Compatible with aroTHERM air-to-water heat pump hybrid system – Making the perfect entry into renewable systems 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 Vaillant boilers are sometimes undersized when fitted and are not large enough to cope with a large house’s central heating system. This is usually below the boiler but there could be an external flexible filling loop anywhere on the system, sometimes hidden away in cupboards or behind boxing. Knowing how to release pressure on a Vaillant boiler might save you from some boiler problems. If you repressurise a Vaillant boiler too much and cause the pressure to go too high, you will need to release the pressure.

What I have learned and understand so far is that there should be a release of air from the valve when activated when the boiler is switched on or off.If the pressure gauge is reading zero (or close to zero) your boiler needs to be repressurised to get it working. Total system solution available from one manufacturer – Intelligent controls and accessories available The pressure on a Vaillant boiler should be between 1 and 1.5 bar when the central heating is off and the radiators are cold. Correct Vaillant boiler pressure

This means the expansion vessel on the Vaillant boiler might not be big enough and can cause problems with the pressure. 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 The most common cause of a Vaillant boiler losing pressure is a leak, this could be on the boiler or anywhere on the central heating system. Removable side panels and push-fit flue system - For improved accessibility and ease of installation They do have manual pressure gauges also but they are useless to most people as they don’t have any numbers on them. Vaillant boiler pressure gauge

Combi expansion vessel

Getting the best combi boiler for a large house is very important, but adding an external expansion vessel that is large enough for the central heating system is also an option rather than upgrading to a bigger boiler. External expansion vessel fitted If it is below 1 bar, you should top the pressure up. If you have to keep topping the pressure up, you have a problem that needs to be fixed. You should ensure the heating is turned off before repressurising the boiler as it will sometimes fire up as soon as it reaches the minimum working pressure. Here is my situation: I have a Vaillant Ecotec pro 28 combi boiler that is about 6 years old. It is stored in the loft of a 3-bed house and until now I've never had any problems with it apart from a small amount of pressure loss which is so gradual I only needed to top it up every few months or so. I do this using the 2 valves underneath boiler as instructed by a plumber friend. A couple of weeks ago I switched the heating on (after it being off all Summer) and since then the pressure has been dropping pretty much every night so that in the morning there is an F22 fault code and the heating doesn't come on. To get around this I have been adding pressure as before and then the heating works again. This is most likely an expansion vessel problem, if so, you will need to recharge it or replace the expansion vessel if the diaphragm inside is split.