Restricting feed to header tank

[Anna Rack]

Due to British Gas not adding inhibitor after draining my Boilermate 2000 (it's not their policy!) I partially drained again and added 2 litres of X100.

It mentions in the installation instructions "Once the system is finally filled, turn down the servicing valve for the ballvalve in the F & E cistern to the point where the warning/overflow will cope with the discharge arising from a ballvalve failure."

Are normal screwdriver type ball valves safe to leave in the almost closed position or are they more likely to leak? To be honest I would rather leave it turned off and then back on once a year to top up the tank in the unlikely event the level has dropped.

 

[SimonG]

Overflow should be capable of coping with full bore mains.

Just leave it open.

 

[Best]

I don't think there can be any problem with turning a slotted screw type cheap isolating valve to nearly off position. Lots of them are turned down a bit to reduce flow & don't give any more trouble than full on.
It is the proper way to reduce the flow into the heating tank as it doesn't need large flow in & will keep it reduced in the event of a overflow.
A stopcock would be better if you wished.
I should add, - I always turn down any valve on the mains fill to a heating tank. Just the way I was taught & because the tank is only really mainly going to be a slight top up tank, a greatly reduced flow to ball valve is plenty.

 

[gassafe]

I don't think there can be any problem with turning a slotted screw type cheap isolating valve to nearly off position. Lots of them are turned down a bit to reduce flow & don't give any more trouble than full on.
It is the proper way to reduce the flow into the heating tank as it doesn't need large flow in & will keep it reduced in the event of a overflow.
A stopcock would be better if you wished.
I should add, - I always turn down any valve on the mains fill to a heating tank. Just the way I was taught & because the tank is only really mainly going to be a slight top up tank, a greatly reduced flow to ball valve is plenty.

seems a good practise, like you say it's only topping up, and if it were to overflow it gives the overflow pipe more chance of coping with the water... Still can't believe BG don't add inhibitor tho... That's like the mechanic draining your oil & saying we don't re fill your engine!!!

 

[PhoenixServices]

Where do you think they get all the power flushing from?!

 

[Ric2013]

5 years ago, I partially shut down the cold feed screw isolator valve to a washbasin with low-pressure hot water and direct cold feed, to give the taps both had the same maximum flow.

Can't comment on whether it did the valve any harm, but it's never leaked, and gives a more refined washing experience

 

[Anna Rack]

Thanks for the replies. It seems it's an accepted method and no problems have been reported.

But did find this on the TLV website

Ball valves are usually only recommended for use in the fully open or fully closed position. They are not suited to regulate flow by being kept partially open because ball valves make use of a ring-shaped soft valve seat.When used in the partially open position, pressure is applied to only a portion of the valve seat, which can cause it to deform. If the valve seat deforms, its sealing properties are impaired and it will leak as a result.

 

[gassafe]

If you would prefer, then shut it off & open it to top it up every few months, but probs more chance if the isolation valve leaking when there touched more often!

A permanent solution is a stop tap partially open as mentioned before.

 

[zzzjim]

. ......If the valve seat deforms, its sealing properties are impaired and it will leak as a result.

At times these theoretic excuses , get quoted as get out clauses ,
missuse -vs- manufacturer liability -- lower quality matterials worsening performance !
== Saves money ( Was it fully closed / open === less valid claims )


Leave set in place - may deform - but then better to not open / close once mishapen !
Quality parts will do better -than cheapies

 

[Ric2013]

If the valve seat deforms, does that mean it will leak through the spindle though, or may 'let by' slightly when closed? The latter is probably less of an issue than the former.

 

[zzzjim]

If the valve seat deforms, does that mean it will leak through the spindle though, or may 'let by' slightly when closed? The latter is probably less of an issue than the former.

I'm going with " let by ", especially if repeatedy open/close chewing into deformed mating surface
(as leaks from the spindle are bad for business)

 

[thorn]

It's not British Gas policy? Sounds abit of a joke really, how can they justify that

 

[Anna Rack]

I'll probably just leave the valve in the slightly open position, hopefully won't have to touch it again anytime soon - and they're not exactly expensive.

The BG engineer who came and did the job said inhibitor's not a good idea as it could mix with the drinking water etc!!!

I phoned BG to have a moan about this and they said that unless the customer supplies it they don't add inhibitor as there are all different types etc

Think I might write a letter of complaint, quoting the Gledhill installation instructions:

On filling the heating system and before the boiler is fired up, it is important to ensure the system water is treated with a suitable corrosion inhibitor, in accordance with the boiler manufacturer’s instructions.
Since the concentration of inhibitor present in a system can become diluted, for a number of different reasons, the system should be checked annually and re-treated as required, or after every full or partial drain-down.