Need Help With Bad Odor

My husband and I noticed a sewage odor in the house which got progressively worse. It seemed to be coming from our vents and every time the heat came on, the smell got worse. We checked our cesspool and sumppump and everyting was dry and there was no problem with our drains or any backup whatsoever. We finally found the problem which was some sort of 3 inch drain pipe in the gound i our burner room that was covered with a tile. The previous home owners never told us it was there. The tile was sealed over it but apparently came loose over time. The smell was unbearable. My husband sealed the hole with a rubber boot and plastic end cap which was threaded into the boot. The smell is no where near what it was but it is still lingering. My question is, is it safe o completely seal that hole? I was worried about any Methane Gas and it's been 2 days now and I can't stop worrying about. Please tell us what we need to do or if it is ok to keep it sealed.

Thanks

Check for a dry trap on your HVAC condensate line.

I would also suggest getting rid of the direct connection of your HVAC to the DWV system by using a condensate pump.

I would restore the floor drain and put a trap primer on it.

The odor will be H2S (sulfur) gas. Methane is odorless. High concentrations of either can be dangerous.