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ASHP flow through pipes is noisy and preventing us from using at night......looking for help.

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(@dannymoss23)
Trusted Member Member
118 kWhs
Joined: 6 months ago
Posts: 25
Topic starter  

Hi, I'm hoping to get some help, advice or just common experiences......we're really struggling with the noise from the flow pipes. Not with expansion and knocking - we did have some of that but the installers have come back to secure the pipes and add foam to stop any rubbing on the floorboards and jousts. The noise we are struggling with is the actual noise from the flow coming from the ASHP to the cylinder and back again. 

 

Some scene setting:

We had our Ecodan R32 11W ASHP installed in late October, after the original design had the heat pump on the exterior wall outside the bathroom, chosen by the sales guy as the shortest route to the cylinder - which is housed in our old airing cupboard in the 1st floor bathroom. But once the technical pre fit team came around they said it couldn't go there as it was too close to the neighbours planned extension, so we decided to house it behind the garage on the opposite side of the house and run the flow pipes under the 1st floor floorboards across to the bathroom - where the cylinder still lives. I should at this stage point out that we were replacing a gas powered air blown heating system from the 70's, so no boiler, no radiators and no pipework. Just a massive gas blown system in the kitchen and lots of air ducts leading up to the loft or down in the floor and then to vents in the rooms, horrible inefficient system that had to go.  

So the install went ahead and the guys fitting it used several miles of copper pipes - more than they thought they needed (at no extra cost I ensured) and managed to get it all in during the week. And the system is in, works great from a heating point of view, I'm getting around 3.5 COP and the massive rads we needed are able to heat the house. The pump is working very hard on the cold days and I'm spending more than £10 per day whilst it's less than 5 degrees which I'd like to optimise over time. But the problem I have is that we can't run it at night because of the noise of the flow coming through the bedroom from the garage. I think the noise may be getting caught in the cavity in the exterior wall as the noise is most prevalent behind the headboard inside the wall. 

I've turned our pumps on the pipes down to the lowest setting to reduce the noise but they are still running at 21. 

Has anyone had any similar issues or have some suggestions to reduce the noise? 

Hopefully my ramblings made sense, I'll do my best to clarify any points if not! 

 

Thank you in advance. 


   
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(@iancalderbank)
Noble Member Contributor
3640 kWhs
Joined: 2 years ago
Posts: 644
 

hi danny

you mention pumpS , does that mean you have more than one? If yes, do you have a system diagram or an understanding of which pump is circulating what water? where are the pumps?

When you say "running at 21" - 21 of what?

what size (diameter - 22/28/35) are the pipes in question? did they fit insulation around the pipes where they come into the house and continously inside under the floor? insulation helps with noise as well as heat loss. 

  Is it "flow noise" - which is the whooshing of high speed water going through too small a pipe, think the noise you'd get if putting your head in contact with the pipe feeding a basin tap thats fully on but you can't hear the water splashing out of it? Or is it the humming / vibration noise that is due to the actual  water circulation pump?  I ask because "flow noise" is usually hard to hear unless you're really close to the pipe, but "pump vibration noise" can carry further.

Re your spending comments , which can be the foundation of a peformance discussion: It really helps if you can speak in kwH, as none of us know what electricity tariff you are on, and relative to your actual heat usage as well, and at what exact outside temperature you get that much usage. . Also take a look at what COP you are getting on a day by day basis relative to outside temp. SCOP of 3.5 long term is perfectly decent but performance issues (if there are any to find) are usually best tracked by looking at shorter term performance.

My octopus signup link https://share.octopus.energy/ebony-deer-230
210m2 house, Samsung 16kw Gen6 ASHP Self installed: Single circulation loop , PWM modulating pump.
My public ASHP stats: https://heatpumpmonitor.org/system/view?id=45
11.9kWp of PV
41kWh of Battery storage (3x Powerwall 2)
2x BEVs


   
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(@andygo)
Trusted Member Member
108 kWhs
Joined: 3 years ago
Posts: 20
 

We have a similar issue, ours is because we have 2 CH circulation pumps (1 for UFH, 1 for upstairs rads), this is in addition to the pump in the ASHP.

When both of the CH pumps are working the system is noisy. Installer said it's expected as the pumps are in series.

Our solution is to only run the UFH at night. Not ideal but works for us at the moment. I plan to get our system improved in time.

If you have more than two pumps on your system try just running one at night.

Also be careful turning down the speed of the pump...it may effect overall efficiency if they’re too slow.


   
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(@dannymoss23)
Trusted Member Member
118 kWhs
Joined: 6 months ago
Posts: 25
Topic starter  

@iancalderbank Hi Ian and thank you for reading and replying. I'll try to answer your queries the best I can. 

Posted by: @iancalderbank

you mention pumpS , does that mean you have more than one? If yes, do you have a system diagram or an understanding of which pump is circulating what water? where are the pumps?

so I have 2 x Grundfos UPS3 pumps outside of the cylinder on the pipes in the bathroom:

 

Posted by: @iancalderbank

When you say "running at 21" - 21 of what?

The running speed I'm referring to is the reading on the Mitsubishi wall unit in the following place: Service menu - Running Information - Code 540. This then displays the litres per minute rate of the Flow rate of the primary circuit. When I put the pumps on level 1 the flow rate actually shows 20 L/per min, on level 2 it shows 23 L/per m and on the top level 3 it shows 26 L/per min. Level 3 is the setting the installers left it on but it is noticeably louder than level 1, as you would expect. I've had it running on level 1 for a month or so now to reduce that flow noise level. 

Posted by: @iancalderbank

s it "flow noise" - which is the whooshing of high speed water going through too small a pipe, think the noise you'd get if putting your head in contact with the pipe feeding a basin tap thats fully on but you can't hear the water splashing out of it? Or is it the humming / vibration noise that is due to the actual  water circulation pump?  I ask because "flow noise" is usually hard to hear unless you're really close to the pipe, but "pump vibration noise" can carry further.

The reason I think it is "flow noise" is that I get the noise in the bedroom where the pumps are furthest away, now it's possible there is a pump in the garage which may be causing the noise but 3 pump would seem a bit much for the size of house (193 sq m). 

The pipes are insulated in the garage and in the cylinder cupboard but not in the floorboards in the house, pictures below are from the install week, now the installers have been back since to stop the expansion rubbing and I don't have pictures of what they did but I was told they just used clips and the odd bit of foam to sit the pipes on over the woodwork. The flow noise did not change after that work. 

 

Posted by: @iancalderbank

Re your spending comments , which can be the foundation of a performance discussion: It really helps if you can speak in kwH, as none of us know what electricity tariff you are on, and relative to your actual heat usage as well, and at what exact outside temperature you get that much usage. . Also take a look at what COP you are getting on a day by day basis relative to outside temp. SCOP of 3.5 long term is perfectly decent but performance issues (if there are any to find) are usually best tracked by looking at shorter term performance.

So in KwH on the smart meter, these are the last few days:

10th Jan: 34.70 KW, Avg Temp: 4.4 C

9th Jan: 40.15 KW, Avg Temp: 2.6 C

8th Jan: 44.75 KW, Avg Temp: 2.06 C

7th Jan: 45.50 KW, Avg Temp: 2.46 C

6th Jan: 37.27 KW, Avg Temp: 1.83 C

5th Jan: 36.32 KW, Avg Temp: 4.98 C

4th Jan: 24.02 KW,  Avg Temp: 5.42 C

3rd Jan: 33.62 KW,  Avg Temp: 7.1 C

 

COP is a tough one to track as it relies on noting the details from the unit on the day- unless there is a better way? - and I don't have that historic data but I'll try to keep a track of it. 

I've tried to upload pictures but the site is not playing ball, I will try again from my tablet shortly. 


   
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(@dannymoss23)
Trusted Member Member
118 kWhs
Joined: 6 months ago
Posts: 25
Topic starter  

@andygo 

The two pumps I have don't seem to work independently, one I think is for the flow to and then back. I've put the pumps back on speed 3 to see what difference it seems to make. 


   
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(@dannymoss23)
Trusted Member Member
118 kWhs
Joined: 6 months ago
Posts: 25
Topic starter  

Not sure why but I’m unable to upload photos or videos into my media or directly, the site just says upload aborted?

 

This post was modified 6 months ago by DannyMoss23

   
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Mars
 Mars
(@editor)
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@dannymoss, we are experiencing all manner of issues with the site at the moment, and we're looking to migrate it to a faster server that will improve the performance of this site.

 

Try again now. Uploads should be working. 

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(@iancalderbank)
Noble Member Contributor
3640 kWhs
Joined: 2 years ago
Posts: 644
 

@dannymoss23

noise:

so seems like you have 2 pumps a primary-side and a secondary-side. which is common. I wouldn't expect there to be a 3rd one. what you have explained that changing the pump speed alters the flow rate visible on the controller makes total sense, and also that the noise comes from away from the pumps. But the noise is at a  location directly next to the primary pipes, is that right? flow noise comes from excessive flow velocity, which is caused by too fast a flow through too small a pipe.

what size pipes are the primaries?

with the primary at 20L/min this will give a flow velocity in 28mm copper of 0.61 m/sec.  At 26l/min the flow velocity will be 0.81 m/sec.  The rule of thumb is that the flow velocity needs to be below 0.9 m/sec to avoid flow noise. 

If they are only 22mm this would be a problem as the flow velocity at 26l/min will be 1m/sec.

for tracking the performance, I don't have a mitsubishi so can't give detailed help, but there are plenty of threads on here about using the mitubishi system to get performance trend data out of it and/or another owner may be along shortly to tell you exactly what to do.

My octopus signup link https://share.octopus.energy/ebony-deer-230
210m2 house, Samsung 16kw Gen6 ASHP Self installed: Single circulation loop , PWM modulating pump.
My public ASHP stats: https://heatpumpmonitor.org/system/view?id=45
11.9kWp of PV
41kWh of Battery storage (3x Powerwall 2)
2x BEVs


   
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 Gary
(@gary)
Reputable Member Member
1104 kWhs
Joined: 1 year ago
Posts: 118
 

@dannymoss23 

 

Do you have a Mitsubishi preplumbed cylinder, if you do and you have have already stated you have 2 zones, 1 for UFH and 1 for rads then there should be 4 pumps in total.

1 is the primary pump for the heat pump circuit, mitsi don't have one in the outside unit, this is the one you will be able to hear the speed changing when you change the pump speed from 1-3, you already have it on 1 and have enough flow so you can't slow that down anymore.  Then there will be 1 pump each for the UFH and Rads and a 4th for DHW.

The noisiest of these is the primary pump due to the speed it has to run at to get 20L/min but yours is on the lowest setting, I barely here my other pumps above the primary and mine is in the airing cupboard its a constant hum but doesn't disturb sleep.

In terms of performance, its exactly where I would expect it to be at this time of year, my 8.5kw Ecodan is consuming similar amounts of kwh you quoted above so at least its performing normally from a heat perspective.


   
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(@dannymoss23)
Trusted Member Member
118 kWhs
Joined: 6 months ago
Posts: 25
Topic starter  

Hi Gary, 

 

Just to confirm we only have rads and no UFH. The noise that we are keen to try to dampen in not coming from the cupboard where the pumps are but instead from within the outside wall in our bedroom. The pipes flow through this wall and into the garage ceiling where they then go out to the heat pump. My best guess is that the flow is echoing through the cavity wall and increasing the noise. Not sure but I was hoping this new system would not make the house sound like a Victorian build, but I guess part of my posting here was to see if this is just a fairly normal ASHP outcome or do I need some more work doing to help quieten the system. 

I have some pictures and videos to share but the site is not letting me upload them at present.  

 

I'm checking the pipe diameter for Ian and will pop this in here. 


   
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(@dannymoss23)
Trusted Member Member
118 kWhs
Joined: 6 months ago
Posts: 25
Topic starter  
IMG 8534
IMG 8532

   
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(@dannymoss23)
Trusted Member Member
118 kWhs
Joined: 6 months ago
Posts: 25
Topic starter  

I have the measurements and the pictures of the flow pipes coming into the bedroom for context 

 

IMG 8545
IMG 8541
IMG 8540
IMG 8543

these are next to the bed and going in and out of the exterior wall in the garage ceiling 

 


   
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