plumbing question?

[Ricey06]

I have a friend who thought it was better to add a second 50 gal. electric hot water heater rather than replace the first 50 gal. with a much larger unit. He read on the web. and plumbed it but can't get them to work together? We get many electrical questions here but I see few about plumbing? Hoping somebody can explain the way it should be to work or tell me it can't work? Thanks Jeff

 

[Janicholson]

THey can be plumbed in parallel, but there needs to be a throttling valve (ball valve) used the equalixe the flow from both, and the actual temps need to be adjusted to match. Jim

 

[wore out]

In my area MANY years ago the REA Co-op offered (and still does) an off-peak water heating rate.

They simply suggested connecting a second water heater in series with the existing one for more storage capacity if your WH was in good condition and you did not want to spend the big $$$ for an 80 or 100 gallon new unit.

MANY MANY houses around here were set up like that, including mine, and they've worked just fine for 40-50 years.



To the O. P., what problem is your friend having with his setup?

 

[Ricey06]

I work with his wife, She says that with the temps all set the same, one will heat but the other will not? I do electrical but told her I would ask here and come over and check wiring? I'll let you know what I find.

 

[Steve@Advance]

No need for them both to work together.

Plumb them in series, set the first one a couple degrees higher than the second.

You will be drawing out of the second.

The second will only kick in if the hot water supply from the first one is exceeded.

They don't even have to be the same size, you're just after adding capacity.

If the old one is calciumed up, it needs to be cleaned out. If it has a bad element, it needs to be repaired. If it is leaking, time for a new one. Double teaming them won't solve anything but capacity problems.

 

[Mike(NEOhio)]

She said one would heat, the other would not. What does that mean? One is not heating or they are not heating at the same time. Are they in parallel or series? Not enough information.

 

[showcrop]

The only way that I can think of that they would judge how they are working is to take ahold of the outlet while drawing hot water. If there is any significant difference in friction loss such as elbows, valves, smaller pipe, longer distance, one is always going to out draw the other so the one that is not drawing will not be heating up the pipe for them to feel it. As others said just tell them to plumb then in series.

 

[rrlund]

Before we bought an 80 gallon commercial for the milkhouse, we had a 50 and a 30 in sequence.The 50 fed straight in to the 30, so the 30 was always full of hot water coming in from the 50.

 

[MarkB_MI]

An obvious question is 'why would 50 gallons be insufficient?'

The obvious answer is 'because one element is burned out'.

He needs to replace the burned-out lower element in his original water heater.

 

[moresmoke]

Why would 50 gallons be insufficient?


Depends how many women live in the house!

 

[Brian G. NY]

Depends how many women live in the house!

Hee, Hee, Hee....ain't that the truth. My son had 3 teenage daughters and an electric water heater....between looong showers and washing tons of clothes,it cost him a fortune and they ran out of hot water at times. When he put in his outdoor wood boiler, the girls were very happy.

 

[JMOR]

(quoted from post at 16:47:18 03/19/21) I have a friend who thought it was better to add a second 50 gal. electric hot water heater rather than replace the first 50 gal. with a much larger unit. He read on the web. and plumbed it but can't get them to work together? We get many electrical questions here but I see few about plumbing? Hoping somebody can explain the way it should be to work or tell me it can't work? Thanks Jeff

eries is correct. Parallel is wrong.

 

[Dusty MI]

Plumbed Series,
Wired Parallel

 

[bc]

(quoted from post at 07:10:48 03/20/21) Plumbed Series,
Wired Parallel

Good catch!

 

[1948CaseVAI]

(quoted from post at 19:04:46 03/19/21) An obvious question is 'why would 50 gallons be insufficient?'

The obvious answer is 'because one element is burned out'.

He needs to replace the burned-out lower element in his original water heater.

If you have more than two teenage daughters 50 gallons isn't even a start. Around here there are several folks who have put two 50 gas gas units in series and AFAIK are satisfied. Putting them in series makes them easy to plumb in to both the water and gas systems.

 

[MarkB_MI]

> If you have more than two teenage daughters 50 gallons isn't even a start.

If you have more than two teenage daughters, running out of hot water is the least of your problems.

There are easier and cheaper solutions than plumbing in a second water heater. Start by installing water-saving shower heads. Use cycles on newer washing machines that use less water, and use cold water for all cycles. If that doesn't do it, install a water-tempering valve on the water heater and raise the water heater thermostat.

 

[Dusty MI]

Go to a gas fired Nat./L.P.

 

[showcrop]

Cold water washing is a myth. Nearly all commercial, Industrial, hospital hotel and nursing home laundries wash in 160 degree+ water. All the larger ones get the temp up through steam injection.

 

[504]

THe first one has to be colder so the second one will come on. You are trying to jump start the recovery time of the second heater. After almost twenty years with a tankless heater junk the tank. Only if you have LP or natural gas. I have an electric tankless now,150 amps. that is a lot of juice. I had a LP one,just make sure you have a freeze proof gas fired one. My first one was not.

 

[Janicholson]

Just because the temps are set at the same knob position does not mean they are the same actual temp. Jim

 

[bc]

And if all else fails, just tell everyone what the early bird gets.

 

[da.bees]

You must first realize that from the factory both elements are never on at the same time. FOLLOWING #s were used as example,adj as needed. Starting with tank of cold water,top element come's on and remain's on until water in top half of tank reaches 135F. At 135f,top go's off and bottom come's on and remain's on until (A) bottom half reaches 115f OR top half drops below 135f in which case bottom is turned off and top come's on. TOP STAT IS THE MASTER. Unless you rewire stat in both tanks,a secound 220v supply must be ran to supply new tank. Plumbed in series,water enter's tank #1 at 70F where lower stat is set to 85F and top stat to 100F then continue's to tank #2 where lower stat is set to 115F and top stat to 135F.

 

[MarkB_MI]

> You must first realize that from the factory both elements are never on at the same time. FOLLOWING #s were used as example,adj as needed. Starting with tank of cold water,top element come's on and remain's on until water in top half of tank reaches 135F. At 135f,top go's off and bottom come's on and remain's on until (A) bottom half reaches 115f OR top half drops below 135f in which case bottom is turned off and top come's on. TOP STAT IS THE MASTER. Unless you rewire stat in both tanks,a secound 220v supply must be ran to supply new tank. Plumbed in series,water enter's tank #1 at 70F where lower stat is set to 85F and top stat to 100F then continue's to tank #2 where lower stat is set to 115F and top stat to 135F.

Precisely. Even if the lower element in the second heater isn't burned out, it will never come on until the incoming water is well below the lower thermostat set temperature. I suppose the normal hysteresis of a water heater thermostat is around ten degrees F. The water coming from the first heater will have to be no more than lukewarm before the lower thermostat in the second heater comes on.

Two water heater elements running at the same time will draw about 50 amps. If the house electrical service is marginal, that might well be more than it can handle. Particularly if there are other major electric appliances, such as the range and dryer.

 

[Dusty MI]

I wonder how it would work if someone took two 220 volt circuits to one 50 gal. electric water heater and put each heating element on it's own circuit, not tied together at the top double throw thermostat.

 

[MarkB_MI]

> I wonder how it would work if someone took two 220 volt circuits to one 50 gal. electric water heater and put each heating element on it's own circuit, not tied together at the top double throw thermostat.

It would draw a maximum of 50 amps or more. Which is why water heaters aren't wired that way.

 

[showcrop]

(quoted from post at 04:49:05 03/22/21) > You must first realize that from the factory both elements are never on at the same time. FOLLOWING #s were used as example,adj as needed. Starting with tank of cold water,top element come's on and remain's on until water in top half of tank reaches 135F. At 135f,top go's off and bottom come's on and remain's on until (A) bottom half reaches 115f OR top half drops below 135f in which case bottom is turned off and top come's on. TOP STAT IS THE MASTER. Unless you rewire stat in both tanks,a secound 220v supply must be ran to supply new tank. Plumbed in series,water enter's tank #1 at 70F where lower stat is set to 85F and top stat to 100F then continue's to tank #2 where lower stat is set to 115F and top stat to 135F.

Precisely. Even if the lower element in the second heater isn't burned out, it will never come on until the incoming water is well below the lower thermostat set temperature. I suppose the normal hysteresis of a water heater thermostat is around ten degrees F. The water coming from the first heater will have to be no more than lukewarm before the lower thermostat in the second heater comes on.

Two water heater elements running at the same time will draw about 50 amps. If the house electrical service is marginal, that might well be more than it can handle. Particularly if there are other major electric appliances, such as the range and dryer.

Mark, read the OP again.

 

[Scott 730]

I have 2 off peak heaters in series. I don't know exactly how the wiring is configured, but the lower stat was removed from the 2nd heater, and there are wires connected to that lower element. Must be fed from a stat on the 1st heater. Been this way for 25 years. Installed with local electric co-op oversight by a licensed electrician when I built the house.

 

[Dusty MI]

At one time the electric utility put an electric water heater on a time clock, lower element I think. I also think that you got a reduced rate for doing that.

The time clock looked somewhat like the meter and was mounted beside it.

 

[Ricey06]

Update on the issues. 1st , he tried it in series, then in parallel but not with equal piping. He then researched more and re-piped too equal both tanks. When it still didn't work, he got in touch with me. I went over Saturday and found the upper element was bad. Changed it and all is well. Think I would rather see it in series though. Thanks for all the help. Jeff

 

[MarkB_MI]

> I went over Saturday and found the upper element was bad.

He could have saved himself a lot of aggravation and expense if he'd asked for your help BEFORE he bought a second water heater.