Manifold ghosting heating
Hi.. I’m looking for some advice on a "Ghost Heat" issue with my wet Underfloor Heating system that is driving me a bit mad.
I suspect I have a passive flow issue due to a missing zone valve, but I’d appreciate a check from the experts here.
In the airing cupboard, the main flow from the boiler branches into three:
Branch 1: Upstairs Radiators (Has a Honeywell 2-port valve).
Branch 2: Hot Water Cylinder (Has a Honeywell 2-port valve).
Branch 3: Underfloor Heating feed (Goes straight into the wall, No zone valve/silver box present).
Whenever the Hot Water or Upstairs Radiators are on, the UFH manifold downstairs gets extremely hot, even if the UFH thermostats are totally off.
Before some recent work, I noticed the flow meter pins on the manifold dropping (showing positive flow) whenever the boiler pump was running for the other zones.
My plumber recently replaced the white thermal actuators on the manifold. Now, when the HW/Rads are on, the manifold bar itself hits 60C and is too hot to touch, and the plastic pipes of the flow and return are a little bit hot.
My Theory:
Because there is no 2-port valve on "Branch 3," the boiler pump is shoving 60C water directly into the UFH manifold whenever it’s firing for the tank or rads.
The new manifold actuators are successfully "holding the door shut", but the manifold itself is just sitting there being "cooked" at boiler temperature.
The Questions:
- Is it standard practice to have a UFH branch without a dedicated 2-port zone valve in the airing cupboard?
2.Does it sound like adding a 3rd Honeywell silver box to that UFH branch is the only way to stop this passive flow/dead leg heating?
- Is it dangerous/damaging for the manifold and those new actuators to be sitting at 60°C constantly while the boiler is doing other jobs?
Any insights would be greatly appreciated and if I need another plumber to look into this or a heating engineer?
Thank you