DHW high load

joel_28

om guys here is my dilemma. I've got a client that just bought 1 of these Kohler shower things that will burn through 12.5 GPM a minute. plus they want to run another shower so that makes it 15 per AND in the future may be adding another kohler shower thingy at 12.5 additional. that would give us say 40 gallons a minute. Figure 40-45f from the well in winter.
they currently have a blue oil boiler with tankless coil that we'll be switching for the big V.

Current boiler is 121k I'd hate to size up just for domestic but what can you do? bank 3 120gallon vert cells? They do have propane anybody feed a Rinnai off a big indirect to smooth out the boiler lag/recovery?

joel_28

and

How much can they really use this is a well so 10-15 gpm is probably about it. These shower things stink it's gonna suck fuel like the space shuttle.

Constantin

Consider a GFX of similar heat recovery device...

... pipe it into the waste line below the shower and pre-heat the cold water coming into it. Such devices are perfect for showers.

... As for the customers, I'd ask them to sketch out how long they shower, then do some calcs based on storage capacity, input rating, etc. I would be surprised if a 120Gallon Verticell would not do the trick... Alternatively, you could set up the piping to allow additional Verticells to be added as needed with minimal hassle. Then let them live with it... if they do run out... add another Verticell. That minimizes the number of moving parts, maintenance, etc.

However, if money is no object, I'd also consider going with a smaller tank and a fat, dedicated condensing boiler just to keep the tank (and the customers) happy. Fewer standby losses, though at a higher initial investment (and more maintenance). However, at those flow rates, you are looking at Commercial equipment... hence, my suggestion to add Verticells initially.

Jack

Skip the indirect

Go with multiple Rinnai's. For a short term use appliance it makes no sense to maintain any large vvol of water to meet that demand. Try to put them as close to the fixture as possible. The advantage of the 3 untis it takes to do the 15gpm is that you have the comfort of use of the fixture when you want it but you have no energy consumption when the fixture is off. As well, if junior washes his hands the system will modualte to meet only that demand.

Larry Weingarten

There is a new...

... multi-headed shower out there that has a tub area you stand in. (sorry I don't know the name) Fill the tub with warm water and the unit uses a pump to recirc the water up to the shower heads. Basically it's a vertical bath tub. You might want to take a rinse when done with the shower part. My eighth grade science teacher thought tubs were good for "soaking in your own juice". Anyway, it turns out to be quite water (and energy) efficient.

Yours, Larry

Tim_41

hot water

This past winter I installed 5 custom showers. Each had 4 sprays a temp valve and 16" diameter shower heads. Also, a laundry room with 2 commercial washers. The owner said "I don't want guests running out of hot water" We put in 3 rinnias with 3 115 gal storage tanks all piped reverse return. Also planned for the future. I've been there with all of the showers going at once. They won't run out of hot water.

Steve Ebels_3

Whew!

Tankless?..........A 70* rise at 28GPM means an output rate of about 1,000,000 btu's. That's 6 Rinnai's, Takagi's, Bosch or whatever firing at 199,000 and 80% efficiency.........

I think I'd have a chat with the owners and give them the option making sure you have all your numbers right. Find out their showering habits. Run in, run out or stand and soak. Teenagers would be problematic if they are anything like mine were.

As a general rule, I would say it's safe to assume that folks with the kind of coin to buy bath fixtures like that, typically don't like to run out of hot water.

My personal choice would probably be a couple 120's with a dedicated boiler. The heating boiler(s) will take a long time to recharge that much capacity if sized correctly for the heating load.