Twin water heaters

[lcarney]

Just purchased older house with 2 water heaters connected in series. what should the settings be? Should the first heater have a higher or lower temp? I would think that the correct way would be to have the first tank at the lower temperature than the second tank. Please advise

[Robert Stephen MortonParticipant]

Homeowner. I dont know from where you eminate, but in Australia & I believe Plumbing is pretty much the same around the world, you have described a twin bank of hot water services.
The hot & cold water should be configured so that equal water pressure comes from both HWServices so that you should have the same draw off from each HWS. Therefore to answer your question both temperatures should be the same.

Regards Bob

[Harold KestenholzParticipant]

To prevent legionella disease, hospitals are having to scald their lines periodically to stop the spread of respiratory disease throughout the building. If the controls are set to 90F in the first tank the water enters and then 120F in the second, the temperatures are just right to grow the legionella.

If however, the temperatures are set to 150F in the first one the water enters, the organisms are scalded to death. Then, the sanitized water can enter the last tank set at 120F, providing only dead organisms to be temporarily stored in the final tank. The second tank would need only to heat when the tank lost heat through the day.

If the first tank is set at 130F and the second at 150F, that would also sanitize the water. In most instances you would need a quality mixing valve to reduce the water temperature to prevent scalding children; they have been damaged by 110F water. The choice is yours.

[Harold KestenholzParticipant]

Unfortunately, Robert is incorrect. Australian water is upside down to that of the North American continent and most civilized countries. Without the World Series as an example, the word series has another meaning in Australia. There it means parallel, so the tanks have to be balanced equally; in the USA of North America, the World Series unbalances plumbing work for the entire season.

[Robert Stephen MortonParticipant]

Harold Kestenholtz. I apologise for standing on my head too for far too long. Your methods of heating are very interesting, but the homeowner never stated from where he/she emanated. Could you be wrong?
You describe a preheating heater & a final heater, I dont know why a far superior professional would waste a heater in that way but I suppose that is where we Australians learn our mistakes.
From our perspective, wouldnt it be more responsible to supply two 75 gal hws & get 150 gallons of hot water than to supply two 75 gallon hws to get 75 gal of hot water.
We have some plumbers in Australia who do not know how to ballance a bank of Hws.
Regards Bob

[SylvanLMPParticipant]

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In reply to message posted by Homeowner:
Just purchased older house with 2 water heaters connected in series. what should the settings be? Should the first heater have a higher or lower temp? I would think that the correct way would be to have the first tank at the lower temperature than the second tank. Please advise

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You heard from the rest NOW listen to the BEST (ME)

Setting in “series” the 1st heater would PREHEAT the water for the 2nd and final heating.

The theory behind this hook up is not to KILL both heaters as neither one will have thermo shock of very cold water entering a hot tank plus much less condensation.

Figuring cold water supply is 40 degree F. and being heated to 90 degrees then the 90 degree water is then heated to 125 in theory neither tank is going to labor very hard making hot water. This saves lots of therms and latient ASK Harold LOL

Now for a better way to hook up heaters In my professional opinion.

Have a professional hook up these tanks in parallel with everything being equal.

The way I hook these things up when I need a lot of volume FAST like peak demands for an apartment building or whirl pool installation is as follows

I install all piping equal lengths and have the cold water lines fed through a 27″ heat sink loop as there can be no cold water stratification more then 27″ down these type of installations ( I DONT NOT USE DANGEROUS CHECK VALVES)

I place a temperature gauge on the hot water discharge of each heather and use a globe (balancing) valve to fine tune the temperature so both discharge are the exact same temperature to a common header

Now Here is what we professionals do that separate us from the tract house mentality.

WE install a Holby Mixing Valve BUT just before we temper this water we take the 140 -160 degree HOT water and send a dedicated line to the following fixtures 1 line goes directly to the residential dishwasher to kill all the bacteria.

NOTE commercial dishwashers requires 180-200 degrees in lieu of chemicals for disinfection.

We take the hot water 140+ and use it in the DOMESTIC washing machine (clothes washer) again to make sure bacteria is going to be snuffed out.

Now we temper the remainder of the hot water to around 125 degree to kill most of the regular house hold bacteria that can be found on lower temperature systems like that crap under slab heating which can be an incubator for all kinds of great diseases.

It is alsp advisable to instal a temperature guage on the mixed ( tempered) temperature piping header right after the Holby.

Now because people today are no longer responsible for being stupid we have to protect them from themselves by way of temperature and pressure balancing valves located at the basin, shower, bath tub and any other place a moron can get burnt.

We also use a “Just right” from Nibco to have return circulation without the need for a circulator.

There are lots of games the real professional can do with hot water tanks in series or parallel or even a “bridge circuit” using both of these combined tricks of the trade a “real plumber” can do.

Hey Have a great One now you have options…

Just kidding Mates you blokes are great

[bungieParticipant]

Question,

If domestic dishwashers are connected to the cold as directed by the manufacturer. And people use cold water washing powder in much larger quantities than hot water powder, why create a dual system in a domestic situation when Legionella is killed in the hot water system??

Homeowner, both tanks should be at greater than 66c to ensure no growth of legionella. (bet I’m a degree out, and get bitten for it
)

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DISCLAIMER

All advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or will be taken. And yes, I am a licensed Plumber and Drainer with my own business in Brisbane Australia

[SylvanLMPParticipant]

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In reply to message posted by bungie:
Question,

If domestic dishwashers are connected to the cold as directed by the manufacturer. And people use cold water washing powder in much larger quantities than hot water powder, why create a dual system in a domestic situation when Legionella is killed in the hot water system??

Homeowner, both tanks should be at greater than 66c to ensure no growth of legionella. (bet I’m a degree out, and get bitten for it
)

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I have never seen a dish washer hoked up to a cold water line EVER, BUT I have seen a temperature booster (like a small boiler) to raise the temperature to the dish washer to germ killing temperature

[Harold KestenholzParticipant]

You can see from the disclaimer above, that Aussies can recommend scalding temperatures like 66C and get away with it. North American plumbers have to tell customers to use mixing valves to bring the fixture temperature down to civilized temperatures because the US government makes standards in Fahrenheit. 151F is too hot to run onto people by many state code officials (and even common sense.)

[SylvanLMPParticipant]

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In reply to message posted by Harold Kestenholz:
You can see from the disclaimer above, that Aussies can recommend scalding temperatures like 66C and get away with it. North American plumbers have to tell customers to use mixing valves to bring the fixture temperature down to civilized temperatures because the US government makes standards in Fahrenheit. 151F is too hot to run onto people by many state code officials (and even common sense.)

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Harold dear Harold my man, Check this out.
According to health department rules WHICH the NYC Master license test is given we professionals know the folowing HEALTH

Domestic water to a residencial dishwasher 140 BUT this is no longer possible thanks to people not taking personal responsibility.

People are to stupid to know hot water burns

Water to a commercial dishwasher shall be 140 -160 degrees F for washing and 180 for sterilization IN LIEU of chemicals.

The colder the water the more chance of someone getting seriously sick BUT Lawyers are the ones writing the new codes it would appear

[Robert Stephen MortonParticipant]

Harrold. In Australia it is a requirement of law to have the water contained in a HWS at or above 60C, it is also a requirement of law in any new dwelling to deliver any water to any water used for personal at no more than 50c or for institutions for the aged, infirmed or children 45c.
You see our Government cares for the populace & places Plumbing, , Drainage & Gasfitting at the higher end of the scale for safety. Plumbers Drainers & gasfitters are licensed & not much work in the industry is unregulated.
Harrold you should come to Australia & see how we run water upside down.
Regards Bob

[Harold KestenholzParticipant]

Ah,then what is your favorite mixing valve to assure that these conditons are met? I gather there is not much other choice for making 60C water into 45C water there either. No one seems to check if the safe conditions are met here until a scald.

[SylvanLMPParticipant]

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In reply to message posted by Harold Kestenholz:
Ah,then what is your favorite mixing valve to assure that these conditons are met? I gather there is not much other choice for making 60C water into 45C water there either. No one seems to check if the safe conditions are met here until a scald.

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There is ONLY one Mixing valve the one made in NYC HOLBY of course

are there any others? I DONT THINK SO

Quality I am talking about Anything less then why bother?

[bungieParticipant]

Yo,

All domestic dishwasers, even imports, recommend a cold water connection. They ALL heat their own water, at a more cost effective rate than taking it from the hot water supply. Plus the added benifit of a cold water rinse first.

Temperature Control Products

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DISCLAIMER

All advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or will be taken. And yes, I am a licensed Plumber and Drainer with my own business in Brisbane Australia

[Robert Stephen MortonParticipant]

Harrold. RMC – Reliance Manufacturing corp – tempering valves, alternatively Horne Thermostastic Mixing Valves.

[bungieParticipant]

h <

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thats the letter missing from my post before.

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