When I turn sprinklers on, the water pressure is practically zero for sprinklers and also in house. Upon turning sprinklers off, house pressure returns to normal. Leak detection service found no leaks. Replaced house regulator. No change. Previously noticed that when sprinklers initially go on there is a bit of a vibration "jolt", which might be a separate issue. Next step plumber wants to take is to replace irrigation regulator…? My irrigation regulator is as old as the house. (Built in 1989).
Plumbing – Sprinklers on = no pressure in both sprinklers AND house
plumbingwater
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Best Answer
It could be a faulty safety pressure valve, f.e. used upstream of an electric/gas/oil boiler in the cold water inlet pipe.
In combination with the - assuming long - sprinkler lines/hoses, a sort of pressure (standing/reflected or other type of) wave could be established that opens this SPV periodically or permanently if the sprinkler is opened. The sprinkler itself could start that pressure wave if it is of a type that sprinkles intermittently.
Needing resonance, it would be only generated with the right matching length and cross section of hose/pipe.
The SPV could also be dirty inside. Many SPV have manual handles to turn/snap them open for a short moment in order to clean the valve.