Category Archives for "Vaillant Boilers"

Vaillant Boiler Pressure Going Too High

Vaillant Ecotec Pressure Too High

Vaillant Ecotec Pressure Too High – note silver vessel inside the boiler on the right. This is the expansion vessel.

I had a job to do today on an older Vaillant Ecotec combi boiler.

The system pressure kept going really high when the heating was on. But when the heating cooled down, the pressure went really low and caused an F22 fault.

What Causes Boiler Pressure To Go Really High

This is a common fault on Vaillant Ecotec boilers and is caused by the expansion vessel losing its charge.

From the factory they’ve got a 1 bar charge, but over time they lose it, which causes the pressure dramatically to rise when the heating is on.

How To Fix It

The good news is it’s a simple job to fix.

On this one, I just drained the boiler (not the whole system) and put a track pump (like a bike pump) on the expansion vessel valve and recharged it to just over 1 bar.

See pic below:

This is the expansion vessel that loses charge. I pumped it up from the Schrader valve to solve the problem.

I then just refilled the boiler, vented it and tested the system. It’s a nice easy job that shouldn’t take more than an hour.

What Else Can Cause This Problem?

Split Expansion Vessel

If you have another brand of boiler and not a Vaillant, there’s a chance that recharging the expansion vessel may not fix the problem because the vessel has split internally. If this is the case, you would need to replace the expansion vessel, not just recharge it. This almost never happens on Vaillant boilers though.

Faulty Filling Loop Letting By

Other causes of the pressure going too high on a Vaillant Ecotec are the boiler’s built in filling loop letting by. This is the part of the boiler that lets you top up the system pressure if it goes down. Sometimes these valves don’t close properly and keep letting water in the boiler.

This over pressurises the boiler giving similar symptoms.

Need any help or advice about your boiler?

Please get in touch here. I’ll be happy to help!

Vailant Ecotec F28 Fault Code

Vaillant Ecotec F28 Fault Code (Cause and Solution)

F28 Error Code On Vaillant Ecotec Combi Boiler

Vailant Ecotec F28 Fault Code

Today, I had what seemed like a pretty standard callout to a Vaillant Ecotec Plus 831 combi boiler in Greenhithe. It was showing an F28 fault code.

This code means that the boiler tried to light unsuccessfully 3 times in a row. It does this as a safety measure to stop a dangerous mixture of unburned gas building up in the boiler.

Common Causes Of Vaillant Ecotec F28 Faults

No Gas

Yes, one of the most common reasons for your Vaillant to show an F28 code is because there’s no gas to your property. Reasons for this include gas works on your road, someone accidentally turning off the gas at the meter, or credit on a prepay gas meter running out.

If you have another gas appliance (like a gas hob or gas fire) you can try to light them. If they don’t light, it means there’s no gas to your appliances. So the problem isn’t with the boiler, it’s with your gas supply.

Faulty Spark Electrodes

Spark electrodes are a bit like spark plugs in a car. They create a spark near the burner and light the gas when the boiler turns on. These can crack or lose continuity which will stop them from making a spark and lighting the gas. This will create an F28 fault.

Broken HT Lead

The lead that connects the spark electrode the boiler’s circuit board (also called PCB) can also break. Again, this will prevent the electrode from making a spark, which will stop the boiler lighting and cause an F28 code.

Gas Valve Fault

This is more of an issue on more recent Ecotec’s from about 2012 onwards. Their gas valves seem to fail more often than on the older models. I (or any other good heating engineer) can test to see if the gas valve is opening at the right time by doing a simple pressure check.

So what was caused the problem?

On this particular boiler, I changed the spark electrode because it was in such poor condition, but it wasn’t the cause of the F28 fault.

The cause was the spark generator on the circuit board (PCB) – see picture.

Vaillant Ecotec PCB

You can see the spark generator as the grey plastic square on the right hand side of the PCB.

This was only working occasionally, so most of the time the boiler wouldn’t light, but sometimes it would, which made it quite hard to diagnose.

You can replace just that part of the PCB, you need to replace the whole thing.

To help save the customer some money, I bought a reconditioned one from a boiler pcb reconditioning specialist, which saved them about 50% on the price of a new one – and it still comes with a 1 year warranty.

This solved the problem instantly (and saved the customer about £100 on the cost of a new PCB).

Would you like me to fix your F28 fault?

Vaillant Ecotec Plus 831 Combi BoilerIf you would like me to fix your Vaillant F28 fault and I cover your area, please do get in touch.

It won’t cost you anything for me to assess the problem. From there I can give you a fixed price quote to do the job, then all you have to do is say yes or no. Easy. So why not call today? The number is 01322 788418