Heat recovery or not?

[r.bartlett]

We always quote the fresh air via HE units. However one customer has bulked at the cost so wants just 2 fans one air in and one out. Cheap as posible (they said they probably won't use it anyway)

What are the regulations for mechanical ventilation with regard to fresh air or is it just that HE's are considered best practice and that's about all?

Thanks

Richard

[RSTC]

If your customer is baulking at cost...
for every 1m3/s of air is 13.4 kwHrs (average could be up to 24 kwhrs) of reheat needed

for 2000 running hours that's about €4,500 per year (don't know what that is in paseos)

You know it makes sense Rodney

[frank]

What are the regulations for mechanical ventilation with regard to fresh air or is it just that HE's are considered best practice and that's about all?

Thanks

Richard
Hi Richard.

For occupied rooms without opening windows (natural ventilation) a basic 10 l/s per person of fresh air is required under Part F Building Regulations http://www.planningportal.gov.uk/england/professionals/buildingregs/technicalguidance/bcapproveddocumentslist/
The use of heat recovery can be an energy saver for the pre-heating of the incoming air but it is seldom sufficient on it's own during the throws of winter. Some form of additional heat input is normally required to prevent the occupied space from becoming uncomfortable due to cold draughts.

Using 2 fans on their own will be OK for the extract, but would you like to sit under the input grille when it's -5C outside? :D

[r.bartlett]

Hi Richard.

For occupied rooms without opening windows (natural ventilation) a basic 10 l/s per person of fresh air is required under Part F Building Regulations http://www.planningportal.gov.uk/england/professionals/buildingregs/technicalguidance/bcapproveddocumentslist/
The use of heat recovery can be an energy saver for the pre-heating of the incoming air but it is seldom sufficient on it's own during the throws of winter. Some form of additional heat input is normally required to prevent the occupied space from becoming uncomfortable due to cold draughts.

Using 2 fans on their own will be OK for the extract, but would you like to sit under the input grille when it's -5C outside? :D

Thanks Frank

We've sized up for 20 @ 10l/s so we're bang on the money here but they are quibbling at the cost. So now they just want a simple 2 fan jobbie.

I am trying the Part L route to convince them of their Carbon footprint and making sure they take responsibility if the BC inspector picks up on it..


In all honesty we don't usually add pre heat to VAMs and not had anyone complain...and it does kinda defeta the object of the bloomin things

[VRVIII]

In all honesty we don't usually add pre heat to VAMs and not had anyone complain...and it does kinda defeta the object of the bloomin things


Richard,

VAM preheaters are usually very small and designed to protect the heat exchager from frost damage not to control supply air temp. The running cost of 2 fans or a VAM unit with 2 internal fans would be similar however the heating energy saving due to the heat reclaim should cover the extra cost in no time.