Replies

1. 
   sigep739 | Oct 29, 2013 07:55pm | #1

   Just as an FYI.. I did do some research on this system. It sure does run a lot. The settings are set to 4 bedrooms (I have 5), 80 CFM and 3100 square feet. When I test, it blinks red - which supposedly indicates not enough airlflow. But when I increase the CFM to 120, the red does not blink. The question I have is - does raising the CFM to 120 - is that a measurement I set based on what my system can handle? I'm afraid to change that one and screw up my system.

   Thanks.

2. GBA Editor
   Martin Holladay | Oct 29, 2013 08:38pm | #2

   Joe Pa,
   If you have correctly identified the ventilation equipment in the link you provided, then you have a central-fan-integrated supply ventilation system. To read more about this type of system, see Designing a Good Ventilation System.

   There are two possible problems. It is possible that your system is running for too many hours a day. More importantly, it's possible that your air handler fan is an energy hog rather than a fan with an ECM (an electronically commutated motor -- one that is energy efficient). If your type of ventilation system is paired with an energy hog fan, the bills will kill you.

   You need to get an HVAC contractor who understands ventilation systems to analyze your system and (at a minimum) commission it by measuring the ventilation airflow and adjusting the number of hours per day that the system runs.

   If, as I suspect, your air handler has an energy hog motor, solutions are more elusive. You can buy a new air handler, which is expensive, or see if it's possible to retrofit an ECM into the unit, which is also expensive, or you can abandon your ventilation system and install ventilation equipment that is cheaper to run.

3. 
   sigep739 | Oct 30, 2013 02:06am | #3

   Martin -

   Thanks for your help. I went up in the attic today - so I know that I do have a central-fan-integrated solution... I think the technology is kind of weak. I don't understand the science whatsoever - but it doesn't seem to adjust depending on factors (i.e. windows open, etc). No doubt - I have an energy hogger. Right after we closed escrow, the house was vacant for about 2 weeks with zero energy use other that the system. No fridge - nothing in the house. I used a steady .58kw/hour. That's 417 kwh per month just to run the system. That's some serious cash.

   If you're able to help me - I have a couple of questions -

   What is the penalty of turning this thing off? Living in Sacramento (typically dry during the summer) - is there any downtick to having it off? And during the winter, we often have the windows open.

   Secondly - how do you suggest I find a HVAC contractor that knows this stuff? Should I call Honeywell?

   All in all - I really doubt we're going to do something that is crazy expensive.... but, at the same time, I dont want to damage my house. So I am trying to assess the importance of this system during all seasons. I read your link above - seems to be some controversy. I just dont want to use this much electricity.

   Thanks!

4. GBA Editor
   Martin Holladay | Oct 30, 2013 05:36am | #4

   Joe,
   The only way to let a ventilation system know that you have chosen to open your windows is to turn the ventilation system off. How easy it is to turn the ventilation equipment off depends on the type of equipment that has been installed in your house.

   If you live in a climate that allows you to open windows frequently, it may be rarely necessary to operate a ventilation system. It's possible to use common sense to figure this one out.

   Ventilation systems have a few purposes. One purpose is to prevent humid indoor conditions during the winter. If you see condensation on your windows during the winter -- especially if you have liquid water dripping on to your window stool -- then it's time to turn on your ventilation system.

   Ventilation systems also address indoor smells. If your house seems smelly, you need to turn on your ventilation system.

   It is harder to determine whether you need to run a ventilation system to address odorless gases like formaldehyde that may injure occupants' health. This whole area is controversial. But if you live in a climate that allows you to open your windows, common sense can rule here too.

   In short, I wouldn't worry too much about damage to your house. You can adjust your ventilation rate based on common sense.

5. 
   sigep739 | Oct 30, 2013 10:32am | #5

   Martin-

   Thanks so much. You've been extremely helpful. I have one last question- thanks so much for your patience.

   In Sacramento, the fall and spring are beautiful... Heck, even winter. I leave several windows open each night (during the day when people are not home, that is not always the case).

   Since it is a comfort thing, rather than home safety, I can tinker with this. First, I am a dummy when it comes to this stuff... But in normal, not-very-windy conditions, assuming I leave the ceiling fans running, do you think leaving a couple windows open upstairs will be sufficient?

   Secondly, if we are not home, let's say we go in vacation and lock all windows, is there a huge need for this thing? In the summer we are very dry and the winters are about 50% humidity when it is a bit overcast.

   Thanks again... I know these answers have a lot of science behind them- and to a guy like me you can really only answer in basic terms. Thanks!

6. GBA Editor
   Martin Holladay | Oct 30, 2013 10:47am | #6

   Joe,
   Q. "In normal, not-very-windy conditions, assuming I leave the ceiling fans running, do you think leaving a couple windows open upstairs will be sufficient?"

   A. Sure. Depending on the outdoor temperature, two open windows could easily be too much ventilation. The bottom line is: let comfort be your guide.

   Q. "If we are not home, let's say we go in vacation and lock all windows, is there a huge need for this thing?"

   A. If no one is home, turn off the ventilation system.

7. 
   user-626934 | Oct 30, 2013 11:07am | #7

   Joe,

   Just to give you a little more information on your ventilation timer/damper (if it is indeed the Honeywell 8150)...

   The HVAC contractor is supposed to actually MEASURE the ventilation rate and input that rate on the dial, along with the actual number of bedrooms and floor area. Then, the Honeywell unit does a (simple) calculation in order decide how many minutes per hour it will keep the damper open and run the air handler fan in order to provide whole-house ventilation that is compliant with the ASHRAE 62.2-2010 ventilation standard.

   Changing the airflow dial will NOT change the actual airflow...but it will change the run-time on the system. For instance, if you increase the airflow rate on the dial, the run-time will drop. The run-time will also drop if you decrease the number of bedrooms and/or floor area on the dials.

8. 
   sigep739 | Oct 30, 2013 12:53pm | #8

   You guys are absolutely amazing. Thank you.

   I think I'm just going to tinker around. It'd make it a hell of a lot easier if I had a remote instead of having to get into attic.

   First, I'm going to change the airflow rate on the dial to 110 or 120 per the manual. When doing so, the test no longer blinks red.... Let's just hope my builder made the ability to have that much airflow! Maybe this will do the job and have more reasonable run times

   That said- as I alluded to, we keep our windows open a LOT. We have a great climate. But it would be a pain to crawl in attic when I need the system running. I suppose I could have someone wire it to a more convenient place.

   By the way... The builders rep didn't event know what the system was. He had to call a contractor. He's aid it was to ventilate and was to keep the foam insulation in our attic up to par. But my guess is he meant that as a result of the very efficient foam insulation, that is WHY we have the system... Because the house is "tight"...

   The thing that is weird to me about this whole thing is that it calculates it based on the dial settings. Seems like it would be much better (albeit more expensive to install) a system w a sensor.