Replies

1. 
   Hubedube | Aug 18, 2004 01:29am | #1

   In order to make sure your home is not under a "negative"/ or positive pressure is to have it checked by a Pro HVAC Tech. Special air measuring instruments are used to "Balance" the air being circulated and expelled thru-out the home... Especially your ERV/HRV needs a balance (via a magnehelic guage )to ensure the proper amount of air is not only coming in, but also that the proper amount of air is being exhausted . Also, with a fireplace unit this Air Balance is essential for your own safety.  Good luck   Hube

2. 
   TRice | Aug 18, 2004 05:30pm | #2

   The Skuttle (a barometric damper) will only function when the fan is running.

   The ERV can be balanced positive or negative, to some degree.

   Unless you plan to build a home of unusually tight construction, have an inordinate amount of exhaust, or something else unusual, there is not a great deal of concern.

   While in the planning stages, things you can do to make the home better, from the point of make-up air are:

   1. Install sealed combustion appliaces, such as a high efficiency, condensing boiler and/or water heater that have CA provided directly to them via pvc piping.

   2. Use the exhaust side of your ERV to exhaust some or all of your toilets/bathrooms/powder rooms.

   3. Install the skuttle and run the fan on low speed continuously (a variable speed air handler is excellent for this purpose).

   4. Provide for direct supply of CA to you fireplace.

   These are mostly basic and/or just good practice. Any professional contractor will be familiar with all of these methods to maintain a neutral pressure in the conditioned space.

1. 
   trm1745 | Aug 18, 2004 05:55pm | #3

   Can the Skuttle be installed with separate ductwork, independent of the air handler? I know next to nothing about dampers, but I would assume that a barometric damper only opens when a certain pressure is reached, true? I was thinking if I installed a Skuttle separately then I wouldn't have to run the air handler.

   Thanks again.

1. 
   TRice | Aug 19, 2004 09:02pm | #4

   A "Skuttle", as it is commonly refered to, is simply a valve that opens when a small differential pressure is present. It does not supply air to the furnace/air handler. It merely allows the unit to draw outside air into the low pressure side (i.e. the return) at certain times, when the differential pressure is great enough. Some duct is required to connect the return to the outside air (OA). The closer to the unit the connection is made, the more likely it will always open when the fan operates. These devices will allow more OA in the cooling mode than in the heating mode, all other things being equal.

   You could install it separately, adjust it to open with a lot less pressure, but this is not recommended. Any OA, should be tempered and filtered most of the time. Obviously when the weather is appropriate, this is not necessary. If your air handler (AHU) was operating with 800 cfm , 75 degF return and 55 degF supply and the skuttle was allowing 80 cfm at 95 degF, the return would be 77, and the noticable effect would be nil. A strong wind would open it the other way, dumping hot or cold air into you house.

   Recommendation: Install it on the return of the AHU or don't bother with it at all. BTW, with the ERV, you will be introducing more OA than 99% of the homes in this country. If you have not yet selected the unit, I would suggest selecting a unit that will provide 1/2 to 1 air change an hour for good air quality.

1. 
   trm1745 | Aug 19, 2004 09:38pm | #5

   I appreciate the information. I'm meeting with my HVAC installer this afternoon, hopefully a little wiser:)

   Thanks. tutone