derating for altitude

Chris Spannagel

I am sizing a system for a commercial buliding. I am wanting to go back with a staged system, to bring up the effenciency. My delima lies here: I am puting in 80% units at 10,000 ft, and the derate factor for my area is .61. Do I need to use both numbers as a derate? so 100,000 btu's only produces 48,800? (100,000 X .80 X .61) Or do I just use the gas utiliazation standard for my area? (.61), and size it this way? My heat loss on this building includes the hot water usage at peak usage, total number being 1,013,000. The existing system is an old ajax, that they built the building around, so going back with a big commercial boiler isn't an option. This ones coming out in many small pieces. Looking for ideas too. But if someone out there knows how I need to use the derate, I would be greatful. Thanks for your time
Chris
All American Heating Inc.

Mark Eatherton1

You're correct...

For atmospheric appliances, the normal derate factor is 4% per 1,000 feet. Another way to determine boiler sizing would be to take your base load and divide it by the combined combustion efficiency and altitudinal derate factor. In your case, that combined factor would be .48.

So, based on your base load of 1,013,000 btuH, divided by combined factor (.48) would mean that you'd need a boiler rated for 2,110,416 btuH sealevel. Then, if you wanted to chop it into fourths, then 2,110,416 divided by four would equal 527,604 btuH each.

All of the above rules apply only if the appliances are atmospheric. If they appliances are sealed combustion or high efficiency condensing, then you need to follow the manufacturers recommendations as it pertains to altitudinal derate factors.

Even after you've done all of the above, you will still need to make sure that the orifices are set for proper altitudinal deration based on the caloric content of your local gas, and the gases specific gravity.

Altitudunal deration is the second most misunderstood topic of the college courses I teach. The first most misunderstood is the point of no pressure change.

As an alternative, maybe you could consider base loading the system with a high efficiency condensing appliance for DHW and minimal space heating calls, and leave the peak demand to the less efficient appliance.

Here's a link to some recent article I wrote recently on this very subject.

http://www.contractormag.com/articles/column.cfm?columnid=246

http://www.contractormag.com/articles/column.cfm?columnid=255

http://www.contractormag.com/articles/column.cfm?columnid=264

Also, while we're on the topic, it is entirely possible that you can reduce the size of the physical plant by 50% and not suffer anything. Dave Brunnel (Boilerpro) recently posted information regarding using historic consumption data and historical degree day data to properly size the appliances based on actual load versus theoretical load,

Where abouts are you located?

ME

Chris Spannagel

In the high country of Colorado, and yourself? Thanks for your time in this. I feel like I'm banging my head on a wall with this one.

Mark Eatherton1

I'm from the low lands...

Denver, Colorado. Hopefully the home of the next Super Bowl Champions, GO BRONCS!

I'm just guessing, Breckenridge?

ME

Chris Spannagel

Yes summit county. This is where I have been for most of my life. The codes are not strengent, but I think they should be, so I am trying to step up to the plate, and do somthing right in this place where they slap up houses in a couple of months. So what do you do in our industry?
Chris

Mark Eatherton1

I own property on the other end of the county...

Green Mountain Reservoir. Kinda glad I don't live up there right now.

I'm partners with a guy named Tom Olds in an enterpise called Advanced Hydronics here in Denver. I also teach part time at Red Rocks Community College in Lakewood, as well as travel teaching for the Radiant Panel Association.

I also write a monthly article for Contractor Magazine.

Thanks for stepping up to the pump. Say hey to Charlie with the city.

Heres an aerial view of what I see from my front porch in the summer.

ME

Chris Spannagel

Green mountain looks low in this one........Been awhile since I've been there. I have a customer I take care of in Heeny. He is a good old guy. I enjoy his company.
So you teach? I need to know what kind of classes my partner and I can take to give us an edge in the hydronics relm. I'm good enough to get by, but never comfortable being good enough. My partner is a HVAC tech from florida, boilers are not in his vacabulary. I'm teaching him water, and he is teaching me air. We are both trying to reach out and get as much knowledge about both worlds
as possible. Comfort air has a great place there in Centinnele, for training in the air, but still don't know where or what the best is for the water. So can you point me?
Oh and do you know of a rigging crew that removes these large boilers from the basements?
Thanks for your time again.
Chris

Chris Spannagel

decent 90% commercial unit

Hey Mark I also wanted to ask if they do make a 90% that is over 199k btu? If so, what is it? I really like the new high effeciency boilers, have put a couple in up here, and have had no problems. By the way it is really snowing here not sure if I like living here right now Thanks again
Chris

Mark Eatherton1

It was low...

the lowest it had ever been during that picture. My wife works for Denver Water Dept and got this picture from their drought files.

As for courses, we offer a lot at Red Rocks Community College.

http://www.rrcc.cccoes.edu/constructiontech/hvac/hvac.html

I'm getting ready to start the Hydronics Radiant course this month. It's 15 weeks of talking about nothing but radiant. Radiant walls, floors ceilings, panel radiators, piping systems boiler configurations, 2 way, 3 way, 4 way, Variable Speed Injection. You name it, we cover it.

However, we DON'T spend a lot of time talking about the basics. Thats covered in the Fall class, Basic Hydronics. The name is somewhat misleading...

I've had as many as 4 students at a time coming down from Summit county. A long trek for sure, but well worth it IMHO.

Check it out.

ME

Mark Eatherton1

90 percenter...

Heat Transfer Products has just released their 399,000 btuH condensing Munchkin. It has the potential of operating in the 98% thermal efficiency range, and runs about 90% efficient with high temp (180 deg F) applications.

ME

Mark Eatherton1

Here's what it looks like in the summer...

from my front porch. A panoramic digital photo if you will.

ME

Chris Spannagel

that is a great shot

Like your pic. Do you know Carl Cechennie up there? He is a great customer of mine. Say Mark, I thnik I already asked you in a previous thread, but do you know of a company down there that removes these old boilers? It is going to need a cutting torch I think. I don't want to do this too if I can get a sub and pay them. Plus my window for completing the job is 7 days. which means hustle every chance you get. you know. Anyway, if you know of somone or could point me I would be gereatful. Thanks. By the way the snow has stopped, and left it prime for some snowmobiling. Good stuff
Chris

Mark Eatherton1

Who ya gonna call...

Boiler Busters!! They abate AND remove. In fact, we've even hired them to move new boilers in!! That was a change of pace for them.

Call Eric Leonard at 303.232.1607 Tell him I said hey.

I was going to try and make a run up to the lake this weekend, until the blizzard set in...

No, I don't know Carl, but I'd bet you a donut if you asked him if he knew my father (deceased) he'd say yes. My dad was Joe Eatherton, pool shark at large, master plumber on the side...Spent at LOT of time at the Inn

Good Luck!

ME

Chris Spannagel

thanks Mark

I really appreaciate your time and help. Your full of useful info. I hope to sit in one of your classes soon. I had one more question. I am looking at the munchkin, the 399. I have installed a few Pinnacles I really like them. they are the same as we know. What I need to know, is how do they derate those? I know it is different, but don't know how different. I think I can get away with fewer boilers this way, and I really like the modulating boilers. In combo with a staging control, I can really save these people some money. Thanks again so much for your time.
Chris

Chris Spannagel

A pic for you

Here is a shot out the back door this morning. I live just south of Fairplay, we didn't get as much as breck but good enough.