Medium
1P4 on Atag iS System

The water pressure in your heating system has dropped too low and needs to be topped up to keep the boiler running.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Pressure 0.5–0.8 bar — filling needed

From this model's manual
Verified against the Atag Is System installation & service manual, page 72.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Open the small valve handle(s) slowly until you hear water moving into the system.Watch the pressure gauge on the boiler display and close the valves once it reaches 1.5 bar.

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