NIBE SMO20 UK Humming Noise

[mousetarget]

We have just moved into a house with a NIBE SM020 UK system installed with an air source heat pump.

The system comes on during the night and emits a low humming sound which unfortunately reverberates into our bedroom.

Is there anyway for us to programme the system for it not to come on during the hours of 21.00 - 07.00?

We’d still like hot water for the mornings of course if possible, so this may mean the system has to create the hot water before it shuts off at 21.00?

Can you help at all as we are unable to get a good night’s sleep?

[mike2016]

Is it floor mounted or wall mounted? Check its level and when was the last time it was maintained? I have one downstairs outside my bedroom and can hear it going initially but doesn't bother me after that. It's on rubber bearings and runs for a while after I take a shower in the evening. It is probably driven by temperature drops but the installer should check all is working OK before excumunicating it from power each night!!

[IanR]

55 minutes ago, mousetarget said:

We have just moved into a house with a NIBE SM020 UK system installed with an air source heat pump.

The system comes on during the night and emits a low humming sound which unfortunately reverberates into our bedroom.

Is there anyway for us to programme the system for it not to come on during the hours of 21.00 - 07.00?

We’d still like hot water for the mornings of course if possible, so this may mean the system has to create the hot water before it shuts off at 21.00?

Can you help at all as we are unable to get a good night’s sleep?

 

Hi and welcome,

 

You can schedule both climate and hot water within the SMO20 controller, to set the allowable times for the ASHP to run. Page 22 and 38 of the linked document.

 

A couple of things to think about. Has a schedule been set to match with a cheap rate, over night tariff? Are you using such a tariff? If not then schedule your HP for times that suit you.

 

If you stop climate from working for periods of the day, the heat pump may not be able to put sufficient energy into the house on the coldest days in the hours you have allowed it to run for, so may start to use "Additional Heat" more often (if your ASHP has this). This is a resistive heater, similar to an immersion, that is not as efficient as the heat pump so may cost you more to heat your house. You can block additional heat to check if your ASHP has sufficient capacity to heat you house in the allowed hours. I keep Additional heat blocked all the time.

 

If you want hot water in the morning then don't shower within an hour*** of the schedule switching off at night or bring it on an hour*** before you need hot water in the morning.

 

*** adjust the hour to how long your reheat time is on your cylinder.

 

The noise you are hearing is unlikely to be from the SMO20, but from the circulation pump on the ASHP. Most Nibe ASHPs have an external circulation pump (located in the house) and you may have a second for your emitters depending on configuration - it's likely you are hearing the pump. 

 

Ref. https://www.nibe.eu/assets/documents/23948/231759-6.pdf

Edited August 3 by IanR

[IanR]

Oops.

Edited August 3 by IanR

[mousetarget]

Its floor mounted but as IanR says its not coming from the SMO20 but seems to be the circulation pump ASHP - there is humming, water noise pretty much all the time today but particularly at night, if you put your ear to the skirting board in the bedroom you can hear the noise more loudly - is there anything we can do? we just can't sleep?

[IanR]

44 minutes ago, mousetarget said:

seems to be the circulation pump ASHP - there is humming, water noise pretty much all the time today but particularly at night, 

 

Probably hearing it more at night due to there being less background noise. Scheduling the ASHP off over night is the best option, if the HP has sufficient capacity to heat the house on the coldest days.

 

It sounds like you may have some air in the system if you are hearing a watery noise. Do you hear the same watery noise for both space heating and hot water production? You'll have some air valves in the system somewhere, you could try to blead out any air, or get an Engineer in if you are not confident. When was it last serviced, the primary heating circuit should have been bled then.

Do you have a buffer for your space heating? There's likely a blead screw at the top of that to let some air out.

 

This probably won't deal with the humming noise, just the watery noise. The humming noise is more difficult, but you may be able to reduce it by isolating the pipes either side of the pump at their mounting positions. ie. putting some rubber washers/pads between the pipe mountings and the surface it is mounting to. Depends how your install is to how easy that may be.

Edited August 3 by IanR

[mousetarget]

It does sound like air in the system, the noise is just constant now it used to come on just 4-8 hours at a time. Don't know about air valves in the system as its totally new to us. It was only serviced 4 weeks ago, don't know about the buffer. We are real novices when it comes to this system,  here are few photos of the system. The air/humming sounds seems to be coming from the red valve control area - any ideas so we can sleep tonight?