Town Garage/ Coal Boiler Project

 
ScottB
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Post by ScottB » Mon. Nov. 13, 2017 8:31 am

I now think that if looked at separately, and if we assume a complete new pour of the concrete slab in the new building, the steel building almost screams out for the use of radiant heat. Continuous concrete slab throughout on a good, firm, well drained base, open high volume air space inherent in this kind of building, and the need to quickly reheat air within 6 feet of the floor when large amount of air are lost to the outside when the garage doors are opened. As long as the floor is properly designed, I believe it would work fine. If the removal of the existing slab, ~ $ 25k or so, is too great a swing economically for my board, I'm thinking installing radiant in the new perimeter slab might be the way to go. Well insulate the perimeter edge and underneath, structurally isolate from the existing slab, and design it to heat the whole area. The floor will be warmer then a usual radiant system, but its not like anyones walking around with bare feet. When I think of where people would normally work, it even makes sense. Maintenance is usually performed around the axles, front of the truck near plow equipment, and rear of the sander near dog house. All of these would be on the existing slab but near the perimeter zones that would be heated. Other areas heated would be where piece welding or other operations are performed near or on the work benches. I guess a couple of unit heaters could be placed between the overhead doors or hung from the overhead structural steel above the center slab, if it came down to that. This solution was mentioned earlier in this post and the more I look at it the more it make sense.

A question I would have is could this play well, as far as set boiler water temp, with the HW baseboard heating in the office area, and unit heaters needed in the existing garage area. I guess the answer to this question is as long as its designed properly.


 
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Rob R.
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Post by Rob R. » Mon. Nov. 13, 2017 9:19 am

The different temperature requirements of radiant and baseboard/air handler are not a problem. You would use a primary loop and pull the various loads off of it, and mix down the temperature for the radiant zones.

 
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windyhill4.2
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Post by windyhill4.2 » Mon. Nov. 13, 2017 9:20 am

Unit heaters would be advisable no matter how much radiant floor heat is installed.The unit heaters will quickly replace the heat lost when an overhead door or 2 are open for a few minutes in severe cold. This would be very beneficial when several pieces of big equipment are parked in after being out in the cold for hours.

Yes, i am aware that in-floor heat stores more heat & maintains a better avg temp even when doors are opened...
BUT,floor heat is slow to respond to a quick change in temp.

 
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Post by Rob R. » Mon. Nov. 13, 2017 9:40 am

A lot of people make a mistake with radiant heat. They try to control it with a simple wall thermostat. This create a long lag time, and temperature overshoots.

A slab stat keeps the slab at a steady temperature that is comfortable to work on...room temp recovery after opening the doors is much faster when you have hundreds on tons of concrete already at 80 degrees.

As David pointed out, a few fan coil units would also give a nice "punch" to recovery the temperature quickly.

 
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Post by CapeCoaler » Mon. Nov. 13, 2017 10:12 am

That's the nice thing with a boiler system...
A zone for radiant...
A zone for wash water...
A zone for DHW in the office kitchen, lavs...
Ya did factor in all the heat for wash water, right...
A zone for the office space...
Baseboard or use an air handler for the humans...
you were going to do air conditioning for the summer, any way...
Toss a few modines in the garage if need be...
just pipe some expansion zones in or at least plan for additional zones...
Personally I would sell the 25k demo by the cost savings of the coal heat...
It will just make the garage work that much more pleasurable to have the full floor heated...
And the trucks will thaw quicker and be easier to work on...
Service life of the building is at least 15 years...
so about $1700/year amortized...
If the work environment is going to be a bit nicer to come back to...
Then the long hours of driving and repairing will be a bit more bearable...
Happy wife, happy life...
holds true at work also...
Do what the auto sales guys do break it down to a daily cost...
Would you like the crew to be happier for less than $5 per day?...
Maybe you can get some demo work done by an explosives crew looking for some training...
Offer the slab for free or nominal cost to train on...
Then you can just crush the 'crete for roadbase...

 
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Post by ScottB » Mon. Nov. 13, 2017 10:49 am

My heat loss numbers didn't figure in things like DHW or wash water, nor did I add the heat gains inside the building. I was just trying to understand heat loss to the outside environment. I do take seriously the advice to have install easily accommodate additional loops. When I think of actual use of DHW, and it should be added on top off the heat loss number, but actual use is very minimal normally. And washing is likely to take place at off peak times. I guess the main thing is to plan for it all. Regarding the $25k slab number I mentioned, that's a number thats been suggested that would be an avoidance cost of not having to pour a new slab in the space that the existing 40' x 80' slab occupies. I haven't confirmed that number but it does seem in the ball park if not a little low. The only thing that is probably known about the existing slab is it's in incredible shape considering its age (70 years old) and use (heavy equipment loads), doubtful it has a vapor barrier, and definitely is not insulated. The amount of steel that reinforcing it is anyones guess, and the cost of demoing it I haven't even considered yet.

 
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Post by CapeCoaler » Mon. Nov. 13, 2017 11:15 am

You might be able to elevate the floor and pour over it...
Avoiding any demo cost...
but you must get the compaction done properly around it...
Gotta love the old pours...
Stronger every day and built to last...
Just make sure you have some extra head room on the boiler capacity...
Cold showers on a bitter cold day make everybody grumpy... :twisted:


 
ScottB
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Post by ScottB » Mon. Nov. 13, 2017 1:26 pm

CapeCoaler wrote:
Mon. Nov. 13, 2017 12:46 am
How are you dealing with the exhaust from the running engines...
Hoses or just a general air exhaust...
In existing garage, general air exhaust. I know we have at least a 3' x 3' louver fan, centered and about 12 ft up on the gable end wall of the 40' x 80' existing garage area with similar on far gable end in quanset hut,. Naturally, garage doors are opened when going in or out and probably when first started and warming up. I don't remember if anything is snorkeled during repair/ maintenance. I suspect not. Something else to consider going forward.

 
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Post by hotblast1357 » Mon. Nov. 13, 2017 1:34 pm

Something else to consider during new construction, drop down air hoses with quick couplers to each trucks air tank, so that they can be kept aired up 24/7 so as to shorten run times inside the building. Can be regulated to say 100 psi.

 
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Post by CapeCoaler » Mon. Nov. 13, 2017 1:56 pm

What will you be mandated to provide in your new building...
OSHA, ADA, Showers, lockers, light levels...
It gets crazy but do the research before you start designing...
Change orders get expensive...
And somebody's space gets smaller...
Don't forget the IT infrastructure...
Cameras, alarms...
Make sure you put enough empty conduit for IT expansion/upgrades...

 
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Post by Pacowy » Mon. Nov. 20, 2017 7:39 pm

ScottB wrote:
Mon. Nov. 13, 2017 12:32 am
I'm coming up with a total heat loss of between 280k - 340k...This exercise seems to confirm my earlier size estimate.
Could you please outline briefly the steps you follow to get from your heat loss figure to your boiler size estimate? It might help people formulate potentially relevant comments.

Thanks.

Mike

 
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Post by ScottB » Tue. Nov. 21, 2017 11:20 pm

The heat loss calculation indicated the BTU loss/ hour to the outside environment at the design temp. For my calculation I used a design temp of 80 deg. F. I'm thinking to make up for the BTU loss at my design temp, the boiler would have to have a gross output that was greater then my calculated loss multiplied by the system pickup, or 340k BTU x 1.15. If my loss calculation is in the ballpark, a boiler with a gross output close to 500K BTU or greater should satisfy the requirement with some margin.

 
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Post by ScottB » Wed. Nov. 22, 2017 8:16 am

Rob R. wrote:
Mon. Nov. 13, 2017 9:40 am
A lot of people make a mistake with radiant heat. They try to control it with a simple wall thermostat. This create a long lag time, and temperature overshoots.

A slab stat keeps the slab at a steady temperature that is comfortable to work on...room temp recovery after opening the doors is much faster when you have hundreds on tons of concrete already at 80 degrees.
Rob - If I understand correctly, in this scenario, we would be controlling the temperature of the slab based on the outside temperature.

 
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Post by ScottB » Tue. Dec. 05, 2017 12:44 pm

When reviewing the Van Wert literature I noticed the net BTU ratings were 15 - 18% lower then what I had calculated using the the specified feed rate of the boiler (BTU/ hour Net = (feed rate/ hour x Coal BTU(13000) x efficiency ( 0.80))/ pickup factor(1.15). Is there another factor I'm not considering. Also, anyone have specs for larger EFM units, 900, 1300 specifically. A recent trip south to see a couple of installations has sold me on the idea of going with a refurbished underfed unit like a Van Wert, or maybe a large EFM unit, depending on what is available that would meet our needs in our time frame.

 
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Post by Rob R. » Tue. Dec. 05, 2017 1:33 pm

They used a more conservative efficiency rating and or/pickup factor.


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