Dedicated Tankless Water Heater

[Dr. Dendrostein]

My plan is too use a titanium heat exchanger. I posted a picture of my plan in an earlier post. I'm going to use a DC pump to control the flow through the heat exchanger. By changing the flow, I can control the amount of heat transfer to the aquarium water. I'm sure it will take some testing, but I'll get it figured out. I also have my plumber looking into a separate smaller tankless unit just for the aquarium. I can then play with the water temp of the unit to see what temp works the best.

Having various brands of tankless, if temp is raised to a certain point, you start getting a build up of scale inside tankless w/h,thus ruining tankless. If me, leave tankless at 120 degrees, and do like you said use dc pump and tweek pump flow. Problem with aquarium dc pump, may not last long, heat my effect it. May need to use regular recirculating pump and control discharge with ball valve. And once a year need to descale tankless, every tankless has its kit to descale as maintenance protocol.

 

[KenO]

Having various brands of tankless, if temp is raised to a certain point, you start getting a build up of scale inside tankless w/h,thus ruining tankless. If me, leave tankless at 120 degrees, and do like you said use dc pump and tweek pump flow. Problem with aquarium dc pump, may not last long, heat my effect it. May need to use regular recirculating pump and control discharge with ball valve. And once a year need to descale tankless, every tankless has its kit to descale as maintenance protocol.

We run a softener on our house. My plumber recommends doing the scale (vinegar treatment) once every 3 years.
Problem with a regular recirculating pump is that they are not rated for saltwater. The DC pump will be pushing water into the heat exchanger. The other end of the heat exchanger will dump back into the sump and not directly flow back into the pump. Plus I'm pushing 3,000 gph out of my sump to my 250 gallon and I have another set of pumps pushing over 2000 gph to my 130 gallon tank. Sump is around 140 gallons and I'm also pushing water to a dual set of 40 breeders. The heated water will be dispersed quickly through the system.

 

[Dr. Dendrostein]

We run a softener on our house. My plumber recommends doing the scale (vinegar treatment) once every 3 years.
Problem with a regular recirculating pump is that they are not rated for saltwater. The DC pump will be pushing water into the heat exchanger. The other end of the heat exchanger will dump back into the sump and not directly flow back into the pump. Plus I'm pushing 3,000 gph out of my sump to my 250 gallon and I have another set of pumps pushing over 2000 gph to my 130 gallon tank. Sump is around 140 gallons and I'm also pushing water to a dual set of 40 breeders. The heated water will be dispersed quickly through the system.

Circulating pump to tankless circuit. You mention adding titanium heat exchanger.

Image example

 

[Dr. Dendrostein]

Diagram example

 

[Wiskey]

I'm not sure this would help anything. The advantage of doing something like this is you can use the more efficient heat of a gas hot water tank to heat a very large aquarium. The tankless water heater is electric, just like a tank heater you would buy. I think you may be adding complication for little benefit.

Thank you,
Whiskey

 

[Dr. Dendrostein]

Tankless come in electric, propane, and natural gas, nice thing about tankless is burner flame can be very small or big, depending on demand.

 

[KenO]

Circulating pump to tankless circuit. You mention adding titanium heat exchanger.

Image example

Yes the recirculating pump would be used on the domestic house loop. The DC pump would be used on the aquarium open loop.

 

[aquapaul]

Are those really expensive? I’m toying with this idea my self for a build of a 300+ gallon build.

It depends on setup and what type of heater you use. Can get pricey depending on setup. Still working out some details on how to do redundancy and protection etc. I am in the early planning phases for about the same size tank. Have some house electrical/generator/battery to workout before I go down the heating path.

 

[High Plains Reefer]

would it be possible to just run the loop return to a cold water pipe such as the washing machine hook up that way I could just get a couple of y's and use the not one to feed the loop and the cold one to return the loop to the house

 

[KenO]

would it be possible to just run the loop return to a cold water pipe such as the washing machine hook up that way I could just get a couple of y's and use the not one to feed the loop and the cold one to return the loop to the house

It's been awhile since I asked my plumber that same exact question. If I remember correctly the issue would be if someone turns on a cold faucet somewhere else in the house, you would get hot water out of the cold side. Something like that. Like I said it's been awhile since I set mine up. Maybe someone else with a plumbing background can answer the question.

 

[Larry arowana]

Have been reading everything about what everyone is doing with hot water heaters, heat exchanger, recirculating pumps, I was planning a 1500 gallon plywood build, and my thought is what about a small above ground pool heater? I have a pool outside, 18’ round pool which is 6000 gallons. Couldn’t you use a pool heater? Seems it would have everything you all are building. Just wondering because I will be in the same boat….any thoughts

 

[KenO]

Have been reading everything about what everyone is doing with hot water heaters, heat exchanger, recirculating pumps, I was planning a 1500 gallon plywood build, and my thought is what about a small above ground pool heater? I have a pool outside, 18’ round pool which is 6000 gallons. Couldn’t you use a pool heater? Seems it would have everything you all are building. Just wondering because I will be in the same boat….any thoughts

It would work, I guess it would depend on the efficiency of the pool heater. Just make sure the heater has a titanium heat exchanger. If you have to purchase a pool heater I would compare that to a small on demand water heater. When I was pricing out small ones they were less than $500. Now this was several years back.

 

[Larry arowana]

It would work, I guess it would depend on the efficiency of the pool heater. Just make sure the heater has a titanium heat exchanger. If you have to purchase a pool heater I would compare that to a small on demand water heater. When I was pricing out small ones they were less than $500. Now this was several years back.

Thank you!!

 

[Harpo]

Why not "T" off your existing hot water heater.

In my new build in my new house I will be using the titanium heat exchanger with a grundfos recirculation pump controlled from my ranco temperature controler. I will "T" off a near by hot water supply and return to the cold side input of my hot water heater.

 

[KenO]

Thank you!!

There are other components if you go the on demand hot water heater route. In the end I'm glad I did it. It works great. I know I guy who has a coral business that went this route and it is working great for him.

 

[Enderg60]

I got an excel brand tankless and ventless natural gas heater for my old 300g. The 200g sump was in the unconditioned basement so i was using two 1000w heaters in the winter.

Old setup was the excel heater, Taco circulation pump, watts air separator, 2 gal expansion tank, 100' coil of 1/2" pex and some cpvc to connect it all. This was 10 years ago but my power bill dropped $40 a month and my gas bill didn't make any noticeable change.

New setup is the same but using a pool titanium heat exchanged in place of the pex coil.