Hello everyone,
I have an air-to-water heat pump from Stiebel Eltron, manufactured in 2013.
Recently, I had to replace a bathroom radiator in the attic due to corrosion at the connection fittings.
The new radiator (towel warmer) was installed, the system was refilled and vented. New water was added to the system at 2 bar (29 psi), as before.
Since the radiator didn’t warm up, I loosened the valve head and checked the pin for free movement. Everything seemed normal, but I sprayed Ballistol on it anyway.
When that didn’t help, I initially increased the flow rate at the radiator manifold (the radiator is connected—like another one on the ground floor—to the underfloor heating system), but unfortunately, that didn’t work either. (I now know this setup isn’t ideal, but it had been working fine until now).
In the meantime, I also replaced both the supply and return valves—again without success.
The other radiator on the ground floor and the underfloor heating throughout the rest of the house are working fine.
What else can I try? I’m pretty much at a loss right now.
I have an air-to-water heat pump from Stiebel Eltron, manufactured in 2013.
Recently, I had to replace a bathroom radiator in the attic due to corrosion at the connection fittings.
The new radiator (towel warmer) was installed, the system was refilled and vented. New water was added to the system at 2 bar (29 psi), as before.
Since the radiator didn’t warm up, I loosened the valve head and checked the pin for free movement. Everything seemed normal, but I sprayed Ballistol on it anyway.
When that didn’t help, I initially increased the flow rate at the radiator manifold (the radiator is connected—like another one on the ground floor—to the underfloor heating system), but unfortunately, that didn’t work either. (I now know this setup isn’t ideal, but it had been working fine until now).
In the meantime, I also replaced both the supply and return valves—again without success.
The other radiator on the ground floor and the underfloor heating throughout the rest of the house are working fine.
What else can I try? I’m pretty much at a loss right now.
F
Felix199329 Apr 2025 10:36Hello, that sounds like a tricky situation. There might still be air in the system, even if you have bled the towel radiator, so a complete system bleed could help. Also, double-check the system pressure to see if it remains stable at 2 bar. Sometimes the valves might not be fully open, or the circulation pump may not provide enough pressure. There could also be deposits or blockages in the pipe that are restricting water flow.