Need insulated Manhole cover

[AllexMyers]

I have a concrete filled manhole cover (fitted when a porch was built over about 1980s) and the floor is not insulated. I can't take the floor up but condensation appears around the drain during cold weather due to the cold floor. The drain (brick built 600 x 450) is a surface water about a metre deep. Is there some sort of replacement plastic and insulated cover I can swap the old iron one for? Any other ideas how to keep the moist air in the drain from getting through welcome. It has not been opened in 40 odd years and is in ex condition. Thanks.

 

[freddiemercurystwin]

Water meters have a bit of polystyrene pushed in (think it's more of a foam actually), it's supposed to do the same thing but in reverse, you could try something like that, if you cut the edges at a slight angle so it was a push fit it won't be able to drop down.

 

[AllexMyers]

Water meters have a bit of polystyrene pushed in (think it's more of a foam actually), it's supposed to do the same thing but in reverse, you could try something like that, if you cut the edges at a slight angle so it was a push fit it won't be able to drop down.

I've had another look and I could screw in some large screws about 200mm down and set 100mm insulation board (spray foam around the edge to seal it in and then remove the concrete from the lid and put a foam layer there to be level with the exist floor then lay some soft lino over. I'm hoping that should do the trick and saves digging out the steel frame which after all will take on the temp of the adjacent concrete floor. We'll see how that goes. It's an authority drain as it serves other properties so still accessible if needs be. Thanks.