hot water

shawn laverty

ok i have some questions i need some advice on I have a house that has a 300,000 btu boiler gas it serves 4 hydro air units 60,000 btus a peice also 2 120 gallon storage tanks now the homeowner wants to add a 2nd master bath that with all the heads running it will be about 20 gallons per minute in that one shower i dont think the 2 120 gallons will handle what this guy wants he wants about a 30 min shower now if i were to add 2 more 120 gal storage tanks a total of 480 gallons i dont think the boiler would handle this even if it was on priority i dont know if it would be better to do a bronze boiler or if you think the original will handle four units any comments would help.

Larry Weingarten

Of that 20 GPM...

how much is hot and how much is cold? About 75% of the water in a tank is available as undiluted hot water. So, each tank will provide roughly 90 gallons. If he were using equal parts hot and cold water that would be nine minutes per tank. My question is, does he use SCUBA gear while showering?;~). That's a LOT of shower!

ScottMP

how about

Cranking up the temperature in the two tanks to 160° and installing tepering valves to bring it back down to 125° or so. This would extend the amount of hot water he has.

I have a customer who has two shower heads, a rain head, and four body sprays on a 120 indirect. No complaints yet and believe me his wife would call.

Scott

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Jack_21

On demand

Not the least expensive first cost...but they can take as long a shower as they want and draw no energy when the shower is off. 4- Rinnai 2520FFU direct vent units will deliver 4.5gpm each at 70*F temp rise. they will do it 24hrs a day, or until the well runs dry. From an energy standpoint it doesn't make sense storing the vol of hot water you are talking about regardless of how much money the guy has.

ScottMP

Jack

I had this n the back of my mind nut how do you address the 20 gpm ?

I thought of making a Rinnia a direct unit for the shower maybe even after the tanks so as the temperarure dropped in the tanks the Rinnia would pick up the drop and the temp rise might not be so large as to dropp off quickly.

But you've got that volume of water to deal with !

Scott

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Unknown

Bypass

pipe the tankless primary secondary. Use a flow switch and a high limit on the hot main.

Cliff Brady

Recover the Heat!

> ok i have some questions i need some advice on I

> have a house that has a 300,000 btu boiler gas it

> serves 4 hydro air units 60,000 btus a peice also

> 2 120 gallon storage tanks now the homeowner

> wants to add a 2nd master bath that with all the

> heads running it will be about 20 gallons per

> minute in that one shower i dont think the 2 120

> gallons will handle what this guy wants he wants

> about a 30 min shower now if i were to add 2 more

> 120 gal storage tanks a total of 480 gallons i

> dont think the boiler would handle this even if

> it was on priority i dont know if it would be

> better to do a bronze boiler or if you think the

> original will handle four units any comments

> would help.



It may be cheaper and better for the environment to install a gang of GFX waste heat recovery echangers. I have one that works great, but you may need a gang of them to handle that flow rate.

See http://gfxtechnology.com/ for more information and prices.

Cliff Brady

Recover the Heat!

It may be cheaper and better for the environment to install a gang of GFX waste heat recovery echangers. I have one that works great, but you may need a gang of them to handle that flow rate.

See http://gfxtechnology.com/ for more information and prices.

The ones in the picture look like shorter units than the 5 foot long 4 inch diameter one I have.

Jack_21

You can...

use the higher flow capable model 2532's at a max flow of 8.5gpm being fed from a tank. The 2520 will give max 5.3 gpm. At 70*rise they both produce 4.5gpm. Two 2532's will give you up to 17gpm if you keep your temp rises in the 40*area. What is your ground water temp? Try to put the Rinnai's close to the primary point of use. LP or NG. Going with multiples you have to be spot on with gas line size. If you had the 4 Rinnais you can modulate from 15kbtu-720kbtu. Use the MSA-2M control and two MSA2S's to tie them together and they will rotate the firing order and control the modulation of all 4. Really neat to watch these step around on hi flow systems. Sealed comb (dv), efficient, quiet and best of all, no energy consumption until called for. We have been doing a lot of these on laundromats and did a Dunkin Donuts central bakery six months ago. Spoke to the manager and he said he can't imagine running the place without them. Replaced two 80 gal 199's. Flexibility!! Also, on your tank preheat system you could run cold to the tank with an a-stat controlling a circ to a couple 2532's (I prefer 2532 on circ systems as they have lower pressure drop). You will not circulate any more than 5gpm with any sane size circ. 009 for each or 0013 for 4. If you want to talk this over I'm at 617 834-8751. I'll be at Tim's school tomorrow doing a Rinnai tear down service class. Empty the cabinet, reassemble, make it work, troubleshoot and talk about your system...and others. Fun!!