I get all the weird ones...

Tom_133

So I have a local steel scrap yard that is putting up a 100x50 steel building. They will be spray foaming the outside walls which will be great, and the roof is done in with an R50 insulation. 3.5" high density foam under the slab, with thermal breaks along the slab. They want to maintain about 65 degrees and it cant go below 60 because the hydraulic fluid in the big conveyor needs to stay above 60 degrees. . So it'll be 12 loops of 5/8" tube, and we will be on our way to success!

All that would have been great.

Where it gets weird is today when I stopped in to discuss radiant loop layout, they mentioned they wanted hydronic fan units probably two 100k each. So i asked why and they said that in the winter they will probably be leaving the 22x18 door open most of the day to allow the loader to come in and out. So now, my design has been chewed up and spit out.

My question is how would you design for that? Treat it like a snowmelt design? its going to have 8 hours of open door time and 16 hours to come back up to temp?

I asked if they planned on doing that even when its -20 outdoors, and they were hoping to!

any thoughts?

Illinoisfarmer

So does the building have to be above 60 at all times? My experience would be that the hydraulic fluid might need to be above 60 to 'start', but once the conveyer (or whatever) is operating, the fluid temp will be fine. If that's the case, the temperature only needs to be maintained when the conveyer is idle. Maybe that's what you're saying - with the 16 hours to come back up to temp. There is a buttload of equipment out there that operates below 60 degrees ambient. Most modern tractors will limit cold weather operation until hydraulic temperature reaches 50 degrees, but after that it's game on - regardless of the ambient.

If not, prevailing wind direction is also going to mess with you a bit. Can't imagine the energy (and equipment) necessary to maintain 60 degrees with that door open, bitter cold temperature and a windy day.

Another option might be Low Viscosity hydraulic fluid. Performs better at low temperatures. All depends on the manufacturer's specs though.

Interesting situation for sure!

Mad Dog_2

Can they use those clear, hanging thick plastic "drapes" that you see in factories? Trucks drive right through and they part like the Red Sea, then fall back in place...Conserves most of the heat and definitely better than keeping the door open (foolhardy).

I've also seen motion activated clear, superlight, plastic bay doors that open superfast and shut just as fast. Mad Dog

Tom_133

I can ask about the plastic drapes, thats pretty smart!

I dont know about the hydraulic equipment as much as I need to, but will be digging in a bit.

hot_rod

my Local Toyota dealer has those large super fast overhead door openers

It seems a months worth of fuel cost would pay for that setup

I’ll bet the company that manufacturers those has some fuel saving data

mattmia2

An air curtain on the door will help keep the heat in but not as well as physical barrier options.

Jamie Hall

As noted, @Tom_133 — air curtain or the heavy plastic drapes. There's a supplier for the drapes in Windsor, CT — custom fit, not outrageously expensive. But it's likely you may have an ag. supply outfit closer.

Tom_133

so I ran it by the customer, and he doesnt think when he rolls in with a grapple full of razor sharp aluminum scrap they will hold up very well. I also sent the quick door as hot rod mentioned and he may look into that, but they dont go as big as his door is spec'd for, I did ask if we could shrink it up a bit.

So lets play the idea he wants to keep that door open, and wants to maintain 55 degrees, any ideas how to design for that?

Pumpguy

When we built our repair shop, we had a makeup air heater installed. This was primarily for use when the paint spray booth was in operation to heat makeup air that was exhausted by the paint booth.

We also turned it on whenever we had one of the overhead drive in doors open for any length of time.

Sorry i don't remember the details.

EBEBRATT-Ed

I think they are nuts to think they can keep the doors open and still maintain temp, what a fuel hog. So much for energy savings and going green.

They better have a lot of good scrap to sell to pay the fuel bill.

Air curtains are a good idea.

At my old shop which was 100,000 square feet we had RT units for heat and Ac in the shop. When the units were 20 years old and the HXs were failing (the AC was ok) we installed gas fired radiant overhead.

The difference was amazing. We had 10 x 10 garage doors and they got opened in the morning and all the trucks were moved out and the door was closed. This may have taken 1/2 hour to move the trucks and the place would be freezing by then

With the RTUs it would take an hour to recover on a cold day. With the gas radiant as soon as the door shut the space was back to temp because the slab was a giant radiator.

Open all day doesn't seem feasible to me.

I don't know how long fast opening doors will hold up in a scrap yard environment, probably get smashed in a week.

A good idea though.

MU air heaters may help to pressurize the building to keep cold air out. have it discharge right at the door.

no matter what they do it will be an energy pig.

109A_5

" discuss radiant loop layout " In the slab I assume ?

" the conveyor " is secured to what ? An if they decide to move it ?

Air Curtain ?

Sounds like they want to put themselves out of business with heating fuel costs.

hot_rod

do you have a heat load software program? Run it through the loadcalc.

I use Siggys Heat Load Pro

There is a free demo on his site, Windows based

Although it may “error” when it sees no wall 😲

https://www.hydronicpros.com

Harvey Ramer

Tell them straight up, it's not going to work. They need to figure out a different strategy for material handling. Without knowing the process, I can't really offer suggestions. If they insist on trying to heat a 5k sf building with a 22x18 door hanging wide open, walk away. Working for idiots is financially risky and you won't get any satisfaction.

Jamie Hall

air curtain. They are power hogs for the blowers, but they are oddly effective.

Tom_133

thanks for all the input. I agree this is going to be difficult and possibly not possible.

The conveyor is a big boy that is already in place and built into the floor about 8' down. then the conveyor track rises from the floor 15' into the air and dumps into the end unit that has a piston for squishing the material into a square for banding and shipping.

They need the door open for several reasons, they bring the material in with a loader, and then it gets placed with a 308 CAT excavator onto the conveyor. So they want the door open for the fresh air (i already told them bad idea) but also they run that loader in and out about a 100 times a day.

Im not sure how to make this all work, but there has to be a solution. They are using a waste oil boiler to heat primarily, and an LP backup when that fails. perhaps radiant isn't the best solution due to its long recovery times. It's also a 9" slab tubing will be in the lower 3rd of the slab.

HVACNUT

Since we're just throwing things out there. How about a 50 ft long entrance tunnel with doors at both ends. Only one door open at a time. Overhead IR heaters in the tunnel.

yellowdog

Sounds like they need to hire an engineer to assume the responsibility of the design and the outcome. I would not take on the responsibility of the design.

kcopp

I second Harvey suggestion. Walk away. This sounds like a no win situation.

ratio

At least you heard about it early enough to place enough disclaimers to cover their dissatisfaction with either the temperature or the operational cost. Or both.

Harvey Ramer

"They need the door open for several reasons, they bring the material in with a loader, and then it gets placed with a 308 CAT excavator onto the conveyor. So they want the door open for the fresh air (i already told them bad idea) but also they run that loader in and out about a 100 times a day"

What a god awfull idea. Running a diesel engine inside a building.

Why don't they do things the normal way. An overhead trolley crane with a grapple. Staging area outside for unprocessed material. Crane moves material from outside in through a small opening right to the conveyor. Forklift inside for handling the bales.

GGross

https://forum.heatinghelp.com/discussion/comment/1863470#Comment_1863470

That would make too much sense!

Jamie Hall

Seems to me that maybe there's another way altogether, @Tom_133 ? As I read through your comments, one of the reasons they want to maintain temperature in the building — and possibly the only one which really is important (though working a freezing cold building isn't much fun…) is the hydraulic system. Which is not unreasonable.

So… completely different approach. First, include in the hydraulic system a heat exchanger to maintain the temperature of the hydraulic fluid. Now this may require some thought and additional piping, as the fluid in the hydraulic cylinders doesn't recirculate, and for installations with long piping to the cylinder it might be necessary to have recirculation lines to keep the fluid warm enough. But that's a detail. (An alternative would be a cold compatible fluid, such as is used on aircraft — but that's not cheap).

Then to keep the workers warm enough to work (never mind keeping OSHA happy) the various work stations would be provided with infrared local radiant heaters (gas or electric) and, possibly, heated floor mats.

The concept isn't totally out of the blue — that's how we handle dairy milking parlours.

Tom_133

I appreciate most of the comments guys. I did have a conversation with them verbal and through email, that discussed their expectations. I told them that no matter what we do that building wont maintain a satisfactory temp if any of the 3 overhead doors remain open for prolonged periods.

The best I can offer is at startup in the morning, the space will be 70 degrees, but within mins of the door opening, all bets are off. They understood and think they can manage as long as the conveyor and hydraulic oil get warmed up and rolling. I said keep it on through lunch then!

I dont think I will walk away from this job but I will have enough disclaimers and exceptions it'll make a lawyer wanna high five me!

hot_rod

It doesn't sound like a radiant slab is the best answer to what they expect ?

The scrap yard and transfer stations near me all have over-head radiant. Much faster response to opening and closing doors as you have a much higher temperature you are dealing with. They tend to glow red hot.

If you go to the CoRayVac website they show examples of tall buildings with radiant tubes.

Since they heat what the "see" one right over the hydraulics would warn regardless of the doors being open or closed.

I've sat outdoors under radiant heaters at Chicago restaurants on a windy 0°f day, AHR events in January. It felt like my head was on fire!

neilc

redesign the whole job,

keep the conveyor warm inside,

put the feed hopper outside, maybe under a shed roof if snow or rain matters, have a small opening for the feed conveyor, air curtain that,