Vaillant Ecotec Problem - Air in system and water discharge from condensate pipe

[plural]

I have a Vaillant Ecotec 415 Plus system boiler installed a few years ago. Originally it was an open vented system, but I have recently done a renovation and made the central heating a sealed pressurised system with an external expansion vessel replacing the expansion tank.

Ever since the boiler has been installed, when the central heating fires up, there seems to be a lot of water being discharged out of the condensate pipe for a minute or so. Is this normal?

Also, perhaps related to the water discharge, in the top most radiators in the house, some air seems to become gathered, to the extent that I can hear air bubbling up in the radiator when a heating cycle starts.

Given the old expansion tank was relatively low, just about 2 meters above the topmost radiators, I thought air may be coming back into the system through the pressure overflow pipe that fed back into the old expansion tank. Which is one of the reasons why I made the central heating system a closed pressurised system. But even now, air still seems to get into the system and travels to the topmost radiator.

The system also as an automatic air vent in the pipework just above the boiler, that was replaced with a new one when the boiler was installed.

I’m having difficulty finding anything on the internet related to this problem. So I would be grateful if someone could provide some advice on what the problem may be, and how to resolve it.

My feeling is that the water discharge and air coming into the system are related and are due to the way the boiler has been installed.

Any advice would be greatly appreciated.

 

[diamondgas]

Ever since the boiler has been installed, when the central heating fires up, there seems to be a lot of water being discharged out of the condensate pipe for a minute or so. Is this normal?

Not necessarily a concern and may be caused by the positive pressure produced by the fan. I was watching a condensate trap bubble merely the other day when it first lit up

Also, perhaps related to the water discharge, in the top most radiators in the house, some air seems to become gathered, to the extent that I can hear air bubbling up in the radiator when a heating cycle starts.

In no way can these be related as one is within the sealed system and the other is outside! However if you're having to top up the pressure frequently then you may have an issue that does link them both indirectly

My feeling is that the water discharge and air coming into the system are related and are due to the way the boiler has been installed.

I think you may need someone to take a look at your system 'plural' ... You may have an issue with gassing regards what is collecting in your uppermost radiators. What colour is the system water? Did you have it flushed out prior to making it sealed?

:welcome: to the forum, by-the-way

 

[Millsy 82]

How recent was it? What size pipework is it? If it is a large system it can take a while for all the air to come out of it especially if the pipework is going up and down alot trapping air.

 

[jtsplumbing]

Where is the expansion tank located ? it may be possable that you have a leak in the main heat exchanger !!

 

[plural]

Thanks for the reply.

The new sealed system has only been up an running for about three weeks. The system water is clear. All the radiators are new. It is a concrete house, so the pipework runs externally inside cupboards or above the skirting boards to the radiators. The pipework is all 15mm. All the horizontal parts of the pipework are new, the only old pipework are the vertical parts. It is a three bedroom house with 9 radiators in total.

The pressure only seems to drop slightly over a week or so, but not dramatically. I seem to have to top it up once I bleed the air from the uppermost radiators.

The expansion tank is on the ground floor under the stairs, the boiler is in the kitchen also on the ground floor.

The air in the radiator problem happened when it was a vented system with the old radiators/pipework, but when I had the new boiler put in.

 

[diamondgas]

It could be the system settling in 'plural' ... A well inhibited system will still produce some corrosive gasses with fresh water kicking about! Combined with possible air trapped during filling it may well be just that!

IMHO

 

[jtsplumbing]

Have a look in vaillants installation manual it will show you where the expansion tank needs to be fitted ! if you have to keep topping up pressure you may have a leak, water rushing down condense on start up could be pin hole in heat exchanger ! How old is boiler? If still under warranty get Vaillant out to check it !