The customer had booked a service, but when we arrived the boiler wasn't working and was showing fault F.75. We diagnosed the pump: the boiler's original, 18 years old, with its automatic air vent leaking. We ordered a new high-efficiency pump and fitted it on our next visit, the day before the customer went away on a cruise.
A customer in Moseley had booked their Vaillant ecoTEC in for a service. When we arrived, we found the boiler wasn't working: it was showing fault F.75. We diagnosed a faulty pump. It was the boiler's original pump and had lasted 18 years, and the automatic air vent on top of it was leaking too. We ordered a new high-efficiency pump, which came with a new air vent, and fitted it on our next visit. The customer was going on a cruise the next day, and was extremely happy to have it fixed before they left.
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£99 in office hours (Mon–Fri, 8am–5.30pm) covers attendance, diagnosis and the first hour. Parts and any further work are quoted and agreed before we carry on. Out of hours, the price is quoted by phone before we set off.
No travel charge within 10 miles of B20 2JS. Further out, £2 per mile may apply — always agreed before anything is booked. Full price list
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The customer in Moseley had booked their Vaillant ecoTEC in for a service. It was only when we arrived that we found the boiler wasn't working: it was showing fault F.75.
F.75 means the boiler did not see the water pressure change when its pump started. We diagnosed the pump as faulty. It was the boiler's original pump and had been running for 18 years. The automatic air vent on top of the pump was leaking too, and the second photo shows the water marks and corrosion the leak had left on the base of the boiler.
We ordered a new pump and came back to fit it: a Vaillant high-efficiency pump, made by Grundfos, which came with a new automatic air vent, so the leak was dealt with at the same time. The boiler was back up and running. Our Vaillant boiler repair page covers other Vaillant faults.
The customer was going away on a cruise the next day, so they were extremely happy that we could get it fixed so quickly.
In office hours (Mon–Fri 8am–5.30pm) a boiler repair is £99, covering attendance, diagnosis and the first hour, with parts quoted and agreed before we fit them. Out of hours we quote the price on the phone before we set off. Details are on our price list.
F.75 means the boiler did not see the water pressure change when its pump started. The usual causes are a sticking or failed pump, or a pressure sensor blocked by sludge from the heating system. It needs testing rather than a guess. On this boiler it was the pump.
There is no fixed lifespan. This one was the boiler's original pump and had been running for 18 years before it failed.
A small valve on top of the pump that lets air out of the heating water. When it leaks, water drips inside the boiler casing, so a leak inside the boiler should be looked at rather than left.
A modern pump with an electronically controlled motor, which uses less electricity than the older style of pump. The one fitted here is a Vaillant high-efficiency pump made by Grundfos.
In office hours (Mon–Fri 8am–5.30pm) a boiler repair is £99, covering attendance, diagnosis and the first hour, with parts quoted and agreed before we fit them.
Job attended and photographed by our engineers, October 2026. Written up by Saeed Iqbal, the engineer who leads Synergy Gas & Plumbing (Gas Safe registered 594385). More of our work in the area is on our Moseley & Kings Heath page, and every job we write up is on the case studies index.
£99 diagnosis + first hour
£99 in office hours (Mon–Fri, 8am–5.30pm) covers attendance, diagnosis and the first hour. Parts and any further work are quoted and agreed before we carry on. Out of hours, the price is quoted by phone before we set off.
No travel charge within 10 miles of B20 2JS. Further out, £2 per mile may apply — always agreed before anything is booked.
A routine annual service: condensate trap and magnetic filter cleaned, clean combustion readings. Following the flue into the loft, we found it held only by metal banding with the joint clamps unscrewed. Warning notice left, quote accepted, return visit booked.
Read the case studyThe customer mentioned the leak and the heating staying on when we arrived for the service. The diverter valve had rust and corrosion around its ports, so a new one went in. Combustion tested clean.
Read the case studyThe pressure kept rising even with the boiler off. We found a pinholed plate heat exchanger and replaced it, with the pressure relief valve, from the van. No new boiler needed.
Read the case study£99 in office hours covers attendance, diagnosis and the first hour. Parts quoted before we fetch them.
