The customer had to keep topping up the pressure to get their boiler working, and it kept going off. We found the expansion vessel flat and the pressure relief valve failed. We recharged the vessel, replaced the valve from our van stock, and serviced the boiler on the same visit.
A customer in Erdington booked a breakdown visit and a service for their Main Combi 30 Eco Elite on Thursday 5 November. The boiler kept going off, and they had to keep topping up the pressure to get it working again. We found the expansion vessel flat, so we recharged it and repressurised the system. We then found the pressure relief valve had failed, and replaced it on the same visit with one we carry on the van. We finished with a basic boiler service: the condensate trap cleared of a lot of black muck, the flue gases checked on our analyser, and the rest of the service checks completed.
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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's Main Combi 30 Eco Elite kept going off, and the only way to get it working again was to top up the pressure. They booked a breakdown visit and a service together, and we attended on Thursday 5 November.
We inspected the boiler and found the expansion vessel flat: it had lost its air charge. We recharged it, which you can see in the second photo, and repressurised the system. We then found the pressure relief valve had failed. We carry that part on the van, so we replaced it on the same visit.
With the fault fixed, we carried out a basic boiler service. We cleared the condensate trap, which was full of black muck, checked the flue gases on our analyser and completed the rest of the service checks. The two analyser readings are in the photos: a CO/CO2 ratio of 0.0005 and 0.0003. Our boiler repair page and boiler servicing page explain how each visit runs.
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. A basic boiler service is £95. Details are on our price list.
Common causes are a leak somewhere on the heating system, an expansion vessel that has lost its air charge, or a pressure relief valve that is letting water out. On this boiler it was a flat expansion vessel and a failed pressure relief valve. If you are topping up more than once in a while, get it looked at.
A small tank on the heating system with air on one side of a rubber diaphragm. When the water heats up and expands, the vessel takes up the extra volume. If it loses its air charge, the pressure jumps when the heating comes on and drops when it cools.
It is a safety valve that opens and lets water out of the heating system if the pressure goes too high. Once one has failed and keeps letting water out, the pressure keeps dropping and the boiler can lock out on low pressure.
A condensing boiler makes water from its flue gases, and that water drains away through a trap. Debris collects in it over time; this one was full of black muck, and we cleared it on the service.
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. A basic boiler service is £95.
Job attended and photographed by our engineers, November 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 Erdington 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.
The Powermax had been labelled Do Not Use, so the landlord asked us to quote. Out came the floor-standing boiler and hot water store; in went a wall-hung Baxi combi with a Sentinel filter and scale reducer, the system flushed and the vertical flue properly supported.
Read the case studyThe boiler had locked out on low pressure and the customer could not find the filling loop to top it up. We found it behind the boxing, restored the pressure and checked for leaks, then got the heating going with new batteries in the wireless thermostat.
Read the case studyThe boiler was locking out on overheat because the system pump had burnt out. New pump from van stock, and a straight conversation with the landlord about the sludge that caused it and the flush that would stop it happening again.
Read the case study£99 in office hours covers attendance, diagnosis and the first hour. Parts quoted before we fetch them.
