2 hot water heaters?

tim smith_2

I like doing parralel piping. hot and cold come down to near top of tanks in the middle of tanks. then equall distance piping for hot and cold on both tanks from cold and hot mains. This provides for balance flow through both tanks and keeps cycling pretty much even between the two. It also allows for when one fails you can shut of that one and still run on other tank. Isolation valves on hot & cold to each tank to do this.

Leon in NJ

I want to connect 2 hot water heaters for more capacity. What is the proper way to pipe it out? I assume the cold goes in the first heater with the hot outlet connected to the cold of the 2nd heater. Then the 2nd's hot outlet goes out to the system. Am I right? Also does it matter where the heater vent gets connected to the chimmny in relation the the 7in boiler vent? Should it go above ,below,or level with? Someone told me that if its too close the oil fired boiler exhast will pressurize the chimmny and back down the water heater vent in addition to going up the chimmny and interfere with the flow? Did anyone ever hear this before or test it out? Thanks guys Leon in NJ

bigugh_4

The first W/H

to get cold water should be the last heater to give it to the system (pipe wise, reverse parallel piping) Venting can be trickie. the chimney must be large enough in the first place. the vents of the W/H's should be connected in above the largest input. Your local fire code may prevent you from mixing power vents and gravity vents in the same chinmey. Check with the authorities.

JackFre

Assuming...

Taht these are gas fired atmospheric water heaters the correct method according to nfpa 31 is to connect the gas water heaters to the main flue 12" above the 7" connection from the boiler. Ifyou are unable to get that height you MAY (with the authority having jurisdictions approval) tie the vent connectors together. The gas vent should tie in close to the vertical main vent and make the connection using a wye fitting not a tee. This will make it more likely that the flue gases are heading in the right direction. If you have draft problems at that point you may have to split the system up, reline the chimney using Stainless steel or look for equipment alternatives.

Uni R

2 HWHs

Leon,

If your loads are far apart like at opposite ends of a ranch styled house you may want to consider locating one at each end and separate the heated water supply so that each end of the house is serviced by one of the water heaters.

Upsides:
Doing laundry and dishes won't cause cold showers and your point of usages will be much closer to the heating source saving you both water and energy. You also have the added benefit of keeping them at different temps if you want.

Downsides:
First might be the need to add a long branch to your gas line. Secondly, you'd need a separate flu there. The hot water piping shouldn't be much harder either way, although it'd be highly recommended to make sure the supplies for both water heaters are branched off the main supply before any fixtures except for maybe an outside hose bib. Otherwise the hot/cold balance is gone with one flush.

Rookie

2 Water Heaters ?

Depends on the size and BTU load, Bradford White has a pdf you can download.Bradford White has the specs on there web site also.

http://rightspec.bradfordwhite.com/Piping/Two Heaters, Top Connections, Return Circ.pdf

Leon in NJ

2 water heaters?

Hey "Bigugh" could you explain a little more on how to connect up the two gas fired natural draft water heaters. I'm not familiar with "reverse parallel piping" as you mentioned.

bob young

multiple water heater piping

I am a bradford-white man all the way but a.o. smith has great piping diagrams on this arrangment and i have had success with them.

kevin coppinger_4

i would ...

concurr..If you pipe in series the first heater will end up doing all the work. I see no advantage to piping in series.kpc

bigugh_4

parallel reverse connection

Herb

series w/h

The advantage of the series hook-up is to maximize the available gallons before the water goes cold. By introducing cold water to only one of the tanks, you get the full capacity of the other plus 75% of the first heater. The other benefit occurs where the water attacks the heaters. As was pointed out, the first w/h does most of the work and this can keep replacement cost lower if liming is restricted to one heater.

Leon in NJ

Thank You herb! That sounds like the answer I was looking for. The first heater almost acts like a "filter" for the second. Piping in series it is then. Thank you again and all the rest for making my brain bigger. Leon in NJ

Rookie

re: Treat The water first

If liming is a problem the first step would be correct the incoming water, if first water heater is to be sacrifical lamd then it will not only fail but be inefficient. Treat the incoming water and pipe them in parallel.

Bob Gagnon plumbing and heating

tinman is right

i pipe mine with equal lengths of pipe like Tinman said and it draws off both tanks equally, both water heaters will kick on when only a small amount of water is used, giving you more hot water- plus isolation. bob

Mike T., Swampeast MO

Series/Parallel

I seem in the definite minority preferring them in series. I've fixed two "not enough hot water" complaints when parallel tanks were used by piping them in series.

Piping on one pair was hopeless, the other looked like it should have been drawing equally from both tanks but didn't seem to be.

If you set the first tank lower in temperature than the second (to act like a heated tempering tank) you have the ability for extremely protracted hot water use at moderate draw rates. Fire time among the two will be more consistent than if they are set at the same temperature.

If you pipe as illustrated below you can use either or both tanks. It takes six valves--two more than required to isolate parallel tanks.