NFPA 13 states the following:
8.16.4.1.5 Water-filled piping shall be permitted to be installed in areas where the temperature is less than 40 deg F when heat loss calculations performed by a professional engineer verify that the system will not freeze. For some reason I had always thought that Tyco or some other heat trace provider had a program available to perform these calculations. I feel there is a better way than breaking out my old heat transfer book. Our general consensus is that the risk is relatively high with these types of calculations. I’m sure you been tasked with this before; what is the best approach to going about these calculations? Some owners require these calculations to be performed to avoid dry-pipe systems in Florida, even though the location of the iso-thermal line would require dry-pipe systems - I feel this essentially puts all the liability on the engineer. I'd be curious to see how others would normally approach this. In this case we would look to run calculations to justify that a wet-pipe system would be sufficient without any insulation or heat trace. Thanks in advance. Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe
5 Comments
FIREPE25
10/14/2020 10:15:56 am
Do not put in a space that would be subject to freezing. If there are concerns install a dry system. Working in New England anything that is outside the heated envelope is assumed to have freeze issues.
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Nolan Baker
10/14/2020 10:21:34 am
1. Determine R-Values of wall, door, ceiling, etc.
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Brian Gerdwagen FPE
10/14/2020 10:24:18 am
Get with your Mechanical Engineer, if you have one on the project. Look for the 99.6% Low temperature and use that as a guide. If the piping is installed in an unheated attic and the 99.6% is 39.9F, you are probably fine.
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Felipe Pedraza
10/14/2020 11:51:44 am
This is a very fine line that we are looking into here in deep South Texas with little to no freezing periods that may occur in the year. After dealing with the different code requirement's for 10 years in he prevention office and understand the important and heard jobs that the engineers have in determining the correct numbers for everything that gets done. We also understand the price difference from a wet and dry system and depending on size and number of system it can make a big difference on the price. Perhaps the biggest issue that I see right now is:
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David Castillo
10/14/2020 04:14:36 pm
I would suggest getting with a Mechanical (HVAC) Engineer to have the analysis done. A good HVAC engineer will use ASHRAE data files and a good heat loss/gain program that will do an hourly analysis to determine if freeze protection is required.
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