Large DHW demand

JackFre

I'd recommend looking at breaking up the dhw system and using on-demands without storage where possible and if you can get close enough to the point of use you can eliminate the recirc to parts or all of the building. I'd recommend an on demand system for the big shower/tub fixture. What is the flow going to be? If you know it is a simple matter to size it. The advantage of the multiples is that you can have the capacity when required but zero energy consumption when the fixture is off. Again, try to get close to the point of use. Go to www.rinnaisolutions.com. Register, and go to the "calculator" section. Select the 2532FFU and list your fixtures. It will give you the sizing with and without storage, as well as the drawing you want to use for the storage. Ground water temps can be set by dragging your mouse over the map. You can also set your desired output temp by hitting the red or blue button. It's pretty cool and I've done a lot of successful systems using it.

Alan(OnVacationInOregon)Forbes

Large DHW demand

We're working on a large house in Piedmont, seven bathrooms, kitchen, pantry and bar sinks; hot water recirc.; the showers and tubs have high volume shower heads, body sprays; I think they have a death wish and want to drown themselves; that, or perhaps they do their best thinking in the shower and they figure the more water, the more thinking.

Big, big hot water demand when family and friends are staying the weekend. I originally wanted to install a Noritz N-132 until I saw the fixtures the owners had chosen and realize that even the Gonzo of "flash" water heaters won't keep up with demand. Now, I'm thinking about adding a storage tank like a large Viessmann Vitocell and use the heat exchanger for the basement radiant heating.

We've used the large Noritz before with good success, but never with an added tank. Noritz has simple schematics for this kind of setup. Has anyone ever done this?

Brian (Tankless)

I did it

in a laundry for a nursing home which runs 18 hrs/day feeding 140/150* water to two commercial washing machines.

And all I used was on older model ELM AquaStar 170-HT @ 165,000 btu input, 82% eff, recircing into a 70 gal Ruud storage tank. Hot water off the top, cold in the bottom, with an aquastat turning on the B&G 100 circ which in turn, turned on the AQ burner. Simple, effective & reliable. That was then!

Now, knowing what I know, I would use the Noritz of your choice, or a 235,000btu Takagi Mobius (which you are familiar with) coupled with an Ergomax-type tank.

Heat the jacket/tank water in a closed loop through the heater (no scaling issues for the heater HX), and run constant circ (or timer-ed) around the house off the coils.

Don't forget the Hi-head pump for the heater circuit :O)

Still need more hot water? Stage two Noritz's or Mobius's, or paralell two tanks reverse return. Done!

As Steve Ebels said in a previous thread: "Yes M'am, we can do anything you want to do".

You know you can do it, Alan.

If the tank's in a basement, you may not even need a circ on the DHW side, gravity will take care of that.

Let's know how it goes.

Brian in Swampland.

hr

Consider

a tank in tank style indirect. A Triangle Tube or Weil indirect. Run the instantanous through the inner DHW tank and pull the radiant from the outer. You might find larger sizes and a bit less $$.

Or perhaps two smaller 40 or 50 gallon versions. Seems two 50's cost less than a large 100, as in regular WH tank sizes.

hot rod

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Larry Weingarten

Wondering out loud...

...if some GFX or similar drain heat exchangers might be of use in reducing the size of the hot water generating equipment... and saving some energy ;~) Your clients could think conservatively!

Yours, Larry

Alan(CaliforniaRadiant)Forbes

DHW options

Thanks, guys. I'll try that calculator out Jack.

Alan

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Dave Yates (PAH)

recent commercial app

After calculating peak demand, I suggested a twinned series Takagi Mobius, but their budget was too tight. So, we kept the ASME storage tank, installed a single Mobius and tossed the old inneficient gas-sucker that had fed the tank. When their tank springs a leak, we'll add that second Mobius to meet the shift change hot water demands for showering and hand washing. Works like a dream & it's saving them lots of $$$.

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