Experts PLease: Cold rooms/end of House with Return Vent in Hall Ceiling

[stonemanjr]

When doors are closed to the bedrooms what makes the bedrooms negative?

I dont know, you tell me. All I know is that when we close the BR doors, the rooms warm up within minutes. Either the hot air being forced in remains without being quickly sucked out to the hallway where the return is or it is creating a pressure that overwhelms/defeats any incoming air from the floors or other unknown place or both. All I know is that it instantly changes the conditions in them.

Also, when I stand on a chair in the hallway, I can feel the warm air up there as well as the warmer air rushing out from each bedroom at the top of doorframe.

[stonemanjr]

After you insulate the floor please report the degree of difficulty and effectiveness. It is very helpful when homeowners attempt measures that fail and report back.

thanks Ted. If you are offering to pay for my 3K to foam coat the entire underside of my house, please let me know what we do next if that doesn't solve the problem here? Im not trying to be a smart alec but your sarcasm isnt really appreciated

[tedkidd]

I agree that supply throw and location are more important than return location, I never argued otherwise. But when they are not ideal, as in the OP’s case, a low return might make up the difference needed. What irks me is the sheer denial that there are any benefits from it at all…even when the OP and other sources says it is beneficial.

I disagree. But am not surprised to hear "recommendations" like that from mr one-size-fits-all.

Often return location can have much more importance than supply. One example is complaints that air conditioning upper floors is ineffective. I often solve this complaint simply by recommending covering the low return, opening the high return, and closing bedroom doors.

[tedkidd]

thanks Ted. If you are offering to pay for my 3K to foam coat the entire underside of my house, please let me know what we do next if that doesn't solve the problem here? Im not trying to be a smart alec but your sarcasm isnt really appreciated

In what picture or post did I recommend insulating your floors?

Did someone come to your home, diagnose you are losing heat through your floors and recommend putting insulation under them? Did they cost/benefit that investment for you?

If you have concluded you will poke and hope at solutions, you will be able to help others understand how frustrating it is to do work that is ineffective, and possibly avoid a lot of people from spending money pointlessly. Or are you only interested in taking help, not giving it?

[jtrammel]

If you attempt to seal the floor you first need to find out where to seal, blower door test, otherwise you will be doing lots of unnecessary sealing wasting time and money. Btw insulation does not seal it just acts like a filter for the infiltrated/exfiltrated air

[jtrammel]

You need a professional hvac and comfort consultant to diagnose your problems on site. Fork out the dough you will learn a lot and realize that the testing has to be done before buying equipment if you want the system to work properly and sized right. So you will never make the mistake of paying good money for something that doesn't work right!!!

[hvacrmedic]

The hallway thermostat reads out at steady 69 degrees while the HP continues to work/blow almost constantly with little downtime. The thermostat in the middle of house( dining room stays at about 4 degrees warmer)

That isn't what I meant by the question, but I'll address those points anyway. The t-stat readings don't mean anything for the purposes of troubleshooting air distribution and/or infiltation issues. The thermostats could be out of calibration, there could be infiltration from the hole in the wall behind the thermostat in the hall, the wall temperature may be lower in the hall, etc., etc.. This is a difficult process even with high accuracy pocket thermometers. FWIW "room temperature" is a meaningless expression. The temperature measured in a room will depend upon both when and where in the room the measurement is made. Even simultaneous readings from various points in the room will give different results, even significantly different results. For example, measure the temperature just above the television set while it's on. Measure the temperature of the wall just behind the television. A 30° difference can easily be measured within the space of one foot.

If the temperature was perfectly uniform throughout some room, then that wouldn't necessarily provide a comfortable room. Temperature is only part of the comfort equation. Air movement and RH level also affect comfort. With a range of temperatures in the room, the problem is further complicated. When you're confusing room temperature and thermostat temperature with one another, then what you get is a thread that goes on and on and on.

[Brian GC]

When doors are closed to the bedrooms what makes the bedrooms negative?

This inconsistency should have been apparent to everyone in this conversation, especially to those who are trying to teach others.

In order for the house to infiltrate it must be somewhat negative in pressure, maybe slightly more in the bdrms. When the doors are shut the bdrms go positive. When the bdrms are positive the remainder of the house must be pushed into a more negative condition. So, if the house is more negative than the bdrms are when they do not heat completely, why isn’t the rest of the house infiltrating to a colder state?

PS - Please do not say only the bdrms leak.

[stvc]

Brian, I can see that you are passionate about this and that’s good.
What's bad is that you have a closed mind and are outright argumentative about it. That is limiting your ability to better understand and limiting help to the OP here.

It has been suggested that you take a BPI or similar course here; I think you should and I don't mean this as an insult. I wouldn’t be surprised if you got thrown out for disrupting the class though!

[hvacrmedic]

This inconsistency should have been apparent to everyone in this conversation, especially to those who are trying to teach others.

In order for the house to infiltrate it must be somewhat negative in pressure, maybe slightly more in the bdrms. When the doors are shut the bdrms go positive. When the bdrms are positive the remainder of the house must be pushed into a more negative condition. So, if the house is more negative than the bdrms are when they do not heat completely, why isn’t the rest of the house infiltrating to a colder state?

PS - Please do not say only the bdrms leak.

You're oversimplifying it. You cannot state what the temperature of the rest of the house is. It doesn't have one temperature, it has whole bunch of different temperatures. If the reading on the t-stat in the dining room doesn't change when the bedroom doors are closed, then that doesn't mean that the area around a leaking window in the kitchen or the back door doesn't drop in temperature. In fact the temperatures in these small areas will drop when the bedroom doors are closed. (Unless the ductwork, A/H, and bedrooms are completely leak free of course). The "average" temperature of the rest of the house will not drop enough to measure though, because the t-stat in the hall requires that it remain relatively constant. That's what the t-stat is for. It won't cycle the system off until setpoint temperature is reached. How can that happen if the rest of the house is cooler? The hall has no supply grille and thus no other source of heat other than air in the room where the hall entrance is located....and maybe a little bit of the air from the closed bedrooms, which coming off the cold floor under the doors would actually tend to increase runtime that much more, warming the rest of the house.

It's a complex problem. Trying to simplify it to the level you'd like it to be on is not only futile, but often leads to logical contradictions.

Your argument that the high return is robbing the bedrooms of some of their supply air is valid. The question is, how significant is this effect of the high return vs. low? All of the studies performed agree that in most cases return location (high or low) makes no significant difference. The open door and the throw from the supply would be the significant factor, independently of where the return is located in the hall. So with some rewording and some change in thought we can get part of the argument to work anyway. We can say that "With the door open, some of the supply air is being ejected directly into the hallway, thus introducting a net reduction in heating capacity delivered to the room." This would happen regardless of whether the return was high or low. Sure, the high return would amplify the effect somewhat, but not significantly enough to regard it as the cause, and certainly not enough to justify moving it down low. HTH.

[Piedmont user]

They can poke and hope like this for years, or suck it up and have the house audited.

And no other actions will do? What?!? I'll give you debate points for mildly disparaging any other efforts and opinions (poke and hope; suck it up), but you lose those same points because you are ignoring that envelope and duct sealing and missing insulation are common and easily solved issues.

I'm not here to make any enemies, but this sounds like just another form of the "there's only one solution" solution. And I'm not picking on you, because others have said essentially the same thing.

My point would be that we don't really care about the magnitude of each leak in any one home. What we do care about is that typical homes leak plenty and can use improvement in well known areas.

[Piedmont user]

I like to remind you all of the question you continue to skirt regarding infiltration:
If the floor is porous why do only the bedrooms leak? When the doors are shut the negative pressure would intensify in the rest of the house causing it to go cold. Why doesn’t it?

The answer here is that with the doors closed, the bedroom:

1. leaks out air
2. returns air primarily for the gap at the BOTTOM (cooler air) of the door

1) The leak in the bedrooms is balanced with a corresponding leak in all the other rooms and other floors of the home. I does intensify the overall leakage, but because the additional leakage is spread so widely, it's hard to measure or perceive it.

2) This works just like the low return in the hall, so you of all people, can't deny this one...

[stonemanjr]

The answer here is that with the doors closed, the bedroom:

1. leaks out air
2. returns air primarily for the gap at the BOTTOM (cooler air) of the door

1) The leak in the bedrooms is balanced with a corresponding leak in all the other rooms and other floors of the home. I does intensify the overall leakage, but because the additional leakage is spread so widely, it's hard to measure or perceive it.

2) This works just like the low return in the hall, so you of all people, can't deny this one...

I see hvacrmedic just couldnt help himself and return :O )

Re: above I dont know what point you are getting at but what is your solution(s) to fix envelope, etc.

This is what is on the board at moment for us to consider
1) DOnt insulate the floor, seal it? (with what? and how?)

2) Foam covering the entire crawlspace will be over 2K to do

3) AN energy audit is almost 3K to do

4) A relocation/adding of the return will cost about $300 (work done by self and friend)

5) Insualting the floor between the joists with R-19 was est to be about $400 (work done by self)

6) Change registers in each room and/or add registers to the bedrooms at unknown cost but shouldnt be too expensive

[Piedmont user]

Re: above I dont know what point you are getting at but what is your solution(s) to fix envelope, etc.

This is what is on the board at moment for us to consider
1) DOnt insulate the floor, seal it? (with what? and how?)

2) Foam covering the entire crawlspace will be over ??? to do

3) AN energy audit is almost ??? to do

I was replying to Brian's points that I quoted. BTW, I agree with him, you probably have leaks everywhere.

Have floors over unconditioned spaces sealed (and probably insulated). Don't just have it insulated.

, got to follow them...

BTW, I want to be an energy auditor in your area!

And the rules prohibit much of what I could say...

(P.S. I looked at your profile. Do you perhaps know Lazarus L?)

[tipsrfine]

I see hvacrmedic just couldnt help himself and return :O )

Re: above I dont know what point you are getting at but what is your solution(s) to fix envelope, etc.

This is what is on the board at moment for us to consider
1) DOnt insulate the floor, seal it? (with what? and how?)

2) Foam covering the entire crawlspace will be over 2K to do

3) AN energy audit is almost 3K to do

4) A relocation/adding of the return will cost about $300 (work done by self and friend)

5) Insualting the floor between the joists with R-19 was est to be about $400 (work done by self)

6) Change registers in each room and/or add registers to the bedrooms at unknown cost but shouldnt be too expensive

Don't insulate the floor if you don't air seal. Have you priced how much it would cost to for you to do the walls of the crawlspace yourself? You would need the plastic to cover the ground and glue to seal it to the walls/peirs, polystyrene foam board(?) to cover the walls and some spray foam to seal the gaps.
I also saw that they sell round ceiling diffusers that are adjustable so you can get a downward throw for heating season. It may be "coranda effect" or "ceiling effect" is partly responsible for the bedrooms being cold. The link I posted earlier has a picture of this (in cooling mode, but principal is same).
I'm an energy auditor, and only in my dreams would I be able to charge a customer 3 grand for an audit.

[Shophound]

The hall has no supply grille and thus no other source of heat other than air in the room where the hall entrance is located....and maybe a little bit of the air from the closed bedrooms, which coming off the cold floor under the doors would actually tend to increase runtime that much more, warming the rest of the house.

It's a complex problem. Trying to simplify it to the level you'd like it to be on is not only futile, but often leads to logical contradictions.

Your argument that the high return is robbing the bedrooms of some of their supply air is valid. The question is, how significant is this effect of the high return vs. low? All of the studies performed agree that in most cases return location (high or low) makes no significant difference. The open door and the throw from the supply would be the significant factor, independently of where the return is located in the hall. So with some rewording and some change in thought we can get part of the argument to work anyway. We can say that "With the door open, some of the supply air is being ejected directly into the hallway, thus introducing a net reduction in heating capacity delivered to the room." This would happen regardless of whether the return was high or low. Sure, the high return would amplify the effect somewhat, but not significantly enough to regard it as the cause, and certainly not enough to justify moving it down low. HTH.

All well said, particularly what I placed in bold in your quote above. Thinking about this incredibly long thread last night and Brian's puzzlement over why the remainder of the OP's house is stated to be acceptably warm when the bedroom doors are closed, first thing that popped into my mind was longer run time of heating equipment. You articulated my rudimentary thoughts in your quote above quite nicely, thank you.

[Shophound]

And no other actions will do? What?!? I'll give you debate points for mildly disparaging any other efforts and opinions (poke and hope; suck it up), but you lose those same points because you are ignoring that envelope and duct sealing and missing insulation are common and easily solved issues.

I'm not here to make any enemies, but this sounds like just another form of the "there's only one solution" solution. And I'm not picking on you, because others have said essentially the same thing.

My point would be that we don't really care about the magnitude of each leak in any one home. What we do care about is that typical homes leak plenty and can use improvement in well known areas.

Agree with what you're saying here...while it's preferable to lay out a plan of action and proceed from that point (essentially what an audit is for), for many dwellings the flaws in the thermal boundary are quite obvious, and can be addressed by willing occupants equipped with good information. I HOPE that's what we are here trying to do...give out good information. We might debate on particulars, but I see no reason for it to become ugly or devolve into a talk radio trash session.

OP, it's your house and your money; wade through the info presented here and do what you deem is best for your comfort needs.

[tedkidd]

Unfortunately, 3k is what I'd have to charge you. Wish I was closer. Likely recommendations would be:

Don't insulate the floor, air seal and insulate the crawl walls, waterproof the crawl floor.
Dense pack your walls, this tends to significantly reduce leakage AND reduce thermal losses.
Air seal penetrations and ALL wall top plates in attic and/or redefine thermal boundary to roof deck. Without audit I can't assess which makes more sense financially although comfort solution is more likely with re-define since you have hvac equipment up there.
I would absolutely want a blower door number before starting work. This tells me a number of things. Total leakage, where leaks are worst so I can prioritize, and at the end it tells me how well I did and if I need to do more.

Bedrooms don't sound negative, they sound positive.

using different thermometers or thermostats is meaningless comparisons, there have been some really nice explanations of why.

Nice:

It's a complex problem. Trying to simplify it to the level you'd like it to be on is not only futile, but often leads to logical contradictions.

Not sure what this means:

I'm not here to make any enemies, but this sounds like just another form of the "there's only one solution" solution. And I'm not picking on you, because others have said essentially the same thing.

But this indicates a complete lack of comprehension:

My point would be that we don't really care about the magnitude of each leak in any one home. What we do care about is that typical homes leak plenty and can use improvement in well known areas.

Would you put money in a bank CD without knowing the interest rate?

If you don't know how leaky your house is you can't quantify the cost of your leakiness. If you can't quantify cost, you can't assess if cost of leakage reduction would be better spent elsewhere. If you don't have a blower door, you can't effectively pinpoint the leaks either. You want to caulk places that aren't leaky?

If I have $1000 to spend and am proposed 2 $1000 improvements, one saving $100 per year and the other $10 per year, I know how I want to spend my money.

If I don't know how bad the problem even is, what am I going to do? This homeowner has indicated some paths I KNOW are $10 paths, been there before.

Succint:

..with the doors closed, the bedroom:
leaks out air
returns air primarily for the gap at the BOTTOM (cooler air) of the door

Finally,

Measure before, measure after, and you know if you have accomplished something.
Without that you may have spent a bunch of money and accomplished nothing.

[Brian GC]

I would like to say that this thread is getting more in-depth. Everyone’s observations and opinions are welcome and appreciated. One thing we all agree on is what we first suspect might not be the only or primary cause…infiltration and my low return idea included.

I would also like to say that I may ask a lot of questions but that does not mean I am refuting your claims. I do it as a way of getting you to clarify your points better. And my apologies to those who are irritated by long threads.

I does intensify the overall leakage, but because the additional leakage is spread so widely, it's hard to measure or perceive it.

This comment seems to contradict the necessity to seal the underside of a house. Are you saying that if the infiltration (in this case) is spread throughout the house it may go undetected? And, by opening the bdrm doors it intensifies infiltration so much in that part of the house that it can chill what is probably one third of the house? This seems strange to me.

I think we can agree that this supposed infiltration is mainly caused by negative air pressure in the bdrms. Because there are few penetrations in the ceiling and that it has low ceilings (ranch) we can almost rule out stack effect. So it falls on supply ducting leakage, right? If that is so, a simple test could be done. While the outdoor temp is low run the system on fan only (no heat). This should cause infiltration the same as with heat on but should bring that part of the house into a thermal tailspin. Who here agrees?

[Shophound]

Finally,

Measure before, measure after, and you know if you have accomplished something.
Without that you may have spent a bunch of money and accomplished nothing.

Yep.

In context of determining bedroom pressurization, I like to close the bedroom door and tuck a manometer hose through the gap in the bottom. Turn AHU on. Note pressure reading. Turn AHU off. Note pressure reading. At minimum it can not only tell you if the room is being pressurized with AHU on, it can indicate to what extent it is being pressurized, and whether that is acceptable or not. IIRC, over 3 pascals is a problem, and supplemental return provision is required.

By extension, a whole house leakage determination is just as valuable, if not more. I was chided once for saying this here, but I'll say it again: "You can't manage what you don't measure".