Plumbing outlets in building fabric?

[markdavies87]

Hi all. I'm new on here and after some advice regarding condensing and blow off outlets. My background is building surveying and I have very little experience on the plumbing side of things so please bear with my poor technical knowledge!

I'm currently surveying housing stock for a social housing provider in preparation for external wall insulation. This involves removing and reinstating lights and many other various items on the external wall of properties as well as extending gas flues.

As regards condensing pipes and blow off pipes - what is the difference? How many of each can a single dwelling have or does this depends on the boiler type/size or number of boilers in the dwelling? From my current knowledge a typical dwelling will only have one condensing pipe outlet, however I'm seeing houses with up to three or maybe four similar looking pipes, some plastic others copper?

Do these so called blow off valves 'spit' water out at force? Is that the reason for them to be re-directed in the direction of the wall?

Finally is there a minimum these condensing pipe outlets should protrude from the external wall? I currently find a lot of them only protrude about 15-20mm from the wall and cause staining on the wall below which does look very good, especially on newly rendered dwellings.

Additional information regarding heating sources:
Most of our housing stock have a Worcester 30si combi boiler or a similar but slightly older vaillant model.
Fire places are being changed from gas fire places to an electric alternative - I check these in each individual house.
We are blocking up a lot of the older vents that were initially installed for ventilation of solid fuel/gas fires.
I know that any gas appliance needs to be vented and that blocking these would be extremely dangerous and life threatening. I would appreciate any other information that you feel is relevant.

Thanks in advance.

 

[lame plumber]

you need to have on site advice from a qualified gas safe operative, in order to look at each property in turn, relying on internet advice wont impress your insurer once someone dies.

 

[dancinplumba]

As above

 

[plumben]

As above you'd have to get a gsr to inspect every property

 

[AWheating]

Condense pipes do not terminate open ended if fitted correctly. Warning pipes may do. Blow offs can run like a mains water tap at scalding temps.the condense, flue and blow off must be altered by a gas safe engineer as well any external gas pipe work of course.

before any work is done you need to check...... Boiler visual assessment, Stop tap works, boiler flue parts are available, presences of asbestos in the boiler (along with the other asbestos checks done...... Ie. soil pipe, guttering and rwp, facial and sofit) , condense pipe work is up to regs etc.........

also if the flue comes out of the wall you will need a GSR everyday to disconnect the appliance in the morning and re commission at the end of the day.
This is to protect workers from fumes and allow the flue to be protected from the installation work causing blockages etc...

Gas fires,and any other open flued appliances can be effected by any change in ventilation. Including draught proofing. After every alteration of ventilation ( even adding a seal around a external door) the open flued gas appliances will need checking.

it should also be noted that any change or new extract fan can effect open flues and checks May be needed if one is changed or fitted.

i would expect that you would have a GSR to do a pre start check and then attend every day work is done.