Dedicated Tankless Water Heater

[Deep dive coral]

I'm adding an additional zone to my Navion system. It will be a 3rd zone. I just need to figure out how to get my apex temp monitoring to tank to the boiler circuit. To activate the pump in the sump is easy. Any ideas for the 3rd zone circulator pump?

 

[KenO]

I'm adding an additional zone to my Navion system. It will be a 3rd zone. I just need to figure out how to get my apex temp monitoring to tank to the boiler circuit. To activate the pump in the sump is easy. Any ideas for the 3rd zone circulator pump?

I would assume the zones on a standard system would be controlled via a thermostat. When the thermostat closes the relay the pump for that zone turns on. If the pump for the 3rd zone has a standard plug on it, you would plug it into an outlet say on an eb-832. Then energize that outlet when you need heat.

 

[Deep dive coral]

I would assume the zones on a standard system would be controlled via a thermostat. When the thermostat closes the relay the pump for that zone turns on. If the pump for the 3rd zone has a standard plug on it, you would plug it into an outlet say on an eb-832. Then energize that outlet when you need heat.

Most heat circulator pumps are hard wired. I could add a plug. To the circulator pump. Plumb it in and add it to a 832. But there still needs to be a trigger to the relay for the heater. I assume

 

[Dr. Dendrostein]

Greetings! I've read numerous threads about implementing a hot water tank to heat a system. I've been toying with the idea of a dedicated tankless, one rated for high cycles like a Tagachi. As I understand it, a tankless is triggered by water flow such as the turning on of a faucet. In regard to an aquarium application, I've been pondering ideas to create that flow. I presume an electronic solenoid could be used or perhaps a recirculation pump. Obviously both of those present possible points of failure. So I'm not sure how to create a backup redundancy should one of those fail other than two of each but that could present other problems. I guess just regular heaters in the sump could be backup too. Any thoughts on the matter would be appreciated. Thanks!

Hate to say this but unless your at least a millionaire, or can build a small house or build an air plane. Keep it simple . I hope I didn't offend you. Comrade

 

[Dr. Dendrostein]

I run my heating system with a standard hot water tank but the principals for controlling should remain the same even with a tank less water heater as long as it is activated by water flow. I utilize a RANCO temp controller to turn the re-circulation pump on and off for my heating loop. That controller is plugged into my APEX and was programmed to shut power off to the RANCO and re-circulation pump if an over-temp event occurs. Having dual temperature probes for this type of setup is important in case a temp probe fails. For a re-circulation pump I would not use a magdrive pump as they are not intended to be used with hot water supplies. I would go with a bronze or stainless steel re-circulation pump as the hot water circulating to the tank less heater should not be aquarium water. If you are making a closed loop of water with the tank less heater you must account for expansion and contraction in the lines and they make expansion tanks that can be plumbed into the loop which will allow water to expand and contract without putting additional pressure on the lines that might cause a leak.

Any pictures, comrade

 

[Dr. Dendrostein]

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

On Ebay, Amazon, etc.... there's tiny tankless, for camping, ignition runs on D batteries, but they're propane. Cost, is $90 free shipping.

 

[KenO]

Most heat circulator pumps are hard wired. I could add a plug. To the circulator pump. Plumb it in and add it to a 832. But there still needs to be a trigger to the relay for the heater. I assume

Not quite sure what you mean by the trigger to the relay. Does your tankless heater require a signal to tell it to turn on? As per my plumber, he indicated that once the water started flowing through the Rinnai, the unit would turn on and start heating that loop. I know some circulation pumps have a thermostat connection on them to tell them to turn on.

 

[pdxmonkeyboy]

I have experience using pumps to trigger tankless hot water heaters. I will say that you generally need a strong pump because if you do not have high pressure then it will not trigger the tankless heater to come on. Then the pump just runs and runs and runs. Granted, we were using the cheapest tankless heaters we could find. ebay stuff that was like $200. You will defiantly need an expansion tank as mentioned above.

My friend tried to use a Taco pump and it wouldn't trigger the heater but others have used the taco pumps with good effect.

 

[pdxmonkeyboy]

Not quite sure what you mean by the trigger to the relay. Does your tankless heater require a signal to tell it to turn on? As per my plumber, he indicated that once the water started flowing through the Rinnai, the unit would turn on and start heating that loop. I know some circulation pumps have a thermostat connection on them to tell them to turn on.

Water flows and there is a little diagram that pushes a lever and the heater starts. There is a little thremo coupler that has to get hot after a time period or the gas shuts off as the tank knows it isn't lit.

 

[KenO]

I have experience using pumps to trigger tankless hot water heaters. I will say that you generally need a strong pump because if you do not have high pressure then it will not trigger the tankless heater to come on. Then the pump just runs and runs and runs. Granted, we were using the cheapest tankless heaters we could find. ebay stuff that was like $200. You will defiantly need an expansion tank as mentioned above.

My friend tried to use a Taco pump and it wouldn't trigger the heater but others have used the taco pumps with good effect.

Again, I'm no expert, I'm relaying information from my plumber. He indicated that my Rinnai (I did confirm this in the manual) requires a min of .28 gallons/per min to trigger the heater to turn on. I was also looking at a standalone tankless from Takagi and that one required .78 gallons/min to turn on. So I can see that you might need a higher flow to get the unit to turn on. First place to look is at the specs for the unit.

 

[pdxmonkeyboy]

Right, i just now that we ended up using a diaphram pump to get suitable pressure. It could well be a function of tick poor engineering.

 

[AlexG]

Any pictures, comrade

Here is a diagram of my setup. I have also made a few videos about my heating system on my YouTube Channel. My Heating system is connected to my house water supply. As a fair warning this type of setup can carry some risks for legionella bacteria which is why its best to have a separate heating loop system.

 

[Dr. Dendrostein]

Here is a diagram of my setup. I have also made a few videos about my heating system on my YouTube Channel. My Heating system is connected to my house water supply. As a fair warning this type of setup can carry some risks for legionella bacteria which is why its best to have a separate heating loop system.

Yes, I think I've seen your Youtube video you tide in to existing water heater.

 

[Dr. Dendrostein]

Here is a diagram of my setup. I have also made a few videos about my heating system on my YouTube Channel. My Heating system is connected to my house water supply. As a fair warning this type of setup can carry some risks for legionella bacteria which is why its best to have a separate heating loop system.

so, curious, the heat exchanger is it SS or titanium? Please tell

 

[AlexG]

so, curious, the heat exchanger is it SS or titanium? Please tell

The heat exchanger is ~30-50' of pex piping. No need for SS or titanium heat exchanger. The heat exchange does not need to be super efficient as you don't want to heat your tank up too fast. The heater only runs a couple times a day for ~2 hours per heating cycle. With about 1700 gallons of water in the system I think its pretty efficient and it holds the temp within one degree during the winter when heating is needed.

 

[KenO]

The heat exchanger is ~30-50' of pex piping. No need for SS or titanium heat exchanger. The heat exchange does not need to be super efficient as you don't want to heat your tank up too fast. The heater only runs a couple times a day for ~2 hours per heating cycle. With about 1700 gallons of water in the system I think its pretty efficient and it holds the temp within one degree during the winter when heating is needed.

What was the change to your NG bill?

 

[pdxmonkeyboy]

So your tankless heater runs for about an hour each time it kicks on? From experience I will say that this long of run time will REALLY reak havoc on the small, D battery powered tankless units. I was thinking that 20 minutes or so would suffice for heating time. I am looking at around 800 gallons and would also do the PEX heating coil.

 

[AlexG]

What was the change to your NG bill?

Nothing noticeable. Just a few extra dollars in the winter as that is the only time it runs. I honestly don't look at utility bills often as my Wife takes care of those for the household. When they are not high I never hear about them. Normally in the summer when the AC is running I hear about those bills all the time especially when the power company sends notices stating we use 150% more power than our neighbors every month.

 

[pdxmonkeyboy]

My power bill was $1300/month. But I was growing "stuff" at the time.

 

[KenO]

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

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.