Does Antifreeze make your heating quieter?

[ProDave]

Okay this is probably "silly question of the day"

 

I may have mentioned before that I had a grumble about the noise of the circulating pumps on my UFH manifolds.  They wer both IBO pumps supplied with the manifolds.

 

A few days ago I swapped the pump on the upstairs 0ne (the most troublesome) for a spare Wilo pump and that made that one almost inaudible,  So I was considering buying another Wilo pump for the downstairs one.

 

2 days ago however I laid and connected 2 more UFH loops for the downstairs snug living room.  I took the opportunity while filling them to top up the antifreeze / inhibitor that had become somewhat diluted when I partially drained down to swap my original faulty ASHP.

 

Since connecting that second loop and replenishing the antifreeze / inhibitor the downstairs UFH is substantially quieter, and it's not because it's feeding more loops, even if the thermostat for the newly connected room is turned down it runs a lot quieter.

 

So is it really a case that antifreeze / inhibitor mix running through a pump is quieter than plain water? and why?

[Onoff]

Certainly ethylene glycol is denser than water so that's probably why it's quieter is my guess. Pump will probably consume a bit more power but hey ho!

[Jeremy Harris]

Might it also be that the glycol is lubricating the pump a bit better than water?

[Ed Davies]

Could the noise have been the result of cavitation? Ethylene glycol has a much lower vapour pressure (at least at 20 °C) than water so would presumably be less susceptible to that.

 

Or maybe it's a matter of the viscosity; perhaps making the pump turn slower. Dunno.

[joe90]

I chose wilo for my pumps because of their low noise and low power consumption.

[MortarThePoint]

On 17/11/2018 at 14:11, ProDave said:

Since connecting that second loop and replenishing the antifreeze / inhibitor the downstairs UFH is substantially quieter, and it's not because it's feeding more loops, even if the thermostat for the newly connected room is turned down it runs a lot quieter.

 

What antifreeze/inhibitor did you use?

 

Air bubbles add a lot to the noise of a system, is it possible that when you topped up the system you significantly reduced the amount of air in the system?