Backflow prevention - fluid cat 4

[Newboy]

Advice needed

A commercial client has a number of domestic dishwashers installed.
They have been advised that they must fit RPZs to each installation to prevent backflow.

Questions

1) Should the appliance itself not have sufficient backflow prevention given that it is designed to connect to main supply and contains fluid cat 4 ?

2) If it doesn't have sufficient backflow prevention then why is it permitted to be connected to the main?

3) Does this mean that any household with such an appliance must have a RPZ installed to comply with water regs?

 

[seco services]

Reduced Pressure Zone works different to a double check valve etc.

 

[Newboy]

Sorry - should have said I'm happy with the function of RPZs - I'm just querying the application - I'm sure that there's a good rreason within the regs - I just can't find the relevant info!

Any advice gratefully received

 

[seco services]

I just can't find the relevant info!

i agree. have you fitted it ?

 

[ChrisR]

LOcal water autorities have power to rewuire whtever protection they see fit. It's pretty typical that a higher standard is required for commercial use than domestic.
A Poodle Parlour near me had a similar problem, so they fitted a break tank and small pump.

I'm told that RPZ valves are very rarely fitted, and that there are half as many registered fitters as RPZs, so they get 2 each

 

[Newboy]

No - I'm not an approved RPZ tester (as required by regs?) - at this stage I'm just trying to confirm that RPZs are required. There are plenty of other regs breaches to deal with first !

edit - sorry my reply was to secco's question

 

[Gasguru]

From the water regs....

G15.16 Household machines are manufactured to satisfy cat 3, where they are used in a non-domestic environmet appropriate backflow protection should be provided since they are then classed as cat 4.

Have a look here for clarification. It appears not all non-domestic are cat 4.

 

[muggles]

Advice needed

A commercial client has a number of domestic dishwashers installed.
They have been advised that they must fit RPZs to each installation to prevent backflow.

Questions

1) Should the appliance itself not have sufficient backflow prevention given that it is designed to connect to main supply and contains fluid cat 4 ?

2) If it doesn't have sufficient backflow prevention then why is it permitted to be connected to the main?

3) Does this mean that any household with such an appliance must have a RPZ installed to comply with water regs?

Domestic dishwashers should have at least Cat 3 backflow prevention built in (domestic diswashers are Cat 3, at least in a domestic situation). I think your situation really depends on what they're being used for, and whether commercial-grade chemicals are being used in them. If they're being used with domestic-grade cleaning products only then I would say that, as domestic machines, they are still Cat 3, and that you therefore need do no more than fit them as normal.

Dishwashers approved to Cat3 will be listed in the WRAS directory, as with all fittings.

If it is definitely Cat 4 in your situation (commercial machines are Cat 4, [unless in a healthcare environment when they're Cat 5] I think you've hit on something of a grey area here with having domestic machines in a commercial environment) then the WRAS recommendation is to use a CWSC with a dedicated supply pipe to the machines.

 

[Newboy]

Thanks to all - I've read the relevant section (thanks gasguru) and agree with muggles - the current use does seem like a grey area - I'm sure that will delight the client! (and result in trying to find an approved RPZ installer & tester)

 

[muggles]

Some info on RPZs for you http://www.wras.co.uk/PDF_Files/IGN 9-03-02 RPZ.pdf