Ammonia Smell When Rads on

[JoeRoberts]

When heating is switched on there is a smell like eggs/ammonia in our back porch. This is the first point of entry to the house for the heating and water. The smell is not present when the water is on by itself, only when rads are on.
Boiler is outside in garage and well away so it is not a gas smell.
Has being going on for more than a year now, has anyone any idea what the problem could be.
Spoke to some plumbers and they never heard of it.
I've turned off the rad in the porch so not coming from that.

 

[Leo]

As the heating system is sealed, this smell will not be coming from the water. If you could smell the water, you'd have a major leak that you'd know all about!

Do the hot water pipes enter the house around that location? If the smell is present only when the heating is on, and when the rad there is off, then there may be something around the pipes reacting with the heat to produce the smell. Potential rodent issue perhaps...

 

[JoeRoberts]

As the heating system is sealed, this smell will not be coming from the water. If you could smell the water, you'd have a major leak that you'd know all about!

Do the hot water pipes enter the house around that location? If the smell is present only when the heating is on, and when the rad there is off, then there may be something around the pipes reacting with the heat to produce the smell. Potential rodent issue perhaps...

Yes Leo, this is where they enter the house. But pipes would be surrounded by concrete so can't see how something could be around them. But seems logical idea.
Sealed system but we do have to top up maybe twice a year so obviously some water getting out somewhere but this has always been the case before the smell arose.

 

[Leo]

Yes Leo, this is where they enter the house. But pipes would be surrounded by concrete so can't see how something could be around them. But seems logical idea.

Pipes should have been encased in insulation prior to setting in concrete, and this insulation can break down over time, or be attacked by rodents seeking out heat. Would it be possible to investigate with a dig outside where the pipes enter the house? Mice only need the smallest of holes to gain access.

Sealed system but we do have to top up maybe twice a year so obviously some water getting out somewhere but this has always been the case before the smell arose.

If there was a leak you'd likely be topping up much more regularly.