Posted 3 days ago
Combi heating system completely drained itself
Hi, I'm hoping for any ideas before I start paying a plumber by the hour.
Last night I got home and the heating wouldn't turn on. Annoyingly I'd turned it on remotely before getting home so I've no idea what initially happened. When I checked the boiler (baxi 836) the pressure was entirely gone, zero. In bed I heard a few of the upstairs radiators gurgling a bit, then this morning when the smart thermostats opened everything drained, both upstairs and down.
Using the fill tap I can hear water running down an empty sounding pipe and I don't want to run it for too long when I've no idea where the water is going. I've used an endoscope and can't see anything damp under the floor around the radiators.
I've read that besides a leak it could be a problem with the expansion valve but I've no idea how to check, there's no obvious pipe leading outside. And would it lead to a complete emptying of the system?
Does anyone have any ideas? Thanks
Last night I got home and the heating wouldn't turn on. Annoyingly I'd turned it on remotely before getting home so I've no idea what initially happened. When I checked the boiler (baxi 836) the pressure was entirely gone, zero. In bed I heard a few of the upstairs radiators gurgling a bit, then this morning when the smart thermostats opened everything drained, both upstairs and down.
Using the fill tap I can hear water running down an empty sounding pipe and I don't want to run it for too long when I've no idea where the water is going. I've used an endoscope and can't see anything damp under the floor around the radiators.
I've read that besides a leak it could be a problem with the expansion valve but I've no idea how to check, there's no obvious pipe leading outside. And would it lead to a complete emptying of the system?
Does anyone have any ideas? Thanks
Community Updates
13 Comments
sorted byI could hear entire radiators empty in minutes this morning (edited)
Expansion vessel keeps the pressure steady. If flat or faulty could of caused the pressure to rise, thus blowing the PRV and now its that that's letting by and not letting you fill.
Gas safe engineer required. (edited)
If it’s less then 10 years old and you have it serviced yearly it could be under warranty (edited)
The upstairs (and loft) radiators hissed for a bit then stopped, there was no sounds to suggest water was flowing into them at all.
The downstairs radiators however did let out a small/medium amount of air then fill with water. All except a vertical one in the kitchen that only partly filled before stopping.
That makes me think L0L is likely right. The amount of water left in the system would appear to be enough to fill anything lower than the height of the PRV, and would explain why I couldn't find any dampness under the floorboards.
You can repressurise the expansion vessel with a bike pump that has a pressure gauge.....but if it has failed then the diaphragm inside will be split so this will be a pointless exercise.....an expansion vessel isn't a huge job to renew (unless its an old worcester cdi boiler and sits directly at the back of the boiler underneath the flue outlet). The majority of modern boilers are built for ease of component replacement.
If your radiator pipework had failed inside the house then when you attempt to repressurise the boiler through the filling loop you would soon hear water coming out of the pipework or experience water coming through the ceiling if it was upstairs.
If the pressure has dropped to zero and you haven't opened the filling loop it won't be possible to bleed the radiators.