HRV final checklist / questions

Curious Geroge

Installing a recommended HRV system and the ducting supplied is

- Making sure the ducting is highly insulated
I'm told there is no reason to insulate the ducts if the whole system is within the envelope of the house - does anyone know if there is a spec for this in the planning documents (like part F). Any information of pics appreciated.

- That balancing is carried out correctly.
Is this related to the route or is this making sure that all intakes and extracts are balanced correctly of the manifolds? I ask as I'm having issues with duct routes due to the design of the house and holicore.

- That the Controller is located in a sensible place
I've decided to place the unit in the laundry room on the 1st floor of a 3 story (attic converted). Done for easy access to the filters for changes and to keep within the internals of the house and provide equal duct runs throughout the house. Any thoughts?

The ducting is the recommended anti-microbial which is 75mm and I believe this comes out of the manifold. So the supplies to the manifold should be rigid spiral ducting ?

I referred to the checklist in an older thread
http://www.boards.ie/vbulletin/showthread.php?p=64332295

- Making sure the External Intake & Outflow vents are located an appropriate distance apart.
- get anti-microbial ducting to the supply ducting
- get a boost function for showers etc.
- get a summer core which does not do heat exchange
- put an extract in your laundry/utility room so you can dry clothes
- connecting the system to the smoke alarms to disable in the case of a fire.
- Extract about 3 foot from hob that will have recirculating cooker hood. Easy access to this extract to allow for cleaning and if needed, grease filter or similar. (thanks to gizmo555 for his input)

I'm using this as my guide to make sure all is done correctly re the install but someone may have a better guide.
http://www.brinkhrv.com/heatrecoveryproducts/documents/BCSI-EN002-Renovent%20medium-large-installation-manual.pdf

Does anyone have this system and may advice on the noise levels that it produces under normal running and under boost.

BarneyMc

My installer says that the ductwork within the thermal envelope doesn't need insulating either so I assume that it will be ok.

baby fish

Curious Geroge wrote: »

I'm having issues with duct routes due to the design of the house and holicore.

what issues are you having?

Only route available means your ducting needs become longer than expected, extra bends required?

893bet

Is 75 mm normal for duct runs? I thought 125 would be the pipe?

BarneyMc

My supplier provides either round 125mm or oval 204w x 60h depending on available space. Is there much difference in efficiency going with the 125mm round over the oval (each can carry the same volume of air)?

rampantbunny

BarneyMc wrote: »

My supplier provides either round 125mm or oval 204w x 60h depending on available space. Is there much difference in efficiency going with the 125mm round over the oval (each can carry the same volume of air)?

From what I've read it seems the round is less likely to cause turbulence, and hence less noise. I'm sure there are a whole load of scientific papers somewhere in googleland to back this up.
Possibly easier to clean the round also with a circular brush, but this is probably not an issue for professionals with the right equipment.

4Sticks

Make sure to use only fire resisting inlets/outlets

893bet

BarneyMc wrote: »

My supplier provides either round 125mm or oval 204w x 60h depending on available space. Is there much difference in efficiency going with the 125mm round over the oval (each can carry the same volume of air)?

One wonders why CC supplier is 75mm and yours is 125. Big difference.

BarneyMc

Met with my supplier and looks like I'll be using the 125mm round for the 1st floor and the 204 x 60mm oval for the ground floor.

Curious Geroge

With the 125mm, is this a manifold system? The 75mm ducts are all coming from a manifold and going to a manifold. All extracts and all suppliers have a min of 2 ducts each with larger open plan areas getting 3 ducts.

BarneyMc

Curious Geroge wrote: »

With the 125mm, is this a manifold system? The 75mm ducts are all coming from a manifold and going to a manifold. All extracts and all suppliers have a min of 2 ducts each with larger open plan areas getting 3 ducts.

Not sure what a manifold system is?

893bet

Barney, George what suppliers are you going with? By Pm

893bet

BarneyMc wrote: »

Not sure what a manifold system is?

Manifold is basically a seperate pipe to and from each room as apposed to a single duct with each room branched off too. Seems to be a much better system but has some disadvantages.

Sales people or installers seem to push what ever suits them.

Manifold is a lot more expensive. 5k v 7k roughly.

BarneyMc

893bet wrote: »

Manifold is basically a seperate pipe to and from each room as apposed to a single duct with each room branched off too. Seems to be a much better system but has some disadvantages.

Sales people or installers seem to push what ever suits them.

Manifold is a lot more expensive. 5k v 7k roughly.

Mine is not manifold then.

893bet

BarneyMc wrote: »

Mine is not manifold then.

I think the 75 mm pipe is usually for manifold and the larger 125-150 is the other system (called t duct system I think).

Smaller pipe for manifold as each pipe needs to carry less air as they serve an individual room.

I am undecided as off yet. Have a few people pricing off the plans and a few others who refused to price off the plans and requested a meeting in order to properly discuss the options first. The ones pricing of the plans activly advised against the manifold system saying some bull**** about it being noisy due to smaller pipes and increased air pressure in them.

I put this to the person who wants to discuss all the options and they said noise is 90 percent caused by poor duct design.

Curious Geroge

893bet wrote: »

I think the 75 mm pipe is usually for manifold and the larger 125-150 is the other system (called t duct system I think).

Smaller pipe for manifold as each pipe needs to carry less air as they serve an individual room.

I am undecided as off yet. Have a few people pricing off the plans and a few others who refused to price off the plans and requested a meeting in order to properly discuss the options first. The ones pricing of the plans activly advised against the manifold system saying some bull**** about it being noisy due to smaller pipes and increased air pressure in them.

I put this to the person who wants to discuss all the options and they said noise is 90 percent caused by poor duct design.

I was worried about poor duct design but could never determine what was good and what was bad. Did he give you any examples?

Bubbling

If the MHRV unit is within the thermal layer of the building (internal), then I think the fresh air supply pipe to the unit should be insulated as this will be cold air (outside temperature) until it passes through the heat recovery unit.

fclauson

So some advice

ducts from outside to HRV unit need full insulation from the outside to the unit as they carry cold air in so they will get condensation on the outside if the air outside the ducts is moist and the cold duct reduces it below the dew point

ducts from HRV to outside also need full insulation at least outside thermal envelope as they might carry air which is potentially below the dew point of the air inside the thermal envelope and you will get condensation on the outside of the duct. Once outside the thermal envelope its still worth insulating because you might get condensation inside the duct if the outside (and hence the inner surface of the duct) drops below the dew point

Alway angle all ducts into the HRV so any condensation dribbles into the HRV and away via the HRV drain

always have the HRV drain inside the envelope - you don't want it to freeze and flood the HRV and your house

On duct work and size and design - do the the maths - large ducts - slow airspeed - low noise - narrow ducts higher airspeed more noise
multiple narrow ducts do not equal single wide ducts 1 for 1 - do the maths - check out friction etc of airflow down narrow pipes

manifold systems can be prone to noise in the manifold - lots of air trying to get down a small ducts might make it whistle

use large duct near hrv and at each branch/T move down to more narrow ducting (from memory all my vents are fed with 5 or 6 inch and then there is an 8 inch as the main off the HRV) - if you dont do this then the unit will have to work harder and could be prone to noise

put two filters on the inlet - one at the external wall and one inside the unit - the outer units takes away the "big stuff"

size the unit to run at around 50% max - your boost will need to take it to 80 or 90 probably to achieve the volumes

put a boost button out side each bathroom and one in the kitchen - "click on the way in - click on the way out"
Set boost for around 15 to 20 mins - better to slightly over do than under

I would not duct cooker into HRV - I have a carbon filter

Put micro filter in your laundry/util - have you ever seen the filter on the tumble drier - think of that all in the duct work over 20 years. I use a piece of "bounce" or similar tumble drier anti static sheet (the ones you put into the drier for each tumble) - and swap it around every 3 months - does a great job as an initial filter into the HRV from the space near the tumble dryer. (and its a waste product from the tumble dry process - I made a up a simple retaining ring in the vent above the tumble dryer

and finally remember in summer you can open the windows - even in a passive house - promise the house will not explode with the surprise.

enjoy

rampantbunny

fclauson wrote: »

So some advice
put two filters on the inlet - one at the external wall and one inside the unit - the outer units takes away the "big stuff"

Have you any pics of the external filter Francis? Is it outside the house in the external vent?
Having a break in the intake duct so that a large particle filter could be installed within the house would be ideal so it could be accessed easily.

fclauson wrote: »

Put micro filter in your laundry/util ... I made a up a simple retaining ring in the vent above the tumble dryer

Was there any concern of the extra filter placing additional 'drag' on the system i.e. extracting air through a vent with more resistance than there would have been when the system was commissioned. Or was this taken into account (or negligible)?

fclauson

rampantbunny wrote: »

Have you any pics of the external filter Francis? Is it outside the house in the external vent?
Having a break in the intake duct so that a large particle filter could be installed within the house would be ideal so it could be accessed easily.

check out https://www.facebook.com/Passive.House.Wexford I'll try and add some pics this week end (assuming the harvest is over - no point in changing the filters until all that chaff is still in the air)

They sit in metal boxes just inside the outter wall in the loft space (similar to http://www.fantronix.com/acatalog/Filter_Box.html) and take a fabric filter which I chuck out every 6 months or so

Was there any concern of the extra filter placing additional 'drag' on the system i.e. extracting air through a vent with more resistance than there would have been when the system was commissioned. Or was this taken into account (or negligible)?

Negligible - considering how much I worried about everything else !! The filter was fitted post commissioning (and no I did not go back and rebalance system :mad:) but I can't believe it adds very much "drag" but it does remove a lot of "fluff"

rampantbunny

fclauson wrote: »

Negligible - considering how much I worried about everything else !! The filter was fitted post commissioning (and no I did not go back and rebalance system :mad:) but I can't believe it adds very much "drag" but it does remove a lot of "fluff"

Catch22...the better the filter, the more fluff/dust is trapped and the more drag (if any really). Better to have drag than to have poor air quality or a clogged system.

fclauson

Photos as promised - all changed ready for the winter season

https://www.facebook.com/media/set/?set=a.274858412719270.1073741830.154344008104045&type=3&uploaded=15

BarneyMc

Perhaps this has already been asked but is that 'filter box' something you added yourself or was it part of the kit?

fclauson

BarneyMc wrote: »

Perhaps this has already been asked but is that 'filter box' something you added yourself or was it part of the kit?

It's a standard item from your local spiral duct supplier - I did not buy a "kit" but bought the component parts for the job

893bet

Can some one host the pic for those with no facebook account.. ..

fclauson

No !!

I have about 200 on that facebook page you might find of interest !!

"Dad Get a life and get a facebook account" as my 16 year old so elegantly put it a few years ago

893bet

fclauson wrote: »

No !!

I have about 200 on that facebook page you might find of interest !!

"Dad Get a life and get a facebook account" as my 16 year old so elegantly put it a few years ago

I have an account and am a friend of your page but have diactivated my account.

I will have to use my imagination.

fclauson

Activate it for a day - take a peep at the pics and deactivate - I do not want your imagination designing your HRV!

893bet

fclauson wrote: »

Activate it for a day - take a peep at the pics and deactivate - I do not want your imagination designing your HRV!

I meant I would imagine the picture. The designing I am leaving up to the experts.

Funny enough I have found it tough enough to get suppliers to quote. Ironically enough I am prob going to go with the most expensive quote as so far they were the only people who refused to quote from plans and wanted to meet to assess all the different options.

jakko86

Hi guys I've recently fitted a hrv unit to my house and the unit is in the attic, all ducts are 150mm off the unit to the rooms then reduced to 125mm at vent, all routes are very direct with few bends which is best way to do it I was told? My problem Is my upstairs vents are noisey especially the first point from the machine. All extracts are fine and quiet but supplies upstairs are loud esp as I said the first off the machine. All supplies have baffles (insulated flexi pipe 500-600mm long.
Any advice would be great. I mite add the agent told me I was "too direct" with my ducts to the rooms and that is adding to the problem he said I should have put on a few 90 degree bends here and there!! Sounds to me like BS. As I always thought the most direct route using large rigid duct was the best way to reduce noise and maximise airflow??

fclauson

Have you balanced the system using an airflow meter ?

Sounds to me you should close down the upstairs vents a lot to push the air downstairs

jakko86

Ya the agent came and balanced the system with a machine he said the machine is running at 50% it's mainly the first vent off the machine is very loud but the first extract is closer again to the machine but no noise at all. Agent that sold me system said my duct is too direct that I shoud have put 3/4 90 bends before that vent!!

fclauson wrote: »

Have you balanced the system using an airflow meter ?

Sounds to me you should close down the upstairs vents a lot to push the air downstairs

touchdown77

fclauson wrote: »

I use a piece of "bounce" or similar tumble drier anti static sheet (the ones you put into the drier for each tumble) - and swap it around every 3 months - does a great job as an initial filter into the HRV from the space near the tumble dryer.

I'm about to start up our HRV system in our new house, the painters are nearly finished and cleaning due to start in next few days.

Would you recommend bounce sheets in every extract vent for the first few weeks until the dust settles?

fclauson

Now I am no expert but it would seem a good idea.

Obviously you would need to remove them to balance the system