Filling loop stop valve

[echoes]

Hi all,

When installing a filling loop, I understand that the double check valve / isolator valve end of the loop should go on the mains supply side, and the isolator valve should be on the CH side. Please correct me if I'm wrong.

Now the isolating ball valve (without the check valve) has an arrow on it to indicate direction of flow (from mains supply to CH), but this assumes that the pressure at the base of the arrow is higher than the pressure at the tip, which is the case when the filling loop is in use.

But when the flexi-hose is disconnected, the pressure at the tip of the arrow is >1.5 bar greater than at the base of the arrow.

Does this not risk the isolating valve leaking, since the CH pressure is pushing the ball valve in the 'wrong' direction, back against the spring clip?

Thanks in advance.

 

[Whitespirit66]

Doesn't your loop have an isolating tap at each end? As long as they are both turned off, then it won't leak.

 

[echoes]

Thanks Whitespirit66,

Yes it does have a valve at each end, but with the flex-hose disconnected (as it should be, but not necessarily will be) would the valve-without-the-check-valve be prone to leaking when the pressure across it is against the direction of the arrow?

 

[echoes]

Found this:

IRN 302~

Unvented primary circuits may be filled or replenished by means of a temporary connection between the circuit and a supply pipe provided a 'listed' double check valve or some other no less effective backflow prevention device is permanently connected at the inlet to the circuit and the temporary connection is removed after use

here

which states the check valve should be permanently fitted to the heating circuit inlet.

Is this out of date, or correct?

 

[dumbrill]

Found this:

IRN 302~

Unvented primary circuits may be filled or replenished by means of a temporary connection between the circuit and a supply pipe provided a 'listed' double check valve or some other no less effective backflow prevention device is permanently connected at the inlet to the circuit and the temporary connection is removed after use

here

which states the check valve should be permanently fitted to the heating circuit inlet.

Is this out of date, or correct?

You're reading this as a requirement to have the check valve on the primary circuit side, but having the check valve on the mains water side is also part of the 'inlet to the circuit'. Also by having the check valve on the mains side it protects against someone fitting a dirty hose.

 

[kirkgas]

Found this:

IRN 302~

Unvented primary circuits may be filled or replenished by means of a temporary connection between the circuit and a supply pipe provided a 'listed' double check valve or some other no less effective backflow prevention device is permanently connected at the inlet to the circuit and the temporary connection is removed after use

here

which states the check valve should be permanently fitted to the heating circuit inlet.

Is this out of date, or correct?

You're reading this as a requirement to have the check valve on the primary circuit side, but having the check valve on the mains water side is also part of the 'inlet to the circuit'. Also by having the check valve on the mains side it protects against someone fitting a dirty hose.

i agree with this, as the hose should have been disconnected you need to ensure the hose doesnt allow contaminated water to enter the system, when the hose is disconnected you should fit blank nuts to either end in case the valve does pass

 

[echoes]

when the hose is disconnected you should fit blank nuts to either end in case the valve does pass

That does seem most sensible, although I've never seen it done; in fact I've never seen a disconnected hose!

...but having the check valve on the mains water side is also part of the 'inlet to the circuit'.

Good point, but is the check valve 'permanently connected to the inlet' when the temporary hose is removed? When the hose is removed, the check valve is still permanently connected, but not to the inlet.
In theory, there is nothing to stop another mains outlet without a check valve from being connected to the CH circuit.

Also by having the check valve on the mains side it protects against someone fitting a dirty hose

Agree there.

Anyhow, I'm not planning to lose a wink of sleep over this, but I'm interested in the opinions and practices, so I am very grateful for you taking the time to reply. Any more comments gratefully received.