Outdoor surface warming/ not quite snow melt?

S Ebels

More like poop melt.

I'm trying to come up with a system design for a dairy barn which has roughly 5,200 sq ft of outdoor area they want to keep from freezing. The area is all under a roof plus it will have roll up type curtains to keep most of the wind off in the winter. There is nothing on any of my heat calc programs that would approximate these conditions so I'm looking for anyone's input on BTU's/ sq ft.

The objective of this part of the project is to keep the holding area plus a drainage/manure trench from freezing on its way out to the pit. Design conditions would be -6*F.

Along with this area, the boiler will be driving 1,600 ft of regular indoor radiant floor, a 120K fan coil plus providing 180* domestic hot water for sanitizing and clean up.

This will be an interesting project to say the least. Lot's of design challenges. The dairy supply dealer and myself are trying to design a number of things into the system. One of these is utilizing the waste heat from the water cooled condensers (about 1,1 mil per day to dispose of) to run some of the outdoor load. To date we have an insulated 750 gallon tank buried under the utility room floor that will hold the cooling water from the condensers. I want to draw water from this tank for heating the outdoor and/or indoor area until the temp drops below a useable point, then switch to the boiler. Problem is, this would mean an HX to isolate the boiler from the open side of the system, (the holding tank). It would also require a second HX to isolate the heavily glycoled (izataword?) "outdoor" zone from the fresh water in the tank. Gotta do some more thinkin' about that....... Working through 2 HX's may present to much of a temp drop to be useable. I'm beginning to ramble out loud here.........

Back to the main question which is, how many btu's/sq.ft.?

hydronicsmike

TurdMelt

Have you talked to the guys at Wirsbo yet? Tim Doran would be able to help. 952-891-2000.

If you need Controls, call me at 250-545-7749, Ext. 214

Regards,

Mike

Tim Doran

Cozy Cows

Give me a call, I can calculate this for you. 800-321-4739.

Tim D.

Dan Peel

Like project

I did this dairy barn in 2002 (just the hydronics). E-mail if you want specifics. Avoid the use of glycol around food products - you may end up being required to use double walled HX's. You need really direct delivery to maintain the 180 temp thru the full wash cycle. Enjoy.....Dan

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hr

Could you

drop some coils into that tank for the boiler to storage HX. I would think a simple copper coil or two, singled wall would be fine for this. Then a double walled HX for the glycoled outdoor circuit.

You can buy food grade PG glycol if needed. Think I would go all non ferrous with FG since the inhibitors would be missing. a local Kraft plant uses about 6000 gallons of FG glycol locally. Mostly for taste and scent ability.

I'd be interested in knowing the load figure you come up with for that slab. Seems at least a class 1 snowmelt btu/ ft if wind and cold could get to it.

hot rod

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Weezbo

Be very careful about the buried tank....

it may not be able to withstand very much pressure fluxuation and then You'd be in the Sh...sort to speak.

Kevin Bouwman

I've done 3 or 4 of these. I am a dairy equipment dealer who has been to the Wirsbo school. My first system was an open system that included the desuperheating water heater and an water heater as the boiler. I converted that system to a closed loop sysem with a real boiler ten years later, it's still running. For the holding pen I installed 25 Btu/sq ft. in a -11 degree design temperature area. Install a thermostat with a sensor in the slab; set it for 34 or 35 degrees. Unless the holding pen is empty a large part of the day--unlikely with the square footage of your facility, the system probably won't kick in until the outdoor temp is below 20 degrees for 12 hrs per day for a couple of days in a row. I normally use a dedicated boiler for the holding pen with 50% propylene glycol and a water only system for the "warm" part of the building and the indirect water heaters. On the last system I did, and the one I am currently working on, I put tubing in the pit walls of the milking parlor as well as the floors. Insulate under everything with 1.5" or 2" XPS. I run the surface temps of the milking parlor as high as 100 degrees F in the dead of winter to help with the high heatloss the milking parlors see. I run the warm side of one of the loops tight behind the stainless steel curbs. This keeps the stainless toasty and is greatly appreciated by the milking staff with their often wet hands and arms. As for recovering the heat from the condenser discharge, even with the 70 to 80 degree F supply temp the holding pen floor is going to call for, your condenser water isn't going to be warm enough (probably 80 to 90 degrees F) to move any useful amount of BTU through a heat exchanger. Maybe you could put it in series with the boiler (before the boiler) to preheat the return water. I usually put a small well pump on the tank and send the water out to the cows for them to drink, and/or put a 3 to 5 hp washdown pump on the tank and use the water to washdown the parlor and holding pen.

If you want to know more just ask.
Kevin

freon12

I would size it out for 30 to 35 btu/ft.

Also the best way to get the heat out of the condenser would be, to capture it before it makes it to the condenser, ie: a seperate heat exchanger on the discharge line before it goes to the condenser...Also depending on the refrigeration system, if its ammonia you could also put on heat exchangers on the oil pumps on the screw compressors gaining alot of capacity for the company...I installed a heat exchanger just on the oil lines for a food processor to pre-heat wash down water from 60 to 115 deg and we are capturing roughly 6 millon btu a day on a 15,000 gallon storage tank. Which eliminated the need for one of the 3 50 hp boilers...

good luck.