HepVo valves

[Uno-Hoo!]

I've just installed a new bathroom and added a shower cubicle to where the airing cupboard used to be.

The waste pipe from the raised 'easy plumb' shower tray runs along two walls before joining the main soil pipe. Along its run it is joined by the waste from the wash basin and, finally, just prior to the soil pipe, the waste from the bath.

I'm finding that when the bath is emptying, the water cannot drain away into the soil pipe fast enough and there is a some 'backing up' of the water to the shower tray where there is a slight rise of water around the drain. It's not serious and there is no question of the shower tray filling up - but I'd rather it didn't happen at all.

I'm aware that HepVo valves are designed to allow the flow of water in one direction and then to seal and prevent 'nasty nifs' from coming back up the pipe. I wonder whether such a valve would also work in preventing the bath water from reaching back to the shower tray - or is a flood of water trying to go the wrong way likely to damage the HepVo?

Any views anyone?

Kev

[Palindrome]

These devices are designed for a maximum back pressure of 500mm water gauge*. If that pressure is exceded, the valve element will invert and allow flow in the opposite direction. It is a "design feature" - intended to show that there is a problem with the system. The valve element resets automatically.

*You need to confirm this for the specific model number you are planning to buy. I think that they are all 500mm - but the Devil is in the detail.

If the level of water in the bath, when "the plug is pulled" is not normally >500mm above the height that you are proposing to install the device, it should do nicely.

However, otherwise it would be totally ineffective.

However, if you did run a particularly deep bath for some reason and the valve element did flip, you would basically just be in the situation that you are in now. It wouldn't actually flood the place.

-- Sue

[Ian_m]

Been there seen that, HepVo didn't help as the run from shower tray wasn't steep enough to "push pass" the valve until the water was "deep" in the shower tray, and when it possibly did open the water didn't empty from the shower tray very fast. Oh when the pipe was opened to be "done properly" it was 1/3 full of "yuk" as obviously the flow rate was not fast enough to force soap/scum through the pipe.

Cured by rasing the shower tray onto a plinth to get greater fall in the pipe., but then suffered issues with the bath trap being pulled through, so a 400mm air admitance valve was fitted on a short vertical sub. Apparently the trap pull through due to excessive length of one of the waste runs, see the admittance valve instructions for the recommended British Standard where max lengths of waste are specified.

[Uno-Hoo!]

Ian

Thanks for that - although a bit late as I decided to go out and buy a HepVo before I got your reply!

It certainly works in preventing the 'back-flow' up to the shower tray because I filled the bath and then drained it after installing the valve.

I've tried pouring a few jugs full of water down the shower tray drain (I haven't yet installed the Mermaid wallboards or cubicle yet) and the water appears to be flowing through OK. I'm somewhat surprised by your experience because the HepVo is recommended by Hepworth for fitting below shower trays due to its shallow depth and no need for a deep water trap. My concern mainly was that the valve is designed to prevent air coming back up the pipe, not water, and whether the valve would cope with the back flow from the bath. It certainly seems to be doing that!

Ah well - I'll just have to suck it and see (not literally!!) and wait to see what happens when the shower is operational. I've fitted the valve into the long run of drain just behind the bath panel so I can get at it easily if I have to remove it at some stage.

Thanks again for your views.

Kev

>

[Ian_m]

I think the case I helped on was the shower waste run was generally too shallow and bathwater appeared in the shower tray.

Watch the too shallow run of waste, I have just opened a waste pipe at home to move things around and it was 1/2 full of soap crud along its length (put a wet dry vac on open end and sucked it all out, yuk yuk yuk...), no wonder it was draining slowly. Unfortunately it is fitted under bathroom floor, so just have to remember to wash out regularly with hot water when I have finshed bahroom rebuilding.

Glad you solved it, but be careful of the trap sucking issues in joining

40/32mm waste pipes seen it quite a few times even from a "puny can't get your hands in sink" feeding into the bath waste, which really surprised me considering the tiny volume of water involved.

[Uno-Hoo!]

Yes I'll certainly do that. Fortunately I don't seem to have any 'nasty niff' problems - even on a windy day when I've had the pipes 'open' to the main soil stack during the work, there doesn't seem to have been any smells coming from anywhere.

I'll certainly have to watch the 'crud build-up' situation, however. I'm using an 'easy-plumb' shower tray that is mounted on legs but the outlet from the trap is still only a few inches off the floor and the pipe then has to traverse two sides of the bathroom before it reaches the soil stack which is located in the opposite corner to the shower. Although there is certainly a 'fall', it is by no means steep and I've no doubt the HepVo will cause some standing water - although if it does, it is not living up to it's claims of completely replacing a water trap with no compromise on effectiveness.

Kev

[Ian_m]

Its interesting air pressure in soil stacks (if you like that type of thing). On Monday night when I was re-fitting all the 110mm waste under the bathroom floor (moved pan entry and AAV position) the soil stack was noticable drawing in air, the bag taped over the open end was noticable drawn in. But last night when I was testing for leaks and refitting floor it was noticable drafting out, usually in your face as you worked !!!!

This morning it was neutral, the bag on the pan entry was neither drawn in or out and no niff's either.

[Uno-Hoo!]

Hmm very strange!

In order to reduce the risk of standing water creating a layer of crud along the drain pipes I've now moved the HepVo from behind the bath panel to immediately after the shower trap. This still prevents bath water from rising up into the shower tray - but there is now only an inch or two of

40mm pipe that will have standing water in it. Far easier to clean when necessary, and still easily accesible beneathe the 'easy-plumb' shower tray.

Kev

[harry]

Best of all is to avoid branches in small diameter waste pipes. If possible, run all wastes separately to the 100mm drain.Especially where the wastes originate at differing hieghts. Eg. washhand basin and shower. This avoids overflows, water backing up and traps being sucked out etc. And have at least a one in twenty fall in "horizontal" runs.

[Uno-Hoo!]

Yes, all good advice - but often not practical!

Because of the layout of my first floor bathroom, and the way the joists run, I can only lay the waste pipes above floor level. Because the shower tray is the furthest item away from the soil stack, the 'fall' is dependent upon the height of the shower tray. It's not really practical to have a shower tray a foot off the floor and, because shower trays are designed with an internal slope to allow them to drain properly, you end up with the outlet from the shower trap being just an inch or two off the floor. With a

3 metre run from there to the soil stack, a fall of one in twenty is just not feasible!

Kev