hose to pressurize combi water

[SS]

When I need to pressurize my combi I have to connect the hose to the system, top up, and then disconnect the hose again. Is there any reason I dont just keep it connected and turn the taps when required?

[Lobster]

It's in a byelaw or regulation or something; the idea is that if a valve fails there's no risk of mucky water in the boiler flowing back and contaminating the water supply.

That said, I don't think many people take much heed of it... I've never come across a plumber who has, for a start.

David

[The Natural Philosopher]

Nope. Mine is. Dont tell.

[SS]

Thanks for the replies. Seemed obvious to keep it connected but thought I better check.

Thank you.

[YAPH]

Water Regs guv, risk of backflow. More observed in the breach, and with some mfrs' built-in loops disconnecting them to comply is an actual plumbing job.

(Same with those rings on shower riser rails which the shower hose is supposed to be threaded through so the shower head can't reach the bath and be immersed in bathwater.)

[BartC]

It's sometimes called a filling loop.

Also, sometimes the filling valve can leak, and the system pressure can rise inexplicably.

[Donwill]

It's bad practice to keep the filling loop connected. Valves can leak or maybe left slightly cracked open. The next step for a lazy person is to only close the one valve after topping up. Don

[Mathew Newton]

There shouldn't be any real advantage to keeping it connected as you shouldn't be having to (re)fill it regularly. If you are then you've got a leak somewhere and I'd be inclined to find out where.

Mathew

[Terry Fields]

Thanks for that!

I always wondered why there were holes in the soap dish 'to comply with Water Regulations', though with 3.5 bars of mains pressure (cold and hot) the chance of any bathwater being sucked back into the shower head is about nil.

TF

[Martin Bonner]

to connect the hose to the system,

Maybe. However it is universal practise. I have had five plumbers in two countries working on my central heating systems, and none have ever disconnected the filling loop. (Six plumbers in three countries if you include my mother's system.)

[BartC]

How many valves are there supposed to be? My filling loops generally contain a single, washing machine type valve.

[BartC]

It was more likely with those underwater 'silent' filling valves used on WC cisterns.

Especially when several taps downstairs have been opened providing a more attractive outlet for the mains pressure.

But what about this scenario: the mains stopcock has been turned off (for whatever reason), you turn on a cold tap on the 2nd floor, immerse a shower-head in a bath on the 1st floor, with the cold tap on, and open a cold tap in the kitchen on the ground floor. Wouldn't this be enough to create a siphon? In fact you might not need that open tap above it.

[SS]

two, not sure how it works but one on the combi system and the other to feed the loop when connected.

[<me9]

THe other problem (which I *have* come across,) is the valves leaking (how many people turn both off?) and permanently refreshing the water in the system, causing premature corrosion.