[Brian GC]

That is a very good idea.

Here is another question. At the top of the house there is a triangular area as seen in the picture below. It extends from the back of the house to about 8' of the front windows. There is an exhaust fan in this section, along with one in each side of the house. Do you think it might help reduce the heat load if a grill were put in the side wall all the way back to allow the fan to better pull air through? Or would it not be worth the effort?

I would imagine the heat upstairs is an accumulation of all heat gained throughout your house and not necessarily from above (an attic). And zoning can be an elaborate way of just shutting selected supply grills. So yes, zoning is required in that respect.

 

[energy star]

Could you post a pic of the house? Maybe each side?

 

[lynn comstock]

Kirbinster,
You probably already know that before investing a dime in zoning a simulated test can be done beforehand by externally blocking/closing supply registers.

This is exactly what I was recommending and describing in post 29. If the duct system can deliver enough air to the top floor, Zoning is the answer. That is the purpose of the suggested testing.

 

[kirbinster]

Could you post a pic of the house? Maybe each side?

I posted one of the front earlier, but here are some more shots:

This is of the North side of the house (no windows)

This is the back of the house, only the recessed side is part of the house that is on this HVAC system, the rest is an addition on its own system:

The upstairs room has those three large windows and goes to the left until just before the vent grills to the left. It also continue about 10' to the right of the windows.

Here is a closer shot of the upstairs portion:

This is the southside of the house, the part closest to the camera is the addition, the stuff farther out from the down spout is the original part of the house, but none of this side is on the HVAC system in question, its all on the other system:

This is looking out the big front windows where the new 8" return line is pulling from:

 

[kirbinster]

deleted

 

[DavidNJ]

The problem with zoning is the system was not designed for in 1973 when the main part of the house was built. There is one major rectangular trunk line and all the 5"" or 6"" supply lines pull off random places from that main trunk. Further this is all enclosed behind sheet rock. To get to it all would require replacing all the ceilings downstairs - big cost plus major mess. Even if you could get to it I am not sure what you could do the way it is piped up.

What I am upset about was this was all addressed when the system was replaced last year. The "engineer" said he understood, took measurements and came up with the idea that the extra 8" return line would at least partly solve the problem. I think part of the issue is the old system was circa 1973 and was not designed for efficiency and just ran a much larger blower full force all the time - thus moving a lot more air. This new system is designed for better efficiency and does not move as much air - thus making the problems seems worse. I would guess, its hard to recall exactly, that the differential between level one and three is 5 to 10 degrees worse than it was before - but I don't have exact numbers.

I think someone thought of that problem: Arzel Regidamper: http://www.arzelzoning.com/products/regidamper/

It fits in at the register and uses a pneumatic line, like a commercial damper, that runs in the duct.

 

[Mr Bill]

deleted

 

[DavidNJ]

This must have been asked, but has the thermal envelope been tested: blower door, thermal imaging? It sounds, to me at least, that the problem may be unevenly distributed heat gain rather than solely inadequately distributed cooling.

Moderating the heat loss if possible may be the key. We have R-19 ceiling/roofs. I just shot it with the IR. The one facing south takes a beating. Most of the wall in our unairconditioned house are around 88F. The ceiling is 95-100F.

Others may know all the foam options, however so far I've seen an R-5/inch foam that can be sprayed in with the fiberglass (it just pushes it out of the way). Something like that may be able to give you a more solid R-20 plus and reduce the heat gain from the ceiling.

 

[kirbinster]

No testing of the thermal envelop was ever done. If I point my IR thermometer at the ceiling it reads just about the same as the room temperature. Obviouosly the windows read higher. The Knee walls are about the same temp as the room as well.

 

[DavidNJ]

No testing of the thermal envelop was ever done. If I point my IR thermometer at the ceiling it reads just about the same as the room temperature. Obviouosly the windows read higher. The Knee walls are about the same temp as the room as well.

I thought you said it was a multi-story room that was hot at the top?

 

[beenthere]

If that little attic area has no ventilation in it. Yes adding a vent will help.

Take a thermometer into that area. And see how hot it is in there. You'll see how the ceiling can be transferring so much more heat to your top level then you get in the other levels. Do the same with the knee wall areas.

Do you have receps and or switches in your knee walls. If so. You could be drawing your conditioned air out. When those fans are running. If there is not enough fresh air able to get into your attic area. When the fans are running. Those knee wall areas can give off more heat to the house. Then if they were outside walls.

As someone else said. If your supply air temp is gaining that much heat that you have that great of a temp difference from the supplies. Insulate them if you can.

If you can't insulate those supplies.Then running your fan 24/7 will actually increase your cooling bill. And not from the fan using the extra electric.

If your return and supply duct both are running through non conditioned areas. Then you are gaining heat with the fan running.

And yes. I have no way to know that taking the hottest air in the house. And blowing it into the coolest areas of the house. Will cause those areas to warm up more/faster. Which in turn. Will mean less cool air to mix with the hotter air from the upper level. So that it is still hotter up there.

 

[beshvac]

Its been a long time since I have done anything with them, but I think they are about 18" in diameter with a fan that is controlled by a thermostat. Not exactly sure what you ean by air baffles. The section of the roof above the finished portion of the upstairs has 6" joists between the roof and the sheetrock and is mostly filled with fiberglass insulation. The area behind the knee walls is insulated as is the floor in the unfinished portion of the attic. There is no roof insulation in the unfinished portion, but there are continuous soffit vents the full length of the North and South side of the roof.

With attic fans, they should draw on the attic space and also have a clear path for makeup air from the soffits. When you pull airflow thru the insulation in the slopes you are losing the effectiveness of the insulation. Had a house years ago that had a huge attic fan, it pulled so much air thru the insulation, water was condensing out on the back of the sheetrock and the insulation was wet. Installed proper vents and everything was alright.

 

[tedkidd]

Randomly changing your ventilation strategy is not a good idea. Leakage from conditioned to unconditioned space may be a major part of your problem, and as bes and david mentioned, more may be worse, not better.

Time for a proper audit. Too bad this was not part of the "engineering" you received.

 

[Brian GC]

Randomly changing your ventilation strategy is not a good idea.

Why?

 

[commerce48]

Consider adding a mini split for your third floor. Might do nicely on your north side. Consider wall mounting rather than ground level placement.

 

[Chuck]

Consider adding a mini split for your third floor. Might do nicely on your north side. Consider wall mounting rather than ground level placement.

:ditto:
We have done that several times in multi level homes with no good way to zone, and many times takes the majority of the load off the ducted system. Good idea.

I would still get the energy audit done as has been suggested.

 

[Brian GC]

I would still get the energy audit done as has been suggested.

An energy audit would likely come up with numerous weak points around the house. Those are easy to find. But since the OP’s situation is a mainly an airflow/distribution problem will a person doing an audit be that much more attuned to finding the solution over the people who installed it or the pros on this forum? Do energy auditors really walk on water over the average HVAC contractor? If so, where do they get their knowledge from because the causes and solutions here from experienced HVAC contractors vary widely? Maybe HVAC contractors should read the same books that the auditors are reading if they are so able to pinpoint solutions to problems like this.

Brian

 

[btuhack]

Consider adding a mini split for your third floor. Might do nicely on your north side. Consider wall mounting rather than ground level placement.

Will this offer any satisfaction for the lower level during heating season? If not, it's an expensive solution for 1 season.

 

[beenthere]

An energy audit. Would point out air leaks, inadequate insulation areas, Window problems, etc.

Not balancing problems per say.

Poorly installed registers/register boots/boxes. Can bring lots of unconditioned air into the home.

 

[kirbinster]

I would really like to balance the house out if possible, I already have "split" type solution. Years ago I installed a one ton (12,000 BTU/HR) window A/C unit into the knee wall and hooked up an old slop sink tied into a plumbing drain for the condensate. The attic fan takes away the discharge heat. Anyway, I fired it up yesterday and it fully cools off the upstairs. But it does not solve the secondary issue of the downstairs being 63-65 degrees.

Mike was nice enough to spend some time on the phone with me today, and we tossed around a few ideas. One being that the supply lines to the third floor are gaining quite a bit of temperature on the way up. I went into one side of the attic and found the vent fan thermostat was set at 125 degrees, turned that down. Also found some air leakage where two of the supply stacks come up a pipe chase in the attic. Further, they are not insulated on the way up. So, I went out and got some pourable / blowable cellulose insulation and plan to fill the void space around these ducts on a cooler day, and then cap the area with expandable foam. Hopefully that will help some. Still need to figure a way to move that cold air on level one up to level three, or visa versa.