Water Heater Piping

Mac_R

I am thinking about adding another 40 gallon water heater to my system.  What I am trying to do is increase my GPM out put so my wife who I love dearly can do a load of laundry wile I am in the shower.  Right now she starts the wash and I loose hot water in the shower.  Should I pipe them in series or in parallel?   I am guessing Parallel but I am not sure.  Thank you for your help.

icesailor

Water Heater Piping:

What kind of water heater do you already have installed and how do you heat the water?

Charlie from wmass

Mac the issue may not be the tank

It may be in the layout of the piping in the home. What diameters of piping do you have? Do you have a pressure balance shower valve? Has it been checked to see if it is functioning if you do have one?

Mac_R

Water heater piping

I have 3/4" pex as a main line then it branches off to 1/2" to the fixtures.  At least that is what I can see in the utility room.  I do not believe I have a pressure balanced valve at the shower.  the Last owner put this bathroom in and really cheeped out on a lot of the parts.  I have had to replace almost everything.  It is an electric water heater.  I am going to run a new power line from the box to the new heater.  I am just not to sure on the way to increase my GPM to the house. 

icesailor

Water Heater Piping:

If you are running out of hot water,and you decide to add another water heater, you will be doubling the recovery rate of the DHW system because you will have two elements running as needed where with one heater, only one element ever runs at a time.

If you pipe the two together, I always pipe them in parallel. I make the connections exactly equally spaced between the two tanks to keep them in balance. If you pipe them is series, the cold water comes in the first tank and you draw off the second tank. The first tank comes on after a while but the second tank doesn't come on until the first tank is depleted. When piped as a balanced parallel piping, both elements should come on at about the same time. I've done it for more years than I can remember and never had a problem. It does not work as well with a tank of differing sizes.

Before I went to the level you plan though, I would install a Honeywell AMX101 water heater mixing valve. Run the tank at 140 degrees and let the tempering valve mix it to 120 degrees. Raising the water temperature is equal to having a larger tank. The valve I use is a direct connect to the top of a water heater and comes with a check in the cold water port. I've been using these valves since they came on the market.

Charlie from wmass

I was just talking to a local inspector

in the hill towns of Mass and he claims 3/4" is the minimum size for proper flow to a shower valve if you are using PEX. He got this from the rated flow from the manufacturer we were talking about. (viega) This would mean a 1" main line for the homes hot and cold water lines. He was the inspector, I just smiled and nodded. I have not looked up the flow charts myself yet.

MNPLUMBER

The inspector

Yes even though pex is slightly smaller in size compared to copper you get more flow at a higher rate vs copper. More than makes up the difference. Last time I checked pex is still sized the same as copper and I've never had a complaint regarding volume.

Mark Eatherton

It's not the pipe....

it's the fittings that cause significant pressure drop on flow. Look into a fitting with PEX and see what kind of choke you are building. If it is compensated for (as in one pipe larger than you'd normally use to compensate for extra pressure drop) then it will work as expected.



Speed and ease of installation comes with baggage....



ME

Mac_R

water heater piping

guys the problem is not a pressure drop in the shower when my lovely wife starts a load of laundry.  the problem is I don't get any hot water.  The heater that is there can not produce enough GPM to support both the shower and washer.  I have checked with Bradford White and found out the best way to pipe them would be in parallel.  Thank you for your help.  any other comments are welcome.

MNPLUMBER

Not enough hot water

If you can't do a load of laundry and take one shower with your electric water heater then you have other problems.



I get these calls on a regular basis and 99% of the time if it's an electric water heater then you have an element burned out, most likely the lower.  Check continuity on the element screws. If you don't have continuity then replace the element. Turn the power OFF before you do this.



If the elements are good, depending on the year of the water heater you could have a bad dip tube. There were problems in the past with dip tubes disintegrating.



If it's not the elements or the dip tube the next step would be to test your gallons per minute on your shower head. Is this a newer low flow or an older high flow?



IF mine I wouldn't go in with two water heaters. If everything checks out good and you still want more hot water my advice would be to go back in with a single 80 gallon electric, you will save money.

icesailor

DHW Tanks:

All may not be so.

Electric water heaters with 4500 watt elements recover 18.* gallons per hour. Only one element runs at a time. 30, 40, and 50 gallon gas water heaters with 36.000 BTU burners recover 36+ gallons per hour. A 40 gallon electric water heater recovers 18 gallons per hour. Two 40 gallon electric water heaters piped in parallel will recover 36 gallons per hour because you have two elements running at the same time. The same as a 30 gallon gas water heater. The two 40 gallon electric will have twice the recovery as the 80 gallon electric. You can also futz with the bottom thermostat to make one heater do most of the work by setting one at 120 degrees and leaving the rest at 125 degrees or something like that. Short draws will make the lead water heater work first.

If you live in Massachusetts, that non-pressure balance shower valve is illegal and has been since the late 60's or early 70's. Just because you are a homeowner, doesn't allow you to do your own plumbing or get some friend who has done some plumbing once in his life to install illegal and unsafe shower valves without permits and inspections. They always use the excuse that it is their own house and they can do what they want. Not so. And installing a cheap, 8" center tub filler with shower diverter is only used by them and their family. Until they sell the house to you and you now are stuck with the problem. Their illegal actions are now your problem.

If the wall that has the tub/shower valve is tiled, Symmons makes a plate that covers the hole and you can replace it with a Symmons S96-2 shower valve. You will save money on hot water because the valve comes on in the cold position and it turns to hot. You add to the cold rather than temper the hot as you do with an illegal two handle valve. You can do it from the tile side. It isn't the easiest job but I have done a few. I'd rather do it from the back side. But the plate, though not all that attractive, covers the hole and does the job. Symmons is all brass with all brass parts and is made right here in the good old USA (not China) in Braintree, Massachusetts. Where they have been making them for almost as long as I have been alive. It is the same valve they came out with in the 60's and all parts are replaceable without removing the valve. Including seats, diverter and spindle assembly. Not so with ANY other single lever valve I have seen. Let alone get parts for.

Larry Weingarten

pressure

Hello:  This ultimately is a pressure problem.  Have you taken a gauge and done some testing to see where the flow problem/s are?  I might put the gauge on the water heater's drain and run one, than two, than three taps to see if pressure drops at the heater.  Do the same check at the main coming into the house.  It's harder to check pressure indoors, but some fun combination or adapters and reducer bushings should allow you to test at faucets or the shower.  The problem may be something as simple as rust where a brass nipple screws into the tank.



I'm not convinced it's a PEX problem or a heater problem... we just don't have sufficient info to judge.  You should have a pressure balanced shower anyway, so you might just get that done and see if the problem goes away.  If not, there is testing in your future!



Yours,  Larry

Mac_R

water heater piping

The single water heater is only rated at 1.5GPM.  by running the shower and the laundry at the same time I am exceeding the rated GPM.  By hooking up a second water heater in parallel I am increasing my GPM to 3.  that should be enough to run my shower and laundry at the same time.  I have no problems right now taking a shower then doing laundry or vice verse.  It is only when I am running both that I loose hot water in the shower.  It is not an instant thing ether.  I have replaced the elements.  That did make things better.  not perfect.  Wile I had the element out I cleaned out all the calcium from the bottom of the tank.  There was a lot.  I am now doing that on a monthly bases.  I have the water heater in position.  just need to run the lines to it and give it power from the box.  will let you know how it works out and might even post a picture.  Thank you for all your suggestions.

icesailor

Water Heater Rating:

Where did you get this number of 1.5 GPM? and 3.0 GPM with two tanks?

I said earlier that 4500 watt electric elements recover 18 Gallons Per Hour. Add the volume of your tank and you still don't get to 1 GPH

Mac_R

water heater piping

You know what.  Your right.  Sorry.  I miss read the information I have on the tank.  My bad.  Any ways I got the second tank for free.  I just need to get the fittings, breaker, wire, and everything else to hook it up.  going to do it this Sat with some buddies of mine.  Should be fun.