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Greetings. My house was built in 2014 and has a fire sprinkler system with heads rated at 175, orange CPVC pipe throughout the attic, and a riser in the garage.
When I bought the home, pressures on the gauge were typically in the 155 psi range. Recently, they have been spiking to 185 and above. My fire line and domestic line separate early, right after the city meter at the street. I installed a pressure relief valve, 175 psi, on the drain off the riser, and it has been dripping pretty constantly, about 1 drip every 10-20 seconds or so, depending on fluctuations in air temp. When the pressure spikes, it brings it down to 175 pretty quickly. My question is, would you recommend I have a fire professional come out and install a pressure-reducing valve? Is that something that would be installed prior to the riser? Thank you. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
6 Comments
Anthony
5/26/2026 08:06:18 am
Yes! If water usage and / or over-pressurization, then I would contact a professional fire sprinkler company. Note that additional hydraulic calculations may need to be performed. So having the existing drawings / calculations may help save you time and money. If the installing companies sticker is on the sprinkler riser, I would start with them. 5/26/2026 08:16:36 am
Hi, Most likely the pressure relief is not able to fully close. A 175 PSI pressure relief valve will close once the system pressure is 80% of rating, so the supply pressure would need to be >140PSI. There are other, higher rated pressure relief valves such as 200 PSI or 225 PSI to handle the higher supply pressure.
Jack G
5/26/2026 08:19:01 am
Is it an antifreeze system ? Most residential systems are ( near me).
Robert
5/26/2026 09:56:02 am
Or antifreeze thermal expansion.
Andy Wilson
5/26/2026 10:13:38 am
You really need to install a fire listed PRV valve. You should not use the relief valve as an over pressure device. It is there for emergency situations or when other devices (PRV) fails. You definitely should install a higher relief valve. The sprinkler heads and the CPVC piping(Blaze) are only rated for 175psi max working pressure. If you system is sitting at 185psi then you need a PRV to keep it below 175psi at all times. The relief valve is there if it fails. Leave a Reply. |
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