Small water heater discharge point termination (post tundish)

[Stones]

I've got an acquaintance installing one of the following small hot water heaters in a portacabin style building:

 

ATC-Pacific-Unvented-Water-Heaters.pdf 

 

The installation info shows the discharge point post tundish as 'to drain'.  The project in question requires a building warrant due to the length of time the building will be in place, and therefore needs to comply with the relevant section of the most up to date (Scottish) building regulations:

 

4.9.4 Discharge pipe termination: The pipe termination should be in a visible location and installed so that discharge will not endanger anyone inside or outside the building. Ideally, the final discharge point should be above the water seal to an external gully and below a fixed grating. Other methods for terminating the final discharge point would include:

a. up to 100 mm above external surfaces such as car parks, grassed areas, or hard standings; a wire cage or similar guard should be provided to both prevent contact with discharge and protect the outlet from damage, whilst maintaining visibility

b. at high level into a hopper and downpipe of a material, such as cast iron, appropriate for a hot water discharge with the end of the discharge pipe clearly visible

c. onto a flat roof or pitched roof clad in a material capable of withstanding high temperature discharges of water, such as slate/clay/concrete tiles or metal sheet, with the discharge point a minimum of 3m from any plastic guttering system that would collect such discharges. Discharge at high level may be possible if the discharge outlet is terminated in such a way as to direct the flow of water against the external face of a wall. However evidence of the minimum height of the outlet above any surface to which people have access and the distance needed to reduce the discharge to a non-scalding level should be established by test or otherwise 

 

I recall from previous discussions that some users had been able to terminate the discharge to a drain inside their houses rather than externally.  I'd be grateful if someone could advise what they did / if BC accepted?

[ProDave]

Certainly in England you can use a waterless trap to connect into a drain stack, but I have not seen that done in Scotland, you would need to check with BCO.

 

My discharge pipes terminate above a French drain along the front of the house with a cage over it as per regs.  My BCO expected to see it signed off by a plumber they had previously verified the competence of.

[Jenki]

I did an unvented course a few week back in Inferness, the waterless trap is acceptable, after the tundish. The D1 and D2 discharge pipes still need to be correct diameters and lengths etc, but they can discharge into the SVP, but can't use solvent weld, push or mechanical joints.

[Stones]

32 minutes ago, Jenki said:

I did an unvented course a few week back in Inferness, the waterless trap is acceptable, after the tundish. The D1 and D2 discharge pipes still need to be correct diameters and lengths etc, but they can discharge into the SVP, but can't use solvent weld, push or mechanical joints.

 

Do you happen to have anything in writing from the course confirming that?

[Jenki]

25 minutes ago, Stones said:

Do you happen to have anything in writing from the course confirming that

Unfortunately, it's not in the course paperwork. I asked this exact question as I want to discharge into an internal SVP. They showed examples using a waterless trap.

The only stipulation they gave was they you need to be able to see the tun dish if you do not discharge outside. I.e you must be able to see the tundish or the external discharge point.

[Oz07]

I have a combi discharge into internal drain after a "hotun" branded tundish. Signed off no probs but maybe different with cylinder

[Stones]

Thanks all.