System boiler with tundish?

Yes

As long as there is a satisfatorily air break in the pipework thats fine. The volume of the system is so small that the volume of the released water is neglgible

Chrs

 

Yes

As long as there is a satisfatorily air break in the
pipework thats fine. The volume of the system is so
small that the volume of the released water is
neglgible

Chrs

I know an unvented cylinder can use a tundish and then into a dry Hepvo trap with no solvent weld joints in the waste pipe.

Not 100% sure about a boiler discharge as this will be contaminated as an unvented cylinders discharge will not be. If it is OK use a HepVO trap as no water to dry up and give off drain smells.

 

Uh? I've seen some dodgy unvented installations, but not one where they've actually used waste pipe for the blow-off?!? Given that any water exiting the unvented is likely to be a. very hot and/or b. under considerable pressure I'm not sure how long your Hepvo trap is going to last. Regardless G3 specifies METAL discharge pipework.

Re: system boiler don't forget that most mfrs specify copper pipework on relief for reasons as above.

 

Uh? I've seen some dodgy unvented installations, but
not one where they've actually used waste pipe for
the blow-off?!? Given that any water exiting the
unvented is likely to be a. very hot and/or b. under
considerable pressure I'm not sure how long your
Hepvo trap is going to last. Regardless G3 specifies
METAL discharge pipework.

Look at the BRE certification. Clearly there:
http://www.redbooklive.com/pdf/042-97.pdf

Re: system boiler don't forget that most mfrs specify
copper pipework on relief for reasons as above.

Not sure about boilers into a HepVo trap. The temperatures will be about the same, so whether contaminated water should be discharged into the drain I not clear on.

 

I spoke to Hepworth re. this issue. A tech support
engineer started going on about the temperatures
plastic waste pipes can withstand but after
questioning him for 15 minutes, was unable to give me
a technical reason why it should not work perfectly
with a boiler discharge pipe.

The only answer he could justify was that it had been
certified for use with unvented hot water systems but
not boilers and therefore if the installation was
inspected it would not pass.

I wonder why they have not also got it certified for
this use?

That is the way I understood it after some investigation about 5 years ago. I wasn't sure if it had changed. And he is right, there is no reason why a boiler can't be discharged into a HepVo trap. If it was approved, then a boiler manufacturers could supply the whole tundish and HepVo trap in one bolt on assembly so cowboys and DIYers can't go wrong. I wouldn't like one in the kitchen at eye level, as steam could come out. In unvented cylinders they generally are in cupboards out of the way, which defeats the object, as a tundish is supposed to be in a position that can be noticed.

 

I wonder why they have not also got it certified for
this use?

Hepworth are missing a big market by not doing so.

 

Now I'm really confused... I checked the lastest Part G (2006) and it still specifies "metal" for both pre and post tundish. Which obviously contradicts the Hepvo spec?!

Will dig a little deeper on this one, since I can see great advantages in using a Hepvo. Not sure how the downstream pipework would cope though with a large rumbling unvented...

 

Now I'm really confused... I checked the lastest
Part G (2006) and it still specifies "metal" for both
pre and post tundish. Which obviously contradicts
the Hepvo spec?!

Will dig a little deeper on
this one, since I can see
great advantages in using a
Hepvo. Not sure how the
downstream pipework would cope
though with a large
rumbling unvented...

Using the high temperature mPVC pipe should be fine and equivallent push-fit fittings. Solvent weld is no good. Make sure is it swell clipped.

I would connect my own boiler with HepVo trap, but would not do it for others. Pipes, and flues, on the outside of buildings look really naff.

 

Now I'm really confused... I checked the lastest
Part G (2006) and it still specifies "metal" for both
pre and post tundish. Which obviously contradicts
the Hepvo spec?!

Will dig a little deeper on this one, since I can see
great advantages in using a Hepvo. Not sure how the
downstream pipework would cope though with a large
rumbling unvented...

Look at this, Atmos have a discharge into a HepVo trap and internal drains:

"Combined Safety Discharge and Condensate Drain
This is a unique option which means that there is no need for an external copper discharge pipe, as is normally required for unvented hot water systems. The 32mm waste pipe is taken to the nearest soil pipe or internal drain connection."

Look at this:
http://www.atmos.uk.com/corefiles/productDoc(135).pdf

All in colour and clearly visible with a HepVo trap and brass Tundish.

 

http://www.atmos.uk.com/corefiles/productDoc(131).pdf

Look at the above too. There is clearly two tundishes. One for the unvented side of the com,bi and one for the boiler discharge. Both feed into a HepVo trap.

 

You can use a hep vo via supplied tundish with an unvented cylinder ( 600 mm below relief valves of course) , it can then be run in waste pipe to a stack BUT that waste pipe cannot share anything else ( sinks baths etc) and preferably labelled as such . Never seen anyone put the prv of a combi or system boiler on a hep vo though , not sure why ? I use a mushroom or turn the pipe back on itself

 

High temp' plastic waste pipe must be used. One of the Atmos boilers used a HepVo trap for the boiler PRV. Look at page 26 and 27 here. Pretty clear that the PRV can go into a HepVo trap. High temp plastic pipe with no solvent weld fittings are to be used.
http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0CGgQFjAI&url=http://www.atmos.co.uk/wp-content/uploads/2012/04/Atmos-Multi-Mk2-Installation-Manual-2Dec08-Amend-18Jun10.pdf&ei=_991VI3rNc6y7Qayn4HoBg&usg=AFQjCNGA_7hvCL-g61FPa2A66_ToXjCvWA