This filling loop is connected 'incorrectly'?

WIAWSNB

Not mine, and I don't think a biggie issue either, but I'm trying to trace pipes for someone, and started at their Vaillant EcoTec pro 28 boiler - I'm guessing around 6-odd years old. 

First head-scratch - surely the CH Return is the RH pipe, and that's where - conventionally - the filling loop should be connected to? This one is to the LH pipe, which I understand is the flow.

I'm guessing it doesn't matter too much as they have been successfully topping up whenever needed, but does anyone know the reasoning?

Thanks. 

Ectophile

You'd have to check the manual to see which is the flow and which the return.  Unless it's been conveniently marked on the bottom of the boiler.

But it makes no odds anyway.  The flow and return are connected to each other, so the pressure will equalise whichever end you fill it from.

WIAWSNB

Ectophile said:

You'd have to check the manual to see which is the flow and which the return.  Unless it's been conveniently marked on the bottom of the boiler.

But it makes no odds anyway.  The flow and return are connected to each other, so the pressure will equalise whichever end you fill it from.

Thanks. Yes, it has been topped up a couple of times and worked fine.

Pretty sure the LH pipe is the flow, and I'm familiar with installation instructions always adding the loop to the return. It's the same with fitting an external Exp Vessel - always to the return. 

As you say, it should - and surely will - balance. I wonder if it's because the 'flow' has the diverter valve on it, so potentially the 'flow' could be cut off inside the boiler if that valve is in the DHW position? Yes, it would then balance through the rads, but perhaps there's a scenario with all the rads fully closed off too?!

Highly unlikely, but just curious.

Anyhoo, I won't be suggesting he has it changed...

FreeBear

Ectophile said:

You'd have to check the manual to see which is the flow and which the return.  Unless it's been conveniently marked on the bottom of the boiler.

Pipework on boilers follow a pretty standard layout. The only difference is likely to be the spacing of the pipes and the location of PRV vent & condensate drain.

Vaillant are a major manufacturer and are unlikely to deviate from convention - Had a quick look at the installation manual, and they do indeed follow the "standard" layout.

WIAWSNB

FreeBear said:

Ectophile said:

You'd have to check the manual to see which is the flow and which the return.  Unless it's been conveniently marked on the bottom of the boiler.

Pipework on boilers follow a pretty standard layout. The only difference is likely to be the spacing of the pipes and the location of PRV vent & condensate drain.

Vaillant are a major manufacturer and are unlikely to deviate from convention - Had a quick look at the installation manual, and they do indeed follow the "standard" layout.

Yes, it's def the flow on the left, and convention def has the filling on the return. No idea why that plumber did this, on an otherwise very neat and pro install.

But, not a biggie. 

I can only imagine it's if the rads are fully shut off, and the boiler last used in DHW mode, so possibly water sent in the flow can not go anywhere?