Boilers (More Info)

Your Boiler is the heart of all your Central Heating and Hot Water needs and that is never more apparent than when it goes wrong!

Panic invariably ensues, abated only by confirmation that a knowledgable Heating Engineer will shortly arrive to diagnose and repair the problem, reinstating those often taken for granted hot showers and toasty warm rooms.

Just like your car, your Boiler should be looked after, serviced regularly and maintained in good working order to avoid those moments of horror and correct issues before they arise.

We at CPHG Services are technically familiar with all major brands and types of Gas Boilers and can advise on, supply, fit, service, repair and maintain all of them.

1. A Combi that went wrong, being put right

What is a Condensing Boiler?

"Condensing Boiler" is an umbrella term used to describe all types of modern Gas Boilers, Combi’s, System & Regular Boilers, (details below). Without getting too technical, modern condensing Boilers are more cost efficient to run than non-condensing Boilers.

To achieve this, they recover some elements of the flu gases, cooling them and using the recycled heat to heat the water, reducing gas consumption.

It is worth noting however that any condensing Boiler MUST be installed and the system set up correctly in order for the Boiler to operate in the efficient cost saving condensing mode.

All condensing Boilers have a ‘condensate drainage’ pipe connected to them which is strictly governed as to where it can terminate and drain. Next, the three domestic Gas Boiler types.

2. Modern Condensing Boilers

1. THE COMBINATION BOILER:

'Combi Boilers' are the most common type of domestic Gas Boiler in use today.

They are easily identified, they provide instant hot water when a tap or shower is turned on in addition to running Central Heating.

They are also easily identified by the many pipes connected to them, Central Heating Flow, Hot Water Distribution, Gas, Cold Main Flow, Central Heating Return, Pressure Relief, & a plastic Condensate Pipe, (7 in total).

3. Inside a Combi Boiler

• Central Heating is working but not hot water (arghh!) …This problem, more often than not, is a faulty ‘diverter valve” which directs the hot water within the Boiler to heat either the Central Heating or Hot Water demand. Sometimes it can just ‘stick’ in the Central Heating position, (usually after summertime when the central heating hasn’t been used) and it can be manipulated and ‘freed’ up. Often though it will require the fitting of a manufacturers new diverter valve part.
• Hot water supply runs hot and cold and / or extremely hot… this is often a fault with either the hot water temperature sensor which can be replaced with a new part or can be due to a scaled-up and blocked ‘plate heat exchanger” that heats cold mains water directly in the Boiler. If the latter is the case, it is often accompanied with a noise when the hot water circuit is running, similar to the sound of a kettle Boiling, known as ‘kettling’. This unfortunately usually means the secondary heat exchanger needs to be replaced in the Boiler.
• Boiler losing system pressure: This is a very common issue. The main reasons for loss of system pressure can vary between a leak somewhere in the radiator circuit, (which can sometimes be difficult to locate if pipework is running under the ground floor), or a faulty ‘pressure relief’ valve in the Boiler, (which is indicated by water dripping or pouring from the pressure relief pipe which terminates outside the property). It can be a very frustrating issue to resolve if loss of water is not immediately visible. Of course, the pressure in a sealed system will occasionally have to be topped-up due to natural evaporation, but regular need should be investigated.

6. Boiler Pressure Gauge

2. THE SYSTEM BOILER:

System Boilers contain the heat exchanger within which the system water is heated, the gas valve and the system pump which pumps the water around the system, (as well as some other technical controls and parts).

A System Boiler can be identified by the fewer number of pipes attached to it than a Combi Boiler.

It will have, Central Heating Flow, Gas Supply, Central Heating Return, Pressure Relief & a plastic Condensate pipe (5 in total).

System Boilers are used in conjunction with additional & external Hot Water Cylinders, (the old style ‘open-vented’ Central Heating and Hot Water systems with header tanks in a loft or the more modern Sealed Unvented Hot Water Cylinder systems.

7. Inside a System Boiler

Disadvantages of System Boilers:

• Surprisingly the disadvantages of System Boilers themselves are rather moot when compared to Combi Boilers simply because they are each unique. If you have, want or need an external Hot Water Cylinder system you would have either a System or Regular Boiler, not a Combi Boiler. The associated disadvantages of System Boilers are, however, the actual requirement for a Hot Water Cylinder, the space required in your home to locate the Cylinder, the additional pipework and controls required to plumb the cylinder into the system and the associated installation costs if new & the possible additional maintenance and repair costs for system component faults and breakdowns.

Common System Boiler problems / faults:

• As a System Boiler contains a lot less mechanical, electrical and functional parts than a Combi Boiler, they are far less likely to develop a fault.
• If they do, it is generally to do with a faulty pump or a faulty electrical temperature sensor, both of which are more often than not either easy to repair or not cost prohibitive to replace.
• Most faults / problems with systems that utilise a System Boiler are usually with components outside of the Boiler, like the system zone valves.

8. System Boiler with an Unvented Hot Water Cylinder

3. THE REGULAR BOILER:

A Regular Boiler is the most basic Boiler of all.

It contains everything a System Boiler has, except for a pump, (the system pump would consequently be cited externally as part of the zone-valve arrangement normally adjacent to a Hot Water Cylinder).

The points above for the System Boiler apply to a Regular Boiler, except for anything to do with an internal pump.

9. Inside a Regular Boiler