Open Vent Boiler with no header

[selfbuildextension]

I've just had a boiler and unvented cylinder installed, a completely fresh install with no pre-existing pipe work other than the cold main.

We will be running underfloor heating throughout the whole house soon, for now there is a flow and return in place coming from the boiler to the manifold locations and the cylinder coil has also been connected. The cylinder has an expansion tank connected.

I am concerned as the plumber has used an Open Vent boiler (Valiant Eco Tec Plus) and there is no header/storage tank in the house. The boiler has no pressure gauge but he has installed a filling loop and a blow off valve.

I don't understand how using an open vent can be ok in this scenario with no header or expansion vessel on the heating side.

My understanding is a system boiler should have been used? Is there a way to use an open vent without a header tank?

Thanks

 

[selfbuildextension]

There is also no pump installed, my understanding is an open vent doesn't have a built in pump?

 

[gas112]

get him back and quiz him , how has he tested it if no pump

 

[selfbuildextension]

It's still to be commissioned but work is complete, I'm hoping I'm totally wrong tbh and didn't want to be a awkward with him if he hasn't done anything wrong but i cant see how the hot water is going to flow to the cylinder coil...

 

[Madrab]

I think you need to be sure whether you have an open vent set up or whether you have a system boiler. It can't be an open vent without a Feed and Expansion cistern.

Do you know the model number?

Is it a 4xx ( regular open vent) or a 6xx (system sealed) or an 8/9xx (combi boiler)

 

[terryplumb]

As above eco tec come in 3 variants

 

[selfbuildextension]

The model is : vu306/6-5 ovz (h-gb) its a 430.

100% no feed and expansion cistern, cold main is connected directly via filling loop.

so definitely not an open vent "setup" but I guess the question is can the boiler still be used as a sealed system and does it need a pump on the hot water side.

 

[Madrab]

If it is that boiler then you would be correct, it is designed for an open vent system. It is classed as a regular boiler and lots of regular boilers can be used in a sealed system, will this model, probably, but you would need to check with Vaillant whether they support it like that or not. If not then it wouldn't be covered by their warranty.

I would recommend a quick call to Vaillant and they will confirm, if they won't support it as a sealed system then as suggested the installer needs to be quizzed about all of that ASAP. Yes it will need a pump somewhere out on the system.

 

[selfbuildextension]

Thank you for your help @Madrab, really appreciate that.