It's a mistake to say without a load calculation somebody's going to end up with a system that will be undersized. Most of the time when people are putting in systems without doing the load calculation they end up oversized
True, but we should always do a load calc. Most of the time here in the California central valley you are fine just replacing the system with the same size because most units are oversized by the contractors. In addition, now that we use variable speed it is not as much as a concern, not counting the extra cost for a bigger system. However, don't assume that the contractor that installed the original system actually did a load calculation along with a duct design. In 2006, I was the general contactor building homes in Copperopolis California for a developer. I had done the load calculations on these homes myself and specified the size of equipment. Unfortunately, my HVAC company was too expensive to do this project as I had a developer I was doing the homes for and I couldn't justify the expense of my company when several bids came in thousands less than my HVAC company. I picked a company out of Salida and used them for the HVAC. However, I was watching the owner of this company laying out the ducts in the home I had severe doubts because he would look at the room and I heard him say 8"or 6", he kept repeating this as he marked on the floor the size of the duct and where he wanted the registers as he moved around the home. I asked him how he knew the sizes as he didn't have a layout of any sort. He said "I have done this long enough that I know what size needs to go to each room". He didn't know that I had been doing HVAC for over 20 years at this time and had been doing true duct design using wright soft for almost 8 years. In the end I redid the duct design myself and insisted he change the sizes to the rooms to fit my design. He went ballistic even though this would negate any liability he would have for sizing the ducts. We got into it and I did the typical builder MO of telling him I would withhold payment unless he complied. That's when he found out who I was and called me up and asked "Who do you think you are Mitch some big F*****g developer?" In the end he complied and we switched to my company on the project after he finished the houses he had contracted to do. The best part after our run in every time I sent anything to him I would sign it Mitch Bailey BFG Which of course stood for Big Fu****g Developer. I don't think he ever caught on.
Mitch BFG...enjoyed the video and story on real world duct sizing!
It's a mistake to say without a load calculation somebody's going to end up with a system that will be undersized. Most of the time when people are putting in systems without doing the load calculation they end up oversized
True, but we should always do a load calc. Most of the time here in the California central valley you are fine just replacing the system with the same size because most units are oversized by the contractors. In addition, now that we use variable speed it is not as much as a concern, not counting the extra cost for a bigger system. However, don't assume that the contractor that installed the original system actually did a load calculation along with a duct design.
In 2006, I was the general contactor building homes in Copperopolis California for a developer. I had done the load calculations on these homes myself and specified the size of equipment. Unfortunately, my HVAC company was too expensive to do this project as I had a developer I was doing the homes for and I couldn't justify the expense of my company when several bids came in thousands less than my HVAC company. I picked a company out of Salida and used them for the HVAC.
However, I was watching the owner of this company laying out the ducts in the home I had severe doubts because he would look at the room and I heard him say 8"or 6", he kept repeating this as he marked on the floor the size of the duct and where he wanted the registers as he moved around the home. I asked him how he knew the sizes as he didn't have a layout of any sort. He said "I have done this long enough that I know what size needs to go to each room". He didn't know that I had been doing HVAC for over 20 years at this time and had been doing true duct design using wright soft for almost 8 years.
In the end I redid the duct design myself and insisted he change the sizes to the rooms to fit my design. He went ballistic even though this would negate any liability he would have for sizing the ducts. We got into it and I did the typical builder MO of telling him I would withhold payment unless he complied. That's when he found out who I was and called me up and asked "Who do you think you are Mitch some big F*****g developer?" In the end he complied and we switched to my company on the project after he finished the houses he had contracted to do.
The best part after our run in every time I sent anything to him I would sign it Mitch Bailey BFG Which of course stood for Big Fu****g Developer. I don't think he ever caught on.