DIY Aquarium heater using hot water from the house -- has anyone tried this

[ianjirka]

I was thinking of trying to use the household hot water system to heat my aquarium. Two goals in mind:
1) Reduce energy/electricity use overall
2) Eliminate the need for me to run another 15A line to the aquarium to support the heaters. On average I think I'm okay going with electric heaters but at peak load probalby not.
3) If the power fails, I can maintain gas heat and the power to run the pump is minimal. A decent UPS should be able to run it for a while; long enough to get other stuff in place.

I had a washer box put in (Drain, hot/cold) where I plan to put my setup. At the time I didn't think the hot water would be useful. Now I think I might be able to use it to heat the aquarium.

Here is what I am thinking. Take one of those water circulation pumps -- the kind that brings hot water to a far location in your house and pushes the cool water back down the cold water line. Connect it via a controller to an aquarium temperature probe. Inbetween the hot/cold, run the water through a series of coils in the tank to do the thermal transfer. This way I'm not dumping the raw water into the tank (of course).

A couple of problems I can think of:
1) Depending on the rate at which the 'heater' turns on, you'll tend to get cold water first. Not sure how much of an issue this would turn out to be in a ~270 net g setup.
2) Copper piping directly in aquarium water is probably not a good idea -- chillers must have solved this problem so will likely need to dupe that idea. Need a way to prevent contamination of the water w/o reducing the ability to exchange heat
3) If anything goes wrong with the coil you have contaminated water entering your system. Chillers should have the same problem, but with much worse contaminates (I assume)
4) Increasing pressure in the line while pumping may have a negative effect on the RO/DI system. I haven't been able to determine from reading websites what the net pressure gain is with these systems.

I haven't been able to find anyone that tried this before -- anyone here with previous experience and/or thoughts on the matter?

Thanks much,

-Ian

[mak3mydae]

Where does the water go after? (probably a stupid question haha)

[dantimdad]

There is a thread on another reef forum in the diy section about this. Apparently it works incredibly well.

[ianjirka]

Originally Posted by mak3mydae

Where does the water go after? (probably a stupid question haha)

It gets pushed back into the cold water line. Hence you don't waste a ton of water. Pretty cool actually

[ianjirka]

Originally Posted by dantimdad

There is a thread on another reef forum in the diy section about this. Apparently it works incredibly well.

Ah, cool. Do you happen to know the name of the forum? I have looked around but haven't been able to locate a similar topic.

Thanks,

-Ian

[tydtran]

I am wondering if this is too much effort. It might be worthwhile with a really big tank, say in the many hundreds of gallon range, but for average size tanks, is this needed?

I have a 90 gallon acrylic tank. In the winter, ambient temp in the house is 70 degrees. With 350 watts of lights, 30 watts from powerheads, and 60 watts from a return pump, my tank holds 75 degrees without a heater. For me, cooling is much more of a problem because with the house at 80 in the summer time, my tank runs 85 + degrees without cooling.

As for power outtage, if you have gas, you could just as easily boild water, put it a bottle, and place the bottles in your sump to warm up the water. The times I have had power outtages, water circulation was much more of an issue than temperature drop.

[BeanAnimal]

Folks,

This only makes sense if you have a gas water heater. If your water heater is electric, then it is MORE efficient to use submerisble heaters IN the aquarium. A WATT is a WATT.

The principle is simple. ALL electric heaters (water heaters, baseboard heaters, hair dryers) etc. run at EXACTLY the same efficiency. That is they put out EXACTLY the same number of BTUs per WATT consumed. Heating water in an ELECTIC water heater, to transfer heat via a heat exchanger to your aquarium is going to be about 20%-30% less efficient than heating the water directly with aquarium heaters(s). This is due to thermal losses in the water tank, plumbing and heat exchanger.

Secondly, there is NO UPS that you can afford that will run an electric water heater, let alone do it for any reasonable amount of time. The smaller units are rated at 4.5kW. So to run one (pure resistance) you would need AT LEAST a 6kW UPS, but more likely a 10kW. A 220V 6kVA UPS will run you about $4,000 and get you 2-3 minutes of run time. Add another $1,500 in batteries and you can get maybe a half an hour or so.

If you are talking about using a GAS water heater, then there are a couple of threads here regarding the subject and how people have set them up.

The setup cost is substantial so the size of your tank and average heating needs will dictate if and when you realize real world savings.

[Jeff000]

Originally Posted by BeanAnimal

Folks,

This only makes sense if you have a gas water heater. If your water heater is electric, then it is MORE efficient to use submerisble heaters IN the aquarium. A WATT is a WATT.

The principle is simple. ALL electric heaters (water heaters, baseboard heaters, hair dryers) etc. run at EXACTLY the same efficiency. That is they put out EXACTLY the same number of BTUs per WATT consumed. Heating water in an ELECTIC water heater, to transfer heat via a heat exchanger to your aquarium is going to be about 20%-30% less efficient than heating the water directly with aquarium heaters(s). This is due to thermal losses in the water tank, plumbing and heat exchanger.

Secondly, there is NO UPS that you can afford that will run an electric water heater, let alone do it for any reasonable amount of time. The smaller units are rated at 4.5kW. So to run one (pure resistance) you would need AT LEAST a 6kW UPS, but more likely a 10kW. A 220V 6kVA UPS will run you about $4,000 and get you 2-3 minutes of run time. Add another $1,500 in batteries and you can get maybe a half an hour or so.

If you are talking about using a GAS water heater, then there are a couple of threads here regarding the subject and how people have set them up.

The setup cost is substantial so the size of your tank and average heating needs will dictate if and when you realize real world savings.

+1.

Also keep in mind almost 300 gallons of water plus all the sand and rock will take a good while to drop in temp enough to worry.

I have no idea why you would need to add another 15amp circuit, you are not trying to fight blizzard cold with the heater, just overcoming room temp.



How long are these power outages you are talking about?
A UPS to run just your circulation pump for an hour is going to run you at least ~200 bucks. And replace it every couple years if you want it to maintain an hour run time.
If you want a UPS to run just your pump for 8-14 hours, which your tank will still not cool enough to matter in, you will need a UPS that is well into the 1000's.
Just buy a 5000kw generator for a few hundred bucks, it will be cheaper and easier by a long shot and will give you power for weeks. Get a 10000kw unit and then run the basics of your house too. But I am assuming you are talking an hour or less power outages, so don't worry about your heat. Keep the pump running,

[ianjirka]

I'm new to saltwater systems, so definately willing to learn from people who have done this before.

My hot water system is gas, completely agree this makes no sense with an electric water heater.
I will put the tank in the basement. Basement never gets above 72, even if it's 100 degrees outside. Ambient temperature floor is 65, which it will reach ~8 months out of the year (basement is on a separate zone)

The thing with the circuit is I only have one 15A for the room, and other things will run in there. With LED lighting and energy efficient pumps, I think I can keep the usage to ~600W peak, excluding heating. What concerns me is that for a ~270G system, using the 2-3w/gallon rule of thumb for heaters, that there is a 'peak' load potential of ~500-750W from the electric heaters alone. So any additional consumption in the room aside, that pushes me outside of what I can rely on a 15A circuit to provide.

Maybe I'm focusing too much on that aspect of it, and I should run a dedicated circut (or two since I'm at it), anyway.

Re: power loss, we were out for a week two years ago. But mostly its a few hours max. Good point about circulation being more of an issue than heat during power loss, I'll think about that more.

I'll dig around more for what other people have done and do a deeper cost analysis.

Thanks for the thoughts everyone,

-Ian

[der_wille_zur_macht]

Here's a thread you might want to read:

http://www.reefcentral.com/forums/sh....php?t=1561871

[Jeff000]

Originally Posted by ianjirka

I'm new to saltwater systems, so definately willing to learn from people who have done this before.

My hot water system is gas, completely agree this makes no sense with an electric water heater.
I will put the tank in the basement. Basement never gets above 72, even if it's 100 degrees outside. Ambient temperature floor is 65, which it will reach ~8 months out of the year (basement is on a separate zone)

The thing with the circuit is I only have one 15A for the room, and other things will run in there. With LED lighting and energy efficient pumps, I think I can keep the usage to ~600W peak, excluding heating. What concerns me is that for a ~270G system, using the 2-3w/gallon rule of thumb for heaters, that there is a 'peak' load potential of ~500-750W from the electric heaters alone. So any additional consumption in the room aside, that pushes me outside of what I can rely on a 15A circuit to provide.

Maybe I'm focusing too much on that aspect of it, and I should run a dedicated circut (or two since I'm at it), anyway.

Re: power loss, we were out for a week two years ago. But mostly its a few hours max. Good point about circulation being more of an issue than heat during power loss, I'll think about that more.

I'll dig around more for what other people have done and do a deeper cost analysis.

Thanks for the thoughts everyone,

-Ian

For power is your basement finished? If not then by all means run a dedicated circuit, I would probably run a 12/3 and give yourself two 20 amp circuits. But thats overkill, lol. You have about 1440 watts constant use available, but 1800 for a few hours would be fine, could run probably 2500 watts for a minute or two, but depends on what brand breakers you run really lol. What else do you plan on putting in that room?

For 8-10 hours just keep worried on your pump circulating, that alone will cost you a fair amount. For 2 weeks... heat is your last concern at that point.


RE der_wille_zur_macht's linked thread, His power costs are very high where ever he lives or he miss calculated. Also make sure to read that he killed his tank with this set up. He also killed the pump a short time later, increasing costs even more.
And fast temp changes are far worse then slowly getting colder then ideal temps. Also getting too hot is worse then getting to room temp. What happens when the temp probe fails or pump jams (from operating far hotter then designed) and your heater runs constant and heats the tank to the 130f that your hot water is?

It is neat, and for huge tanks (500g +) I can see it working better and with less risk.

[Camel413]

I have tried using the search function but I couldnt find the answer. This may be a dumb question but what does UPS stand for, all I can tell is it is some sort of battery back up for power outages.

[BeanAnimal]

Uninterpretable Power Supply

Most commonly used for communications, computer and hospital equipment. The average person does not understand that MOST UPS systems are designed to hold the load over for a few seconds to a few minutes until a standby generator comes online and picks up the load. Very rarely are UPS systems sized to actually run a piece of equipment for more than a few minutes during a power outage.

[Jeff000]

Originally Posted by BeanAnimal

Uninterpretable Power Supply

Most commonly used for communications, computer and hospital equipment. The average person does not understand that MOST UPS systems are designed to hold the load over for a few seconds to a few minutes until a standby generator comes online and picks up the load. Very rarely are UPS systems sized to actually run a piece of equipment for more than a few minutes during a power outage.

Yup, residential UPS supplies are more for the power outages that last just a few seconds, or the ones made for computers can be set up so once the UPS hits 10% power remaining then the computer will shut down, this requires a data connection to the UPS though.

Battery power is very expensive compared to a generator.

[BeanAnimal]

When we size commercial UPS systems (I sell them) we only size them for a few minutes of run time. Desktop UPS systems (if well maintained) are typically sized to run a PC for 10-15 minutes so that short outages can be bridged and applications and work can be safely closed/saved if the outage persists. Desktop workstations are not usually backed up by generator power.

[Jeff000]

Originally Posted by BeanAnimal

When we size commercial UPS systems (I sell them) we only size them for a few minutes of run time. Desktop UPS systems (if well maintained) are typically sized to run a PC for 10-15 minutes so that short outages can be bridged and applications and work can be safely closed/saved if the outage persists. Desktop workstations are not usually backed up by generator power.

Depends whats on the EM system. You sell them and I install them... well more the gen sets. I have seen printers plugged into the EM in hospitals, phone chargers, etc, you name it I have seen it. Server rooms are UPS till gen power.

My UPS at home can run my computer for about 5 minutes, it will run my 45 gallon tank without lights for 8 minutes, 3 with the lights on.


Sorry for getting off track.

[ianjirka]

Originally Posted by Jeff000

RE der_wille_zur_macht's linked thread, His power costs are very high where ever he lives or he miss calculated. Also make sure to read that he killed his tank with this set up. He also killed the pump a short time later, increasing costs even more.
And fast temp changes are far worse then slowly getting colder then ideal temps. Also getting too hot is worse then getting to room temp. What happens when the temp probe fails or pump jams (from operating far hotter then designed) and your heater runs constant and heats the tank to the 130f that your hot water is?

That was a very interesting thread, thank you der_*. I'll start out with electrical and get the rest of the house in order before contemplating the hot water idea again.

Originally Posted by Jeff000

For power is your basement finished? If not then by all means run a dedicated circuit, I would probably run a 12/3 and give yourself two 20 amp circuits.... What else do you plan on putting in that room?

Basement is finished, but I have some conduit in place to help me run it outside and around the house (tank location is pretty much opposite corner and down a floor from the electrical panel. x/3 was what I was thinking myself, might as well get two circuits for the pain of doing the run.
Main worry is something like a vaccum cleaner which draws 10A -- and it's a rec room so stuff is bound to end up there, especially as the kids grow older.

Thanks everyone for the thoughts and info...

-Ian

[Jeff000]

Originally Posted by ianjirka

That was a very interesting thread, thank you der_*. I'll start out with electrical and get the rest of the house in order before contemplating the hot water idea again.


Basement is finished, but I have some conduit in place to help me run it outside and around the house (tank location is pretty much opposite corner and down a floor from the electrical panel. x/3 was what I was thinking myself, might as well get two circuits for the pain of doing the run.
Main worry is something like a vaccum cleaner which draws 10A -- and it's a rec room so stuff is bound to end up there, especially as the kids grow older.

Thanks everyone for the thoughts and info...

-Ian

The vacuum only draws about 3 amps (mine only draws 2.1 and its a nice dyson), it will have an inrush of about 10-12 amps, but that is fine, breakers can handle inrush current just fine.

But if you can get good power to your tank that easy then thats what I would do.