air to air exchange - needed or a waste?

jeff_51

then you of course need make up air. The air to air is to control the make up air and exchange the stagnant polluted air that gets locked up in a house in the winter. We certainly recomend them and they are required in our class 1 housing out here. I have done houses so tight that you couldn't keep a furnace or boiler lit. They use up all the 02 in a house. They are alot better now than ten yrs ago but do need some maint

owner builder in central NJ

air to air exchange - needed or a waste?

I am getting conflicting advice regarding the use of air to air exchange system in new contruction in central NJ

- some say its needed because tyvek and other contruction methods do not allow for enough air infiltration for healthy indoor air

- others say its a wastes what otherwise would be a highly efficient system and adds cost (whether to radiant only heating design with forced air AC, or forced air heat & AC)

I am considering either 2 stage, variable fan forced air OR hydronic radiant heat (if I can find someone who knows what they are doing with radiant in central NJ and who does not charge an arm and a leg for it -- this is not New England for this, yet anyway!)

Thanks.

Bob Cooper

Jeff:

I'm building a SIP home and am going to need one of these as well. Any suggested brands/models?

S Davis

Venmar

You might look at Venmar they have some good units that have HEPA filteration built in.


S Davis

Apex Radiant Heating

Constantin

I would take a long, hard, look at this...

... the Ultimeateair unit from Stirling Technologies is probably the best unit on the market today. Phenomenal energy recovery (94%) and standardized parts make this a very attractive choice. A tip of the hat to Jerry Scharf for pointing it out to me.

Unfortunately, I had already ordered my Lifebreath TRV's which are duel-core units with an ERV and HRV core in them. They may not be as efficient as the Stirling unit, but most energy recovery systems are manufactured by Nutech in Canada and rebranded as needed. So, I'd go with the original brand, rather than a private-label they may also manufacture.

Weezbo

I will vote Venmar and also the hepa filter .....

and not just because the guy who first installed and tested them is here...:) A?

BillW@honeywell

If you seal up your house like a thermos bottle...

you and your appliances will still need to breathe. Provide your heating equipment and water heater with their own outside combustion air. Products are readily available to do this, especially for oil burners. Don't forget that you will need make-up combustion air for your range & oven, air for your kitchen vent fan and your dryer. In Central NJ (I live here too), an HRV is recommended over the ERV. The function of any HRV is to bring in and exhaust equal amounts of air and recover some of the heating/cooling energy, and dilute & exhaust gases, vapors and odors. Typically, they are about 80% efficient. In new construction, it's a lot easier to install HRV's than it is for retrofit. You also may need more than one unit, depending on the size of your home. Consider putting intakes in baths, laundry rooms and the kitchen. The discharge will be from all your diffusers, and only at about 150/200cfm, barely noticible. Optional timers are handy, and usual practice is to run these units 24/7 at low speed, and use the higher speed for parties, cooking or other times when you have a large crowd.

Honeywell's HR series units need ambient air during their defrost cycle, and a drain as well. They can't be attic mounted. We also offer a complete line of whole-house air cleaners; electronic, HEPA and media filters, UV bioaerosol killers and humidifiers. All these products are designed for ductwork mounting, but if you have AC, you can use that duct work, just add a reheat coil to temper the discharge in the winter. If you use an HRV stand-alone, install the discharges high on the wall, since these units are only 80% efficient, the discharge may be chilly on cold days. Check them out at our website, www.customer.honeywell.com.

Also check "Find a Contractor" above for anyone in Central NJ.

jerry scharf_3

it depends

> I am getting conflicting advice regarding the use

> of air to air exchange system in new contruction

> in central NJ

>

> - some say its needed because

> tyvek and other contruction methods do not allow

> for enough air infiltration for healthy indoor

> air

>

> - others say its a wastes what otherwise

> would be a highly efficient system and adds cost

> (whether to radiant only heating design with

> forced air AC, or forced air heat & AC)

>

> I am

> considering either 2 stage, variable fan forced

> air OR hydronic radiant heat (if I can find

> someone who knows what they are doing with

> radiant in central NJ and who does not charge an

> arm and a leg for it -- this is not New England

> for this, yet anyway!)

>

> Thanks.

jerry scharf_3

it depends

There are two questions that I like separate. One is about exchaning air and the other is about allowing for make up air when a kitchen or bath exhaust is running. One way or another you need to deal with these.

You generally want .35 iar changes per hour (ACH) to have good air in the house. To get the CFM of air speed needed to get 1 ACH, take the volume of the house (heightxwidthxdepth) of the conditioned air space and divide by 60.

A note that the ACH rate you put into a hea loss program is not the same as for ventilation. With the heat loss, you are assuming the maximum temperature driven exchange, whereas for the ventilation, you want it to work every day of the year.

How tight is the house being built? If I assume that it is being built to current energy efficiency standards or better, then there is not enough air infiltration through the walls/windows/doors to handle either of the above problems. Old houses were so leaky that none of this was a problem.

To allow for the exchange of air without losing all the heat, then you use a ventilator. These come in 2 flavors, a heat recovery ventilator or an energy recovery ventilator. The difference between the two are that an HRV only moves the heat related air temperature, and an ERV does that plus moving the heat related to the moisture. One issue with an HRV is that in can produce condensate, and needs a drain. an ERV doesn't create condensate.

There is a way to do this with a barometric damper from the outside into the return air plenum. It's tricky to set up and you lose more heat, but it's better than doing nothing.

jerry