Questions & Answers

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Boiler Servicing

What is included in a standard boiler service?

A standard boiler service at Thames Boilers includes:

Flue gas analysis
Gas pressure and/or flow check
Inspection of the flue (where visible) and the boiler’s interior for leaks or wear
Removal and cleaning of the condensate trap (for condensing boilers)
Check and recharge of the boiler’s expansion vessel pressure (if applicable)
Check for gas leaks inside the boiler
Removal and cleaning of the magnetic filter on the heating system
Issuance of a digital service record and certificate in PDF format.

What is included in a full boiler service?

Full boiler services are recommended every 2-5 years for most modern boilers (every year for Viessmann boilers) and include everything in a standard service plus:

Removal, cleaning, and inspection of the burners
Access, inspection, and cleaning of the dry side of the main heat exchanger
Replacement of burner gaskets and/or sump seals if needed
Water quality check, including pH levels, inhibitor levels, and corrosion
Bleeding of all accessible radiators
Check of radiators’ heating and notation of any that are not heating properly
Recommendations for any further or remedial work on the boiler or heating system

What boiler brands do you service?

Thames Boilers services Vaillant, Worcester Bosch, Viessmann, Baxi, Potterton, Ideal, Alpha, Glow Worm, Vokera, Main, and Keston boilers.

What types of boilers can’t you service?

Thames Boilers does not service electric boilers, LPG boilers, oil boilers, or commercial boilers.

Will a boiler service fix any existing faults on my boiler?

No, a boiler service is preventative maintenance. The cost of repairs is not included in the service and must be paid separately.

Does a boiler service guarantee that my boiler won’t break down in the future?

No. Thames Boilers is not liable for future boiler breakdowns.

Boiler Repairs

What guarantees do you offer for boiler repairs?

Thames Boilers offers a 12-month guarantee on replaced parts. Further issues with the boiler or heating system after the repair are not covered and will require further payment.

Should I repair or replace my boiler?

For older boilers that haven’t been well-maintained, replacement is usually recommended due to the likelihood of recurring breakdowns.
For boilers under 10 years old that have been serviced annually, repair is usually recommended.
Boilers from lower-quality manufacturers (Biasi, Ferolli, Vokera) are usually recommended for replacement.

What is your availability for boiler repairs?

Summer bookings are usually available within a day or so.
During colder months, the wait can be a couple of weeks due to high demand.
Up-to-date availability is on the company’s booking page.

How much does a boiler repair cost?

Costs vary. Repairs taking an hour without parts will only cost an hour of labour. Major part failures may take 2-3 hours plus the cost of the part, which can range from £150–£350. An estimated cost is given during the initial diagnostic visit.

Do you offer free quotes for boiler repairs?

No. Diagnosing and proposing fixes requires skilled labour and takes time. Customers must book and pay for a diagnostic visit to find out what’s wrong with their boiler.

My boiler isn’t working. Should I book a service or a repair?

Customers should book a boiler repair, as a service is routine maintenance and won’t fix existing problems.

What boiler brands/makes can you repair?

Thames Boilers can repair Vaillant, Worcester Bosch, Viessmann, Baxi, Potterton, Ideal, Alpha, Glow Worm, Vokera, Main, and Keston boilers.

What types of boilers can you repair?

Thames Boilers can repair combi boilers, system boilers, heat-only boilers, and back boilers.

What types of boilers can’t you repair?

Thames Boilers does not repair electric boilers, LPG boilers, oil boilers, commercial boilers, or “Powermax” boilers.

Boiler Problems

My combi boiler has no hot water, but the heating is working.

This is usually caused by a faulty flow switch or a stuck diverter valve.

My conventional boiler has no hot water, but the heating is working.

This is usually caused by a faulty motorised valve.

My combi boiler has hot water, but the radiators aren’t heating up.

This is usually caused by a stuck diverter valve or a problem with the room thermostat or programmer.

My conventional boiler has hot water, but the radiators aren’t heating up.

This is usually caused by a faulty motorised valve or a problem with the room thermostat or programmer.

Tip: Ensure your programmer is set to turn on heating and your room thermostat is turned up.

The pressure gauge on my boiler keeps going down.

This is usually caused by a leak in the system or the boiler, a faulty expansion vessel, or water leaking from the pressure relief valve.

The hot water on my combi boiler runs hot and cold.

This is usually caused by a blocked plate heat exchanger. If it’s only happening in the shower, it’s usually a faulty shower cartridge.

My boiler has a fault code.

This can indicate various problems. Google the fault code and your boiler make for more information.

My boiler is making a loud banging sound when it turns on.

This is usually caused by a faulty pump preventing water circulation and causing overheating. It could also be due to air in the system or a blocked main heat exchanger.