Thermosyphon system

[Oconnellshawn88]

So wondering to be sure on thermospyoning and gravity fed system. Ive got 2 water heaters that are different size. My plan was to just run loop back from the upstairs shower line being the highest and furthest away fixture. But i also have a toilet and vanity and wash machines on basement level. Since those lines will run below height of water do they require a check valve or back flow preventer and wouldnt those lines just get cold if u did put one. Still torn on using these in tandom rather than series only because of potential of not same amount of piping or btu so it ends up not working properly. But series would mean if one goes then im pretty much screwed and makes the recirculation system a lot more complicated. And dont really want a recirculation pump mainly cause of the extra use of the hot water heater and electricity and noise and seems more overall cost efficient and appliance safe. But now am not sure cause the water lines to the basement fixtures will all be in floor trusses. Which is above water heater already. So when piping back down to the basement bathroom does that screw up the entire loop?

 

[Fitter30]

The only way to pipe 2 heaters different sizes or even models. Reverse return thats where its first in last out. When piping in series the first heater traps most of the mineral deposits.
kcwaterheater.com/water-heater-piping/

 

[Sponsor]

 

[Jeff H Young]

The only way to pipe 2 heaters different sizes or even models. Reverse return thats where its first in last out. When piping in series the first heater traps most of the mineral deposits.
kcwaterheater.com/water-heater-piping/

I see KC water heaters on you tube decent channel he has

 

[Oconnellshawn88]

The only way to pipe 2 heaters different sizes or even models. Reverse return thats where its first in last out. When piping in series the first heater traps most of the mineral deposits.
kcwaterheater.com/water-heater-piping/

Im not running them in series cause if one heater goes to hell then have no hot water. Ive been looking at the temperature control valves where it mixes the cold and you crank up ur heater to like 140. If i got them to be coming out at the same temp and the same amount of pipe from the bottom of the tanks and i tee’d my two hot lines together before the control valve. What issues could i have? Then for the return line i read something about how it should go to both the tank and the cold input of the valve but that didnt make any sense to me.

 

[Fitter30]

Im not running them in series cause if one heater goes to hell then have no hot water. Ive been looking at the temperature control valves where it mixes the cold and you crank up ur heater to like 140. If i got them to be coming out at the same temp and the same amount of pipe from the bottom of the tanks and i tee’d my two hot lines together before the control valve. What issues could i have? Then for the return line i read something about how it should go to both the tank and the cold input of the valve but that didnt make any sense to me.

Reverve return isn't in series. I4 valves just like the picture a heater fails it can be valved off. Pipe two heaters any other way the heater that has less pressure drop will do most of the work.Valves are at the heater piping on the diagram.

 

[Oconnellshawn88]

Reverve return isn't in series. I4 valves just like the picture a heater fails it can be valved off. Pipe two heaters any other way the heater that has less pressure drop will do most of the work.Valves are at the heater piping on the diagram.

Reverve return isn't in series. I4 valves just like the picture a heater fails it can be valved off. Pipe two heaters any other way the heater that has less pressure drop will do most of the work.Valves are at the heater piping on the diagram.

Saw that right after sent message. So will thermosyphoning still work without use of a pump as long as i loop back from furthest highest fixture which would be upstairs shower. And which water heater should the water enter first to maximize length and efficiency

 

[John Gayewski]

You just need one check valve where the return line comes back to the heater(s). Imagine the path of the hot water floating to the top of the system and then cooling and falling back down. It will only be able to fall down past the check valve amd back into the heater as your fixtures in the basement give it no return path.

 

[John Gayewski]

You just need one check valve where the return line comes back to the heater(s). Imagine the path of the hot water floating to the top of the system and then cooling and falling back down. It will only be able to fall down past the check valve and back into the heater as your fixtures in the basement give it no return path.

 

[Oconnellshawn88]

You just need one check valve where the return line comes back to the heater(s). Imagine the path of the hot water floating to the top of the system and then cooling and falling back down. It will only be able to fall down past the check valve and back into the heater as your fixtures in the basement give it no return path.

So why is it that i cant run in parallel with different size heaters? As long as i use same amount of pipe which would make my cold water tee slightly closer to the shorter tank which is the same difference in height. And if i verify the temperature is coming out the same by simply closing one at a time and using thermometer i dont understand why there would be any issue

 

[John Gayewski]

So why is it that i cant run in parallel with different size heaters? As long as i use same amount of pipe which would make my cold water tee slightly closer to the shorter tank which is the same difference in height. And if i verify the temperature is coming out the same by simply closing one at a time and using thermometer i dont understand why there would be any issue

I'm not sure what you're saying. You can run parallel water heaters. You just run one line back to one of the heaters after the last fixture.

 

[Oconnellshawn88]

I'm not sure what you're saying. You can run parallel water heaters. You just run one line back to one of the heaters after the last fixture.

Was just told in this thread that only way to have recirculating system with different size water heaters is reverse return system which isnt parallel cause doesnt branch back into one pipe after the water heaters. Id be fine with the system in the picture im attaching if can do it without the pump but i dont see how it would be balanced and the first tank not end up doing more of the work. The other question i keep running into seeing is have been told the recirculating line has to go into the discharge of the first tank. I just want the two heaters to work equally and efficiently and prolong life of both as much as possible and dont want to deal with scheduling or a pump running. Whatever way is actually the best is what my concern is.

 

[Oconnellshawn88]

Was just told in this thread that only way to have recirculating system with different size water heaters is reverse return system which isnt parallel cause doesnt branch back into one pipe after the water heaters. Id be fine with the system in the picture im attaching if can do it without the pump but i dont see how it would be balanced and the first tank not end up doing more of the work. The other question i keep running into seeing is have been told the recirculating line has to go into the discharge of the first tank. I just want the two heaters to work equally and efficiently and prolong life of both as much as possible and dont want to deal with scheduling or a pump running. Whatever way is actually the best is what my concern is.

Then i never can get anyone to respond or say why.

 

[Reach4]

Then i never can get anyone to respond or say why.

You get the responses, but you don't believe, I think.

 

[Oconnellshawn88]

You get the responses, but you don't believe, I think.

When. Each response has contradicted the previous one. And idk how else im supposed to ask and cant Find a decent template to draw out anything anywhere. It might be simple to all of u but im pulling my hair out and frustrated as hell over this. Most of it makes sense to me but at the same time a lot of the ways that seem the norm confuse the hell out of me. Like the entire idea of the recirculatin pump sounds awful to me. Why force feed more water than necessary into the water heater? it might not run as long but it will be running a lot more or i would assume anyway. And as if there arent enough things to remember and to schedule like thermostats and furnace and water filters everywhere, and im not saying that i have a problem doing any of those things but i dont like reminding people who have paid me to do a job what they need to do or how they need to live or take care of the work i did do. If that makea sense to anyone maybe im in the minority or maybe im wrong altogether about everythin. There are so many new products and updated parts and methods i wouldnt doubt it for a second. Im trying to simply make people enjoy their home for as long as they can and as affordable and efficiently as possible. And right now im trying to accomplish something i have never done or seen before and i dont know what route to go… and ive asked numerous people numerous times for advice and searched hours and days for answers and its a complete crapshoot on the response with so many conflicting opinions from what someone else says. And that worries the hell out of me. So i dont know how to start my initial hot run, idk how to merge the two heaters with any confidence before or after water is heated. And im not sure where to tie in the return line when it gets back to the tanks. 50% say on the discharge of a heater but that would make system way off balance and others say after the softner before exp. Tank…. is a balancing tee gonna be necessary, can i just test the temperatures out of fixtures by closing off one of the heaters at a time and dial it in until get same reading. So maybe u do see my answer to all of these but i personally am seeing conflicting opinions with no definitive resolution and so i am not confident at all that this system can work but science says it should i just dont want to get anything wrong the first time and end up redoing it…

 

[Jeff H Young]

draw up how you pipe the system and let us know how it works personally Ive never built a circ system w out a pump and Id like to hear how it works for you Ive always used a pump I would install one with a pump rather than go cheap but if a customer wanted me to give it a try take his chances Id pipe it his way

 

[Fitter30]

So why is it that i cant run in parallel with different size heaters? As long as i use same amount of pipe which would make my cold water tee slightly closer to the shorter tank which is the same difference in height. And if i verify the temperature is coming out the same by simply closing one at a time and using thermometer i dont understand why there would be any issue

The heaters themselves have different pressure drops.

 

[Reach4]

People will not contradict these:
1. In series is simpler, because you have no problem with balancing.
2. Parallel can be done, but needs special care to balance.

http://waterheatertimer.org/images/Two-water-heaters.html has some good info, including talking about recirculation.
There is more than one right way.