Series Or Parallel? - Hot Water Heaters - Plumbing - DIY Home Improvement | DIYChatroom
Advertisement


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Plumbing

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread
Display Modes
Old 06-09-2016, 10:52 PM   #1
Member
 
Join Date: Oct 2015
Posts: 207
Rewards Points: 388
Default

Series or parallel? - hot water heaters


my 1990 house was built with 2 water heaters which each feed a zone. Since we have recirculating loops on each zone, I refer to them as "loops," of which we have 2. In other words, they are plumbed in parallel. When we bought the house, one hot water heater had kicked the bucket, and that heater was removed from the system. The 2.5 yrs we've lived in the house, we've never run out of hot water off the single 50 gal heater, but it was re-plumbed to run at max and then a mixing valve cooled it off a bit before it tee'd off into each zone.

When my wife called my yesterday to let me know the last water heater - from 1993! - had given up the ghost, I decided to replace both. I got them both plumbed up and going how they were originally installed, in parallel. I know in other homes that we've owned which were newer, they installed the heaters in series, one fed into the other. Obviously, the benefit of in series is the combined capacity is available to any where in home, versus it being dependent on where you are using water. But, there is a low probability we would run a single heater (50 gal) out of water is there any other reason to hook this up in series? OR should I just let it ride as is? Thanks!
1acre is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 06-09-2016, 11:28 PM   #2
JOATMON
 
ddawg16's Avatar
 
Join Date: Aug 2011
Location: S. California
Posts: 14,615
Rewards Points: 18,220
Blog Entries: 2
Default

Re: Series or parallel? - hot water heaters


If it was me, I'd plumb it so it could operate either way.

Then figure out which method gives you better performance
__________________
Even if you are on the right track, you will still get run over if you just sit there.

My 2-Story Addition Build in Progress Link ... My Garage Build Link and My Jeep Build Link
ddawg16 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 06-10-2016, 05:34 AM   #3
A "Handy Husband"
 
rjniles's Avatar
 
Join Date: Feb 2007
Location: South Carolina Low Country
Posts: 11,104
Rewards Points: 812
Default

Re: Series or parallel? - hot water heaters


I would plumb the in series. You could keep the first 1 turned off and use it as a tempering tank. Turn it on if you expect high demand.

OTOH, if you are not running out of water with a single tank, why install 2?
__________________
My electrical answers are based on 2017 NEC, you may have local amendments.

Location: Coastal South Carolina
rjniles is online now   Reply With Quote
Sponsored Links
Advertisement
 
Old 06-10-2016, 07:19 AM   #4
Member
 
listo's Avatar
 
Join Date: Nov 2008
Posts: 227
Rewards Points: 107
Default

Re: Series or parallel? - hot water heaters


If it's in parallel I'd be concerned that one is getting used more than the other one. If water flows to the system easier or flows into it easier I'd think it would be used more. Same is true for series I suppose the second one wouldn't have to work as hard as it would always be getting pre heated water.

Sent from my LG-H812 using Tapatalk
listo is offline   Reply With Quote
Old 06-10-2016, 08:59 AM   #5
Member
 
Join Date: Oct 2015
Posts: 207
Rewards Points: 388
Default

Re: Series or parallel? - hot water heaters


I don't know about plumbing it for either direction...seems like a lot of work, and they don't give brass ball valves away.

I think installing 2 is better overall. 1st, the system was designed that way. and 2nd, to meet the demands we had to work the other water heater at full capacity and then mix in some cold water. I'm also certain with 3 young girls (4, 2 and 1 week), hot water needs will increase with time.

It amazes me how well the house was built for 1990. The "zones" are pretty well thought out with the master and laundry on one zone and everything else on the other. I know this because in 1990 (again, amazing) they installed recirc loops and since they pulled off the bottom of the tanks, only one loop was getting instant hot water.

So, I'm not really hearing anything that is game changing....as I stated in the OP, you have an obvious bigger capacity for the entire house. but, input cold water temp is a given and we decide where we want the output temp, so we'll use the same BTU's regardless if we have 1 tank, 2 tanks in series and 2 tanks in parallel. So, there doesn't seem to be any other benefit outside if you want tanks dedicated to a zone or if you want everything to pull from a larger overall capacity, correct? Interested in any other insights....
1acre is offline   Reply With Quote
Old 06-10-2016, 04:57 PM   #6
Member
 
Join Date: Mar 2013
Location: Ohio
Posts: 5,660
Rewards Points: 1,866
Default

Re: Series or parallel? - hot water heaters


Good output is a parallel install. A series install makes one tank a holder of water and the other tank works it's ass off heating water.

The best install for 2 tanks and best gallons out is a first one in last one out install that is a self balancing system that allows both tanks to work seamlessly. Notice the cold water feeds the right tank first the left tank last. The Hot water takes water from the left tank first the right tank last. This is a self balancing system. No need to cut pipes to identical lengths. By the way idiot that made picture labeled it wrong.

Each tank should have a ball valve on the cold to each tank And you need an hot water expansion control device mounted on the tanks.


Last edited by Ghostmaker; 06-10-2016 at 05:14 PM.
Ghostmaker is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
water heater drip kdange1 Plumbing 6 10-29-2014 05:26 PM
Water heater solutions to get hot water in timely manner daluu Plumbing 22 05-07-2012 08:44 PM
Twin Water Heaters Installed BigD9 Plumbing 6 04-08-2012 01:06 PM
Efficient water Heaters zootjeff Plumbing 5 05-27-2011 01:50 PM
Tankless Water Heaters Recalled for Repair Due to Carbon Monoxide shimp Plumbing 1 01-22-2008 06:52 PM




Top of Page | View New Posts