New Build Ventilation

Ned78

Hi there

Am looking for some advice.

Am a few months into my self build, all going to plan so far(for now!).

I was going to install a demand control ventilation system from company A. This would include an exhaust fan (approx 13Kw) venting my bathroom/ensuite/kitchen 24/7. The remainder of the rooms would have a vent installed on the wall that would only open when CO2 levels reached a certain level.

Am having second thoughts, I would prefer to keep things simple. Am thinking of installing the traditional vents which can be closed/opened/partially opened along with extractors in ensuite and bathroom.

Questions:
1. has anyone used the demand control system and if so how is it going?
2. if I were to go with the traditional vents can anyone let me know which are best on market, have been doing research, all seem to be the same.

Any advice and help appreciated.

antiskeptic

Ned78 wrote: »

This would include an exhaust fan (approx 13Kw) venting my bathroom/ensuite/kitchen 24/7.

A 13KW fan?

MicktheMan

OP, what airtightness target are you aiming for?

BryanF

Ned78 wrote: »

Am having second thoughts, I would prefer to keep things simple. .

Demand control ventilation is simple
you do apprecaite that you need extracts from the bathrooms and kitchen anyway - so the difference with extract DCV is it regulates the RH and extracts when needed.
in habitable rooms you still core the 'holes in the wall' - but the DCV cover vents has a faciltity to control when the 'hole' is open - ultimately reducing heat loss & drafts.

as other have asked (ill put it another way) - what is in your provisional BER ie is it effected by your decisions here? and have you carried out a first fix air-tightness test? ie under a certain figure and your into mechanical ventilation territory

KingPuck

Bryan regarding the "hole in the wall" Can anyone clarify the official line. I was in a house today (only at first fix) and they had 6" holes in every room.

We did a quick calculation on both the four inch and six inch hole.

The traditional 4" hole in the wall has a cross sectional area of 7,850mm2 whereas the 6" hole has an area of 17,662.5mm. Are my figures wrong? If they are correct that is an increase of 125%. Sounds a bit mad.

If the hole in the wall has inceased has the same increase been applied to trickle vents?

tred

Ned78 wrote: »

Hi there

Am looking for some advice.

Am a few months into my self build, all going to plan so far(for now!).

I was going to install a demand control ventilation system from company A. This would include an exhaust fan (approx 13Kw) venting my bathroom/ensuite/kitchen 24/7. The remainder of the rooms would have a vent installed on the wall that would only open when CO2 levels reached a certain level.

Am having second thoughts, I would prefer to keep things simple. Am thinking of installing the traditional vents which can be closed/opened/partially opened along with extractors in ensuite and bathroom.

Questions:
1. has anyone used the demand control system and if so how is it going?
2. if I were to go with the traditional vents can anyone let me know which are best on market, have been doing research, all seem to be the same.

Any advice and help appreciated.

I use demand controlled (3 years). I am more than happy with it. part of the system are humidity sensing vents, that adapt to conditions as needed.(open or close letting in more or less fresh air) the system itself is simplistic. A low wattage fan in the attic, draws air out of all the wet rooms, and this change of air, causes air to be drawn in by the smart vents. . regulation air changes are achieved. what you don't get is the heat transfer from mechanical heat recovery. but this is balanced out with a lower running costs and no need for expensive yearly or bi yearly filter changes. The air inputs are per room. If you are running a stove,you still need a separate air supply. they wouldn't let in enough air for that.

BryanF

KingPuck wrote: »

Bryan regarding the "hole in the wall" Can anyone clarify the official line. I was in a house today (only at first fix) and they had 6" holes in every room.

We did a quick calculation on both the four inch and six inch hole.

The traditional 4" hole in the wall has a cross sectional area of 7,850mm2 whereas the 6" hole has an area of 17,662.5mm. Are my figures wrong? If they are correct that is an increase of 125%. Sounds a bit mad.

If the hole in the wall has inceased has the same increase been applied to trickle vents?

there's a bit more to it than that - see here

kenobee

I use a Vortice fan in kitchen and bathrooms. It is low noise, is a radial flow fan, rather than axial flow. It pushes the air out at increased pressure through a small non-return flap. There is no back-draught when it is off.

gooner99

tred wrote: »

I use demand controlled (3 years). I am more than happy with it. part of the system are humidity sensing vents, that adapt to conditions as needed.(open or close letting in more or less fresh air) the system itself is simplistic. A low wattage fan in the attic, draws air out of all the wet rooms, and this change of air, causes air to be drawn in by the smart vents. . regulation air changes are achieved. what you don't get is the heat transfer from mechanical heat recovery. but this is balanced out with a lower running costs and no need for expensive yearly or bi yearly filter changes. The air inputs are per room. If you are running a stove,you still need a separate air supply. they wouldn't let in enough air for that.

Hi tred, could you pm me the details of the system you use please?

tred

gooner99 wrote: »

Hi tred, could you pm me the details of the system you use please?

done

PROJECT K

tred wrote: »

I use demand controlled (3 years). I am more than happy with it. part of the system are humidity sensing vents, that adapt to conditions as needed.(open or close letting in more or less fresh air) the system itself is simplistic. A low wattage fan in the attic, draws air out of all the wet rooms, and this change of air, causes air to be drawn in by the smart vents. . regulation air changes are achieved. what you don't get is the heat transfer from mechanical heat recovery. but this is balanced out with a lower running costs and no need for expensive yearly or bi yearly filter changes. The air inputs are per room. If you are running a stove,you still need a separate air supply. they wouldn't let in enough air for that.

Hi Tred, very interested to hear a bit more about your experience with DCV - have looked at all options Centralised MHRV/Decentralised HRV and DCV with Humidity controlled inlets. My preference is the latter but concerned about drafts, lack of ventilation in rooms further away from extract points and obviously lack of heat recovery...

also can you PM me the supplier you went with (and cost if thats ok)?

Cheers
PK