Heat loss calc says one thing, but my currently connected EDR misses the mark by quite a bit....?

adamfre

First off, THANKS for all the help from everyone in this forum. You've helped me make quite a few decisions regarding this house.

After performing a heat loss calculation on my house using HVAC-Calc 4.0, I've discovered the calc thinks my house will need 165,585 BTUH. If you add up all the radiators currently connected in my house, I'm only at 130,080 BTUH. I can't find a previous owner who remembers the heat working, so I don't have anyone's word-of-mouth regarding how warm the original system kept the house, I'm stuck with the numbers (Basically I feel like I'm treating the chart, not the patient... ) It does appear I have one radiator that has been removed, but at the most that only added 36 EDR (8,640 BTUH) to the mix.

My question is, am I going to have to add more radiators to my system, or is it common for my calculation to be so much more than what is actually connected in the house? I've attached a pic of my calc results if anyone is interested....

Thanks!
Adam

Steamhead

Re-check your dimensions- length, width, height, insulation values, window measurements etc. Something is off somewhere. Most old houses are over-radiated.

rick in Alaska

I don't know if you have any insulation in the house, or if the inputs were wrong, but that is some very serious heat loss. Over 50 btu's per foot. I would go back and check the figures carefully before doing anything else. In my area of Alaska, we are in the 15-25 btu's per foot range. I am in what is considered a mild climate area, but still...
I hope your house is more insulated than that, so re-check the inputs before going any farther.
And as far as the steam portion of your question, I am passing that to others as we don't have steam around here except in about two commercial buildings.
Rick

adamfre

@Steamhead I remember reading you saying that somewhere, which is why my numbers surprised me. I'll look again what I selected as materials in the program. I can also print out a more detailed btu report showing individual wall / window / door / whatnot
@rick in Alaska It's an old house built in 1870. No insulation in the walls that I'm aware of, and only a little in the partially finished attic. Although, it's probably a safe bet it gets much colder where you are at then here in Indiana lol.

thanks again!

rick in Alaska

I can't believe anyone would have a house without insulation, but apparently there are a lot out there.
And I will bet it gets colder where you are. Our average low here is about 10-15. Shangri-la I tell you. Most of the East coast is a lot colder and wetter in the winter time than here. But don't tell any one, so we don't get everyone moving here.
Rick

GreenGene

The move was on in the 70's to insulate and energy upgrade homes, Carter had it as a tax write off for all, very simple plan that worked, Reagan/Bush killed it (wonder why), so a lot of homes never got insulated.

Now it's picking up but is controlled by electric companies as a rebate instead of a direct tax write off which creates more interest.

You need to talk to a light foam installer and have those walls filled and the attic beefed up.

Re-do a load calc with the different insulation values and compare numbers.

For a quickie I've used this.

GreenGene

Remember that your number may change by a few thousand and you'll say, "well that isn't much", but that's per hour, x 24 hours = a lot.

My home is 2800 sq ft and is fairly tight, I have R13 walls and R50 attic and double pane windows and my heating load is @84,000.

NY_Rob

Any chance of you getting past usage bills from gas/oil supplier?

Does it make any sense that the 278 sq. ft. "front parlor" can take 22k BTU's to heat? That's basically a 16.5'x16.5' room.
My whole house (1,800 sq. ft.) only needs 27k BTU's at design day temp (15f).

adamfre

@NY_Rob I tried to get past gas bills but the house sat empty for long enough (years) that the gas company didn't have records. I do recall someone saying their kid had a $5000.00 year in gas 5 or so years back, but in that same conversation I was told parts of the house was always cold and others had windows open so in that case i have to wonder if the high gas bill was due mostly to the steam system not performing correctly. (some radiators heating and some not)

Robert O'Brien

NY_Rob said:

Any chance of you getting past usage bills from gas/oil supplier?

Does it make any sense that the 278 sq. ft. "front parlor" can take 22k BTU's to heat? That's basically a 16.5'x16.5' room.
My whole house (1,800 sq. ft.) only needs 27k BTU's at design day temp (15f).

That won't work!!

adamfre

In that particular room, it has 12.5 foot ceilings, 2 west facing 32" x 96" windows, and on the north wall it has a fireplace and a single 32" x 96" window. All vintage 1870. Add all that up with no insulation I expected a pretty high number, but 22k is a tad much

The Steam Whisperer

That sounds really high. My previous 1906 wood frame home in Northern ILLinois that same size with 800 sq ft of windows had about a 52,000 btu load at -4 outdoor. We were well insulated and tightened up ( original windows weatherstripped and walls bases, joist bays sealed, etc.) . One obvious item is that your interior temp is too high. Most uninsulated buildings do not need heating until it is 65F out... interior gains keep it warm above that. Also, masonry structure can flywheel through very cold nights since the masonry protects the interior from shorter periods of extreme cold. I would expect more like 110,000 load for that size home in northern Indiana. Cooling load also looks heavy...unless you have alot of parties and guests in the summer. Again masonry structures need smaller equipment and if shaded, even less.

SWEI

Worst case we've calculated here (10°F design temp) was 29.6 BTUs per square foot -- and that was for an 1861 double wythe brick house with single pane leaky windows, a drafty basement, and minimal added attic insulation. 50 is just plain wrong barring some sort of ridiculous infiltration.

adamfre

Here is the full detail report. It's 7 pages, so I left it as a .pdf. The calc seems to really hate fireplaces.......

Jamie Hall

Just for the sake of muddying the water -- the place I care for has a livable area of about 7,000 square feet. It also happens to have a total exposed area (walls plus roof) of about 8,000 square feet. It has a total of four fireplaces (but all with dampers), one of them huge, and a decent amount of glass -- and very little insulation (almost none in the walls, R16 maybe in the attic). Double hung windows (1810 to 1893) with outside storm windows.

It uses about 25 BTUh/sq. ft on a design day (86 degree delta T, indoors to outdoors) (176,000 BTUh).

Something seems wrong with the calculation...

MikeSpeed6030

What prompts you to worry about this now? Is it necessary that you replace the boiler before you get a full year under your belt? What is the rating of the existing boiler?

I certainly wouldn't add radiators yet.

BobC

Along with the rating (in sq ft of steam) you need the EDR rating of each radiator. I suspect there is something wrong with the way the system is operating, do you know which radiators are not working correctly?

Some pictures of the boiler and the piping around it might prove useful.

Bob

adamfre

At one time my basement flooded, putting the gas valve, manifold, and burners under water. They drained the basement but didn't service the boiler, resulting in rusted out burners, a manifold full of rust, and a ruined gas valve. The boiler is a generation Peerless no longer stocks parts for soooooo, it's time to purchase a new boiler. I also need to replace my wet returns which were buried in my crawl, repair a few mains that were saw-sawed out to make room for AC ducts (??) and a few other odds and ends. Seems now is the time to complete this project, rather than waiting.

adamfre

Hi @BobC I've got pics of the system, and my EDR numbers listed in other posts on the steam forum. I think the posts reference a steam house in Indiana....

adamfre

Looks like I DID goof the report a bit. I didn't add the fact I have storm windows. Attached is the corrected report.

adamfre

Very good information there, @Hatterasguy . Re-running the calculation at a ΔT of 59F (I simply lowered the inside design condition winter temperature to 65, as you recommended, to accomplish this). That totals out to 139,710 BTUH, within 10K of my total currently connected EDR.

gerry gill

i've used hvac calc for years and i do feel it must have a significant safety factor built into its program. It does seem to oversize a tad bit.