Heating and cooling load calcs

Pat_11

Looking for heating and cooling load software for residential. Recommendations?

Constantin

I have used HVAC-Calc for our house

From what I can tell, it's the most affordable heat gain/heat loss option that produces accurate results for homeowners. I wrote up a review of HVAC-Calc that goes into a lot more detail. HVAC-Calc is aimed primarily at the air-side of the business

Other programs do additional things, such as helping you lay out a Manual-D compliant air conditioning duct system, radiant loops, etc. These features are usually added on as modules to a core set of features, such as a Manual-J compliant heat loss/gain calculator. However, solutions like Wrightsoft, Elitesoft, etc. are pricey and thus only really make sense for professionals who will save a lot of time spec'ing out jobs and all that.

In other words, if you're not a contractor then perhaps your contractor should be using one of these programs. In my mind, a manual-J-compliant calculation is the very least a contractor should bring to the table. A step up is a Manual-D for the duct-sizing, patterns of hydronic heating, etc. Then again, I am a demanding customer (worse, an engineer!).

I am very happy with HVAC-Calc despite its limitations simply because I have no use for $1,000+ software that becomes useless the minute my house renovation is over (i.e. I am a homeowner who is taking an active part in the renovation). However, for $50, some time, etc. HVAC-Calc will allow you to get a pretty good idea about the options you can explore with your house (insulation, types of glass, orientation, etc).

Unknown

software

check out www.wrightsoft.com

best i've ever used!

Robert O'Connor_3

Constantin

I'm interested in if you ever got your answer to your question about heat loss for multi-level stair wells, and for that matter, open, multilevel tower construction? I run into that fairly often, and scratch my head frequently.

Architechtural design nowadays, along with the many options for heating the structure, can be confusing from a heat loss calculation perspective.

What do you think?

Jed

Ken D.

Heat-Cool Calcs.

Carrier Corp. has a very good product in REZCALC. It is accurate and easy to use. They have good support personnel. Hope this helps.

Constantin

Life can be interesting...

...I got one reply at HVAC-Talk to my question from hydronicsman to treat stairwells floor by floor. However, no official answer was forthcoming from Don Sleeth, the author of HVAC-Calc.

Considering that I got banned from the site simply because I asked in a post how to use the duct-sizing part of the program just for cooling loads (impossible, BTW, you have to work around that manually), I didn't really have an opportunity to ask any of my other questions.

Don Sleeth seems overly concerned that any question whatsoever regarding his program could lead to lost sales and hence his response is belligerent, no matter how nicely you phrase the question. As best as I can tell, HVAC-Talk exists solely to generate sales for HVAC-Calc and anything that chips away at the propaganda is punished with prejudice.

This is a shame, because I think he's missing an awful lot of opportunities to improve his program by listening to what his customers want and/or what they are having trouble with. E-mail is not good enough, as there is no follow-up from Mr. Sleeth as to what features he's working on in the next release, etc.

Also, given the trouble that Mr. Sleeth had answering basic questions such as how to treat exterior fireplace dampers (this time by e-mail), I suspect the calculations inside HVAC-Calc are simply a computerized version of the Manual-J tables. Hence the ommission of garage doors, HRV's, and other relatively common building components in modern homes.

Despite its limitations, I like HVAC-Calc and I wish Mr. Sleeth best of luck with his program. However, unless he starts offering better add-on modules like the competition from Wrightsoft and Elitesoft, he may find his market opportunity shrinking. After all, once a contractor has tasted the advantage of getting the heat loss/gain right with a Manual-J compliant calculator, why would they not want a Manual-D-compliant duct calculator also? How about a BOM and job estimate calculator? Etc.

This is a classic battle of the computer program suites (Microsoft Office) versus standalone programs (Lotus 1-2-3, WordPerfect). The standalone program may be better than the competing module in the suite. However, if the suite only requires data entry once and then calcs out heat loss/gain, duct requirements, BOM's, estimates, etc. then users will put a much higher value on the suite. Hence, I think Mr. Sleeths business model is in trouble, no matter how he prices the program.

Ted_9

Hey Con, just to let you know that I deal Lennox and the HXS19 is a great unit. But as far as single speed condensers go, we sell 90% R410A and the HSX15 is very quiet.

BTW, I'm in Mass and I have a feeling that I know which dealer you talked to. I'd like to talk to you via email; patriotheatingandcooling@comcast.net

Constantin

Looks great but...

... out of my reach as a mere homeowner. Argh!

Matt Undy

I found the advertising of "single home" misleading. What it actualy is is a limited time license and since I had a multi part project on one house it wasn't acceptable. The person answering their phone to take my order didn't seem to care when I was upset that the license wasn't at all for one house but for a limited time.

Also I found the calculations for outside walls a bit limited, if you have something less than 3.5" of fiberglass(such as 2" or so of balsawool) but more than nothing you have to calculate the loss yourself.

Its losses for ductwork in an unheated basement somehow came up as more than the heat needed to heat the basement.

It does have more choices of component types and allows for a more detailed breakdown than other software I have see in its price range.

Matt

Constantin

I ran into the same problem...

...hence, I bought the permanent license. It was worth it to me, even though my discount for having bought two 2-month licenses before ($100) was a grand $25.

You raise a good point though about the heat losses through the basement ductwork and the limited choice of insulative materials. Like I said in my review, his program seems very dependent for data from elsewhere.

In your case, a "custom" wall config may have been in order. Writing such a module would not be a great challenge. Simply establish a boundary condition and calculate a compound R-value from there. Many textbooks have the R-values of most building walls down pat. A little math later,
and you could accomodate all sorts of materials inside the wall.