Valliant 937 suitable? No one knows!...

[Biggles..]

Best be speaking to Vaillant then as their product doesn't have the required safety device for temp and pressure.

 

[Biggles..]

Blending valves to baths are for new installation where there has never previously been a bath installed (new build/house extension) theis can be satisified by a single valve at the source of hot water or individually at Waac new bath.

Part g of the building regs

 

[Beerlover]

They have a 10 bar safety valve and overheat protection is provided by the boiler itself. Shuts off at 82 ° (max opreating temp) and goes to F20 overheat at 95 ° (volatile lockout)

Retook my G3 at Vaillant - They told me about the G3/937 issue

 

[Bunnyman]

sorry beer lover check the MI no g3 for the 937 just double checked with those who must be obeyed

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• Bunnyman
• 26 Mar 2010
• 499

 

[Agile]

Sorry guys but you are all wrong.

Except me! I had gently pointed out that G3 now applied to all unventeds.

The trouble is that as changes to regulations come about there is no automatic advice to us.

Thats fine for us sad lot who keep up to date by following forums but 99% of RGIs dont have any way to keep up to date. Finish work and its in front of the telly on off to the pub!

 

[D_Hailsham]

I'm puzzled by the messages I see everywhere that combis can't manage two showers but unvented tanks can do it easily.

That's because the water stored in the unvented cylinder is at 60°C, while the combi has to heat the water immediately.

Say you have a shower delivering water at 10 litres/min (that's total flow - hot + cold) at 40°C. If the hot water is at 60°C and the cold at 20°C, you would need a 50/50 mix of hot and cold, i.e 5 litres/sec from each. You therefore get five litres of hot water removed from the cylinder and replaced by five litres of cold. The temperature of the water will therefore slowly reduce. Assuming you have a thermostatic shower, the proportion of cold water used will reduce so the temperature is maintained at 60°C. The water in the cylinder will not get reheated until the temperature has dropped to about 50°C, which is still more than enough for a shower. In fact the temperature of the water in the cylinder could probably drop to about 45°C before anyone noticed a reduction in the shower temperature.

You therefore do not have to heat the water so quickly. A 15kW boiler and an unvented cylinder would probably do the same job as a 50kW combi boiler, depending on the size and reheat time of the cylinder.

 

[Biggles..]

They have a 10 bar safety valve and overheat protection is provided by the boiler itself. Shuts off at 82 ° (max opreating temp) and goes to F20 overheat at 95 ° (volatile lockout)

Retook my G3 at Vaillant - They told me about the G3/937 issue

They would also have taught you that there are 2levels of protection required to comply with the regulations and that max operating temperature isn't one of them.
1st level is over heat that requires a manual reset,this must when activated stop the store being heated.
2nd level is a physicaleans of discharging the overheated water, a 10bar prv isn't suitable as the device has to be temperature operated. That is where the TPRV comes in.

Ive today spoken with Vaillant on this issue and have also been told you don't need G3 to instal it nor is it designed to comply with G3, that was the whole reason the store was sized as is to avoid all the issues that come up.

 

[Bunnyman]

thats what i said lol

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• Bunnyman
• 26 Mar 2010
• 499

 

[harold5]

beerlover is right. took mine recently to. G3 is a building reg .it used to cover unvented over 15 litres only. now it covers all hot water systems including vented,combis,oversink etc. it even covers storage cisterns.
what i dont know is do you now need your G3 qualification to fit anything that isnt >15l unvented.?

 

[Beerlover]

Bunnyman, those who must be obeyed will say what they need to say to protect sales.

Building regs are not retrospective.

Speak to Ian J; Ex Bunny but God when it comes to the real world.

BUT 937 is pants without a blending valve fitted, and only a sales rep would think anything different. They don't mention the dodgy shunt pump, controller or flow limiter.

It is, all show no go! or to use a gypsy expression; Handsome is, as handsome does.

 

[Bunnyman]

well we have to agree to disagree then a few remsheid ex bunnies on here vaillant golf day yesterday head of product said no g3 wheres 831 when you need him ?

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• Bunnyman
• 26 Mar 2010
• 499

 

[Biggles..]

937 does not satisfy 3.18 of the amended part g of the building regs,the product came before the regs and was certified as being compliant hence it's CE mark.
As such the MI's rule and they don't state the requirement of a G3 installer.

If you want to follow the rules exactly as written then,without a Temp relief valve you cannot fit this product.

 

[Agile]

The latest G3 also says that other methods of protection may be acceptable as well.

I must get out more often!

 

[Biggles..]

Only other is 2 stage manual reset thermal overheat.afaik this boiler doesn't have that.

 

[Agile]

937 does not satisfy 3.18 of the amended part g of the building regs,the product came before the regs and was certified as being compliant hence it's CE mark.

WHO "GIVES" CE MARKING/ CE CERTIFICATE?

The biggest myth about CE Marking is that one has to "go" to a "certifying agency" that will "give" the "CE Certificate". The fact is that, there is no "CE Certificate" as such. The manufacturer uses "Self Declaration" wherein the manufacturer tests the product (himself or from a test lab), he himself declares conformity (through a document called as “Declaration Of Conformity (DOC)”) and himself affixes the CE Mark on his product.