Cast iron soil pipe vent

[roofnovice]

Hello,

I noticed that the cast iron soil stack that I have does not have a vent attached to the top:

There also looks like some corrosion going on near the top, looks to my untrained eye as though there used to be some kind of sleave that was there previously and was removed.

My first thought was to buy this and attach at the top: (FloPlast Vent Terminal 110mm): https://www.amazon.co.uk/gp/product/B07BWQX8BG/ref=ewc_pr_img_1?smid=AR5NTANTFUHVI&th=1

Further research tells me that the push fit mechanism on that is meant for UPVC soil stacks, not cast iron, so it won't work here.

What are my options here? Would an adaptor like this work: https://www.amazon.co.uk/SHMOX-110mm-Universal-connector-Adaptor/dp/B0D5RCX9VT

Thanks!

 

[denso13]

No need for anything to be honest.

 

[roofnovice]

Ever since I've moved into this property (5 years), I've had some sewer smells coming from upstairs bathroom, every now and then. Stronger in the summer months.

We have had Thames round to investigate whether it is a problem with their drains and on most of these occasions they did find blockages downstream that they cleared. When we've talked to neighbours, they all said they could not smell anything on those times things were blocked, whereas in our house the smell was quite strong.

I'm wondering whether that missing vent has any bearing on this - ChatGPT suggests it could:

The Problem of a "Bare Pipe" Termination​

Even though the pipe extends above the roof line, a simple, open-ended pipe is a flawed design for three key reasons:

1. Wind-Induced Downdrafts (This is likely your main problem)
This is the primary reason cowls were invented. Think of the vent pipe as a chimney.

• When wind blows across the top of an open pipe, it doesn't just go over it. It can actually create a pressure vortex that forces air down into the pipe.
• This wind-driven air pushes the sewer gases right back down the pipe they're trying to escape from. This pressurized gas now has to go somewhere, so it finds the easiest exit: your fixtures inside the house, causing the smells you notice.
• A cowl is specifically designed (with louvers, a hood, or a specific shape) to break up this wind flow, preventing downdrafts and ensuring gases can only exit, not enter.

2. The "Rainwater Funnel" Problem
An open pipe is a perfect intake for rain, snow, and debris, exactly as described in the first answer. A cowl's primary job is to keep these elements out while still letting air flow.

3. The "Pest Hotel" is Still Open for Business
Birds, insects, and rodents looking for a home see a perfect, protected, cylindrical cavity in an open pipe. They don't care if it's 6 inches or 2 feet above the roof line. A cowl acts as a physical barrier, usually with a screened opening, to keep them out.

 

[accelerator]

It would be good to get some black metal paint on that while you're at it.

 

[roofnovice]

Nice idea, never occurred to me to paint it

 

[accelerator]

So, is the smell worse when it's windy?

The missing cowl is unlikely to be the cause of the problem IMO, but worth a try.

There are a number of posts re sewage smells on this forum, so might be worth a search. It's probably related to the rest of your drainage system and possibly poor design somewhere.

 

[Hugh Jaleak]

By that logic every chimney in the Country wouldn't work, it's a load of utter bullocks. All that would have been on there originally was a Wire Cage to stop birds nesting, your odour issues are nothing to do with the vent.

Do you have any drains running under the property?

 

[roofnovice]

Yes, calling a plumber to check the drains a reasonable thing to do in this scenario. However, I don't have the money to spare atm. This seems like a low hanging fruit that may yield a benefit. It may not, but no harm in trying. Worst case, I get something that looks better than currently.

Would anyone be able to suggest if the two attachments I've posted would do the trick?

 

[Harry Bloomfield]

Would anyone be able to suggest if the two attachments I've posted would do the trick?

Just to repeat - the top, and what is, or is not on it, will make absolutely no difference. The cause of the smell is much nearer the ground. Find out where the manhole is, that your toilet, bath and sink discharge into. Flush your toilet, and have someone else see, if you see an immediate and brisk flow into the manhole, and back out the other side.

 

[accelerator]

Yes, we're not suggesting you call a plumber. There are some people on here that will be able to make suggestions about how to fix your problem, but you will need to provide some detailed info/answers about your plumbing and drainage arrangements.

 

[Hugh Jaleak]

Would anyone be able to suggest if the two attachments I've posted would do the trick?

Neither will make one iota of difference, save your money. Wind blowing over the stack will actually have the opposite effect and draw air out of the system, same principle as a chimney draws from a fireplace below.

Problem will be much lower down, Harry has given good advice, please follow that and report back.

 

[accelerator]

Re the connections, I don't think what you've posted is going to work. I would suggest searching on YouTube for:

"how to attach plastic soil pipe to cast iron pipe?"

to get some more ideas.

 

[roofnovice]

Thanks everyone, I appreciate the input.

Okay, so for context, it's a terraced property that has a single storey rear extension. We have a manhole but the extension has been built over it (probably been for decades). It's not accessible without lifting up floorboards (and my kitchen!)

The smell comes upstairs from the bathroom mainly but it's not year round, mainly seems to be in summer times and lasts for few days at a time, goes away and comes again for a few days then we won't smell it for many months. There does no issue with water being blocked, it moves smoothly from toilet, bath and sinks.

Quite a few of those times that the smell manifested, it corresponded with an actual blockage downstream a few houses to ours (which Thames Water unblock). On one particular bad occasion the Thames engineer who came to unblock something several houses down, he mentioned that the smell would have been progressively worser downstream - yet having spoken to a couple of the neighbours downstream, they could not smell anything - just confused what it is about my property that allowed the smell to propagate but not theirs. This led me to think it's something to do with p-traps and venting.

 

[Hugh Jaleak]

Choices are I suspect, either live with the issue, or uncover that manhole. Just because water is flowing freely from upstairs appliances, doesn't mean there isn't an issue lower down.

Also, unlikely to be an odour issue downstream of a blockage, as there's not much to cause an issue, any smell is more likely to be emanating from a build up for decomposing sewage, sitting behind a blockage.

 

[Madrab]

If the drains, soil stack and pipework are all in good condition then there shouldn't be any smell emanating from the drains into the property, it should all be sealed. The primary reason for all the outlets having traps with water seals is to stop that exact issue from happening. If there are no obvious signs of a blockage, I.E. bubbling up through the toilet, poor drainage etc then if there are smells then it can only be down to a few reasons.

A break in a pipe somewhere that is allowing gases to escape.
A bad joint somewhere leaking and allowing gas/waste water to escape and then stagnating
A blockage in the main drains and an inspection cover or parts of the drain not being sealed properly

Cowls/leaf guards/homemade chicken wire top etc are all a good idea for the top of stack vents and rainwater downpipes, just stops stuff ending up down the pipe and blocking it up.

.... And please don't listen to AI, it really doesn't have a real world clue what it's talking about.