Filling loop double check valve - which side?

[M.Joshi]

I am replacing part of our faulty filling loop as the ball valve has seized up in the combination double-check valve.

I was just wondering which side the double check valve should be installed? Mains cold water feed or central heating pipework.

I have seen both configurations on different systems.

It would make sense to have the double check valve on the mains cold water feed so the normal isolation valve on the central heating side can be used to add chemicals into the system. Although, some filling loops do not have a combination ball valve with the double-check valve which would mean that it could only be installed on the central heating side with a normal ball valve on the mains cold water feed.

 

[Noxer]

im guessing on guessing the double check would go on the mains side, as you dont want heating water getting back into the mains pipe

 

[mountainman]

Check valve should be fitted on the heating side of the filling loop,
Once the system has been filled then the braided loop is removed and the open ends capped.

 

[JCplumb]

Double check on mains side, iso's on both sides.
Yes you 'should' remove the filling loop as per regs, but nobody does in my experience.

 

[mfgs]

Double check valve on the heating side so you can disconnect the loop and add chemicals through the check valve. If the double check valve is on the mains side when you take the hose off you have no way of stopping the mains water.

 

[JCplumb]

The double check valve is on the mains side to comply with water regs.
The iso on each side stops the water.

 

[mountainman]

Unless water regs have changed then there should be no permanent connection between the mains and the heating circuit.
I know many boilers have internal filling loops but I'm talking about the proprietary flexible loops available in merchants.

 

[mfgs]

The double check valve is on the mains side to comply with water regs.
The iso on each side stops the water.

Not all filling loops have isolation on the check valve side though. So the check valve goes on the heating side.

 

[dontknowitall]

With all this confusion, why not put a check valve at each end then use a hose pipe when it needs filling?

 

[dancinplumba]

check valve goes on mains, water regs 1999

 

[JCplumb]

Not all filling loops have isolation on the check valve side though. So the check valve goes on the heating side.

There is no need for iso's on the flexi itself. they should be on the permanent pipework
So the branch from the cold feed goes into a check valve, then into an ISO. The branch from the heating return just needs an ISO on it.
The screw on end caps that 'should' be compulsory for when the flexible filling loop isn't attached cap up the end of the ISO on each branch.
There must be a check valve on the cold feed as per water regs for potable water.

 

[mountainman]

check valve goes on mains, water regs 1999

How would that work with a FL kit comprising of a 15mm valved tee a flexible hose and a Double check valve with a 15mm compression joint at one end and two half inch chromed caps?

 

[dancinplumba]

use correct type of fill loop, reg been in force since 1999, its to prevent backflow to mains. someone could connect hosepipe to it or anything that could cause cross contamination.

 

[M.Joshi]

I ended up fitting the double check valve with combined isolation valve to the mains water side as it was originally. This is the filling loop that I purchased which has an isolation valve at both ends and is WRAS approved:

http://www.screwfix.com/p/r24-filling-loop/83905

It seems to be well made but doesn't come with end caps. Why do other larger plumbers merchants such as Plumb Center etc. charge £20 upwards for filling loops?!

 

[dancinplumba]

merchants are still selling wrong type of filling loop

 

[mountainman]

merchants are still selling wrong type of filling loop

Can you illustrate the correct type please or is this a wind up lol

 

[dancinplumba]

they have two isolators, one with check valve attached, mjoshi has put link to correct type
not a windup

 

[mountainman]

http://www.****************/images/library/stock/webbig/35419.jpg?rand=130153667

Nothing wrong with this though!

 

[dancinplumba]

you then have to put an iso on cold main, then check valve, and just the iso on ch pipe.

 

[M.Joshi]

Incidentally, when I fitted the double check valve with combined isolation valve, I wrapped about 6/7 turns of PTFE tape either side and around the compression olive.

How do I know that the compression is tight enough and won't work loose with the mains water pressure? It seems that I could go a little tighter but didn't want to overtighten.

 

[mountainman]

Incidentally, when I fitted the double check valve with combined isolation valve, I wrapped about 6/7 turns of PTFE tape either side and around the compression olive.

How do I know that the compression is tight enough and won't work loose with the mains water pressure? It seems that I could go a little tighter but didn't want to overtighten.

Keep on like this and you'll be a professional plumber in no time!

 

[dancinplumba]

Incidentally, when I fitted the double check valve with combined isolation valve, I wrapped about 6/7 turns of PTFE tape either side and around the compression olive.

How do I know that the compression is tight enough and won't work loose with the mains water pressure? It seems that I could go a little tighter but didn't want to overtighten.

pay me to come and tighten it just the right amount for you
ps: i wouldn't have used any ptfe

 

[dancinplumba]

Keep on like this and you'll be a professional plumber in no time!

nah he's used to much ptfe lol

 

[M.Joshi]

Keep on like this and you'll be a professional plumber in no time!

Thanks - that wasn't my intention though!

I was speaking to a plumber at the shop I purchased the filling loop from. I wasn't going to use PTFE tape at all, just jointing compound. Instead of using jointing compound, he advised me to wrap 6/7 turns of PTFE tape around and on the compression olive.

The original valve did not have any PTFE tape on the compression.

 

[tamz]

How do I know that the compression is tight enough and won't work loose with the mains water pressure? It seems that I could go a little tighter but didn't want to overtighten.

If it hits the far wall during the night you'll know it wasn't tight enough :smile:
Generally hand tight + a half turn will be enough but it is something you just know.