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Mitsubishi ASHP - Circulating pump noise?

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(@snuffy)
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120 kWhs
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Hi,

We had our ASHP installed about 2 weeks ago.  Hot water and heating all work well and the outside unit is much quieter than I expected it to be.  Unfortunately it's the noise inside the house that's the problem.  There a constant whooshing noise whenever the heating kicks in.  I set the schedule to stop the water heating overnight and have set the honeywell  thermostat to 15 degrees at night to stop the system running at night so I can at least sleep.  This worked until the outside temp dropped below 5 degrees and suddenly the pump started circulating constantly from 11pm until  6:30 am.

We've had the installed back who says it should be quieter and must be residual air in the system which can take time to clear, just keep topping up the system to maintain pressure around 1.6 bar.  I'm hoping this is all it is but it's been nearly 2 weeks and I'm topping up daily yet there are times I fancy it's getting louder and sometimes its so intrusive. I wonder about getting the whole system removed and going back to gas boiler.

Our installer had been very good and he's disabled the frost protection to stop it running at night soI can now sleep but I do worry what will happen in winter, not so much for house temp over night but for potential damage to the ASHP itself.  As far as I'm aware, there is no antifreeze in the system as the manufacturer advises against it apparently.

The system is set to flow temp 46 degrees, we can't use the auto setting as the room thermometer is Honeywell so we've been advised to leave on flow temp setting.

Does anyone have any thoughts?  Is there anyone who's had the same experience and it has settled down or they've found a fix?

Our system is:

Mitsubishi 6 Kw Ecodan Standalone (PUZ-WM60VAA) 150 L cylinder, low loss header/buffer tank.

Thanks 


   
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(@derek-m)
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Posted by: @snuffy

Hi,

We had our ASHP installed about 2 weeks ago.  Hot water and heating all work well and the outside unit is much quieter than I expected it to be.  Unfortunately it's the noise inside the house that's the problem.  There a constant whooshing noise whenever the heating kicks in.  I set the schedule to stop the water heating overnight and have set the honeywell  thermostat to 15 degrees at night to stop the system running at night so I can at least sleep.  This worked until the outside temp dropped below 5 degrees and suddenly the pump started circulating constantly from 11pm until  6:30 am.

We've had the installed back who says it should be quieter and must be residual air in the system which can take time to clear, just keep topping up the system to maintain pressure around 1.6 bar.  I'm hoping this is all it is but it's been nearly 2 weeks and I'm topping up daily yet there are times I fancy it's getting louder and sometimes its so intrusive. I wonder about getting the whole system removed and going back to gas boiler.

Our installer had been very good and he's disabled the frost protection to stop it running at night soI can now sleep but I do worry what will happen in winter, not so much for house temp over night but for potential damage to the ASHP itself.  As far as I'm aware, there is no antifreeze in the system as the manufacturer advises against it apparently.

The system is set to flow temp 46 degrees, we can't use the auto setting as the room thermometer is Honeywell so we've been advised to leave on flow temp setting.

Does anyone have any thoughts?  Is there anyone who's had the same experience and it has settled down or they've found a fix?

Our system is:

Mitsubishi 6 Kw Ecodan Standalone (PUZ-WM60VAA) 150 L cylinder, low loss header/buffer tank.

Thanks 

Do you have radiators or UFH?

 


   
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(@gfletcher)
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Joined: 2 years ago
Posts: 24
 

Hi @Snuffy, we had the same with our Mitsubishi system, it did calm down after a while (a good few weeks). I found that there was air in the system settling in the upstairs radiators (on the same level as the hot water cylinder. So I did a weekly radiator bleed for a few weeks too, and therefore had to top up the tank to get the pressure right. It is a lot quieter now. So the system got quieter after a few weeks, the air in the system took 2/3 months to work through, but it was a while before I found that the radiators needed bleeding. 


   
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(@snuffy)
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Posts: 16
Topic starter  

@derek-m

Radiators.  Had 2 replaced as part of the install 


   
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(@snuffy)
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Posts: 16
Topic starter  

@gfletcher 

That's good to hear.  I've been bleeding the radiators from the start, first morning the towel rail in the en-suite was cold so bled it on the off chance and loads of air came out and I've been checking every couple of days since. Seems to settle mainly in this one.  The others stay pretty clear.  

Least I know it should improve.


   
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(@derek-m)
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Posted by: @snuffy

@derek-m

Radiators.  Had 2 replaced as part of the install 

Try bleeding all the radiators, starting at the lower level and working your way upstairs. Don't forget to keep topping up the system as you progress.

 


   
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(@snuffy)
Eminent Member Member
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Joined: 1 year ago
Posts: 16
Topic starter  

@derek-m 

Thanks,  I've been bleeding them and topping up.  Only the last one seems to have anythingin it now so hopefully not much air left to shift.  Just worried as it didn't seem to be improving, there might be something else going on.  Looks like I'm worrying over nothing though and just need to be allow more time.

Fingers crossed it'll settle in a few more weeks 


   
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Toodles
(@toodles)
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Hello, our Daikin EDLA 8 kW/h system was installed in mid-February and the system has been bled approximately once per week and I think almost all the air is now out of he system. The ASHP only supplies space heating via 10 radiators - DHW is via a Sunamp Thermino ePV210 unit. I used to find that in the previous heating system with a gas boiler, the first radiator (bathroom) took the gulps of air and other radiators tended to stay totally clear of air. The new pipework has been extended with a dual fuel radiator above the new bathroom radiator. I find the towel rail now takes all the circulating air (possibly because it is the highest point in the system now); a quick bleed and then a pressure top-up seems to be showing the system as settling down nicely now. Fortunately I have not had noise problems though I used to with the old gas boiler installation. I think this is partly due to the low-loss header tank having the 2 pumps - 1 on the ASHP itself and the secondary pump circulating the water around the ten radiators. I have the Wilo Pico pump set fairly low and this tends to have the advantage of little to no noise from lock shield and TR valves too. Regards, Toodles.

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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Transparent
(@transparent)
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Posted by: @snuffy

I wonder about getting the whole system removed and going back to gas boiler.

Aaagh! It's that bad?

Is this just one sort  of sound, or a mixture of different types?

If you put your ear to a radiator, for example, do you actually hear a pump motor running?

Any chance you could post a photo here if we wanted to see something?
The point where the external pipes enter the house would be a good start.

Save energy... recycle electrons!


   
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(@derek-m)
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@snuffy

A further thing that can create noise is if the water flow rate is  too high. How many water pumps are installed and what are their speed settings?


   
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(@snuffy)
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Topic starter  

@transparent

I think wanting to rip it out was the product of a couple of bad nights sleep after listening to it all night but it is pretty loud.  It usually starts a a loud whoosh before settling to a quieter, constant tank filling type noise.  Probably only about 45 dBA but enough to be heard throughout the house.  Mercifully it doesn't run for very long.  You can heard it queitly through the radiators if you put your ear to them but yhe noise is largely airborne.

I've added pictures below

20230416 171844
20230416 171835
20230416 171828
20230416 171735
20230416 171712

   
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(@snuffy)
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Posts: 16
Topic starter  

@derek-m

I think 2 pumps. No idea about how they're set though.


   
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