if I couldn't use it for both heating and cooling.

I think mine may be undersized. Probably it will work for heating, but it's clearly inadequate for cooling. If it's not cutting it in mid-sept., there's no chance for July or August. I am having some issues getting decent flow through the cooling circuit, so I am going to have to take the plumbing apart to see if I can figure out why (well pump pressure is on the low end at around 45, but that is fine for upper floor showers so it shoud be fine here also) - but with even the lower flow, the 'waste' water remains quite cool suggesting that not enough heat exchange is happening. Quite disappointing actually given what I paid for this thing.

 

[ca1ore]

The Ranco does not have wifi capabilities so you dont get the redundant alerts and monitoring but it comes at the cost of a cheaper relay. I have inkbirds running a number of things including tanks in the past and have never had one fail so I feel comfortable with them but i have heard the Ranco's are slightly more accurate and reliable.

Yes, true on the wifi. My experience with them was not good, but that was early on so perhaps they are more reliable now.

 

[Biglurr54]

you can experiment with the flow on both sides. I know that heat exchange is efficient at certain flows and drops off at high or lower flows. I'm not sure on the physics of it as its out of my scope of knowledge but i know from experimenting with my sidearm heat exchanger and wood stove tempering coil, slower flows created better exchange to a point then efficiency dropped off with too slow of flow.

 

[Dennis Cartier]

Any update on how the exchanger is working for heating? I am looking at doing something similar for my 500 G build and will need to source a decent solution for this. My choices are RK2 Systems, AE (Bill) or plain old DIY.

Your comment about needing the patience of a saint to deal with AE is spot on, lol. I have been waiting almost a year for my A.C.R to be shipped. I keep thinking happy thoughts, lol.

Dennis