ankle deep

[wayno63]

Hi folks, fitted a new shower over the last couple of weeks, didn't alter any of the plumbing work apart from new traps, used the shower with no issues while withing fof a basin stand to be delivered to store. now that the basin is installed the shower is not draining away fast enough with a bit of gurgling from the shower trap. thinking it may be a venting issue now the basin is installed? is it worth changing for a vented basin trap? or any other suggestions welcome.

thanks wayne

 

[Madrab]

Yes, fit an antivac trap, that should help vent the run.

That being said the shower waste should drain without issue unless:

a) it doesn't have enough fall
b) pipework isn't large enough
c) run is too long
d) or the current run is restricted.

 

[wayno63]

thanks for the reply, a shower has been there for 10+ years, all I have done is replaced it and new traps, none of the fall has been interfered with and as I said without the basin fitted with just the waste pipe open there was no problem, will try a different trap tomorrow.

 

[Madrab]

Appreciate that but if the waste system was optimum and didn't have any issue then it should drain properly. Trying an anti vac trap may help but if it's suffering from a positive pressure issue then it won't. Is the soil stack open vented?

 

[wayno63]

don't think so

 

[Madrab]

If your soil stack has a durgo (AAV- auto air vent) too, then that vent will allow air in, that specifically releases any vacuum in the run and stops the traps being pulled on. If there are any restrictions in the system though then a positive pressure can build up and any AAVvent or anti vac will not allow that positive pressure to be released, that can then slow down the flow through the waste pipes as it's has to push against that pressure.

You can try an anti vac on the basin trap and see if it works, if it does then there is a vacuum being created at some point sepcifically in that waste run but if it doesn't change then you want to find you soil stack and see if it has a valve on it, if it does and you remove that and then everything drains properly, then it's usually down to a restriction somehwere.

 

[wayno63]

there is no vent, soil pipe runs under floor boards, exits to a 90° bend down to sewer, hopefully the basin vent will do.

 

[wayno63]

Well that didn't work......this is the soil pipe was thinking maybe adding a junction which would mean cutting some of the decking above into a reducer and venting above the gutters or possibly squeezing an air valve just under decking level, would this be ok?

 

[CBW]

Is there a ventilating stack on your property or nearby?

 

[wayno63]

Yes but not an option to connect to

 

[Madrab]

All soil pipes/sewers need to be vented both positive and negative. You mention that is decking? Is that elevated and was a later addition? That piece of stack may have been a normal vertical vented stack and then to cater for the decking, the branch and vertical was removed and then the horizontal run was just connected directly to what was left of the stack. As it is it sounds like the drain/sewer is vented by another stack so that's great, that means that stack specifically may be restricted or somewhere further upstream closer to the shower and basin waste pipes.

If you remove the trap from the basin waste pipe and then compress a plastic bag and seal it over the end of the pipe and run the shower, if the bag start to fill with air whilst the shower waste empties ok then you have a restiction somewhere downstream specifically on that part of the waste and there is positive pressure being created. The trick is finding that as just adding in a vent open to atmosphere further down may not be in the right place to relieve that pressure, if that makes sense. Chances are it's just years of gunge that's built up somewhere in the waste pipe and needs to be cleaned out.

 

[wayno63]

tried the plastic bag trick, did inflate so there's a blockage somewhere? best way of clearing?

 

[CBW]

tried the plastic bag trick, did inflate so there's a blockage somewhere? best way of clearing?

Depending on the blockage and it’s location, usually a drain Snake type, although I have no experience of this model, I’ve used similar like a monument, but they are dearer.

 

[wayno63]

Borrowed a snake but cann get passed the what I assume is a 90° bend under floor

 

[Madrab]

Borrowed a snake but cann get passed the what I assume is a 90° bend under floor

If you can't get anything mechanical down the waste pipe then a pressure plunger may help to clear it with lots of hot water and a detergent (not the strong acid unblocker types)

Fill the basin with the plunger acting as the plug, then lift the plunger and let some of the water run down into the waste then hold it with the plunger and then plunge it back and forward to try and loosen whatever is in there.

If that doesn't work then I'm sure you can guess what would be next.