Hole in floor under old warm air boiler?

Happyfairy94

Hi!

I have just had an old warm air boiler remover and left underneath it is this very dingy looking hole/pipe/vent?

The plumber who removed the boiler said it didn’t appear to be connected to it, but it was covered by this metal box the boiler sat on.

My bungalow (1970 build) has concrete floors and I honestly have no idea where this goes to, I’d assume a vent but I haven’t seen an external vent that would account for it. I had thought the warm air boilers pulled air in via the chimney flue in the loft.

Am I able to just fill it in, or would leaving it with a vent cover be better?
I will be screeding and flooring over the existing floor (asbestos tiles).

WIAWSNB

How far does yer arm go?

Happyfairy94

There is no possible way I’m putting anything down there 😂

WIAWSNB

Ha-ha - I don't blame you. 😵‍💫

I can only guess it's as you suggest - it was the air intake for the hot-air unit. Did you notice whether the unit had a matching 'hole' on it?

Do you know the make of the unit?

Anyhoo, assuming - as is almost certain - that it is a vent pipe, I'd sort it by filling it using builder's expanding foam, going quite deep - a good foot or more as it'll act as insulation - and then cap it off with a good 2" of mortar, smoothing it flush.

Not sure my curiosity could resist trying to tracing where it goes, tho' - no vents on the outside wall below DPC level?

fwor

Are you certain it's not just the return air flow pipe? Or have you already identified that? AFAIK all warm air systems have one - if you just take air in from outside you end up pressurising the entire house and blowing warm air out of every gap to the outside.

WIAWSNB

https://forums.moneysavingexpert.com/discussion/comment/82168017#Comment_82168017

That makes sense.

So there will be a return pipe, as well as a delivery pipe, behind each grill? And the returns will join up and feed back to that hole?

Happyfairy94

https://forums.moneysavingexpert.com/discussion/comment/82168010#Comment_82168010

the only thing I can’t account for on the house wall is there is a drain pipe that runs from under the ground and is secured up to the roof. I’m wondering if it’s related to that, although it looks like the initial descent into the ‘tunnel’ points the opposite direction 😅

It is quite a mystery!
The warm air boiler was a Johnson & Starley, and I believe the original one was too. But it didn’t look like this one was connected to it, although it was sat over it so maybe it was?

I just want to be sure that I’m not going to be somehow obstructing air flow into the property and causing damp but it does seem unlikely as it was completely sealed off under the old boiler.

If I had a camera I would definitely try that, but no appendages are going down 😂

Happyfairy94

https://forums.moneysavingexpert.com/discussion/comment/82168017#Comment_82168017

I always thought the return air flow was the vent that’s above the boiler cupboard door. But what you’re saying makes sense.
it seems odd it would be in the floor though, as my bungalow only has warm air vents in the ceilings and walls, there are none connecting under the floors? And no sign there ever was.
I thought most of the air exchange happened in the flue in the loft which had all the ducting connected to it.

Happyfairy94

https://forums.moneysavingexpert.com/discussion/comment/82168088#Comment_82168088

If I remove a grill there is only one duct behind it, at least from what I can see.

WIAWSNB

The hole is lined with a pipe - what is that made of?

The pipe you say runs from the ground up to the roof is presumably a soil 'vent' pipe, but a photo would confirm. Is it adjacent to a toilet inside?

WIAWSNB

There are vents in the ceilings and the walls? In the same room?