Heat Loss discrepancy

Tom_133

I am quoting a boiler swap that is 6660sqft, with a ton of windows and doors. I did the heat loss on Uponors radiant heat loss program and got 145K btu than I had my salesman stop by and he did it on Slant fins program and came up with 220K!!



What are most guys using for heat loss programs? I would love an Ipad Heat loss app!!



Thanks Guys!

Snowmelt

Taco

Ever try taco flow desighner?

Rich_49

Slant Fin

manufactures boilers and baseboard . Uponor does not , what do you think ?  I have never had a bad Uponor ADS heat loss in 9 years . Just make sure you entered everything right .  Just finished a house that is 7267 and design load was 108K so 145 sounds about right . 

Jamie Hall

Do make sure

that you have entered everything right -- particularly window type and quality and insulation.



Either figure could make sense.

icesailor

Not true:

Slant Fin has no connection to the design and implementation of the "Heat Loss Explorer" other than to take the heat loss calculation, developed and taught by IBR since the 1940's. Until they stopped teaching it.

ASHRA and ACCA Manual J programs are warm air programs, adapted to hydronics and heat. There were a lot of political issues with bringing the IBR program to computer users. When IBR went out of existence and was taken over by the GAMA, somehow, it was resurrected and adapted by Slant-Fin in a WIndows format. If you ever took the IBR heat loss classes, and used them extensively, you will see that what the Heat Loss Explorer does is use the IBR factors to run the program. If you get a H-22 Heat Loss Guide from the GAMA or have an old IBR H-22 guide, you will see all the same factor numbers.

I can't say this as a fact, but I was told from way back to the beginning of Radiant Heat (late 1970's, early 1980's) that with Radiant, you didn't need as much radiation. Perhaps that is true and taken into the calculations of Uponor and other programs. I had a Heatway program and a Watts and other programs.  I have owned many computer heat loss programs, going back to an old DOS program that was based on ACCA Manual J. The factors are completely different. Like building orientation for solar gain. IBR says that the sun doesn't shine at night so disregard it. They worried about roof overhangs. Solar gain was considered for cooling, not heating. I never found any computer program that gave comparable results to any other. "Crackage" is just another way of calculating "Infiltratiion". Electrical appliances ADD heat and don't need to be added in.

Its disingenuous to say that the Slant-Fin Heat Loss Explorer isn't any good because Slant FIn uses it to sell their equipment. More people use it because it is cheap (free), accurate, and easy to use if you understand heat loss and how it is calculated. Most don't.

Well over 90% of baseboard I installed was Slant Fin. I've never installed a Slant-Fin boiler in my life. But regardless of what the emitters I was using, as long as I picked emitters that covered the loss, that's all that mattered. Regardless of who or what said what to use. The only thing that is "Tricky" is Cathedral Ceilings. They are in all programs. You have to know how to "force" the program.

icesailor

Slant Fin

I'd trust the Slant Fin. But only after YOU (or I) did the calculations.

That's how and why I started doing my own calculations. Its not that a salesperson is trying to sell you more than you need, they are more worried about not enough heat being installed and getting a call about a cold house. Its called CYA. I've heard stories from Salespersons.

If you did the HL calculations on the Uponor programs, get the Heat Loss Explorer. I'll tell you that it is easier to use than any other HL program I have ever used. If you can run the Uponor program, you can run the Heat Loss Explorer. I've never seen any HL program that is more transparent.

Just be sure that you are comparing two kinds of oranges and not two different fruits.  

nicholas bonham-carter

Two heat loss programs arriving at a different result

The difference may come about be cause a different design day temperature had been entered into the program.

That can make a big difference.--NBC

Tom_133

Should be closer

I was with him as he did slant fin program no padding or bologna business. I can see being off a few thousand but we're miles apart.



I was hoping to get some feedback on what others are using and if anyone is using their program on an Ipad. I really want heatload pro but it will be an expensive venture due to not owning any PC based computers.



I can also post the 3 three floors of numbers and if you want to run the numbers as three big rooms for argument sake



The building is 74 x 30 = 220

basement floor is 2220sqft 9' ceilings, with 15 sqft windows and 92 sqft of doors

first floor is 2220sqft with 10' ceilings, 215sqft windows and 443 in doors

2nd floor is 2220sqft with avg of 9' ceilings, 149windows and 121



lots of glass and for kicks I measured the baseboard that was installed in 1984 and it matches the slant fin heat loss dead on. The boiler is even perfect size for the slant fin estimate.

icesailor

Seeing:

Did you see what loss factors he used? Unless you understand what loss factors he set for the parameters, you have no way of knowing what is being done.

For example, if it is a wood frame house with 2"X4" framing and 1/2" plywood and sheetrock, and 3.5" of insulation, the factor is .07. Remove the insulation and it becomes .25. If the wall is insulated and 2"X6", the factor is .05. Understand that ".07" means that each 1 Sq. Ft area of wall looses .07 BTU's per degree difference between the inside and outside when the inside is 0 degrees and the inside is 70. Changing the outside temperature makes a huge difference in a 8' X 12' wall. And the radiant programs I saw, all used a lower inside temperature. That makes a difference. If you use a Heat Loss Explorer program, when you set the wall loss, when you click on the box to get the choices, wall types will come up so you can pick your type. Every factor listed is straight out of the IBR H-22 heat loss guide. Did he give you a printout of his calculations? You can check his factors. I could never figure out the factors used in other programs compared to IBR.

The reason I started doing my own calculations was because I lost two jobs to a competitor who used a different company. I had a bigger boiler and more radiation on the same job. To the point that there wasn't enough wall space for baseboard. I asked the calculator how he did it. He was one of the owners of the family owned wholesaler. He told me he did it like his uncle taught him and never had a complaint. He gave me his copy of the H-22 heat loss guide which IBR used in the classes. It gives you the problem and shows you how to calculate. His uncle taught him to use .25 on any wood frame wall. Like it was uninsulated. All the factors to use were circled in pencil. The factor should have been .07, for an insulated wall. It changes glass loss, infiltration, everything just cascades down. From that day forth, I always did my own. Its just as easy to use the worksheets. The Windows Heat Loss Explorer gives you that nice computer printout. And you don't have to use an eraser to change anything.

icesailor

Missing Info:

You've left out a lot of information.

Wall type

Window types and design.

Outside wall exposure length

How many outside walls per room (for infiltration.)

Ceiling height per room. Ceiling construction and insulation factors.

And more.

If you measured the job and it correlated with heat loss explorer, it must have been figured with the proper IBR numbers.

I'm not questioning your methodology. You asked if some were using different programs to come to lower conclusions because Slant Fin was using "their" program to sell more of their products. That's the same foolishness I get from homeowners about Oil Companies. So, they switch to gas because they think they are getting screwed by oil companies. Oil companies with that attitude are called "Out of business". Meanwhile, the Wall Street Crime Syndicate has put in place the same mechanism for the East Coast that Enron did to bankrupt California and the West Coast. Courtesy of our Bankster Buddies.

CMadatMe

I Have Been Using

ADS since its conception 20 years ago. It is a Manual J based program. The critical part to the software for accuracy is air exchanges.. If a home has R-19 Walls, 30 Attic, Updated windows I use a .75 for air changes when doing baseboard. R-11 Walls, i'll use a 1..



I would question that 145K was high IMO. That's 46 btu/hr sqft based on the square footage you posted. At that rate curtains would be blowing from all the convection pouring from the board..

icesailor

Discrepancy's

"Air Exchanges" are "Infiltration".

With IBR, a room with one outside wall is calculated as .012. or 1/2 an air change per hour. A room with two outside walls equals 1 air change per hour. .018. If three outside walls, its .027 or 1 1/2 air changes per hour. That's with insulated and weather stripped walls. If the walls aren't weather stripped and insulated, the factor numbers go up. Its all relative and all roads lead to Rome. Or, a happy and comfortable room.

CMadatMe

That's Old School

Methodology..What's in the wall? What type of windows, etc all go to infiltration. There is no way that this particular house needs 46 btu/hr sqft based on that 140K heat loss.



I just did a 9,000 sqft house, all radiant, total heat loss = 54K. Average conventional heat loss for a 3,000 sqft house R-19 Walls, R30- Attic, Low-E Windows is around 40K. I think Rich's number for his last project is much closer to what the heat loss of this house is then the original poster.

gennady

heat loss

radiant heat loss is quite different from convection. The boiler size required for radiant heating system is at least 30-35% less than a conventional heating system. This is because the way the heating is distributed from floor to ceiling is different with one vs the other. Radiant heat has hotter temperature at floor and coldest at the ceiling, while convection is reversed. With convection radiators the coolest temperature is at the floor and hottest at the ceiling. Also feeling of the comfort with radiant heat is around 67-68F while with convection its around 72-73F. Personally I installed 135,000 input boiler for 7800 SF house, and this winter with 6F outdoor temperature they were comfortable.

Mark Eatherton

Gennady, what if its a radiant ceiling???

Just wondering… :-)



ME

gennady

Radiant ceiling

Radiant heating conducts heat via heat waves, transmitting heat from hot surface to cooler surface directly, without heating air. convection heating happens via air circulating between transmitter of the heat and receiver of the heat. So in radiant heat to be comfortable there is no need to heat and move all air in the room. Ceiling radiant is nice, but sitting at the table feet will be pretty cold. Shade, you know. Just my 2 cents.

Jason_13

Heat loss

Yes I hear the same that manual j was all about warm air furnaces. All types of heat other than radiant heats with convection heat. The more air currents your system creates the higher the heat loss.

Radiant heat works on infrared radiation.

Mark Eatherton

I am just yanking your chain Gennady...

I know you know what you are doing.



Regarding shadowing, in my house with radiant ceiling, the only time the area beneath the table feels cool is when the house is warming up from a cold start. I keep the house @ 40F when not there, and 68 when there. After about 24 hours, the temperature below the table in just as good as the temperature above the table. It's Mother Nature at her finest. She despises any imbalance in temperature and does her best to balance it out.



But I don't think I've ever seen a thermal profile of a radiant ceiling before. At least not next to the profile for a radiant floor...



ME

ChrisJ

IR radiation

They all work on IR radiation, that is what heat is.  I think technically it's via photons in the IR spectrum.

The difference is with hot air furances none of the IR heats objects in the room, only air passing through the heat exchanger.   With cast iron radiators you get a huge amount of IR output, but some convection as well.  With baseboard you get some IR, but mostly convection.

NYplumber

45btu/sqft

Fourty five btu per sq ft sounds like adding safety factors to safety factors and then going to the next size boiler. So long as you know what insulation is in the walls, and the ceiling you should have similar numbers across the board.



From my findings, the difference in programs is the safety factor added and the air change rates. I have been asking taco for a while what "light, medium, etc" are equivalent to on their software, yet have no concrete answers to this date.



On another note, measure the edr to see if that size replacement boiler is smaller or larger than what the house can emit.

NJ, Designer

Can you post the load calcs

If you can post the complete load calculation I can try to look it over to see if you put in anything to make such a large difference,



Regarding load calculation software, for manual J acca.org approves only 6, some of them work on a I pad (mobile), I know wrightsoft mobile is only a block load, meaning it can't do room by room load calculations only the whole house. Now for your problem I would try to do a very tedious load calc, with any one of the approved software for manual J and then you can be sure you are oversized by 10-20% like some of the techs here mentioned, with radiant heat you don't need as much heat as with scorched air systems... windows can make a big difference almost all windows even low e and extra insulation are only as good as a R-4 at best, so with large windows you got to know at least how many panes etc...

SWEI

Don't forget

to include window coverings, if you tend to use those in the middle of the night during winter.

Tom_133

Was just hoping...

That someone could let me know if there was a program that is trusted and could be mac or ipad friendly. I do think Gennady nailed it when he said "radiant heat loss is quite different from convection. The boiler size required for radiant heating system is at least 30-35% less than a conventional heating system". That makes sense and could be the discrepancy in the numbers. This house was built in the 80's has 2x6 walls and probably about an R-18 or so in the outside walls. It has very thick heavy curtains on all the windows and it's only a second home used for ski weekends in Stowe Vt. All the baseboard matches the HB Smith that is currently rotting away in the basement about 216K Btu Net load. Thanks all for the help.

Rich_49

A window

Even the best window you could purchase is a horrible wall .  Aside from having a terrible R value it is a surface that will always absorb radiation making your system less efficient .  Don't be fooled by smaller room square footages either . A small room with large windows will almost always require more heat than a larger room with the same windows . Just one of those anomalies I have noticed over the years

CMadatMe

Heat Loss Program Blah

Forget any program for a minute and think about this. No matter radiant, forced air, baseboard, etc you cannot get around his simple math problem to calculate heat loss thru an out side panel. Air Exchange/Infiltration is the moving target.



(Ti-To)/R-Value = Btu/hr Sqft



Ti = Temp Indoor

To= Temp Outdoor

R-Value is self explanatory.

icesailor

Knowing:

Its too bad that IBR stopped doing their heat loss calculation classes. Heat loss is heat loss.

IMO, when you talk about "Infra Rad heat gain or radiant gain, you're talking about "Heat Gain". I thought the topic was "Heat LOSS". The rate that heat energy was lost through a building to the outside. If you are using Manual J for AC/Heat, they are compensating for heat gain, whether it applies to heating or cooling. IBR is ONLY Heat Loss. The rate that heat is lost through a structure to the outside. ACCA is concerned with the rate that heat is gained into a building. Which will be infra-red radiation and straight convection. Heat loss ONLY is through convection. How a heat emitter adds heat shouldn't be considered. Just its ability to heat the building.

If you bother to read and understand the IBR heat loss tables, the comments on the different glass/window types don't matter, as long as you use the proper kind or type. The window type is used and compensated into the total wall type. If you have a triple pane double hung window, in a wall that is un-insulated, the wall looses more heat energy than the window. But if the wall is insulated, the window looses more heat energy per square foot than the insulated wall. It is compensated for in the line on the work sheet or program.

IBR says that the sun doesn't shine at night, when the coldest temperature is found for very short times. So, disregard it. ACCA is all worried about solar gain. Solar gain is a fine thing when you are heating only, a house. The only time I worried about solar gain was in the location of thermostats. Put a thermostat in an East and South East facing room room, and the room gets hot in the morning the thermostat doesn't run, and the rest of the house is cold. In the afternoon, the Weat side gets hot when the East side thermostat is running.  

I don't have any of my IBR books anymore, but I think that if you have Heat Loss Explorer, and you take the same type walls I listed above, the wall loss will change with the change of windows, automatically. If you had the H-22 heat loss guide, every loss factor page has window factors that correct for the type of window in the wall.

ChrisJ

IR

icesailor, I completely disagree that heatloss is only via convection.



You put a cold concrete sidewalk near a house and there is an example of IR loss. Trees, mailboxes, anything cold will suck heat from the walls, windows and doors of a home.

icesailor

Yes but:

That may be, but is the heat from the inside flowing to the colder outside? Is the concrete ADDING to the heat or just slowing down the rate of loss?

I was always under the understanding that heat ALWAYS flows to cold within certain rules, and that dampness flows to dryness.

Water in a lake has the hottest water on the top because the hotter water is lighter and the colder, lower water is below. Until the water reaches 39 degrees which and when it achieves its maximum density. Then, the cooler/colder water drops, giving heat away to the above water. When the water at the bottom of the lake becomes 39 degrees, ice can form on the top. The "Lake Effect". The WATER at the top of the lake and under the slab will be 32 degrees and as you drop in depth, the water becomes warmer. The top of the ice will be the same as the OAT. If the slab is 8" thick, it will be down to 32 degrees at the water level, but still ice. Heat is being lost through convection under the ice. It is also gaining. Ice may melt on the top from OAT, wind convection and solar gain. It only melts on the bottom because of convection. Life on earth depends on this phenomenon. Marine life will perish if the water always froze at the bottom of the oceans and lakes.

Floating ice also expands as it gets colder, and contracts as it heats up. It will develop cracks as it warms up that fill with water from the contraction. At night, when you get radiational cooling, the ice expands and the water in the cracks freeze. The expansion causes one layer to rise over the other, causing "Reefs" or Pressure ridges.