I installed one a few years ago They're very effective at sucking all the smoke out of the house when the wife burns the dinner too.
LOL. The iced tea I was drinking came out my nose on that one!
I installed one a few years ago They're very effective at sucking all the smoke out of the house when the wife burns the dinner too.
This balancing problem is harder than you think because you are trying to make a static system of
* fixed vents/registers
* single temperature sensor at tstat
balance a dynamic system where
* each room has a different heat loss/gain
* the relative heat loss/gain varies with time of day and time of year
* each room's door may be open or closed
* rooms are used at different times of the day.
We have two rooms that have floor over garage and two exterior walls. These rooms are ALWAYS cold by about 3F vs the setpoint and 5F off of the warmest upstairs room. We have under cut the doors and have full air flow to these rooms. In the spring and summer the problem was less pronounced.
I am still working this problem but I think to provide 365/24/7 balance more dynamic elements (registers, zones, fans etc) are required, or your standards need to be reduced.
Disclaimer: I am not an HVAC guy, just an engineer who knows enough to be dangerous!
I am an HVAC guy, for 20+ years now . . I understand your points, that's why in my post I said " this will not correct an extreme uneveness between areas, especially because of east/west exposure differences"
the only way to achive perfection would be seperate systems for each distinct area with different loads, not an economical choice for residential installs . . so we do the best we can
assuming we're in heat mode, all regisers full open, if you limit air flow to the warm room(s), that air will go somewhere . . keep balancing until it ends up in the cold room(s) . .
you could do load calculations, get an air-flow hood, and balance that way . . but the end result will be the same . .
and either way may not be perfect, but at least your getting the best performance out of your equipment . .
if you want to automate a few outlets at this point to achive greater comfort, go for it . . limit (don't cut-off) air to the over-conditioned spaces and it will end up in the under-conditioned spaces . .
I am an HVAC guy, for 20+ years now . . I understand your points, that's why in my post I said " this will not correct an extreme uneveness between areas, especially because of east/west exposure differences"
the only way to achive perfection would be seperate systems for each distinct area with different loads, not an economical choice for residential installs . . so we do the best we can
assuming we're in heat mode, all regisers full open, if you limit air flow to the warm room(s), that air will go somewhere . . keep balancing until it ends up in the cold room(s) . .
you could do load calculations, get an air-flow hood, and balance that way . . but the end result will be the same . .
and either way may not be perfect, but at least your getting the best performance out of your equipment . .
if you want to automate a few outlets at this point to achive greater comfort, go for it . . limit (don't cut-off) air to the over-conditioned spaces and it will end up in the under-conditioned spaces . .
Pete:
I appreciate your reply and I understood your caveats.
When speaking to our HVAC contractor he won't even go to the point in acknowledging that there is a problem since he balanced the system. In our house these two rooms are an extreme case where our cold rooms have 3 of six sides seeing outside our unheated garage, while the other bedrooms only see one outside wall. It just doesn't look like this can be balanced out. Exacerbating this is the fact that I think these two rooms suffer a design flaw on his part as the registers are very close to the doors, thus providing a short circuit for the hot air to follow. Further exacerbating the problem is that the cold room is the babies room... very low WAF IYKWIM.
Pete:
I appreciate your reply and I understood your caveats.
When speaking to our HVAC contractor he won't even go to the point in acknowledging that there is a problem since he balanced the system. In our house these two rooms are an extreme case where our cold rooms have 3 of six sides seeing outside our unheated garage, while the other bedrooms only see one outside wall. It just doesn't look like this can be balanced out. Exacerbating this is the fact that I think these two rooms suffer a design flaw on his part as the registers are very close to the doors, thus providing a short circuit for the hot air to follow. Further exacerbating the problem is that the cold room is the babies room... very low WAF IYKWIM.
Pete:
I appreciate your reply and I understood your caveats.
When speaking to our HVAC contractor he won't even go to the point in acknowledging that there is a problem since he balanced the system. In our house these two rooms are an extreme case where our cold rooms have 3 of six sides seeing outside our unheated garage, while the other bedrooms only see one outside wall. It just doesn't look like this can be balanced out. Exacerbating this is the fact that I think these two rooms suffer a design flaw on his part as the registers are very close to the doors, thus providing a short circuit for the hot air to follow. Further exacerbating the problem is that the cold room is the babies room... very low WAF IYKWIM.
Did your HVAC guy design and install your system, or is he just your service contractor? If he did the design he is BSing you, he did not figure enough air for those rooms and/or undersized the ductwork. He should have also installed your registers at the outside wall, instead of saving a few bucks on the duct runs. He owes you a 'properly working system', if your rooms are cold and heating unevenly, it's not working properly.
This is a typical outcome of using "rules of thumb" to design a system, instead of figuring the actual load.
If he is just servicing your system, he may be doing the best he can with what has been installed.
On my residential heating jobs I like to install one register below each window in a room. If I'm doing individual room returns, this usually goes behind the door.
Do you have access the the ductwork? Do you have individual dampers on each supply branch? (duct/flex start collar to each diffuser should have a manual damper (small handle w/ wing nut)). What size ducts serve the cold rooms, and what size are the rooms?
Pete:
He had control over the whole thing. I know better but I never reviewed the detail design, just the big picture (single zone, furnace location, return locations, basic duct locations). Once I saw it done I asked why the register wasn't on the far side of the room, he hemmed and hawed and said it would balance just fine. I do have access to the duct work so I can fix it. I'll look at the sizing and dampers. It is in the attic on the far side of the house (I have blown in insulation so I want to minimize my access up there. When he was in the entire house was down to studs except the ceiling sheetrock in those two rooms, I am pretty sure he placed these registers so he wouldn't have to crawl 12ft in the attic area.
Thanks...
On my residential heating jobs I like to install one register below each window in a room. If I'm doing individual room returns, this usually goes behind the door.
(kinda hi-jacked the thread, but still on topic I guess)
what part of the country are you in? (or what country?) most info I give is based on northeast US (when it matters))
In my redneck engineering wisdom I have assumed individual returns and everything on dampers is really the way to go.
This is the only way to strategically pull and push air to areas to balance, or at least I can see no other way.
Also on Rob's attic fan in fire situation, it somewhat hard to say. Obviously if a window/door is open you will feed the fire, if on the other hand you could pull a vacuum the fire would die almost instantly. This is seomthing I have spent much time contemplating at it is completely possible if designed into the house initially. It doesn't take much vacuum for most combustables but the house would need to be designed specifically for it. Lots of issues, windows ane doors are only the start, conventional toliets could overflow many things possibly not considered.