Heat Load Calcs (ACCA Manual J Calcs.....)

[That Inspector Guy]

I am a third party contractor, assigned to a community in a Philly suburb. For the last 2-3 years, they have been making HVAC contractors submit heat load calcs (meeting the requirements of the ACCA manual J) for new systems, or for replacements, as per M1403. HVAC contractors all cry about it, especially for replacements- the mantra is "why load calcs?? We're replacing it with the same size!" to which my answer is always "How do you know the existing system is properly sized?" I'm just along for the ride with this Community, not trying to rock the boat, but I am wondering if they are overboard with this whole thing.

Anyways, the questions are:

1. Does anyone else on here make them submit load calcs, or do you let them submit the old "Heat Certification Letter?"

2. Are we overdoing it by making them submit the calcs for system replacements???

3. Are there any good training programs or websites that show you how to interpret the different Load Calc printouts that are out there??????

 

[TJacobs]

I make them submit them. So at least there are 2 of us nutballs...

 

[jar546]

1) Yes, Load calcs, Manual J

2) No

3) Don't know

 

[88twin]

1) yes, manual J

2) no

3) 3rd party providing training in Vail CO. in september

 

[vegas paul]

I used to require them (and do them internally to check) in my old jurisdiction, I'm trying to encourage it now, but I don't want to make too many real big changes right away... give me a year or so!

 

[Mule]

1. Does anyone else on here make them submit load calcs, or do you let them submit the old "Heat Certification Letter?"

Submit load calcs on new systems

2. Are we overdoing it by making them submit the calcs for system replacements???

Yes. We required that for a while and the AC contractors screamed. I sat down with one of the AC contractors that I had been working with for many years and discussed this at length with him. After the discussion our department quite requiring calcs on change outs. The AC contractor convinced me that any contractor can "tweak" the calculations to end up with whatever system they were trying to sell.

So why bother requiring calcs if they aren't true calcs? The AC guy is trying to sell a 4 ton unit...the calcs show 3 ton is adequate...tweak the calcs a little and go ahead and sell the more expensive unit.

3. Are there any good training programs or websites that show you how to interpret the different Load Calc printouts that are out there?????? Without purchasing the software I doubt it!

 

[Daddy-0-]

They are supposed to do the calcs here but we rarely ask to see them. If something really looks wrong we will ask for them but not all the time. It is hard enough to get them to install the units correctly. Asking for a manual J might push them over the edge.

 

[klarenbeek]

We basically do the same as Daddy-O, for heating. Asking for cooling calcs is useless, because there is not temperature a system must be able to cool to. The contractor could simply say he's designing it to cool to 85 or even 90, and there's nothing in manual j or the code to say he can't do that. We actually had someone do that, because the building owner didn't was to pay for a larger system.

 

[That Inspector Guy]

We basically do the same as Daddy-O, for heating. Asking for cooling calcs is useless, because there is not temperature a system must be able to cool to. The contractor could simply say he's designing it to cool to 85 or even 90, and there's nothing in manual j or the code to say he can't do that. We actually had someone do that, because the building owner didn't was to pay for a larger system.

I dont even ask for cooling load calcs as there is no code requirement for cooling.