Service Valves

[jabba]

Hi, checked to see if this had been answered before but could,nt find it....

Why are full-bore service valves not allowed to go onto central heating pipes, this would make changing radiator valves so much easier as you would not have to freeze pipes or drain a whole system.

forgive my ignorance, im not a plumber but am very interested

Cheers

 

[WaterTight]

They are allowed as far as I know???

 

[dontknowitall]

My understanding is it's not good practice as they can be turned off too easily and cause possible expansion problems. Having said that when I come across them I don't remove them as it makes the job of fitting/removing radiators so much easier!

 

[SimonG]

As far as I know they're not rated above 65C. All the ones I've seen on heating systems weep, if I find them they come out.

 

[justlead1]

There is a limit on the belt and braces approach. Apart from extra potential leaks, the DIY enthusiast still has the problem of draining the water from the rad, this in it self can result in disaster.

 

[Ian10261]

As far as I know they're not rated above 65C. All the ones I've seen on heating systems weep, if I find them they come out.

A small percentage of the ones i've seen on heating weep but i dont think they're as bad as the ball type C/H pump valves. You only have to look at those and a jet of water gets you in the eye, and presumably they HAVE to be rated at above 65 degrees.

 

[stevetheplumber]

and where would you stop? another valve before that one in case it needs changing?personally i wouldnt leave a ballofix under boards to unreliable
larger heating system i try to add gate valves for each floor but only above floor level
most comercial heatingwill be zoned this way

 

[NathaP]

I've fitted service valves on heating, the price of these valves can vary and so can the quality. Experience tells me which valves to avoid...

Never fit a service valve to isolate a safety valve from a boiler.

On a commercial system boilers tend to have service valves fitted along with its own safety valve so the boiler can be isolated without fear of it exploding, unless the safety valve was scaled shut... I've never seen one scaled shut yet though, even on a secondary (tap water) circuit.

In my opinion fitting service valves of good quality to radiators is fine.

Some pics on my phone of one I done a few months ago.

 

[EPH]

If you need to better to fit lever valves made for the job IMHO obviously out of sight!

 

[NathaP]

Yes, and if you can't fit them out of sight, sometimes taking the levers off and hiding the moving part can help.

You may see in my pics I did not leave the allen key operated part visible to people standing in the room.

 

[missplumb]

i assume the OP meant why are reduced bore valves such as isovalves not allowed as i dont see any problem with FULL BORE valves being fitted but these would mainly be gate valves!!

 

[stonedagain]

I will shortly be replacing the flexible hoses supplied with my Smith's plinth heater, due to the integral isolation valves leaking intermittently (This is the second set that leaked, Smiths replaced them under warranty). The ones they sent me this time have no isolation valves. Is it advisable to fit separate isolation valves or just to fit the hoses without them?

 

[stevetheplumber]

I will shortly be replacing the flexible hoses supplied with my Smith's plinth heater, due to the integral isolation valves leaking intermittently (This is the second set that leaked, Smiths replaced them under warranty). The ones they sent me this time have no isolation valves. Is it advisable to fit separate isolation valves or just to fit the hoses without them?

as these are hidden under plnth id recomend a pair of gate valves just dont leave then fully open,open fully then turn back one turn

 

[WaterTight]

I've heard that trick mentioned lots of times about gate valves. Don't really understand why it would work though. Why would it be any less likely to seize mostly open than fully open?

 

[mikegas]

Just easier unseize as you can move both ways

 

[AWheating]

i cant really se a point to iso valves of any type on most domestic heating systems (fitted all around). They can be an advantage if the system is in stages of installation for example but otherwise just a waste of money and another point to leak imo. all radiators have valves that can be isolated for decorations etc... most systems that reqiure maintenence probably could do with a flush anyway, so drain down and re treat.