Underfloor heating thumping noise

[steve1986]

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

[PeterW]

Is there any blending valve on the manifolds as that looks like it’s dumping boiler temp water into the floors ..?? The thumping is probably hammer as the valves all start to open - if they are old then it could be slow opening valves causing the problem. Can you take a photo of the top of the valve ..?

[Nickfromwales]

There should be a pump sending water to these 2 manifolds, sucking heated water through a remote TMV? ( @PeterW, the same as was at @newhome's when we got there, eg the red Reliance TMV's which governed the flow temps to the floors ).

 

Agree it's likely to be weak / dying actuators, OR worst case the flow and return the wrong way around on that one problematic manifold causing the actuators to 'jump' whilst opening.

 

@steve1986 these wax actuators start to open around 30-60 seconds after they get fed with 230v ( and the wax in the head slowly starts to get melted ) so the elapsed time, where you are hearing this issue, is relative to the actuators going from partially to nearly fully opened. This is deffo being caused by the actuator(s). If you wish to fault find before buying new actuators, simply swap the 4 there over to the other manifold, as a process of elimination, and see if the issue migrates or not.

[steve1986]

Thanks all for your comments.

 

@PeterW - I can't see a blending valve.  Both manifolds look the same, so yea, not sure how the "blending" works in this case.  Does seem unusual that there is no mixing or blending though (?).  I'll try and take off an actuator and get a photo of what's in there.

 

I've attached a photo of the GRUNDFOS pump which pumps water from the boiler (presumably there is something between the boiler and the pump moderating the temperature but I'll need to take a further look at this when I'm back later on).  

 

These look like older manifolds but not sure to be honest as I can't get hold of the guy who installed it.  I can only guess maybe that the blending wasn't required in this case?

 

@Nickfromwales I think these are motorised actuators as when they get fed with voltage, a little black tip (tell-tale) slowly rises up, takes a few minutes to get fully up.  See new photo (actuator) where they are all closed.  I don't know how the actuators are connected to the valve in this case though so I'll try and take an actuator off and take a look.  They are very tight but I'll give it another go.

 

Thanks

 

 

 

[Nickfromwales]

2 hours ago, steve1986 said:

I think these are motorised actuators as when they get fed with voltage, a little black tip (tell-tale) slowly rises up, takes a few minutes to get fully up

Deffo NOT motorised. The motorised Salus ones open in a few seconds   these open slowly as the 230VAC goes into a heating element which melts a wax in a sack. That resultant energy turns into force which slowly pushes the pin hammer outwards to open the valve. 
Can you tell us what the flow temp is when the system is operating? The water temp getting to the 22mm pipes at the manifold please. 

[steve1986]

@Nickfromwales OK yea that makes sense.  I did think a motorised one would (should) be quicker then these ones! ?

 

So the top Robot dial measures temperature into the system but unfortunately that dial is all deformed somehow, you can see it in the image but not sure why.  Checked the equivalent upstairs system and temperature going in seems to be about 50^oC.  I can't say that is exactly what the problematic manifold is reading but I'd guess (hope) it was pretty similar.

[joe90]

My temp gauges on my manifold (Wunda) just pull out of a pocket, if yours are the same just swop them round to measure the input temp

[PeterW]

43 minutes ago, steve1986 said:

Checked the equivalent upstairs system and temperature going in seems to be about 50^oC.  

Ouch !!! That’s about 10-15°C more than it should be depending on the floor finishes. 

[joe90]

5 minutes ago, PeterW said:

Ouch !!! That’s about 10-15°C more than it should be depending on the floor finishes. 

No wonder that dial melted ?

[steve1986]

1 hour ago, steve1986 said:

@Nickfromwales OK yea that makes sense.  I did think a motorised one would (should) be quicker then these ones! ?

 

So the top Robot dial measures temperature into the system but unfortunately that dial is all deformed somehow, you can see it in the image but not sure why.  Checked the equivalent upstairs system and temperature going in seems to be about 50^oC.  I can't say that is exactly what the problematic manifold is reading but I'd guess (hope) it was pretty similar.

 OK actually, this may have been wrong.  Sorry I'm still getting used to this - bear with me and I'll double check the temperatures in/out tomorrow when the system comes on.  I just need to double check which pipes come from the boiler.  

 

Thanks for ongoing advice.

[joe90]

3 minutes ago, steve1986 said:

I just need to double check which pipes come from the boiler.

Which usually is the top rail coming from the boiler, lower rail return.

[Nickfromwales]

5 hours ago, joe90 said:

Which usually is the top rail coming from the boiler, lower rail return.

Usually, but not always   

[steve1986]

For the problematic manifold, I swapped the gauges around so that I can actually read temp going into the manifold.  Upon start of heating, temperature on dial went up to ~58^oC, which is actually what our boiler thermostat is set too as well.  It then dropped down to about 40/45 and stayed there for a while before slowly rising again, up to 55^oC after about 30mins of running.

 

The grundfos pump pictured earlier is connected to the lower pipe of the manifold and the arrow on the pump is away from the manifold (presumably back to boiler).

 

I cannot see any evidence of a mixing or blending valve regulating temperature of the water by mixing it with cold.

 

I am also not really familiar with this type of manifold as all my searches on google reveal manifolds that look nothing like this one.  I can't see any identifying marks or serials on it so who knows.

[steve1986]

The gauge actually continued to rise and went above 60^oC so I pulled it out so as not to melt it as well lol.

 

Turned it off for now as I'm not sure the guy who set this up did it correctly!

 

[joe90]

10 minutes ago, steve1986 said:

as I'm not sure the guy who set this up did it correctly!

You aint kidding , it needs blending down from radiator temps to UFH temps, no wonder that gauge melted.

[Olf]

15 hours ago, steve1986 said:

temperature on dial went up to ~58^oC, which is actually what our boiler thermostat is set too as well

Can you try to reduce boiler setpoint? You should really work with as low as possible to reach your comfortable temperatures. As a bonus the efficiency will increase. I've dropped to 40^oC (with standard radiators upstairs), if you manage to get somewhere there, the need for mixing valve may disappear.