Noisy UFH system. better controls?

[fenwick458]

I have just had an extension built and put in a 30m2 underfloor heating kit in the extension. it's run from a baxi combi, flow is split using zone valves so both the radiators and ufh can work independantly.

the problem i've found is the system is quite noisy. I've been bleeding it at the magnaclean just below the boiler almost every time i walk past the boiler cupboard and a little bit of air comes out, this has been for 2 weeks on and off as i've been away a bit.
i've also noticed the following
I can be sat at my desk downstairs at 4.30pm and hear the boiler fire up and the UFH system will start pumping, and then by 4.45pm it gets noisy i think this happens when the mixing unit is satisfied, by noisy i mean i can hear the sound of water being pumped through pipes.
also if i'm upstairs in bed i can always tell what system is firing the boiler just by hearing it, with the radiators the boiler fires up and pumps water(normal), with the UFH system the boiler fires up and then goes off shortly after and is just pumping water round.
then looking at the mixing unit there is a TRV heard on the mixing unit (it's currently on 35degrees i'm slowly warming it up 5 degrees per week) and if i turn the TRV up by 5 degrees it goes quiet, also if i turn it down it gets louder. so I think the unwanted sound is produced when the boiler is pumping water through the bypass loop when the mixing unit is satisfied, and also the excess noise from the boiler is when it's pumping.

I'm thinking of adding some better controls to the system so that once the mixing unit is satisfied the boiler and boiler pump turn off. this would silence the boiler, and the unwanted noise from the water pumping

but 2 other things worth considering are
-will the system just be quieter all round once it's completely bled of air?
-and once i have the mixing unit set to full (45degrees?) will the UFH supplied rooms heat up much quicker and reduce the amount of time the boiler is on anyway? at the minute the UFH is on for 2 hours in the morning and it never reaches 21 degrees so the boiler will just be on and pumping water for the full 2 hours.

 

[king of pipes]

Pictures would help do you have a separate pump unit for the underfloor like this ? How did you fill the under floor heating pipework ?

 

[Chuck]

if i turn the TRV up by 5 degrees it goes quiet, also if i turn it down it gets louder. so I think the unwanted sound is produced when the boiler is pumping water through the bypass loop when the mixing unit is satisfied, and also the excess noise from the boiler is when it's pumping.

Pump setting may be too high. The main issue is probably that UFH should normally be configured to remain on 24/7 not come on and off like a traditional radiator.

 

[Jones82]

May need a heat sink radiator on the underfloor zone or an automatic byepass, the underfloor zone on its own could be too small, the minimum energy the boiler is creating is to much, your likely hearing the internal bye pass in the boiler working or the pump whining

Sorry just reread your post, your right your likely hearing the bye pass but the boiler is designed to run for a few minutes after heating is satisfied to dissipate the heat, reducing scale in the boiler, called a pump overrun. Increasing the length of the bye pass could work or the auto bye pass may not be set correctly

 

[Sharp Point]

Possibility that the loops have air pockets in them still, were they filled and purged prior to the manifold going on?

 

[Sharp Point]

Also can we see a pic of the pipework configuration of the flow and return from the boiler going into the manifold ?

 

[fenwick458]

heres a picture. I don't know how it was filled my plumber did it