Combi Boiler on Party Wall - Advice Needed

N0CARSGO

Hi, hoping someone can help me out with this.

I recently moved into a new house, its a 1930s terraced house. The previous owners had installed a Combi boiler in the attic with a wifi activation switch. We use the wifi switch when we want heating but don't use it regularly, other than that I just have the hot water mode active all the time on the boiler (but doesn't trigger unless you run the water).

My next door neighbour (whose adjoining wall the boiler is attached to) just knocked in and informed me that the boiler is causing significant noise problems in his house at night. This is obviously something I would like to correct but I am not sure what is causing the noise exactly. He mentioned the wifi switch that the neighbours used as being a solution to the problem but I am not sure exactly what they were doing with. For us it is off almost all the time bar when I turn on the heating.

I guess my solution long-term is to call out a plumber to take a look at the boiler/installation. In the meantime I was hoping someone could help me understand exactly how the Combi with a wifi switch might work. Is it possible for me to turn off the hot water mode with the wifi switch? (Currently it only affects the heating). Separately, is it possible to run the heating or hot water mode in a way that might reduce noise? (Neighbour mentioned that it seems to heat up water which causes noise and then goes into an 'overdrive' mode towards the end of the cycle which is very loud). Any help is greatly appreciated.

Thank you.

10-10-20

Hi,

Do you have a photo of the boiler and also then one of the Wifi switch? Also show some of the pipe-work and how the exhaust is fitted.

You might need to spend some time in the attic and have a listen, many noises can travel down walls and may seemingly amplify.

The noise at the end of the cycle may be a cooling process for the heat-exchanger, it might not be possible to reduce it. Somebody else might know better, but I think that photos will help.

Ush1

Is it central heating causing the noise or hot water. My suspicion would be that the hot water is fed to the boiler with a pump, and that's the noisy part? If it's the central heating making a lot of noise, look into lowering the flow temp, will probably make it more efficient also.

N0CARSGO

https://www.boards.ie/discussion/comment/120114953#Comment_120114953

Thanks for your comment. I have attached a photo of the set up. Just ran the hot water and the boiler makes quite a low whirring sound when heating water. I'm a bit confused because the party wall is solid brick so I wouldn't have expected the sound to travel so much.

N0CARSGO

Thanks Ush1, I think it is the hot water because we wouldn't typically have the central heating on at night. I thought maybe the pump too but just tested it and the pump is very quiet. The boiler itself makes a low whirring sound when heating water.

Alun

Some combi boilers have a feature whereby they continually maintain a small reservoir of hot water inside the boiler so that when you want hot water it first starts to use up what's in the reservoir to avoid too long a delay.

My Viessmann combi boiler does this also, but you can turn the feature off by putting it into "Eco mode".

Maybe your boiler is regularly starting up briefly during the night and this is what they're complaining about?

N0CARSGO

https://www.boards.ie/discussion/comment/120115049#Comment_120115049

That's actually really helpful and could be it only I don't think my boiler stores any water. I need to check though in case that is it, and if so - how to turn it off.

Ush1

https://www.boards.ie/discussion/comment/120115025#Comment_120115025

I'd be 90 percent sure the noise is the hot water pump. It might be quiet next to it but it's the vibrating that creates the noise next door. The brick is conducting the vibration. Call into your neighbour, get your missus to run a hot tap and check.

If that is the case, there is a couple of options;

1. If gravity feeding the combi boiler meeting the minimum water pressure it needs, you could get a switch put in for the pump and only turn it on when having a shower.
2. Create a plinth for the pump and use a lot a sound insulation board to mount it on to absorb the vibrating and reduce sound.
3. Replace the pump with a quieter one or a submersible one that can be placed inside the cold water tank.

N0CARSGO

https://www.boards.ie/discussion/comment/120115078#Comment_120115078

That's really helpful. Just to confirm, do you mean the pump beside the water tank?

Ush1

https://www.boards.ie/discussion/comment/120115222#Comment_120115222

Yep. Its basically the same setup I have.

10-10-20

https://www.boards.ie/discussion/comment/120115078#Comment_120115078

Just looking at the photos following on from your comment and was just thinking that if it is the pump causing this, I wonder if some of the noise is being transferred into that vertical 3x4 beam running up to the roof. That could be picking up the vibrations more-so than the wall and transferring them into the wooden joists.

NOCARSGO - are the pipes touching that wooden pillar at all?

Otherwise it all looks like a neat job except for that small drip on the pipework.

N0CARSGO

https://www.boards.ie/discussion/comment/120115418#Comment_120115418

Thanks for the advice. I just checked with tap running, while one pipe is slightly touching the beam the beam itself doesn't vibrate when the pump is operating. I might try to wedge some foam between the two anyway, just in case. Planning to call around to my neighbour and run cold vs. hot taps and that should help me to determine whether it it the boiler or the pump.

Also leaning towards cold as I couldn't understand why he would be hearing so much noise (he specified it was a problem after midnight), when we wouldn't be using a ton of water at that time. More understandable if it's loud when running cold taps or flushing toilet etc.

I just hope we'll be able to quieten the pump down, will try one of Ush1's suggestions.

kegblag

We did put a wifi controlled socket for our shower pump, which happened to also connected to one hot tap. Basically we have it timed to only turn on that pump for times when we'd have a shower.

We didn't want the noise, but also I didn't want the pump turning on unnecessarily.

In our case when we turn off that pump - we still get how water, just not pumped.

The external pump in the photo maybe is to feed water to the combi boiler as the pressure wasn't high enough? (clueless about plumbing - only guessing).

From what you describe about it previously solving the problem, I expected that pump to have a wifi socket - but it's just plugged into the wall.

N0CARSGO

https://www.boards.ie/discussion/comment/120117740#Comment_120117740

Hi Kegblag, I think you've just described exactly what I am going to do. I called into the neighbour yesterday and did some testing and confirmed that it is 100% the pump. Tested everything with pump off and it's really only the shower that needs it so I have ordered a wi-fi socket for easy switching. I think long-term I would like to dry to address the vibration from the pump but from reading a lot about it, it seems that people have mixed results at best.

It seems to only be an issue for the neighbour at night time anyway, and he said he didn't care about it going off during the day. The cold tap in the bathroom has very low pressure when the pump is off (still usable but just about), so I might keep it on during the day for that reason.

finnyob

https://www.boards.ie/discussion/comment/120118737#Comment_120118737

We have a similar problem with our pump (Walrus HQ400), plumber mounted it on a piece of insulated plasterboard in between two joists in the attic and pipe clipped onto rafter nearby. Apparently the pump should have been mounted onto solid blockwork to dampen vibration. From the attic, it's reasonably quiet, but the vibration transfers through the woodwork both from the pump and pipework and the noise is pretty bad from below. Looks like you have a PU foam mat underneath your pump, I would have hoped that should dampen the vibration a lot as I've been keen to get one for our pump. Does any of the pipework from the pump vibrate onto any of the woodwork in your attic too? Have a good feel around and see as the vibration has to be coming from somewhere attached to that pump.

Edit: I just popped over to Ballymount and picked up an anti-vibration mat for our pump (literally a piece of PU foam glued to a PVC sheet), placed this under our pump with the foam side up and unclipped the cold water supply pipe from the rafter. It's made a substantial difference in the vibration. Looking at OPs pictures, you could try to reverse the anti-vibration mat under your pump, so it has foam side up, and see if that makes a difference.

N0CARSGO

https://www.boards.ie/discussion/comment/120118878#Comment_120118878

Mine is a Walrus HQ200, I will check when I'm home re. vibration around the attic. I think the foam mat removes some of the vibration but not all of it. They are pretty cheap though, I think this one is similar to the one I have (https://www.domesticpumps.ie/product/the-silent-mat/) and is only €15 so it's probably worth a try.

To be honest the noise wasn't even an issue for me, it was only because the neighbour raised it and then I started to notice it. And even then, he had said he didn't care about it once it is before midnight but he only notices it when its very quiet and he's going to sleep. You wouldn't really notice it over a TV or other sounds around the house during the day. That might give you an idea of how loud it is - so if your current set up is considerably louder, then a foam mat should reduce it a good bit.

N0CARSGO

https://www.boards.ie/discussion/comment/120118878#Comment_120118878

Thanks for the update, glad to hear you managed to improve it! I will try to flip it around see if it makes any difference.

finnyob

https://www.boards.ie/discussion/comment/120119132#Comment_120119132

Actually, that's exactly where I got the mat, I had been considering it so decided to bite the bullet and tip over to them to pick one up. Nice earner for them, 2 minutes gluing the PVC onto the PU foam, 15-20 quid depending on the size. The chap in there was also suggesting to replace the in/out supply to the pump with flexible fittings, but that's probably more hassle than it's worth. I should think you could also double up on the mats to reduce vibration even more.

Best of luck with your effort anyway.

Ush1

https://www.boards.ie/discussion/comment/120118737#Comment_120118737

Check the minimum pressure required for DHW by the boiler, feeding it with just gravity might be too low. Unless you can be sure nobody will use a hot tap unless the pump is turned on.

N0CARSGO

https://www.boards.ie/discussion/comment/120120077#Comment_120120077

Hi Ush1, the water from the bathroom sink is hot just at a lower pressure with the pump off but still usable. I know the boiler has a minimum pressure but not sure how I would translate that into gravity from the attic. If the tap is running okay (albeit with less pressure) does that imply this isn't an issue or are you suggesting that it might damage the boiler over time if pressure is too low?