In Aug 2003 we had a new boiler and hot water tank (Heatrae Sadia Megaflow CL170) fitted. Recently I've noticed when HW only is selected via programmer the radiators on the top (3rd) floor get hot. I've called out our CH maintenance contractor (Eon) who have diagnosed a faulty Drayton Mid Position Actuator. (Proposed replacement is a Honeywell) HOWEVER, the engineer also says our sealed pressurised system should be fitted with a 'zone valve'. Is he right? Should the inital installer have fitted one? It passed building regs - but apparently is not as it should be. Any thoughts? Eon did inspect the system before taking on the service contract - and didn't identify this apparent fault at that time - so I might be able to come to an agreement with them if they want to charge for this particular item. But do I actually need one?
ZONE VALVE ON HEATRAE SADIA MEGAFLOW?
- Thread starter NIGELB
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Tis correct...a zone valve( 3 wire) in addition to the mid position is usually required.
Ring the cylinder manufacturer to confirm.
Ring the cylinder manufacturer to confirm.
Although up until now it has been accepted that this was the case, fitting a 2 prt valve as the final cut off, the regs actually state that there must be come form of cut off/protection against overheating of the cylinder, not necessarily a 2 port valve fitted.
A presentation is currently being given to have this antiquated rule changed.
A presentation is currently being given to have this antiquated rule changed.
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No that would be wrong to remove the requirement.
The rule is you must use a zone valve which fails shut i.e. spring loaded to shut off any source of heat to prevent inadvertent overheat thus becoming one stage closer to the explosion. Every level of safety in unvented cylinders is beneficial and should not be removed.
All you have to do is buy another zone valve andwire heating S plan.
The rule is you must use a zone valve which fails shut i.e. spring loaded to shut off any source of heat to prevent inadvertent overheat thus becoming one stage closer to the explosion. Every level of safety in unvented cylinders is beneficial and should not be removed.
All you have to do is buy another zone valve andwire heating S plan.
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