I have our local code book which should put you close to the number in the IRC. I sited the code above. I will also remind you that I am a municipal inspector as well as contractor. Man. J is the only named/approved load calc in a resi change out. At inspectors discretion other methods may be used.
Are there areas covered by no codes or others that don't require load calcs. Sure, but you gave a matter of fact opinion that Man J is not needed or appropriate here. BS. Come out to MI see how that works for ya.

You continue to mis-inform.

Joe, what you describe is what inspires and motivates some people to avoid getting permits and dealing with inspectors. That is a very bad thing. Fortunately, the inspectors where we operate are very cooperative, reasonable and actually appreciate the value of good engineering.

Joe, what you describe is what inspires and motivates some people to avoid getting permits and dealing with inspectors.

My position has been that code requires load calc. (specifically manual J) in many areas for OP's job. So you appear to be suggesting that my assertion that this code (law) may be enforced deters people from getting permits? Or are you endorsing working without a permit since you already suggest that following the code is unimportant?

I don't think I'm the one promoting lawlessness here.

Fortunately, the inspectors where we operate are very cooperative, reasonable and actually appreciate the value of good engineering.

Me too providing they follow the code or use approved alternative solutions.

You aren't the ME in the out fit are you? Most of MEs wouldn't be caught dead arguing that load calcs for a resi retrofit are not necessary.

Again Joe, all my comments were in regard to this specific cited example. Please stop quoting my statements out of context and then generalizing my statements. I didn’t state that “ load calcs for a resi retrofit are not necessary”. I suggested that doing a more accurate and lower cost actual energy usage analysis in lieu of Manual J was more appropriate for this situation and should be approved (either with or without a PE stamp). I am sure that there are locations where the inspectors will only approve Manual J analyses and perhaps even if only accomplished by some specific contractor(s). However, that is an entirely different subject altogether and I suspect people in those locations find creative ways to address this in less than good ways.

Mr. Ami, you unethically took sailwayrb’s quote out of context and you already answered the question yourself that you asked me to answer! Here is the correct full quote of what sailawayrb said two weeks ago to respond to Chris J when he accused her of hawking:

“I think most people can see the difference between providing helpful information versus endlessly just hawking Manual J analysis as the cure all for world hunger and that they do it.”

That was my point and what this thread has been all about and little else…hawking Man J. And then today sailawayrb even said:

“Well, you can’t really fault someone just for marketing what they do for a living provided that they don’t overly distort the facts when doing so.”

So even when she tried to cool my jets you still lost your cool and you still attacked her relentlessly.

So Mr.Ami, are you the chief ME of your highly esteemed firm? Or perhaps you are in a state like Badger where you don’t even need a HVAC license to operate and you only need a pulse to do Man J…

I am sorry but some of you guys are just wack jobs that distort the facts to apparently try to get some business. That is unethical too. So yeah I am calling you out on it.

Mr. "bound"
As far as context I'll remind you that this trail started by quoting you:

"Sounds like Man J hawking to me when it clearly is not needed by the OP given his situation."

You took this a step farther by describing an industry standard and often legal requirement as a:

"questionable practice"

I asked sailor to ammend her statement as YOU were taking it out of context and too far.

Instead Sailor added:

"Joe, Manual J is indeed not needed here and is not even appropriate here..."

and some variation more than once. Since it is true that it is not simply needed but legally required where the IRC or something like it is enforced than the comment is dead wrong in any context.

I think sailor realized that and back paddled with this final comment:

"I only suggested that doing a more accurate and lower cost actual energy usage analysis in lieu of Manual J was more appropriate for this cited example and should be approved"

I find it slightly confusing due to the "lower cost" and "marketing" comments as it is not customary in my AO to charge for a load calc as it is a required part of the replacement. I let it go however as it appeared my point had been made with someone (Sailor) who usually offers good advice.

Apparently the point is still lost on you, but as long as you don't start handing out advice with your 10 minutes of experience in the HVAC business you wont harm anyone with your misguided opinions.

"So Mr.Ami, are you the chief ME of your highly esteemed firm? Or perhaps you are in a state like Badger where you don’t even need a HVAC license to operate and you only need a pulse to do Man J…

Personally I hold 10 Licenses and multiple certifications in the state of MI and elsewhere. Yes licenses are required in MI to contract and inspect.Perhaps you could tell us about your HVAC licenses and years of experience...

I am sorry but some of you guys are just wack jobs that distort the facts to apparently try to get some business. That is unethical too. So yeah I am calling you out on it.

....and some people are trolls looking to cause disruption wherever they go. Distorting facts would be saying you and sailor were mistaken? Saying Man. J is an industry standard and code requirement in some places? Sorry wrong again, that's called stating facts.

Since you are "calling me out on it" can you show me where I have not spoken the truth. Heck I cited code numbers. Why don't you cite codes where Man. J is not required or called "questionable". Again I remind you, YOU were the precipitous of this path with your misguided comments where you misquoted, embellished and took Sailor out of context.

Since you are "calling me out on...." being unethical and trying to get some business, perhaps you'd like to point to the occasion I asked for money or offered anything for a fee in my years and 4,000 odd posts here. I could offer you scores of examples of advice, visits and assisting in aquiring a full refund from a manufacturer in MN to a consumer in OH all at no charge. There might be one or two occasions I charged a modest fee, but this is not just a hobby for me is it? I bring decades of industry experience to the table, no? Tell me why I'm unethical for giving away time, sometimes product and good advice.

Now tell me what you have brought here other than venom and discord in your 2 dozen posts. Tell me about all your free professional advice from your years in HVAC and geothermal, or engineering, or building or.......

Mr. Ami, your opinion and position is based on your close-minded and rigid inspection policy in MI. The OP is from NY. As sailawayrb suggested inspectors in the vast majority of locations would accept a energy analysis instead of Man J for the OP’s situation “(either with or without a PE stamp)”…another out of context quote… I only asked you one question…the same one you asked sailawayrb…are you the chief ME in your esteemed firm? I am glad you have more than a pulse unlike some experts here but with all your words you still didn’t answer this one question. So I will ask more questions…are you even an engineer at all? Does someone have to be an engineer to be knowledgeable about HVAC design and to get their design approved in MI? I feel pretty the certain the answer to all these questions is NO. You were not the person I called out for hawking Man J business but you feel compelled to defend this person which is your choice but another indication of your true character. I just came here to get ICF info but I have found great joy in calling out BS and finding the truth.

Mr "bound",
The IRC stands for International Residential Code, so it is not limited to MI by any stretch of the imagination. I have repeatedly stated facts and rules, not opinions.

I already mentioned that inspectors under the IRC may approve alternatives, but you may find that many don't, because manual J is an industry standard.

I am the owner of my company, it is not necessary to be an ME to be a mechanical contractor in most cases I'm aware of, nor to be a code official. It is however required to be knowledgable of the law and follow the code.

Here's a tidbit for you since you think it's different because OP is in NY:
• Heat loss calculations and system sizing (ECCCNYS 503.3.1
and Chapter 3)—Heating and cooling load calculations must be
done according to a specified process.
Air Conditioning Contractors of America (ACCA) Manual J (see
Appendix B for ordering information) is required by the 2000 IRC
One and Two Family Dwelling Code (see Section M1401.3). The
design parameters used for these calculations are given in ECCCNYS
Chapter 3.

This from the New York energy code. It even cites the IRC (why they must like the "closed minded and rigid inspection policy in MI). It's the effing law in NY- genius. So tell me again how the load calc is clearly not required.
It appears the NY State would not agree with you that this is a questionable practice.

The nice thing about being the self appointed BS monitor is you don't have to be trained, licensed, knowledgable, accurate etc. to spew your BS. I never attacked Sailor, I implored her to correct her mis-statement because you took it a step farther (hoping she would talk you down since you seem to take everything she says as gospel).
Nor did I quote her when this started, I quoted your BS.
Nor did I defend anyone, I said your statements and some of sailor's were inaccurate.

BS is accusing with no supporting docs so put your cross hairs on you not me. I have referenced 2 codes now, you have referenced nothing. Took me two seconds to google the NY energy code, but you never bothered because you don't concern yourself with facts. Why don't you leave the discussion of industry practices to the grown-ups who practice them?

Mr. Ami, sailawayrb already eloquently explained how IRC can be departed from and when it can not so I don’t have need to provide anything. If you choose to be a close-minded rigid and maybe even crooked inspector that is your business and your problem. Now you are just writing many words to save face but your character has already been exposed for all to see. Just because you are stuck in a low paying inspector job and have to play the geothermal con game on the dumb public to try make a living do not take your frustrations out on intelligent people who actually believe and acomplish good green construction. And I was right about the answers being NO to all the questions, eh?

Joe,

You might have noticed the similarity in opinion and arrogance between the sailor and her new "advocate". A bit more strident and vulgar, but still the same old crank.

It is a waste of your time...

You are perfectly correct, of course,and smart people get it.

Mr. "bound",

How charming. So much easier to name call than support a position demonstrated to be inaccurate.

.....and now you are smarter than every geo owner and installer.

But that trolls could be forced back under rocks.

Badger, even Sailor came to understand the folly of their position.

And yet...

...the quality of typical Manual-J's performed by NY state HVAC contractors are just as lousy as in most places, if experience is any guide. :-)

Sanity checking anybody's Manual-J against a fuel use calc when looking at replacement equipment is still (a modest amount of) time well spent. If it differs by a relevant amount, make the contractor defend their numbers at every detail.

I've yet to hear of a code official taking an HVAC contractor to task for oversizing, though it's at least theoretically possible in California, where oversizing beyond a given fraction is technically a code violation under Title 24. There are a lot of ways to sneak a thumb on the scale, and it takes a fair amount of due-diligence to ferret those out. But a fuel-use calculation should be able to determine when it's complete crap, if not the exact location of all the errors of omission/commission.

Dana,
I agree with you that the quality of manual j in the field is not stellar. Worse yet is understanding of manual D.

I'm certainly not here to suggest that manual J is an end all be all, I simply pointed out that is was a code requirement unless some alternative was approved.

I'm certainly aware of inspectors requiring load calcs. One local contractor comes to mind that has made a career of buying 100MBH furnaces and 18x8 duct with a "1 size fits all" attitude. In many areas this contractors feet were held to the fire and that was one of the codes quoted in his citations.

Some time ago I mentioned that whether or not it is enforced the contractor must still do the work or it is actionable. RE better calculators, remember the code is a minimum standard not an ideal job.

We are required to present a heat load in most of the cities here in the Minneapolis area, they like the local gas companies--modified Manual 'J'. They will accept a "real" Manual 'J', but I am quite certain no one ever sees them.

The gas company could be more helpful in verifying the fuel use and incorporating it in their popular, if crude, form.

We are trying the raise the bar by insisting our "competitors" produce a heat load to the homeowner in order to qualify for a job. The homeowner must take charge and insist.

Sadly we have often measured available radiation and concluded that the boiler specified is twice too big for the radiation and still been ignored!

Posted By joe.ami on 28 Apr 2015 09:56 AM
I'm certainly not here to suggest that manual J is an end all be all, I simply pointed out that is was a code requirement unless some alternative was approved.

Precisely so...and far better alternatives are often approved in many jurisdictions these days.

Posted By Dana1 on 13 Apr 2015 12:14 PM
The importance of thermostat settings and heating degree-day base can be illustrated on a recent set of numbers I ran for house in Portland, ME.

The house a ~1400' 1940s Cape, heated with cast-iron propane and the owner was converting to natural gas. He wanted to spec a mod-con solution rather than converting his aging propane burner.

Before knowing that the house was kept in the low 60sF during the use period (and knowing nothing about plug load inputs, etc), the 65F fuel use calc implied a heat load of ~25,000 BTU/hr @ +2F (ACCA's 99% outside design temp for Portland ME.)

After learning the true low-60s indoor temp during the fuel-use period, I worst-cased it using a 55F balance point, then interpolated to a higher 70F interior temp, whe rose to ~32,250 BTU/hr.

That's a whopping 29% higher, but that's also most likely to be worse than reality, since with a ~62F interior temp and some occupants the balance point was likely to be higher than 55F, independent of any reasonable assumptions on plug loads and mammalian occupant output.

At the implied 32K number that's about 23 BTU/hr-ft^2 , which is pretty high for an insulated 2x4 house, even at the modest 1400' footprint, which suggested to me that the foundation may lack insulation &/or the house has a lot of parasitic air leakage. (Have yet to hear back on those details.) Reality might be closer to 30K, but it's probably still worth lowering the load for comfort reasons.

But even if we upsized 25% from the 32K number it would not change the boiler choices, but even if we sized it EXACTLY at 32KBTU/hr output the system would have margin at +2F outdoor temps, since the assumptions in the fuel-use calculation were all skewed to the high side, such as assuming 85% combustion efficiency on a 25 year old 140,000 BTU/hr input propane burner ~4x oversized for the load, and a balance point that was 7-8F under the interior temp in an unoccupied house with minimal plug loads, etc.

The TT Solo-110 he had been considering (as recommended by his heating contractor) has a min-fire output comparable to the 99% heat load, which seemed ridiculous on the face of it, but I ran the numbers for him (twice) anyway, and suggested he look for those heat leaks, since they're probably worth fixing just from a comfort point of view, and would likely be cost-effective on fuel use savings over the longer term. He has sufficient cast-iron radiation to run at the edge of condensing with the Solo-110, but it's ridiculous to have a modulating boiler if it literally never modulates. I recommended he insist on going with the smallest of the line Solo-60, but he might be better off finding a different contractor.

The guy now reports that he hired someone to do a an energy audit & Manual-J, which came in at ~29,000 BTU/hr.

Simply splitting the difference between the known overestimate from the original base 65F calc and the known underestimate based on the base 55F calc comes at ~28,625 BTU/hr , which is within 2% of the Manual-J derived number. Just lucky, I guess !?!   It's within the calibration error of the measuring instrument (the nameplate efficiency of the old boiler), and within the inherent error of any Manual-J.

The auditor also suggested that the load can be brought down to about 20,000 BTU/hr with retrofit air sealing and insulation, which is credible, given that the house reportedly has no foundation insulation.

At the post-retrofit heat load it means even the Solo-60 is oversized for his average winter load, and it won't modulate very much, but he may go with it anyway.  His contractor is still lobbying for installing the Solo-110, which has a min-fire output quite a bit more than the post-building-upgrade heat load of the place, which is absolutely nuts.  (I'd find another contractor if it were me, which I've suggested multiple time.)

So yes, a fuel use calc can be very useful stake in the ground (even if it's not a code-approved method ), and the accuracy issues can be managed.

"So yes, a fuel use calc can be very useful stake in the ground (even if it's not a code-approved method ), and the accuracy issues can be managed."

Just to set the record straight, I never said other methods weren't useful, I simply corrected the opinion that the manual J was unecessary and the characterization that it is a "questionable practice".

The reason the distinction is important to me is that people come here for advice and many are DIYers. If we have a contributor editorializing on an "industry professional's" comments that manual J is not preferred and the same DIYer tries to sell that to his inspector when the time comes, that out come may not be desirable.

I'm not conflicted by telling folks what the law is and telling them there are better ways to achieve the intent. I have mentioned designs where man J would have grossly oversized the system and actual use helped us pin it down. I'm also not conflicted by saying the code is a bare minimum standard and wrong headed in many cases.

Frankly most inspectors aren't going to ask unless something is obviously off sized. If they do ask and one were to show them size based on actual use, most inspectors would accept that. I said before however many inspectors likely couldn't do a calc by usage if asked and some likely couldn't do a manual J.

I have also said there is little consequence in oversizing a gas furnace unless it is grossly so. In fact jumping one size or so might reduce operating cost. Particularly on a retrofit where a larger system was planned for in the duct design.

So my intent was to correct an inaccurate comment. As early as page 2 someone began referring to Man J as a money making ploy (which implies that it is extraneous) and as early as page 3 I mentioned that load calcs were part of a no charge estimate in retrofits for us. This is also where I first commented a larger furnace might reduce operating costs.

In day to day practice my intent like Badger's is to educate folks to look for the contractor who at least does a man. J load vs sizes by thumbulator.