seeking past experience in Norther Virginia

Discussion in 'Quotes and Proposals' started by huyle23, Feb 20, 2011.

  1. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Yes, I do a manual J, yes I do it off the plans, yes it takes about 20-30 min for a straight forward new built house with a full basement.
    No, I do not charge for it, and no, I cannot see how I do my customers a disfavor. I need to calculate the thermal envelope of the house, and I do it in order to correctly size the system I am going to propose.
    So you put in that R-value for the walls, for the windows, for the roof. Size the windows, the doors, you look at heatgain and heatloss, and you come up with a number. That number is usually within 5% of the actual usage number.
    How do I know? We put monitoring systems on most of our systems. So what if I am off by lets say 10%, or worst case 15%? Well, heatpumps come in 1 ton increments, the jump from 3 to 4 tons means a 33% increments. So most commonly, both of us would pick the same size system, assuming that you are always right on target and are never off. Worst case scenario, with a system which is right between two sizes, I pick a 3 ton and you would have picked a 4 ton, or vice versa. What is the operational cost difference? You would be hard pressed to measure a difference.
    Retrofits are more difficult, because both you and me would have to do a guesstimate what to specific Rvalue of a certain wall is. Or a door.....
    At the end of the day, the difference is the time each one spends on it.....and yes, $990, which your customer gets back when he orders a system with you which might be $990 more expensive.
    Guys, don't get too fixated with on the manual J, it is suppose to assist you to design the system, but it is only so good as the numbers you feed the software with.

    It reminds me of the customer of mine who had spend $2000 for an engineering firm to design his 5 ton vertical loopfield for his 2400 sqf new built one story house. They came up with a design which would have supported an 8 ton system. Then they hit natural gas after 100 feet. Then they called us and asked for help, we threw the $2000 design out of the window....and put a 5 ton horizontal slinky loopfield in. Took me 5 seconds and $0.00 to design it.:)
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    My 2cents

    It is a bit more involved for us than 20 min, but we could do one in 20 min if pressed. Just not something we would pass off. Relevant for quoting purposes only.

    We do a lot of room x room analysis for example. Important for the radiant systems we work on.

    The building loads ( commercial and residential) are the most crucial step. It is also usually a back and forth discussion with the builder/client.

    So give them away for free or charge for them, but I would fall towards " you get what you pay for".

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