Buffer tank does it require tundish?

[elite]

Just planning the plant room, and there will be a cool energy buffer tank in there. Space is a little tight, so I was wondering if the the PRV on the buffer needs full G3, (e.g. tundish, 300mm etc) or if it can just go straight into waste? I suspect it does need full G3, but hoping it doesn't 

 

Thanks

[Temp]

Pretty sure it will, and a possibly a water trap.

 

Edit Actually there are dry tundish that don't need a water trap.

 

Edited May 29, 2023 by Temp

[dpmiller]

why does a buffer need a PRV?

[joth]

If this a heat pump with glycol? If so any pressure release overflow should technically be captured into a separate vessel to be reused or safely disposed rather than flushed into the public sewer. The MCS approved bucket to capture it is like £100 though ... For something you don't intend to ever use it is a bit OTT

[elite]

57 minutes ago, Temp said:

Edit Actually there are dry tundish that don't need a water trap.

I didn't know that - thanks 

 

42 minutes ago, dpmiller said:

why does a buffer need a PRV?

 

It was supplied with one 🤷‍♂️ - I guess becuase it is a sealed system, but I'm happy to be corrected and delete it if possible

 

37 minutes ago, joth said:

If this a heat pump with glycol? If so any pressure release overflow should technically be captured into a separate vessel to be reused or safely disposed rather than flushed into the public sewer. The MCS approved bucket to capture it is like £100 though ... For something you don't intend to ever use it is a bit OTT

 

It is a heat pump, hoping to avoid glycol and go with antifreeze valve

[Nickfromwales]

5 hours ago, elite said:

Just planning the plant room, and there will be a cool energy buffer tank in there. Space is a little tight, so I was wondering if the the PRV on the buffer needs full G3, (e.g. tundish, 300mm etc) or if it can just go straight into waste? I suspect it does need full G3, but hoping it doesn't 

 

Thanks

If it's a true buffer and has no immersion, you can blank the T&PRV as it will be already present elsewhere in the system. The buffers only need G3 and T&PRV if there is an immersion heater installed.

I've just installed one, last week, from Telford. It came with the empty 1 3/4" immersion boss and the blank 1/2" tapping for the T&PRV to be screwed into, but neither are wanted or required as it's a buffer only. Both will be blanked off, and only the UVC will need G3.

[elite]

Thanks @Nickfromwales and everyone much appreciated

 

I was planning for an immersion for backup, so will rejig things for G3. I think I can gain the height needed by wall / shelf mounting  the buffer with my network cabinet below rather than above -  pray for no leaks 🙏

[Nickfromwales]

2 minutes ago, elite said:

Thanks @Nickfromwales and everyone much appreciated

 

I was planning for an immersion for backup, so will rejig things for G3. I think I can gain the height needed by wall / shelf mounting  the buffer with my network cabinet below rather than above -  pray for no leaks 🙏

Why not just use the factory backup heater that will be already integrated inside most decent modern ASHP's?

[joth]

8 hours ago, Nickfromwales said:

Why not just use the factory backup heater that will be already integrated inside most decent modern ASHP's?

In my experience if the ASHP  has failed it's likely to be supply failure (trip) or something foobar in its controller (or cloud portal there of). Either these would take out its backup heater too.

That said, it'd likely also take out control of the circulation pumps and manifold actuators etc. One of several reasons I'm slowly moving my systems to have the ASHP just heat (cool) the buffer when told to and have Loxone manage everything downstream of that. 

[dpmiller]

all our controls and the secondary pump come off a different supply. Even if the ASHP was to expire and need to be isolated, we can heat the whole house either by immersion or boiler stove. Indeed even during a power failure everything bar the immersion can happily run off an inverter if needs be.

[Nickfromwales]

5 hours ago, joth said:

In my experience if the ASHP  has failed it's likely to be supply failure (trip) or something foobar in its controller (or cloud portal there of). Either these would take out its backup heater too.

That said, it'd likely also take out control of the circulation pumps and manifold actuators etc. One of several reasons I'm slowly moving my systems to have the ASHP just heat (cool) the buffer when told to and have Loxone manage everything downstream of that. 

Just install a Willis heater in the flow to the manifold(s) with manual bypass / changeover valves then?

 

TBH if you've already a G3 requirement with the UVC then go with KISS and put the immersion in the buffer  

[elite]

Thanks - yes G3 for UVC, so going to stick immersion in buffer, wall mount the thing to give me the height for G3.