Underfloor heating thumping noise

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OK, so we have recently moved into a house which has underfloor heating installed throughout and generally it works really well.

The system is fed from the hot water boiler. There are two manifolds, one for upstairs and one for downstairs. Both manifolds have pump which drives the water into the manifold.

Upstairs, we have no problems with.

Downstairs has three zones, Kitchen, Living Room and Utility/Bathroom.

The Manifold is shown in the Manifold_PreStart.jpg file which is how it looks when no heating is on.

Heating comes on at 6pm and at that point, the pump starts, shown by the red light in the Manifold_PostStart.jpg image.

A few minutes after starting, we get a thumping noise seemingly from the manifold but it is difficult to exactly pin down. I have a video of it which is on YouTube here:
- noise starts about 55s into the video. The thumping lasts a few seconds, probably less than 10 and is kinda juddery in nature, its sort of a duh-duh-dumm, duh-dumm.

The past few days I have been experimenting with different zones demanding heat via thermostats and when a single room (e.g. the kitchen) is the only one demanding heat from the system, then there is no juddering or thumping.

Only when multiple rooms are demanding heat, does the noise occur. For example, today, we had the kitchen and the utility requesting heat and the thumping happened.

I don't know much about the system as I didn't install it and there are no manuals etc, but it looks to be mostly Emmeti products.

Another thing with this downstairs manifold is that the top "Robot" dial is warped a bit. This dial seemingly measures temperature of the water going into the system. See Warped.jpg. Any idea why this could look like this?

Heating is currently on at pressure in the system seems to be about 1.7bar

Any ideas what could be going on in this system? The floors get warm just fine by the way.

Thanks
 

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CBW

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The noise sounds like a trv, so I’d say look at the actuators?
 
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DP

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Where is the blending valve and UF pump?
Is the flow temperature 70 degrees or is the temperature gauge goosed
 
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Are those valves on the manifold directional requiring water flow through them in a particular direction?

I see an arrow on the side of one of the valves in the photos pointing into the manifold, and that half of the manifold looks to be the incoming hotter water side if the guages are accurate.

If the water is being pumped the wrong way through them it could be making the valves rattle around causing water hammer effect in the pipework.

EDIT: Oh and the guage front is likely distorted from the plastic being melted by someone being careless with a blowtorch whilst soldering pipework.
 
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