Problem with new boiler

Igotadose

I had an old Firebird boiler replaced with new Grant Vortex 15 unit in May. 2 zones, one for house heat, one for immersion tank. House is 20 years old, I think the radiators are original, the immersion tank might’ve been replaced once.

Everything seemed fine in May. Boiler wasn’t used through the summer. Turned everything on in mid-October. The boiler would run for about 10 minutes, then stop running. Radiators would not heat up. Thermostat was calling for heat, zone valve was open. But, no boiler.

Installer came out and said there was low pressure in the lines causing the problem. Showed me a gauge in the back of the boiler registering 0 BAR. He pumped water into the system and the pressure went up to 1 BAR. Said to check it in 2 weeks.

Boiler ran fine up until today (8 days later). Today, only half the radiators warmed up, and the boiler cut out. The gauge registers 0 BAR. I’ve called the installer again.

I bled one of the radiators, the one at the end of the line, because that one has had air in it, in the past. Nothing there, either, seemed not to be much trapped air based on my prior experience with it.

I’m trying to understand why the pressure is dropping. If the radiators were leaking, I’d expect to see water somewhere, or hear a hiss, or smell something. Nothing like that.

If the installer comes out and pumps more water into the system, this might work for awhile, but isn’t really a viable solution. Could the problem be with the new boiler itself?

Explosive_Cornflake

Do you have a red expansion tank near the boiler?

Igotadose

duplicate

Igotadose

https://www.boards.ie/discussion/comment/122758852#Comment_122758852

Yes, the installer checked it. The boiler is outdoors, while everything including the expansion tank, pump, etc. is indoors where the old Firebird used to be

Biker1

https://www.boards.ie/discussion/2058377609/problem-with-new-boiler

If it's dropping pressure like that then you have a leak somewnere. Suggest a new plumber.

SVI40

I was having the exact same issue. It turned out to be a radiator that was leaking. It went unnoticed as it was partially behind a kitchen cabinet, and also has a radiator cover on it.
Since then, all radiator covers have been removed.

Igotadose

https://www.boards.ie/discussion/comment/122759148#Comment_122759148

Installer came out again, with a plumber. They found that the valve that feeds water into the radiators from the tank in the attic was closed. It apparently has always been this way, and they left it alone. We looked at each radiator with the system re-filled and the boiler running, and no leak.

Is it possible the old boiler, the Firebird, wasn't bothered by the low pressure? Because it ran more or less reliably, but inefficiently, and never had this issue i.e., it never just ran and cut out.

Is there a trick to finding leaks? Should we flush the radiator pipes (somehow) and refill with something that might block a leak?

hydrus21

Possibly a leak on pipework close to boiler (outside). Heating system water used to be fed from a attic tank so would be constantly filling if there was a leak.

In that case old boiler would just keep tipping away.