BER A2 house great idea but heat recovery noise is UNBEARABLE

ArnieSilvia

We recently bought a brand new house with BER A2 rating and while we like general design and idea behind energy efficient house is great (and it actually works) there's an issue with heat recovery system. House is very comfortable to live in and built in a "sustainable" way, very comfortable, with large attic, storage in the basement, underground car park and on top of that great sense of community (common yard for residents) etc. It's so good that we wouldn't want to move out ever.

I'm going to talk with the builders about it but I want to know if there's any regulations related to HRV systems about noise and functionality.

As for the issues:

1. If we cook something in the kitchen with door closed, the smell is distributed to the rooms upstairs via vents. I presume something is wrong there and suspect that they never installed the carbon filters in the HRV unit so this might be fixable.

2. Patches of dust around exhaust vents after 1 month of use, indicates filtration problem.

3. BLOODY NOISE and I'm not kidding. When we came to view the house, the HRV system must have been turned off. I think that we would walk away from it if we knew. It is so noisy that it's unbearable.

To give an idea:
- in the bedrooms, extractor fans give a constant noise similar to being on a jet flight. I sleep with ear plugs.
- the fans are making howling noise in the attic that can be heard very well upstairs

3. Heat recovery in the summer and heat control. Basically I don't want heat recovery on hot days, it turns house into a heat sink. I have no control over this other than to shut it off completely.

4. In the kitchen, there is an extractor fan installed above the gas cooker but it's only a carbon filter type one so it's going back to the kitchen. There is a vent in the ceiling to suck air out but it's not sufficient even with that laughable "HRV boost" joke. Idea behind it is heat recovery. It doesn't work well, however. When cooking anything, additional heat and steam from cooking combined with no extraction to the outside, means it turns kitchen into a sauna even with door wide open. I'm going to replace this shyte with extractor fan to the outside plus replace gas cooker with induction type.

I presume, like with few other things in the house (solar panels etc) that the system wasn't set up correctly and needs to be put right with my intervention. I think the following might be the issue:

1. Missing carbon filters in the HRV unit

2. Flow rate is WAY too high causing too much noise. Free flowing vents along with crappy windows would give max 10% of the air exchange this HRV provides. While super comfortable (no draughts, cold spots, same temp all day/night long and real heat recovery) noise generated outweigh the benefits greatly

3. Kitchen sealed completely is NOT a good idea and I'll put in a true extractor fan with vent outside. I know I'll be losing on heat but it'll improve comfort greatly.

So, what you think, and do I have something to refer regulation-wise when I ask the builders to fix it?

I can provide spec of the system if needed.

shedweller

I dont have much to add other than that the extract hood should exhaust outside (through the heat exchanger in this case) and the exhaust point be far enough away from the hrv inlet to avoid smells coming back in.
The noise could mean the fan is going too fast and slowing it down may help??

sydthebeat

as this is a "brand new house" there is obviously commissioning issues.
The builder has a contract with the HRV suppliers so its up to them to get them back in to see whats going wrong.

as above, the kitchen smalls shouldnt be getting back to the rooms because the exhaust air and incoming air do not actually mix.... and could be an issue that the exhaust outlet and intake outlet are too close together.

Drift

With regard to the summertime:

1. Some units have a bypass mode for the summer although I don't think this is too common.

2. A lot of units have a "boost" mode which essentially increases the fan speed so that there is more air brought in faster from outside and hence less heat transfer. Obviously if you already have noise problems this will likely make the worse and will cost more. I think I'd just open the windows if you find it stuffy in the hot weather.

None of this fixes the noise problem - which should not be occuring!

ArnieSilvia

Thanks for the replies, makes me more comfortable to know that I might have a point when dealing with builder about the issues.

I don't know how to post pictures yet but dark rings around exhaust vents in the rooms are obvious enough signs of bad setup

I like the heat exchanger idea for hood extractor as it breaks my heart to make hole in a wall and then have 3m of what essentially is a cooling tube in the winter. On top of that I'll have to make another hole for vented tumble dryer (I know most ppl would kill me for doing this but the boss in the house knows better;) although I might still persuade her into buying a condenser dryer)

blacktea

I am open to correction, but the noise from the fan could be a capacity issue i.e. The hrv unit is too small. If the house is over a certain size, you may need a unit for upstairs and downstairs or one larger unit. There could also be a ductwork configuration issue affecting the air flow which in turn could affect the fan creating the noise

fclauson

I did a lot of research on this for my build

Noise = airspeed + fan speed

So you neded to go back to the installer and ask
1 - how did they size the unit (ask for the maths to show they comply with Part F)

2 - check what duct sizes you have (larger ducts=slower airspeed=quieter operation). Narrow ducts leads to more noise

1 - cross fertilization of smells sounds like wrong duct work
2 - dust - which vent is this - inlet or extract - if inlet then dust in duct work (should have been cleaned) - extract - dust in room=fact of life in new build, paint after 6 months
3 - Noise - see above
4 - ask if they system has manual or auto bypass - in any event heat exchange in the summer is not a big issue as the house can never get hotter than the temp is is (i.e it will not go on getting hotter). Ideal is to have a bypass
5 - extractor - always an issue - if you extract to outside check issues of cold bridge/condensation in the extract duct

bertie 56

Do you have mufflers in the pipes straight out of the unit to attenuate the sound going out of the unit ?
Check this as well !

ArnieSilvia

Thank you all for great advice, it was very beneficial and this way I knew where I stand

So I got the builders in to check the system and once they heard the noise they confirmed it's not right.

Apparently the HRV unit was over sized for this application and that it's normally operating at 40%. There is about 3m of flexible piping with bends (are these called mufflers??) that I was told should quieten down the airflow.

Upon checking the control panel which had few potentiometers in it, it was clear that someone turned it up to 90%. Don't know who but hey!
Filters were also dirty but came back clean after vacuuming.
There was no obvious trace of airflow mix within the unit (in/out)

Once motor was slowed down it become nice and quiet in the rooms. The airflow noise can't be heard at all now but the HRV unit in the attic can slightly, but nowhere near the levels it was. I'd compare it to a noise created by desktop computer fans running in adjacent room. Or to a noise of older type fridge next door.

I'll try to put some insulation around the unit to see if it can quieten it down further but it can't be eliminated completely.

The unit has summer bypass facility and all I need to do is to fit a switch. I'll go a bit further and install a decent thermostatic electronic switch (have one here with .2 degree acuracy) so heat recovery will be controlled by temperature in the house i.e. no heat recovery over 21 degC (23 degrees in the house at the moment, outside 18 deg C, no heating on obviously). The temperature in the house would rise to 25+ deg C in warmer weather and it's very difficult to cool it down, annoying when going to bed - too warm (all windows open etc) so bypass is a must.

The smell issue is not as evident as it was with greater airflow. I'd risk a statement that issue is gone now but I didn't do much cooking recently (too busy!!!)
There were two potential causes for the smell distribution:
- pressurisation of the kitchen (system unbalanced between rooms) so air was forced out of kitchen and moved upstairs
- too much airflow within the unit itself forcing air between seals - think this is more probable cause

All in, happy days, enjoying now my quiet, warm and well designed comfortable house that I'll be improving as I go along. Lots of learning on the way!!!

ArnieSilvia

I also got a decent condenser dryer in the end so no need to drill through walls and create a long cold bridge. I was bit disappointed once I saw a heat pump one (electrolux A+ rated) in DID today (around 650 euro) but the one (B rated) I bought (mere 250 euro) should be not too bad.

I decided to install a proper extractor hood and vent it outside as there's too much heat in the kitchen as it is, won't make harm. I can always retro-fit the heat exchanger for winter months if needed. I choose comfort over extra cost always.

galwaytt

ArnieSilvia wrote: »

I also got a decent condenser dryer in the end so no need to drill through walls and create a long cold bridge. I was bit disappointed once I saw a heat pump one (electrolux A+ rated) in DID today (around 650 euro) but the one (B rated) I bought (mere 250 euro) should be not too bad.

I decided to install a proper extractor hood and vent it outside as there's too much heat in the kitchen as it is, won't make harm. I can always retro-fit the heat exchanger for winter months if needed. I choose comfort over extra cost always.

Re the dryer: whether A rated or B rated won't make much difference if it's not used much. (E.g. Only when not possible on the line or clothes horse.)