Leak from Hot Water Cylinder Discharge Pipe into Toilet Waste – Advice Needed

[seabook]

Hi all,


I’ve discovered a leak under my toilet where the 22mm hot water cylinder discharge pipe connects directly into the toilet soil/sewage pipe. I know this setup isn’t ideal, but a plumber charged me £720 just for investigating and quoted another £1,600 to relocate the pipe properly — something I simply can’t afford right now.

You can see the connection in the photo below.

The leak seems to be coming from the joint between the discharge pipe and the waste pipe. I’m trying to find a temporary or budget-friendly fix to stop the leak, ideally without having to reroute the whole pipework.

• Is there a reliable way to seal this connection, even short-term?
• Should I be using a specific type of coupling, sealant, or strap?
• Is there any DIY fix that won’t risk making the situation worse? for example, replace the 90 degree elbow with a pan connector or

Thanks in advance for any advice — I’m really stuck here and appreciate any help.

 

[dilalio]

Is it an unvented cylinder discharge?
Show images of your cylinder.

It should be metal or heat resistant to high temps.

And that is no way to terminate a D2.

 

[seabook]

The cylinder is Ariston WRc-NSF Classico STi 150. The unvented cylinder discharge pipe connected to a tundish and Hepworth Hep2O under floor to the soil pipe.

 

[Madrab]

a plumber charged me £720 just for investigating and quoted another £1,600 to relocate the pipe properly

Ooo - How much .... wow - where abouts (roughly) do you live?

Is there water running in the tundish - small black cage to the left above the red valve? As suggested - plastic water pipe isn't rated for the possible temps that the TPRV could release under fault conditions

Or is the water leaking out of that hole when the toilet is flushed? Nightmare of a place to have fitted that TBH. If anywhere a saddle clamp on the waste pipe to the right would have been better than that.

 

[dilalio]

You paid £720 for investigation?
How long did it take him? 2 days?

 

[seabook]

Ooo - How much .... wow - where abouts (roughly) do you live?

Is there water running in the tundish - small black cage to the left above the red valve? As suggested - plastic water pipe isn't rated for the possible temps that the TPRV could release under fault conditions

Or is the water leaking out of that hole when the toilet is flushed? Nightmare of a place to have fitted that TBH. If anywhere a saddle clamp on the waste pipe to the right would have been better than that.

I live in Essex, just outside London. There's no water visible in the tundish, but water leaks whenever the toilet is flushed or the sink or shower is used.

It became clear the plumber was not acting in good faith. The leak is directly beneath the toilet, and it started immediately after using the shower. Despite this, the plumber spent two hours inspecting the heating system, bath, and sink — none of which were related to the issue.

Once he finally opened the ceiling, he identified the leak location immediately. He then made a show of making two phone calls for "advice," only to tell me he couldn't do anything about it that day. He left me with two outrageous quotes: £1,600 + VAT to relocate the pipe, or £5,800 + VAT to replace the cylinder entirely.

He then charged me for 4 hours (£600 + VAT) and left a gaping hole in my ceiling where the leak is still active.

 

[polesapart]

£600 to not fix the problem?? Ahem..

• Is there a reliable way to seal this connection, even short-term?
• Should I be using a specific type of coupling, sealant, or strap?

Clean and degrease mating surfaces and apply CT1 or similar to glue the speedfit elbow into the soil pipe. Secure with cable ties, daisy-chained to achieve length.
Allow, if possible, overnight to set.

Won't make the unvented install correct but should solve immediate issue for a decade or two.

 

[Mister Banks]

I live in Essex, just outside London. There's no water visible in the tundish, but water leaks whenever the toilet is flushed or the sink or shower is used.

It became clear the plumber was not acting in good faith. The leak is directly beneath the toilet, and it started immediately after using the shower. Despite this, the plumber spent two hours inspecting the heating system, bath, and sink — none of which were related to the issue.

Once he finally opened the ceiling, he identified the leak location immediately. He then made a show of making two phone calls for "advice," only to tell me he couldn't do anything about it that day. He left me with two outrageous quotes: £1,600 + VAT to relocate the pipe, or £5,800 + VAT to replace the cylinder entirely.

He then charged me for 4 hours (£600 + VAT) and left a gaping hole in my ceiling where the leak is still active.

Unfortunately you appear to have come across one of those tradespeople who shouldn’t be in business.

 

[endecotp]

How did you find this scammer tradesperson?

 

[Madrab]

Has your insurance been notified? They really should have been the ones to have first refusal at that I would suggest. I hate to ask, have they been paid and were you invoiced?

That original job wasn't the best TBH - the way that waste system is as plumbed, there was always a risk that a problem may occur I'm afraid. Especially with a toilet evacuating down into the branch like that and the waste coming in from the right.

As suggested by @dilalio though, the unvented/expansion discharge should be altered to comply and the connections made properly etc.