Question

We are having some major issues with Welsh water over the use of tundish’s and  “A” class  air gaps on 20 Grid Combination ovens.
Because the drain is so low we are unable to get a tundish fitted and maintain a 50 air break above the tundish.
We have spoken in depth with Wade Drains and under floor traps but welsh water are being a nightmare.
Has any other member had issues and how have they overcome it.
We have ensured all items used are WRAS approved and they have been quite helpful   but DWR CYMRU  +Welsh water are not  helping with advice or recommendations at all.
Any help would be much appreciated.

Replies:

1. Yes, we have had similar issues in different parts of the country. The only option (if rational)  is to fit feet extension and change the trollies to match, can’t recall if rational offer any extensions to the trollies. If another brand, you will need to do something similar or speak to the manufacturer on how to combat WRAS approval, it should be contained within the specific WRAS approval special notes.
2. We recently fitted “extensions” to the oven & Trolleys which increased the drain outlet by 70mm. These accessories are Rational products. Hope this helps.
3. We have had this and we had to fit a lift pump, so the unit drained into the pump then the water was pumped up and into a tundish, you do need to fit a vent upstand pipe In the pipe run between the combi and the pump to stop air locks etc
4. Has the member considered a waste water pump to resolve this issue? By installing a pump directly to the oven, the water can then be pumped upward to a tundish arrangement which in turn can then drain to the floor drain. We use either Saniflow Sanicom 1 or Grundfos Sololift2, commercial pumps.
5. Our advice would be to have site use a floor drain and sit the drain over the drain grate this does not require a tundish, we only use a tundish on 6 and 10 grids all 20 and 40 grids would be on a floor drain.  If it is too late to fit a floor drain, then fit a shallow tundish any fabricator can make or I have seen square type tundish’s used and cut down to suit.  So long as you have the correct gap this should suffice.  Some of our engineers also cut the pipe on and angle so that the back flow cannot happen.
6. Have they considered a Saniflow type system to lift the drain water to a higher level, and then drop into a tundish at about 1 metre high. I’m sure Rational do something on these lines.
7. We have installed a number of 20 grid combis they all were plumbed into floor gully’s but terminated above the gully, so we assumed this was the same as a Tundish.
8. From experience with 20/ 40 Grid or even double stacked combi ovens with any water authority there is always a potential drain issue. The options for a compliant installation are only:
   – Install drain over a 400mm (600mm) sq/ dia trapped floor gulley- no tundish but leave pipe 50mm above the gulley cover. ( using larger dia/ sq gulley allows for catching any splashing).
   – Install a combi drain pump- with triangular paddle from 1^st choice directly to oven then it will pump up and you can then if you only have a 2” drain pop up fit a tundish and a trap to the pipe and suspend the drain pipe from the pump 50mm above the tundish.
   Respectfully trying to fit any drain cover over a gulley that has a funnel or tundish style cover will not fit under the drain pipe and give a gap as required.
9. We (Space) recently fitted “extensions” to the oven & Trolleys which increased the drain outlet by 70mm. These accessories are Rational products.
10. We have had this and we had to fit a lift pump so the unit drained into the pump then the water was pumped up and into a tundish, you do need to fit a vent upstand pipe In the pipe run between the combi and the pump to stop air locks etc. Has the member considered a waste water pump to resolve this issue? By installing a pump directly to the oven the water can then be pumped upward to a tundish arrangement which in turn can then drain to the floor drain. We use either Saniflow Sanicom 1 or Grundfos Sololift2, commercial pumps.
11. Our advice would be to have site use a floor drain and sit the drain over the drain grate this does not require a tundish, we only use a tundish on 6 and 10 grids all 20 and 40 grids would be on a floor drain.  If it is too late to fit a floor drain then fit a shallow tundish any fabricator can make or  I have seen square type tundish’s used and cut down to suit.  So long as you have the correct gap this should suffice.  Some of our engineers also cut the pipe on and angle so that the back flow cannot happen.
12. Have they considered a Saniflow type system to lift the drain water to a higher level, and then drop into a tundish at about 1 metre high. I’m sure Rational do something on these lines.
13. I had a very similar experience with Yorkshire water on a 20 grid combi oven. In the end I had to fit a Munson ring and back plate to the floor just next to the trapped floor gulley and lower it to its minimum so that there was still a fall on the waste from the back of the oven and the waste outlet being hovered above the floor gulley created an “air gap” we actually trimmed some of elbow off the rational elbow to increase the gap slightly. On our site this satisfied the water authority.
14. We have installed a number of 20 grid combis they all were plumbed into floor gully’s but terminated above the gully so we assumed this was the same as a Tundish.