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In our area, wet standpipe/sprinkler pipe running through unheated parking garages always gets heat tracing and insulation.
On this current project, the general contractor wants us to run a 4-inch main as high as possible to a 7.5-inch thick post-tensioned concrete deck that has a heated space above it and a 24 deg F 1% design temperature below in the garage. They're looping 14-inches of batt fiberglass with a plastic barrier below it creating an envelope around the pipe. The general contractor is questioning whether the heat tracing is needed. We've got plenty of experience 'tenting' sprinkler pipe in attics but never under concrete. I've suggested they hire a mechanical engineer to do the calculations. Does anyone have experience with this situation? Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe
9 Comments
Mike
2/24/2021 09:12:29 am
Good idea. That's the mechanical engineer's responsibility. GC probably won't want to pay for it, though.
Casey Milhorn
2/24/2021 09:30:33 am
Yes, unless you are a PE and/or have been hired on a design build basis, do NOT step out there and do heat loss calculations. If you are a contractor and have a design build scope here, I hope you have excluded any PE cost or additional work.
Rusty Scott
2/24/2021 09:58:23 am
I would see very few Engineers stepping out on that heat loss calculation. Believe Texas this past week has reminded us all of how quickly full sized mains with limited heat sources become easy failure points.
sean
2/24/2021 10:03:40 am
I have never permitted wet pipe to be in areas not maintained above freezing. The cost of possible loss is way to high.
Rusty Scott
2/24/2021 10:07:57 am
agreed, same @sean
JAMES
2/24/2021 10:28:37 am
I'm in the Midwest US but to be honest I very rarely would recommend heat trace and a wet system to begin with in an unconditioned space over a dry system or other alternative approach. This may be a good example of some cost and energy savings, but at what risk? Just my opinion. This could be somewhere much warmer than here and I'm overthinking it.
Jesse Cecil
2/24/2021 11:24:33 am
A mechanical engineering can run a heat calc for you so you'll definitively know kind of freeze protection you need
Brian Spurrell
2/24/2021 01:07:51 pm
Running sprinkler Piping thru an unheated space unless it is a dry system or glycol is never a good idea. Heat tracing has more failures than success. The added cost of a Dry Valve, Compressor and Drum Drips are considerably less than a catastrophic failure in the main.
Martin Moffitt
2/25/2021 09:06:00 am
Would it even meet code and if yes what code? what does the local AFJ say? Leave a Reply. |
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