Vaillant ecotec 637 and Megaflo controls

[bonesetter]

I just spoke to builder who is also the plumber. He has just had ACL surgery to knee ligament. so out of commission for a while.

I'm going to speak with BCO later to check out their take on this and also see whether this install has it's own certificate issued by them as it was part of a house extension project.

I've also spoken to Megaflo technical re the discharge d2 but it's really not part of their scope.

I also talked about their thermostats in the megaflo and removing any of their stats voids the approval and warranty. I don't know whether the VR10 can fit in the dry pocket with two capilliary bulbs and still work ok.

 

[gaswizzard]

One saving grace being the tundish will act as an air break should the condense back up

That overflow pipe won't react to well with regard to any steam emitted from TPRV.

 

[simond]

Removal of the Megaflo internal capilliaries from the dry pocket invalidates G3 and also therefore building regulations.

Manufacturers wanting to use their own proprietary controls to monitor the temperature in their own unvented cylinders have, in the UK, to get G3 approval for the matched pair.

The OP has no such approval for a Vaillant coupled to a Poxi Batterton Megaflo, and in consequence must wire the system as per Mr UpgradeME.

The fact that a modern condenser finds it hard to get to 100C does not buy anyone a dispensation, EVEN internet experts who think they know more about weather compensation than any other living mortal.

Remember, not all advice on forums is what it seems, caveat emptor.

 

[bonesetter]

So would adding the VR10 to the dry pocket which still has the two capiliaries for the stats and which are still wired to trip the valve invalidate G3 approval?

 

[ALEC1]

3.21 If an indirect supply of heat to an unvented hot water storage system incorporates a boiler, the energy cut-out may be on the boiler.

From G3 itself!

 

[ALEC1]

its the manufacturers that insist on the use of all equipment supplied in package.

As your own cylinder is probably out of gaurantee there is no requirement to use the two port valve.

If you are worried just wire the boiler through the over heat stats

 

[bonesetter]

"The cylinder has a 25yr transferable on site service support guarantee against faulty manufacture or materials provided it has been correctly installed as per the the instructions in the instruction manual and all relevant codes of practice and regulations in force at time of installation."??

Other parts 2yrs apart from cold water valve 5yrs!

 

[ALEC1]

that is true, but how many unventeds fail, let alone fail with in 25 years...I dony know of any...can you cite any examples...

the two port valve was a good idea with cast iron heat excahangers, but with condensing boilers its a nonsense...

when Viessmann sent a 100l storage combi for WRAS approval, WRAS had to ring viessmann how to make the boiler over heat...the answer of course was that it was designed not to, and so it did not!

 

[simond]

It would not present any problems adding the VR10 to the unvented cylinder providing it does not compromise in any way the safety systems put in place by the manufacturer.

G3 does state that the 'energy cut-out may be on the boiler'.

Which scenario do you think this statement is meant to refer to?

A. I have an old Potterton Kingfisher II with an overheat stat so I don't need to use a two port valve.
B. I have a Myson Apollo with an overheat stat so I don't need a two port valve.
C. I have any make of condensing boiler (inc Oil) but it has an overheat stat so I can throw away the two port valve.
D. I have a system solution (boiler, cylinder and controls) all bought from the same manufacturer who has obtained G3 approval for the rig.

If your name is Alec it can be any of the above. If your name is Simon -or anyone else - desiring to work within the Building Regs on domestic applications it is D only.

The way the trade get round this is to include the two port valve wired through the cylinder controls.

If you don't do this to satisfy G3 you are flying close to the wind. Some people think they know too much; if I wired installs without G3 approval I would not be using a public forum to shout about it. But then it tells you more about the author.

Incidentally, Viessmann tell everyone that story, I heard it 7 years ago on the training course. They have to get G3 approval like everyone else selling boiler/cyl combinations in the UK.