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Saunier Duval Boiler Problems
Author: Tom Norris

Common Boiler ProblemsThere’s never a good time for the boiler to go down and to make it worse I can tell you that most boilers breakdown in the winter time, just the period when you need them most.

Over 50% of new boilers fitted in recent years are combination boilers and the most common breakdown in service is simply that the system needs topping up.

Almost anybody with half a brain can top up a combination boiler system but if you have any doubt with regard to your capabilities then you are advised to use our Get a Quote option to find heating engineers in your area that can deal with your problem.

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Check The System Pressure First

Step 1:

Check the pressure gage on the your boiler. Under normal operating conditions it should be around 1 to 1.5 bars but if it is flat lining or below 0.5 bars then that is likely to be good news and your system simply needs topping up. See Pic 1

Pic 1: Boiler Pressure Gauge

If the pressure is above 0.5 bar then you need to Get Some Help as the problem is not associated with topping up the system.


Topping Up A Combination Boiler


Step 1:

Turn the boiler off and switch off power going to the boiler.

Once you’ve cleared away the usual miscellaneous objects from below the boiler you will see that there are approximately 5 to 6 pipes on show, all of them entering the boiler.

The pipe we’re looking for is a small one, 15mm, and it should have a tee section on it with a silver flexi hose attached that is about a foot long. See Pic 2

Pic 2:   Combination Boiler Filling Loop Flexi Hose

If you can’t find the tee section and flexi hose then we suggest you Get Some Help as your installation is not a standard installation and its better to be safe rather than sorry.

If you do find the 15mm pipe with tee section and flexi hose I can tell you that it is the cold water main supply pipe that goes in to the boiler to provide you with hot water, once heated, and the tee section flexi hose is what is used to top up your system.

Boiler ManualGood Idea - Look for Your Boiler Manual

If you have a boiler manual it will provide you with the exact diagrams of how to top up your system and is likely to provide better help than this general guide to topping up a combi. If you can’t find it then read on to see how things work out.


Step 2:

Before you do anything else you need to study Pic 2 below and understand the 2 most important elements in filling up the system which are the Pressure Gage & the Filling Loop.

Pic 2  Combionation Boiler Topping Up


Pressure Gage

The pressure gage monitors the pressure inside the system and is usually set at about 1.5 bar on most combi systems. On many combi systems over time the pressure drops below 0.5 bars which results in a system closedown.


The Filling Loop

The filling loop is used to top us the system and is usually left unconnected at one end in case of accidental operation.


Step 3:

What you now need to do is to connect up the filling loop and ensure that both ends of the filling loop are tight.

What you are about to do now is to top up the system by opening the valve on the filling loop which allows cold water to enter the system and re pressurise.

Generally it only takes a few seconds to top up so you need to keep your eyes on the pressure gage as you open the filling loop valve to allow the water in.

Once you open the valve you should hear the water entering the system so don’t be put off by the strange noises. Just keep your eyes on the pressure gage and allow the water to enter the system until the pressure gage rises to around 1.5 bars.

Once you have achieved that, you have successfully topped up your central heating system.


Step 4:

Once the system is filled to the required 1.5 bars and the filling loop valve is closed make sure to undo the other end of the filling loop.

Once you have completed topping up the system, with dry hands, you can turn back on the electric’s to your boiler and switch on as necessary.

The simplest way to test the boiler for correct operation is to turn on the hot water tap and with a bit of luck you should have hot water.

If the problem is not resolved you can Get Some Professional Help here.







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