combi in cellar

[Mpb-10]

Worked really hard and passed my Acs and am now in my probation period with gas safe. I have put alot into this and I want to do everything properly and safely. Im putting a vaillant combi boiler in a cellar, The flue will come out about 400mm above ground which is ok, theres a sink there to connect into the waste for the condensing pipe, gas meter is in the cellar, its going near a chimney breast, not on it. is there a distance it must be sited away from chimney? ive looked in my book but couldnt find anything. Also can you put blow off into and internal waste pipe? I know its a warning pipe, but is it allowed. 2 different gas engineers told me different things, I want to confirm if i can or cant.

thanks guys.

 

[marleyco]

there are two conversations ongoing regarding this topic, have a look for them. maybe if the sink waste terminates at an open drain or you could tee into the waste above the trap some how, remember your condensate will be connected, so cant allow potential poc entering cellar

 

[Solo Heating]

Worked really hard and passed my Acs and am now in my probation period with gas safe. I have put alot into this and I want to do everything properly and safely. Im putting a vaillant combi boiler in a cellar, The flue will come out about 400mm above ground which is ok, theres a sink there to connect into the waste for the condensing pipe, gas meter is in the cellar, its going near a chimney breast, not on it. is there a distance it must be sited away from chimney? ive looked in my book but couldnt find anything. Also can you put blow off into and internal waste pipe? I know its a warning pipe, but is it allowed. 2 different gas engineers told me different things, I want to confirm if i can or cant.

thanks guys.

The gas industry has a lot of grey areas, much of the time it comes down to interpretation which means no two installers will agree on everything. As long as you can prove you have done everything according to the regs as you understand them then that should be fine, then again ignorance of the law is no excuse so you must ensure you are using a reliable source of information or that you've at least thought about it.

I think everything sounds fine with what you are doing. As long as the flue terminates correctly outside then there's no need to worry about the chimney - treat it as you would any object on the building so you need to consider internal and external corner dimensions that the chimney might create for you outside etc.

Make sure your condensate is going into plastic waste and that includes the soil stack the sink is attached to.

The blow off is probably the area you could come unstuck on. I would say that as long as you can provide a visible means of seeing any discharge from the blow off then that's OK and that means using a tundish or similar on the pipe connected to the drain. I have in the past used a tundish which is very much bigger than normal because the blow off can create a lot of splashing so its best to capture all the water if you can. That way you can show you have prevented scalding. The other issue is whether the internal stack can safely cope with the heat of the water from the boiler if it blows? I'd say it would be fine but could be good to get some more details to confirm this. Unvented manufacturers always use plastic tundishs (usually too small in my opinion) and some boiler manufacturers even use a plastic blow off now so that might help with your argument.

Cheers,

Ben

 

[AWheating]

it is fine to install a blow off into internal waste system (ive seen it and done it loads of times), you will need to have a visable means ie. tundish and a water seal ie trap. best to fit an hepvo valve as its a dry trap so wont allow fumes/smells and is designed to take the heat that may come from the blow off.

 

[andyplumber]

Does the waste for the sink go into the soil stock or does it go into an open drain in the cellar. I have always been told not to terminate a condensing pipe into an open cellar drain, the blow off pipe you could blank off the one for the boiler and put one on the return above the boiler and let it terminate below the flue. Obviously make sure the manufactures allow this, some can be funny

 

[Mpb-10]

it is fine to install a blow off into internal waste system (ive seen it and done it loads of times), you will need to have a visable means ie. tundish and a water seal ie trap. best to fit an hepvo valve as its a dry trap so wont allow fumes/smells and is designed to take the heat that may come from the blow off.

I will put a tundish on the blow off, so the tundish goes on the blow off pipe, and the hepvo valve, that goes on the waste pipe after just after where I connect the blow off into the waste? that right.

cheers everyone for all help, really appreciated.