piping water heaters in tandem

Steve Paul

Michal,
The mechanical drawing is very nice, typical of most architects plumbing drawings. The only problem with it that I can see is the piping for the T&Ps. It shows the piping to be 12" AFF. The code requires no further than 6" or closer than 2" AFF to avoid splash/scalding.

dave_69

gas water heaters in tandem

I am working in the personal home of a contractor we do work for. The house was a two family that he converted into a single there are two brand new water heaters in the basement and he wants to connect them together to have more hot water for the house.
When we finish he will have four full baths and we installed a hot water recirc, are there any pros and cons to piping these two water heaters together on the same distribution pipe or should i split the load to different parts of the house if piped together he will have 90 gallons of hot water.

don_126

Split

the load and get rid of the recirc loop.

Michal

keep the heaters together

You will have a high initial load if two or more tubs are going on at the same time, Keet them together to keepo the storage quantity up, keep the recirc loop this is a very good feature, this also buys you redundence and a higher recovery rate. evaluate the tanks together and see what their total recovery and storage is, and compare them individually, you will beat the recovery rate of a single tank. Thats how its done in large homes and institutions.

Paul Rohrs_4

Parallel Heaters

Basic drawing of two water heaters in parallel. They must be piped with equal dimensions on horizontal and vertical runs. This is shown with gravity recirc. Ballcone check valves (in corresponding locations) are a MUST. We usually pull the existing drain valve, pipe in a nipple and a tee, then re-install the boiler drain


Regards,

PR

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Michal

Piping Detail

Attached is a piping detail Hope it helps

tug boat

thanks for all the help

thanks for all the help i have one more question how would a storage tank fit into this picture, he wants to put in a storage tank also. There is going to be 3 0r 4 more bathrooms added to the house in the future and he wants to do all of the mechanical work now in preperation for the additional bathrooms

Ken_8

If they have the \"cake\" for

this kind of demand/use - they should do it right:

A small super high efficiency condensing boiler, and a stainless steel indirect. We do an entire high school with two small boilers and two W/M Plus 120's. One provides 160º water for the dish washer. The other is for the slop sinks, showers and tap water running around 120. The boilers power both. If memory serves, the boilers are 75MBTU's each.

Never ever run out. The sports dept fills a 100 gallon whirl-tub every day as well, maybe twice a day.

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Michal

you are correct

that detail is for general purposes and needs to me modified a bit depending on the code/state being used at. also thats not architects drawings, but engineers. Good catch, will make a change on that detail.

S Ebels

Paul

Instead of the hassle (sometimes) of trying to match the inlet/outlet piping exactly, why not do a parallel reverse type piping arrangement. Similar to a reverse return on a heating system. First heater off the city supply is the last one back on to the domestic side? We've used this for years with good results. Seems to be easier to ensure equal flow between the heaters as opposed to matching the piping in sometimes cramped quarters.

Paul Rohrs_4

Yes

We have used that as well. The critical element is so that they draw water evenly from both units.

Regards,

PR

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