Leaking Filling Loop, and two of them

[Albumen]

Boiler is a Vaillant Eco Tec Plus 831 Combi. Fitted about 5 years ago. Serviced by Vaillant, last time last June.

There's a filling loop which I use, and was shown how to use by the installer. Here's a few pictures:







I'm only having to top the boiler up every few months. The last Vaillant chap said not to worry about that.

This filling loop is fitted between the cold mains and the CH return. The leak is, I think coming from the actual black tap itself.

So I read the Installers Instructions:

http://www.vaillant.co.uk/stepone2/data/downloads/d7/42/00/ecoTEC_installation_and_servicing.pdf

Especially the stuff around page 31 about how my version of this boiler should have been supplied with a filling loop. Looked closer, and saw it had, just that you don't really notice looking at the boiler from the front, as it's underneath:



That's fitted between cold mains and CH Flow.

So questions:

1. Should I have been using the 'built in' filling loop to top up the boiler? The User's instructions are a bit naff, they tell you to top it up if the pressure's low, but don't say how.

2. Why have I got a second filling loop? I suppose it might be useful for flushing the system, but did it just make it easier for the engineers to install? Which is fine.

3. What do I need to replace it? Do I need something with a tap at each end of the loop? And it needs a non return valve to comply with WRAS? A Screwfix link to the right one would be handy.

4. Or as it seems superfluous, can I just take it off and solder 15mm caps on the end. I've done heaps of plumbing/CH in this house, and avoid compression joints wherever I can, especially if it's connected to the mains.

Many thanks in advance.

 

[ljrgas]

1 yes and no you can use both
2 no idea (other one faulty?
3 replace what? guessing the filling loop (compression caps or soldered)
4 if the other filling loop is working you would have to drain the system to remove the external filling loop then just cap both sides.

also no its not ok to keep refilling the system with water (you have a leak somewhere or there is another problem...

if you have a leak also the inhibitor with become weak and watered down....

 

[Albumen]

Thanks for swift reply. Yes, replacing the external filling loop. Presumably it should have some sort of non return valve built in to comply with regs.

Just reading the Installers Instructions again the 'built in' filling loop is meant to be 'detached' after filling. Which makes the instruction in the Users Guide to add more water if pressure is low a bit useless. Unless there's a second loop. Like I've got.

 

[ljrgas]

Thanks for swift reply. Yes, replacing the external filling loop. Presumably it should have some sort of non return valve built in to comply with regs.

Just reading the Installers Instructions again the 'built in' filling loop is meant to be 'detached' after filling. Which makes the instruction in the Users Guide to add more water if pressure is low a bit useless. Unless there's a second loop. Like I've got.

a sealed system should very very rarely need topping up (ie) never think about it its a sealed system water cannot escape! (unless there is a problem)
the external filling loop has a non return valve on it... also the loop on the boiler has a non return on it....
yes loops should be removed due to back flow but out of 100 boilers ive been to 99.9% of them have the loop connected.

the main thing I would be worried about is if the loop lets by....

 

[Albumen]

It's difficult to say how much I've actually been filling it up due to leaks (which I've not noticed, by the way).

I've done a bit of my own CH work in this house. So over the past 2 or 3 years I'm usually at a point where a new rad or towel rail has been fitted. Or the system drained and refilled. So I assume (incorrectly maybe?) that it takes a while for all the air to find it's way out. I'll spend a week or two after each bit of work wandering round the house bleeding radiators.

But when I do top up it's not massive amounts. I know there's not way of knowing how much water I'm adding, but I'll make a note from now on every time I fill up. Maybe note what the pressure is before and after.

But I'll look for leaks. Where first? Compression joints presumably. The system is a mixture (at the moment) of copper and Hep2O. We've got about 3 feet of space under the house where all the ground floor pipes are. I've been under there plenty but not actually looking for leaks, so there could be a very gentle one that I wouldn't notice.

So is there a reccomended filling loop? Or if it says WRAS is that all I need to know?

Thanks.

 

[ljrgas]

no recomened loop just make sure it has a nrv on it.... you can removed the external one if you need but make sure the one on the boiler works.......

everytime you drain the system you should add inhibitor..... (and not the cheap crap!


#leaks can come from everywhere but my exp is the rad valves.... also check the prv outside...... make sure its not dripping....


nope once filled you shouldn't have to fill again.................

 

[Albumen]

Thanks. Actually I don't suppose I have to replace the whole thing do I? Just the isolator valve (?). The one with the black knob on the back. The double check valve is on the left and actual flex pipe is fine. Just that the less compression joints I have to re-make the less chance of failure.

Thanks for your help. I'll get this done and search for a leak. Thanks for the tip about the PRV pipe.

I'm turning the mains off overnight. The wife is worried about sudden catastrophic failure in the middle of the night. I'm pretty sure it's just whatever seal there is around the tap gland, so should only drip once every 4 seconds (like it is doing). But I'd hate to be proved wrong at 4a.m.

It's been developing over time this. There was a stage when it leaked, but only when I was actually using the filling loop. But now it's all the time.