Heating large tanks with your gas hot water heater. Save 40% on energy cost!

[DBR_Reef]

316 SS is used in the hobby all the time. why does the heat exchanger need to be titanium? I only ask because 316 is much cheaper in price.

At the time I posted this article there were titanium heat exchangers for only a little more than 316 stainless. $170 vs $150. I know that titanium is now around $250, but I still might spend the extra for peace of mind. 316 stainless could be used, but I would want to make sure it is actually 316 and that it had been welded properly. Also 316 will eventually corrode, where titanium will last nearly forever. Basically titanium is overkill, which is what I wanted.

 

[rygh]

Old thread, but might be starting this, so thinking...

Just wondering why you would not simply use a loop of PEX in the tank for your heat exchanger.
Q = K*A*(T1-T2)/d
K = thermal conductivity of pex = 0.38
T1-T2 = hot water - tank water = about 25 deg C
d = pex wall thickness = 0.002 m
A = Surface Area. Assume 25 feet of 3/8. That is 7.62m x .031m = 0.23 m2
So Q = 1,000 Watts

That seems like plenty, unless I made a mistake in calculations.

 

[DBR_Reef]

Old thread, but might be starting this, so thinking...

Just wondering why you would not simply use a loop of PEX in the tank for your heat exchanger.
Q = K*A*(T1-T2)/d
K = thermal conductivity of pex = 0.38
T1-T2 = hot water - tank water = about 25 deg C
d = pex wall thickness = 0.002 m
A = Surface Area. Assume 25 feet of 3/8. That is 7.62m x .031m = 0.23 m2
So Q = 1,000 Watts

That seems like plenty, unless I made a mistake in calculations.

Calculations look good to me- there are certainly plenty of people who have used pex successfully. My main reasons were:
It puts household pressure freshwater in your tank. (I know a heat exchanger basically does this too)
More stagnant tap water
There is debate about how reef safe the exterior of some pex tubing is, particularly if exposed to UV light.
I didn't want/ could not fit 25ft of pex in my sump
The price difference is just not that large between a heat exchanger and a length of pex

 

[CoralStop]

Are these motorized ball valves reliable? I see their life expectancy is around 80-100k cycles. Has anyone had them fail on them? Is it worth it to get a brand name like a Taco zone valve for $120?

 

[DBR_Reef]

Are these motorized ball valves reliable? I see their life expectancy is around 80-100k cycles. Has anyone had them fail on them? Is it worth it to get a brand name like a Taco zone valve for $120?

I never had any issues, but I did keep a spare on hand. I think the most likely failure mode would be a capacitor dying, which would probably give you some warning with slow closing before it fully failed.

 

[flagg37]

Old thread, but might be starting this, so thinking...

Just wondering why you would not simply use a loop of PEX in the tank for your heat exchanger.
Q = K*A*(T1-T2)/d
K = thermal conductivity of pex = 0.38
T1-T2 = hot water - tank water = about 25 deg C
d = pex wall thickness = 0.002 m
A = Surface Area. Assume 25 feet of 3/8. That is 7.62m x .031m = 0.23 m2
So Q = 1,000 Watts

That seems like plenty, unless I made a mistake in calculations.

Hey, did you end up doing this?

 

[iReefer12]

@DBR_Reef Has anyone tried doing this without the ball valve? Be nice to not have another part, just seeing if it's necessary

 

[DBR_Reef]

@DBR_Reef Has anyone tried doing this without the ball valve? Be nice to not have another part, just seeing if it's necessary

The problem is that if you run this on your house heater, and someone turns on the hot water it will push hot water through your heat exchanger. You could eliminate with this by using a one way valve, but the motorized ball valve seemed easier/safer.

 

[iReefer12]

That makes sense. Just bought the ball valve.

Can anyone explain how you go from bare wire on the ball valve to a plug?

 

[AlexG]

The problem is that if you run this on your house heater, and someone turns on the hot water it will push hot water through your heat exchanger. You could eliminate with this by using a one way valve, but the motorized ball valve seemed easier/safer.

That does not happen if the radiant heating is plumbed properly. A check valve on the heating loop will also prevent backflow of hot water through the loop. While a check valve can fail its not any different from a ball valve failure. Even if you used hot water or a shower it's unlikely to be a long enough duration to significantly change the water temperature of the aquarium. I have been using radiant heating for over 5 years in two different homes and have not had issues yet with a check valve.

 

[iReefer12]

Looked into this, can I use the DC24V ports on the apex EB832 to provide power/control to the ball valve? NS sell a 24v to bare wire cable, it should work in theory?

That makes sense. Just bought the ball valve.

Can anyone explain how you go from bare wire on the ball valve to a plug?

 

[iReefer12]

Sorry for all the questions @DBR_Reef… I want to make sure I do this right. Should I put the ball valve before the pump and HE or is it after the pump for a reason?

My thought is that if there’s for some reason a leak on the plumbing, I can use the Apex to remotely close the ball valve and being the first in sequence it then prevents said leak? In theory anyway.

 

[iReefer12]

Starting to come together. Just waiting on the ball valve and a few more plumbing pieces. I wanted to keep it all contained on a equipment board, taken a bit of extra work, but I’m hoping it also makes it easier to take apart and clean.

 

[AlexG]

Starting to come together. Just waiting on the ball valve and a few more plumbing pieces. I wanted to keep it all contained on a equipment board, taken a bit of extra work, but I’m hoping it also makes it easier to take apart and clean.

looks good. You can never go wrong with ease of maintenance

 

[iReefer12]

Got the ball valve today, looking at it, decided to research and apparently this valve is not lead free and has 3.5% lead concentration and is not suitable for potable water? Any of you guys have concerns about using this on your house water lines?

 

[iReefer12]

Attached the panel to the wall. Have a plumber coming to plumb this into the boiler (don’t trust myself)

I found an NSF certified, Lead Free brass ball valve, so going to go with that, should arrive in a week or 2 - will update once I receive and have it tested.

 

[iReefer12]

I was concerned about the lead in the original US Solid ball valve. Searched everywhere online to find an alternative and couldn’t, so I decided to try and take a standard (Lead Free) ball valve from Home Depot, remove the handle, dremel the stem, create an adapter for the motor and replace the current ball valve. It works, it seems the motor has to work a little harder, so it may decrease the lifespan, but worth a shot.

A friend of mine 3D printed the adapter, so I’ve asked him to put it on shapeways or another 3D printing site, and will share the link when he does.

 

[Sayyjimm]

Any updates on your build iReefer12?

 

[Enderg60]

Im setting up my new system just recently found those Ti heat exchangers to replaced my 100ft PEX loop I had been using in sump. Makes things SOOOOO much easier.

Also if youre wondering about using 316 stainless while its rated as marine grade will still rust over time and being a heat exchanger, any buildup can mean a clog.

It comes down to, are you really willing to risk a problem on your HUUGE system for that?

Unfortunately for me I dont have a tank water heater so I ended up getting a really small standalone instant gas heater. Im still getting it piped up with the chiller but its coming along.

If doing a setup like mine you will not need the motor operated valve, but you will need an air seperator and an expansion tank since its a closed system that gets heated.

 

[iReefer12]

Any updates on your build iReefer12?

No updates yet. The HE is plumbed together, waiting for a plumber friend to come run pex from the boiler to it, and then it won’t see any action until the new tank goes up in the summer.

I’ll update my post then.