Domestic Hot Water Piping

AL

I need anyones input on piping domestic a domestic hot water heater for a seven bath house with high flow grohe shower systems. I have installed a Weil-Mclain ultra 155 with a Weil-Mclain Gold Plus 120. I planned to use a three way mixing valve for domestic hot water with a temp around 180 degrees. In Illinois for state plumbing code requirements I have to supply a temp around 130 degrees at the sinks, and 115 degrees to all shower and tub locations. I was wondering if there is a calculation to figure out how many gallons of hot water I can supply at 130 Degrees. And if there is any self tempering three way valves for ultimate performance? I have piped the boiler as recommended by weil-mclain and I am using a 5 pump controller with water heater demand controls. Any Help would be great.

hr

How many gpm do those

Grohes flow at your pressure? Most shower and tub shower valves are avalable with pressure balance anti scald versions. Grohe makes some good ones. I would start with these to protect the tub and shower temperatures.

Weil should have info on the GPH that tank will produce at various inputs (boiler size).

What you really need is to know what the homeowners expect! Will they want to run several showers at the same time? 30 minute showers? A big tub, load? Washing machine use.

It's best to get a fairly accurate expectation and build the DHW system to that. You may need some additional storage if they have a large dump load expectation.

I did a similar system to what you describe a few years back. Un beknownst to me the homeowner bathes twice a day in a two person Jacuzzi tub! I had to go back and add another 120 storage, to help out the 80 gallon indirect, to meet that tub load!

Recovery time was not an issue as he left home after the AM shower, and bed time after the evening. It would take close to an hour to get back up to temperature! This system was driven by a Burnham Revolution which would prioritize DHW and step up to 200° F for more Dhw recovery BANG.

I've yet to have a customer tell me I gave them too much DHW, but I have missed the boat more than once by not asking the right questions

hot rod

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Cosmo_3

Get ready

To SPEND MUCHO $

Your boiler might be sized to heat the house, but w/ 7 bathrooms, and if you have a couple showers w/ multiple body jets your going to require some major boiler horsepower my friend. First thing for you to do is ask your homeowner how many shower's/ whirlpools they expect to run at one time, then consult an indirect water heater manufacturer of your choosing to determine what size, and how many indirect tanks you will need. Then size your boiler(s) (this is where multiple boilers are worth doing) big enough to supply the indirects with all the BTU's they can handle at a low delta T. Or, use tankless wall hung water heaters so you do not have to pay to keep all the water hot (re- more maintenance when used on well systems and water is not conditioned to remove hardness, etc) and after you scare your client to death with the price they either bite the bullet and pay you to do a proper job... or just keep adding one more indirect every 6 mo using the same boiler to try to create enough storage and the homeowner is never happy and blames you for not predicting that this would happen.

In other words, you are smart to ask the question here.

Now figure out how much hot water you need, and how fast you want it to heat up. The water heater manufacturer's technical support guys are a good resource. Add up the gpm total of each showerhead, including body jets. Don't forget that gpm is effected by pressure. Tell us what you have there as far as fixtures and I am sure the smart guys on this website will point you in the right direction.


Cosmo Valavanis

Dependable P.H.C. Inc.