Tundish is a fitting put in a vertical section of a discharge pipe with one side or both opened out so that you can tell when the discharge is flowing and can get something done about it.
If you have suspended (wooden floors) can you run the prv discharge and the condensate under the floor to the back yard or garden with a drop on it (or via a pump) into a rainwater gulley that has kitchen waste going into it, or dig a soakaway as per manufacturers instructions (when you get them) but roughly speaking it's 500mm away from house hole the size of a bucket, buy a ready made 4" pipe with the right holes for about a tenner, surround with limestone chippings (available where you buy the correct part). With the soakaway you could come out of the house below floor below ground level so that you can still get your drop.
We put a lot of soakaways in it's very often the best method, I have heavy breaking equipment, you can hire it for £20 or so.
You would have to be from another planet to entertain not using a condensing boiler.
It is good that you have vocalised just how extra difficult all this economy has made our job, we should be charging twice as much as we did in the non condensing era as most jobs take twice as long. After many such jobs I kick myself for being so optomistic about how the job would go.
