170 degree domestic from an indirrect?

Kevin Bouwman

Hi, I've been installing infloor/inwall radiant heating systems in dairy farm milking barns for a number of years now. I 've be asked to bid adding an indirect water heater to a system I installed a year and a half ago. My favorite supplier handles Crown MegaStor so I looked through the install manual this morning and it said not to use the MegaStor to heat the water over 140. Cleaning the dairy equipment on this farm requires 220 gallon of 170 degree water during the first half hour after milking is complete. This happens three times a day, seven days a week. There is a 120 gallon desuperheater on the farm that preheats water with waste heat from the milk cooler. The desuperheater also has one 6000 watt heating element installed in it located such that the top 40 gallons of water are kept at 170 degrees. The preheating function typically raises the rest of the water to 120 degrees. The new indirect would be replacing a wholely inadequate 80 gallon electric Marathon heater the was provided for free by the electric company. It's (predicted by me a year and a half ago) inapropriateness for the job is leading to dirty equipement and problems keeping the milk inspecter happy. My questions are...does anyone make an indirect that can take the 170 heat and how would you size this, how would you set this up, and why.

P.S. The boiler is a 40Kw Slantfin Monitron.

Paul Pollets

Yes...

The Viessmann VitoCell 300 series stainless tanks can take the heat. I've used several for low presure steam indirect connection. Lifetime warranty does not apply in commercial applications.

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Floyd_5

I did it.....

used a 80 gallon Bock and burnt it up in a couple of years...wouldn't warranty the thing either, said it was a "commercial" application.
Replaced the Bock with Weil Gold 100, works many times better and provides tons more hot water. Had the water to 200 in no time.
Not sure what that boiler is, never heard of it, but the boiler I used was a Weil WGO-4, cranked the boiler right up to 230 and that combo seems to work like a charm... going on 6 months now sure I can't speak to the longevity yet, but it is definetly doing the job.
This indirect is a S/S tank inside of a steel tank.. the tank in tank design seems to work better than the coil jobs.... just my opinion.....

http://www.weil-mclain.com/netdocs/plusframes.htm

Floyd

BTW... this indirect is also a commercial tank....I bet they hold to their warranty for it in your application.
A quick call to their tech support would confirm that.

John Abbott

Superstore

> used a 80 gallon Bock and burnt it up in a couple

> of years...wouldn't warranty the thing either,

> said it was a "commercial" application. Replaced

> the Bock with Weil Gold 100, works many times

> better and provides tons more hot water. Had the

> water to 200 in no time. Not sure what that

> boiler is, never heard of it, but the boiler I

> used was a Weil WGO-4, cranked the boiler right

> up to 230 and that combo seems to work like a

> charm... going on 6 months now sure I can't speak

> to the longevity yet, but it is definetly doing

> the job. This indirect is a S/S tank inside of a

> steel tank.. the tank in tank design seems to

> work better than the coil jobs.... just my

> opinion.....

>

> http://www.weil-mclain.com/netdocs

> /plusframes.htm

>

> Floyd

>

> BTW... this indirect

> is also a commercial tank....I bet they hold to

> their warranty for it in your application. A

> quick call to their tech support would confirm

> that.



Seems to handle the high temps well.There are separate Warraties for residential and commercial if your water temp is set above 140 it gets the commercial one.
As a practical matter I have close to 100 runing at 160 to 180 degreeswith only one failure (my own)nearly 20 years old I put in sparco mixing Valves to allow for two temps

John

Don_44

Turbomax

I have seen commercial dishwashers run off a Turbomax. They require 180 deg water and the Turbomax does an excellent job.

S Ebels

We did it another way

We used a pair of 120 gallon AO Smith storage tanks and a 5x12x40 Flat Plate heat exchanger. The tanks are simply another zone in the whole package. A tank aquastat calls on the circs on bothe sides of the HX and the boiler. The boiler runs at 200* and a motorized mix valve knocks the temp down for the floor. The tanks are piped parallel and we use a recirc pump to ensure all the water stays at 175*. The oldest system we have that was done like this was installed 4 1/2 years ago.It has worked very well with zero problems.

dconnors

farm hot water

I designed a number of hot water systems for farms. I used 2 super stor 60 gal. indirects piped in series. 1st tank 140 deg., 2nd tank 180 deg. Seemed to work fine. Hope this helps. By the way, make sure you have enough pump to get the full benefit of the indirects. Run your boiler at 200.

Dan Peel

Needs horsepower

Do the math - your 40KW (135MBTU)may be challenged to deliver for first wash. The setup in this picture is a 400MBTU Laars boiler feeding through both coils of a double coil JASS stainless indirect to maintain the tank temperature at 180. Enjoy....Dan

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hr

Steve and Dan

Have two excellent points. An external HX as Steve mentioned may be cheaper and a better setup. Large capacity indirects get pricey. And an external HX is easily serviced.

As Dan mentioned you don't have a lot of hp with that boiler. Check to see how hot the manufacture, or the controls, allow that to run. The hotter the boiler the better the recovery. 205 0r 210 may be an option?

I'd contact Flat Plate, or Tony Conner for hx advise.

Dan, is that Jass tank still available. I thought Raymond, and that company, disappered?

hot rod

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Dan Peel

Same stuff, different pile...

The product line is now made by Advance Metalpres. www.metalpres.ca
Enjoy......Dan

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Kevin Bouwman

Floyd,
Thanks this is just what I want to avoid. I am pretty sure that my second choice supplier carries Weil-McLain. I will call them today and visit with them about it.

Kevin

Kevin Bouwman

John, Being able to go to my customer and stand on your shoulders is just what makes these online communities so great. The customer gets better equipment and tech gets to look like an experienced expert.

Thanks, Kevin

Kevin Bouwman

I've thought about doing it this way too. My concern was how quickly the domestic side might lime up if the water is not softened. The water on this farm is about 25 grains hard. I know the Marathon heater has had lime build up in it. Is there any reason to think this would be more or less likely with the plate exchanger?

Kevin Bouwman

docheat53, I'm thinking that if my set point is 170 and my boiler is 200 this 30 degree difference instead of the 50 or more that a residential application would have is the reason for your pump comment. How do you calculate how much pump you should have? If you have your Super Stors in series how do you keep the first tank from going over 140 while you're raising the second one to 180? Do you control the flow separately or is the 140 number approximate? I could get a lot of farm work if I demonstrate both willingness and expertise.

doug_16

Would something like

an Ergomax work? Since the DHW flows thru the coils, it scrubs them clean which would help with your hard water. Also the tank would provide a reserve of boiler water which you could treat after filling the boiler and system.
We use an E44 for my shop and home and the public supply of sediment filled lake water would fill the bottom of a standard tank.

http://www.ergomax.com/

Kevin Bouwman

Dan, I really appreciate your picture. I would love to see an example of the math you are talking about. I might be thick but I have a hard time translating the typical first hour residential and office commercial sizing formulas into the dairy farm demand characteristics. I posted the boiler size because my gut instinct told me it might be close. I have check the on farm needs more carefully this morning and discovered that I was off a little. The actual max 170 degree flow required will be 180 gallons in thirty minutes. What would the max gallons I could expect out of my boiler?

hr

The hard water will

be an issue even with a coil in tank design. That coil running at high boiler water temperatures will really attract the hardness.

Think I would consider Triangle Tube or Weils tank in tank, or maybe an Ergomax might be more hard water tolerant.

Keep in ming lime build up on any transfer surface will make a difference on the output. Sneaks up on you slowly, but it will get you.

hot rod

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Kevin Bouwman

Ergomax

doug,
This looks interesting too but I don't think I have enough boiler in this case to use one of these. I am going to file it for reference for the next job though. The self cleaning, the reduce floor space, and the "endless" supply are attractive.

Kevin

Dan Peel

Calculation

OK Kevin, The boiler first. Your 40KW input will yield 40 X the 3415 BTUH per KW or 136600 BTU per hour. The 1/2 hour available is simply 1/2 that or 68,300 BTU. Now the load. 1 US gallon weighs 8.333 lb. It requires 1 BTU to raise 1 lb. of water by 1 degree F. For first wash, before the desuperheater is in play your entering water temperature from the well will be less than 50 F in most regions - you need a rise of 120 F or 120 X 8.333 = 1000 BTU per gallon to maintain the 170 tank temperature. You only have enough boiler to recover 68 gallons in your 1/2 hour. Now duty cycle - you can underpower, without losing your 170 exit temperature, by adding volumes of preheated (overheated) water. The volume depends upon the run cycle and the temperature you can maintain within your chosen reserve tanks or staging tanks but remember those tanks will stack with cooler water on the bottom and dilute quickly so you only get to use about 50% of the tank volume before recovery comes into play. Big horsepower or big volume are the only ways I know to sustain high temperature outputs in high delta T applications like water heating for dairy.
Enjoy.......Dan

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Kevin Bouwman

Dan, It's funny how you can know the math but

not really understand the problem. The place where I always got stuck was with how to incorporate the useful amount of recovery with the large amount of hot water useage during the early part of the first hour. Dividing the boiler output by the fraction of an hour makes complete sense. Thank you. You would think that a guy who is always doing BTU calculations for refrigeration work could have figured that out.

Again, thanks,
Kevin

Dan Peel

Just...

Cleaning the windshield for you sir......Dan

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dconnors

regulation

the aquastat will control the temps on each tank. pump sizing is based on pressure drop of tank, pipe and fittings, and required btu input needed as gpm on the heating circuit. I have several of these working in northern NY with great success.