Manual J Service FAQ and Frequently Asked Question Tutorial

At we can also offer a Manual J Service, or a Manual J heat loss and heat gain calculation.  We get alot of questions about Manual J so we will attempt to address the Manual J FAQ or Frequently asked questions below.

What is a Manual J in regards to HVAC? 

It is a calculation that compares your construction project and the components to your local climate zone data. This gives you an output of the BTU of heat gained and BTU of heat losses from the structure. This can help you with subsequent calculations like Manual S equipment sizing and Manual D duct.

Is a Manual J Free?

There are several ways to do a Manual J free.  You can learn the calculations by hand, there are spreadsheets, and also online softwares that offer some type of Manual J calculation.  The biggest problem with doing only one or a few Manual J calculations is that it could possibly take you a long time to get the calcuation correct.  If you spend more time on the calculation then what it costs a Manual J service like to create a Manual J then your net savings from a DIY Manual J could be negative.

For example, if you make $50 per hour as a GC and you attempt your own Manual J Heat loss calc and it takes you 4 hours the net opportunity cost would be $200.

Next example, is if you hired to create your Manual J heat loss for $79 your total cost would be $79 to create your Manual J Heat Loss.  The lead time would be about 4-6 hours.

In this example you would save roughly $121 dollars having your Manual created by a Manual J Heat Loss service like, the true value is gained because you can also work on your client’s construction during the time your Manual J is created.  Whereas if you choose a Do It Yourself Manual J route then you will be sidelined for the amount of time that it takes you to calculate your Manual J heat loss, heat gain, and latent load.

How is Manual J calculated?

Manual J is calculated by hand, through softwares, and through spreadsheets that allow you to input the data on your construction project.  This then compares your construction components to the climate zone that you are building in.  The end result is a calculation that includes the heat loss, heat gain, and latent load of your structure.

How long does a Manual J take?

We can create a Manual J in 4-6 hours.  We would need you to email us your order number (obtain a Manual J Heat Loss order number here), jobsite address, and square footage to  As long as your email contains this essential Manual J data, we can typically get it back to you very quickly.  

One caveat is that many other Manual J Heat Loss services actually take days or weeks to return a Manual J.  At we use a “Just In Time Energy Report” processing approach.  As soon as your order arrives with the proper information, we print off a full size set of plans, and start on your Manual J heat loss and heat gain calculation.  

So what is the final answer for how long does a Manual J take?

4-6 hours.  We can complete a Manual J in 4-6 hours.  We need an Order Confirmation number, pdf plans, jobsite address, and square footage.

It can take longer for other Manual J services to complete your Manual J because they spend more time processing the order and moving it through multiple departments in their company.  Each step adds additional time and cost to the Manual J.

Do I really need a Manual J?

If your building department, energy code, or building inspector request it, there is not much you can do to avoid creating a Manual J for your project.  Sometimes you can get an exemption, but this is difficult, to say the least.  If the Manual J is not required on your permit, you do not need one to build your home.  You might want one to ensure that your HVAC system can handle what your climate zone has in store for it during future cold winter days, and hot summer nights.

How much does a Manual J cost?

We charge $79 for a Manual J heat loss and heat gain calcuations.  If you search around the internet, and you probably have, if you are reading the Reschexpert blog.  Then you know most companies charge 4 to 5 times this amount for the same calculations.  We have a streamlined process, we enjoy helping nice people with construction projects, and we ultimately want to help everyone build the most efficient homes possible.  With money and greed not being our only motive, we are able offer a low cost Manual J option to clients that is delivered in 4-6 hours.

The easiest way to make the process go smoothly is to email us your order confirmation number (get it here), jobsite address, and square footage and we will get you taken care of.

How Does a Rescheck Compare to a Manual J?

Related Links:

Rescheck Report for Additions

Entering data into Rescheck Web, Rescheck Desktop Basic Tutorial

Free Rescheck Web Is Online

Manual J Manual S Manual D Rescheck review FAQ

Simple Instructions to Complete a Rescheck




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