Outdoor boiler and rats

looksee

I have a recently fitted (year ago) outside oil boiler in a metal casing. Rats got in and did a bit of damage, which has been fixed, and there is a good bit of evidence with droppings. I have put a rat poison bait inside the casing.

The boiler is standing on a small concrete base. It seems to me the rats are getting in through a largish hole in the bottom of the casing. A hole penetrates the concrete and the casing and is easily accessible from the outside. It has a number of pipes (oil line, heat line etc) going through the holes then disappear underground, again easily accessible.

I had a tile over the hole, which covered it snugly, but its just rough soil/infil around the concrete plinth and they could easily be coming alongside the pipes or through a tunnel they have dug.

Is there any reason why I should not pour some cement into the hole, round the pipes, just at the point where they go through the hole, up to the metal of the casing?

Wearb

Have you considered expanding foam. Messy, but kills 2 birds.
I'd be inclined to protect them with something if using cement. Maybe a bit of spray paint or lacquer.

looksee

Well yes, expanding foam would be easier but I had the impression it was not rat proof?

I was concerned about the effect of the cement on the pipes, not sure it is a good idea really.

stickman1019

+1 for the expanding foam in my experience they don't go near it

stickman1019

+1 for the expanding foam in my experience they don't go near it

looksee

Well that would certainly be an easier solution, I will give it a try. At worst I will be able to see if they have tried to get in! Thanks.

robocode

Having the same problem now, rat droppings in oil boiler outdoor case. Did the foam do the trick? Any particular type of foam? I also need to fill gaps where electrical cable enters unit and wondering if expanding foam is suitable around the wires

twignme

If using expanding foam, plug the hole first with wire wool then spray the foam into it.

looksee

I just saw this post and had forgotten it was my thread! Yes, I stuffed the various holes with scrunched up chicken wire then sprayed expanding foam (can't remember which one but it was just standard foam). Of course it blew up far more than I realised and there were foam warts, but I cut them level and it has worked perfectly. I put a rat poison cube inside the boiler, just to see if it would be taken, and it was not, so I hope the rats are sorted!