Yes, design and size the discharge as outlined in document G3 of the building regs and take off 0.5m of the permissable run to allow for the resistance of the HepvO valve.

There is no specific maintenance requirement especially for HepvO in this application. Unvented systems should be inspected at intervals not exceeding 12 months, and during this inspection the safety valves & discharge pipe should be checked for correct operation, i.e. no blockage. This would indicate that HepvO is also functioning.

This is not advised as the HepvO valve will not be able to suck any air through as the normal water trap seal will be in the way. The HepvO can be installed in this scenario if its only purpose is to stop bad smells from the drainage system.

No. The HepvO is a water trap not a soil trap.

No, this may tear the membrane or turn it inside out.

This is not recommended because if the safety features fail on a combi boiler temperatures as high as 134°c could be discharged down the pipe which will flash to steam. With a tundish in place before the HepvO valve this steam would then enter the property. Without a Tundish in place, these very high temperatures would discharge down the HepvO valve and would damage the membrane. 

Yes.

It will hold up to 400mm water of back pressure.

Yes, the chemicals in the urinal will not attack the valve but the preferred method of installation is vertically. We do not recommend HepvO fitted to urinals in the horizontal position.

Upto 100°c.