D1 confusion

[TBServices]

Right, I've always been under the impression that when installing unvented cylinders, the PRV and TRV discharge pipework must be tee'd together on the D1 before the tundish.

This week I was asked to service a terribly installed UHWC in which the PRV was tee'd into the D2. Bad job I'm thinking, however, today I've seen a picture on FB (no names mentioned) of the PRV on a new cylinder install tee'd into the D2.

Am I going mad, or is this acceptable?

Putting the problems right on the crap job next week (D1 and D2 need re-piping anyway), so I'd like to just clear this up in my mind.

 

[Destroyer2813]

My take is if one goes in before and one after the tundish it is easy to determine which orb may me going

 

[Mike Jackson]

They should be connected together before the tundish. G3 3.50

3.50 Safety devices such temperature relief valves or combined temperature and pressure relief valves (see paragraphs 3.13 or 3.18) should discharge either directly or by way of a manifold via a short length of metal pipe (D1) to a tundish.

 

[TBServices]

They should be connected together before the tundish. G3 3.50

Cheers Mike, couldn't find reference to it in my BPEC book.

 

[vern]

Deffo what Mike said, only exception is if they have separate D2's both still must have a tundish

 

[TBServices]

Do megaflows only have one safety valve?

 

[Mike Jackson]

No, TPRV on side of cylinder PRV on control assembly.

 

[TBServices]

I think Stan's picture quality leaves a lot to be desired. There's some optical illusion stuff going on there.

 

[Destroyer2813]

Post 1 no names post 4 outed him :yes:. New who you where talking about straight away

 

[solutions]

They should be connected together before the tundish. G3 3.50

Am I right to understand that the D2's can be combined as long as both D1's have their own tundish?

 

[Mike Jackson]

I've seen somewhere mention of combining D2s. As long as it is sized appropriately I can't see there being a problem.

 

[sheff paul]

I've seen somewhere mention of combining D2s. As long as it is sized appropriately I can't see there being a problem.

you can join 2 unvented d2's,couldnt find information in bpec on the working out size,when I did it the other week

 

[TBServices]

You can definitely combined D2s, in multiple flats etc, as long as it's sized correctly.

 

[chris watkins]

Temperature relief valves = A safety valve which only operates on temperature i.e. 90-95deg C. (I have not seen one installed on domestic units)
Combined Temperature and Pressure relief valves = What you & I call & T&P, will open at 90-95drg C or at the manufacturers selected pressure setting. (installed on all domestic un-vented cylinders)
Expansion relief valves =The other safety valve, often mistakenly refereed to as PRV (pressure relief) only opens on pressure & is design to indicate a failure of the expansion vessel or bubble top. (& possible the pressure reducing valve) Alway set at a lower pressure than the T&P.

IMHO the discharge pipes from both of these do not have to run through the same tun dish (D1) however it would need to visible at one end to give warning, it would also need to have an effective air gap to meet the requirements of the Water Reg's. (but it makes sense to take it through the tun dish if possible)

You can join together up to 6 discharge pipes (from say a block of flats, any more would make it hard to find the one discharging) so long as the size of the pipe is one size larger than that required by the longest D2 pipe run. (always seemed a bit excessive to me that one whats the chances of 2 going off at the same time?)