Lochinvar Boiler: Losing pressure
If a Lochinvar boiler’s pressure gauge keeps dropping, the system is losing water somewhere, or the expansion vessel / pressure-relief valve has failed. Topping it up repeatedly only hides a leak that will get worse.
If a Lochinvar boiler’s pressure gauge keeps dropping, the system is losing water somewhere, or the expansion vessel / pressure-relief valve has failed. Topping it up repeatedly only hides a leak that will get worse. On Lochinvar boilers, this is linked to 2 fault codes (Flow Switch Open, Low Water). Below are the likely causes, the safe checks you can make, and exactly what our licensed BC gas technicians do — because boiler repair in British Columbia is licensed gas work, not a DIY job.
Boiler repair is licensed gas work in BC. The checks below are the safe limit of DIY. Do not open the boiler or work on gas, combustion or safety controls — read the fault code, reset at most once, and call a licensed technician if it returns.
What you might notice
- Pressure gauge reading low (or very high)
- No heat; boiler will not fire
- Needing to top up system pressure often
- No or weak heat
- Overheat or flow faults under load
- Pump running but rooms stay cold
Safe checks you can make first
These are the only steps a homeowner should take. If they don’t resolve it, stop — the rest is licensed gas work.
- 1Top up to 12–15 psi cold using the filling loop, once
- 2Look for visible water at radiators, valves, pipes and the boiler
- 3Watch the gauge over a few hours — a fast drop means an active leak
- 4Call us to locate hidden leaks rather than topping up repeatedly
Related Lochinvar fault codes
These Lochinvar codes are commonly behind “losing pressure”. Tap any code for its full meaning, causes and fix.
What our licensed technicians do
- Locate leaks across the heat exchanger, pump, valves and fittings
- Test and recharge or replace the expansion tank to the correct pre-charge
- Inspect the pressure-relief valve and auto air vents
- Refill, purge air and confirm stable cold/hot pressure
- Test circulator-pump operation and speed
- Purge trapped air and check for air-bound zones
Lochinvar losing pressure — FAQ
Why does my Lochinvar boiler keep losing pressure?
If a Lochinvar boiler’s pressure gauge keeps dropping, the system is losing water somewhere, or the expansion vessel / pressure-relief valve has failed. Topping it up repeatedly only hides a leak that will get worse. The related Lochinvar fault codes are Flow Switch Open, Low Water. A licensed technician confirms the true root cause with the right instruments before any repair.
Is it safe to keep resetting my Lochinvar boiler when it shows "losing pressure"?
Reset it at most once. If "losing pressure" returns, the boiler is telling you there is a real fault that needs diagnosing — continuing to reset it can make things worse. Call GasBoilers.ca at 604-359-1081 and a licensed technician will find the cause.
Can you repair a Lochinvar boiler with this problem in Greater Vancouver?
Yes. Our Red Seal–certified, TSBC gas-licensed technicians diagnose and repair Lochinvar Knight, WHN and SMART System series across Vancouver, Burnaby, Surrey, Richmond, the Tri-Cities and the rest of Greater Vancouver. Same-day appointments are often available — call 604-359-1081.
“Losing pressure” on other boiler brands
Lochinvar boiler losing pressure? We can help today.
Licensed, Red Seal–certified gas technicians across Greater Vancouver. Upfront pricing, same-day service available.