Hey now. I need some help on an unusual problem and figured the pro’s on Breaktime could offer possible solutions.
I have a client that is very sensitive to alergens and various substances in the air. He lives in a very fine 1 story sprawling home with his office on one wing.
Turns out he had work done in the basement recently and he is negatively effected whenever he is in the house by something in the air. The worst place is in the basement. This is also where the heating system and all mechanicals are. He recently had a HRV fresh air system put in after the problem arose (so it’s not the root cause).
Removing all the work that probably caused the issue is major work and last resort. I suggested creating a positive pressure upstairs, relative to the basement, so the air will always travel from his main living space down to the basement then be removed from there. I think we can do this with the existing HRV ventilation system. Any suggestions on how to accomplish this would be appreciated. Also I would like to measure the pressures to verify. Any device for this exist that has precision required?
Thank you.
Stu
Replies
sorry to bump my own thread but it is prime time....
If it weren't for the fact that the air needs to be heated/cooled, it would seem that a fan through the wall or even a window fan upstairs would drive the air to the downstairs through any conductive passage as the heating cooling system. Um - how to heat/cool that air. I think large building take a portion of their air from the outside to keep the air fresh.
Tink-
This house has a system like that to bring in fresh air. Like I had suspected... I think we can restrict the exhaust and pump relatively a greater supply of air to the upstairs and that will result in greater pressure in the "supplied" zone.
thanks,
Stu
VaTom's house is positive pressurized - bigger "in" fan than "out" on the HRV...add some filters and you're in business...
Basically it's a matter of the placement of air supply and return registers -- you need to have more return in the basement than supply, and more supply than return upstairs.
HVAC guys have ways to measure pressure down to a fraction of an inch. You could get a rough idea with a simple "door" made of cloth or plastic in the basement stair opening -- if it bellies out towards the basement then the basement is lower pressure than the upstairs.
happy?
That's a great idea Dan. Very simple and visual.
Thanks for the response.
You've got an air system that obviously isn't working well. Apparently a matter of poor design. As Brian noted, I pressurized our house, but I wouldn't think your situation is such a simple matter. Spreading polluted air around the house indicates a serious design flaw.
The last 2 times I've dealt with clients and HVAC guys we had great difficulty finally finding one who knew anything about V. The rest were HACs. My guess is that one of them did your installation.
What you really need to do is evaluate the whole air system and find where the design was wrong. It's not rocket science. Think in terms of air coming and going from each room. You want fresh air coming in. It's really that simple.
Positive pressure can have unintended consequences, like pushing indoor humidity into wall cavities. I pressurized here, but knew what I was getting into. My reasoning was for all leaks to go out, and to pre-remediate any possible radon. But our house has no wall cavities for humid air to enter.
If you want to pursue this idea, consider negatively pressurizing the basement. I hope you've already dealt with combustion air and any other particular needs.
PAHS Designer/Builder- Bury it!
Thanks for your opinion and advice. I already found that the intake air grate was half blocked off on my first trip to the house. That is the exact opposite thing we need!Next step is a trip over there on Monday to walk the entire system and follow where the air comes and goes. I'll plan on sealing any leaks that might be detrimental and then formulate a plan based on what we learn in step one. Thank you for confirming my thought to negatively pressurize the basement. I was going to aim for simply being equal to atmospheric down there so it would be negative relative to the upstairs. What do you think about that approach? I hear you load and clear about the HAC guys out there. As with most occupations, it's hard to find the individual that wants to make the effort to learn why they do it that way and then challenge the system. Most simply follow the book without question.Combustion air is a wild card I did not have in the forefront. I will now, thank you. Stu
Stu, I'd be very surprised if you find leaks sufficient to cause the problem. Good that you're going to try to understand the whole system. That's what's needed.
Seems to me that if you provide exhaust to the problem area, coupled with make-up fresh air, you're going to mostly solve the problem. What remains is how the polluted air came to be distributed around the main floor. That's the really troubling part. Apparently a major flaw in the original design, and one that needs correcting.
Bob's not wrong to look at the source, but almost anything you bring into a house will outgas for awhile. You can try to prevent polluting sources, but that's considerably more difficult than remediating a short-term problem. I've dealt with both for chemically sensitive folks. A good air system is much simpler.
Pressurizing, positive or negative, shouldn't be taken lightly. Any air system needs to account for all parts. Clearly, combustion air can be a large factor (zero in our house). Bob knows more about that than I do. You're thinking that by negatively pressurizing the basement you'll draw the polluted air there for exhaust? Maybe.
Better to look at how the problem spread in the first place. I'm pretty sure that once you find why the air system is distributing the basement pollution throughout the house you'll have solved the problem. Whether or not you should provide unequal pressure is another matter, based primarily on the construction of the house. Pressurization is good, done appropriately.
Good luck. Please keep us posted.PAHS Designer/Builder- Bury it!
Thank you for the words of wisdom.
You are correct in saying the system is probably broke since it is spreading pollution. That is well taken. I will address that first and try not to go overboard with the pressurization that I first jumped on.
This client is hyper sensitive. He had issues that he had just cleared up by bagging up all the rugs in his house. Then this happened. I believe it is outgassing and I know that diminishes over time. So I hope to get the fresh air system addressed so that will get the offending gasses below the threshold that effects this particular individual.
I will keep updating when I learn anything. Thanks for everything.
Stu
The HVAC solutions are important, but don't forget that treating the symptom is short term: you need to find out what the problem is.
Try a google search using the words EPA and IAQ (or Indoor air quality) and read the whole set of pages
An industrial hygenist might be an appropriate consult; they know about this stuff.
And what is his sensitivity too?
Mold? Is there carpeting in tha basement remodel?
Formaldahyde? There are a lot of building materials which outgas it for a period of time.
We think he is responding negatively to an outgassing from some new products introduced into the basement of the house. Our thought is to try this least invasive step along with a duel path of finding the exact root cause and dealing with that as well.Stu
Stu- I ain't a pro insofar as HVAC is concerned
I have a client who has multiple chemical sensitivities, and have encountered a similar predicament before. I was redoing their kitchen counters with HPL, and reworking a coupla cabinets, as well as retiling a bathroom for the first phase, then it was installing a new bathroom in the basement in the second phase, from the walls in.
With this client, I had to specify any type of adhesives and materials, which they had to check out on the internet, and believe me they had questions.
You know, I have worked in some terrible conditions (even inside septic tanks!) and although I never noticed it the first few times I was on site, but after a few days, whenever I opened the door to enter, there would be an overpowering smell of chlorine. I never figured out where it came from, but put it down to overzealous use of powerful cleaning materials . When I opened the door to start the downstairs bathroom work, the smell of chlorine greeted me once again. It appeared to be a constant presence in the house. This is the only house I have ever worked in that I have noticed this phenomenon in. The thought occured to me that these folks might be victims of their own overzealous cleaning generating noxious byproducts which affect their health more negatively than any common germ or piece of dust would, but thats not for me to say.
I have never had any sensitivity or allergy suffiecient to be aware of, but last week I replaced a kitchen in a town house where there was a cat, and it appeared that there may have been a vacuum cleaner, but I would be hardpressed to say it worked. I tore out the old kitchen the first day, and vacuumed up the whole mess. I installed the uppers, and a pantry, only drilling screw holes and cutting two pieces of 356 casing with a handsaw. Then vacuumed up again. There were and still are cobwebs and dust bunny's on the walls in the kitchen
On day two 8AM there was a written , massi complaint from the tenant about the "fine sawdust" I had left and how it affected her asthma. I increased my vacuuming, and the next day I was told that her asthmatic problems had resolved.
The rest of the house is loaded with cat hair. On a massiveve scale. On finishing the job Thurs, I vacuumed my way out of the house, and this morning, cleaning out the vacuum cleaner there was as much cat hair in the vacuum cleaner as there was dust, and I know the difference between dirt and sawdust, so dirtiness of the sawdust tells me that if she uses her vacuum cleaner, it just ain't workin.
In my pea-brained way of thinking, why would I NOT expect to be made responsible for her problems. I'm the only "new activity" she can point a finger at.
To make a long story short, here's two clients in my experience who have these apparent sensitivities to construction activities, and two clients, who MAY be the victims of their own lifestyles. I have encountered no others with this degree of sensitivity.
Not that the future might not bring me clients where the situation might not be clearer.
Stu was sayin..."Turns out he had work done in the basement recently"
by you? or by others?
You can be a nice guy and offer suggestions, but for heavens sake, don't take on the liability of solving problems you ain't maybe qualified to answer , whether the problems are real or possibly percieved, and which may have been caused by others.
Outside of suggesting getting the air ducts cleaned, changing furnace filters, using HEPA/charcoal filters, etc and common sense solutions . and unless you is a professional air quality person, make sure that any advice you give is clearly idenitified as non-professional, cause you don't want to assume the liability for this.
Yer client, clearly sensitive and knowledgable about his condition, is likely substatially more tuned into the possible causes of his aggravation, he can and should get an air quality assessment done, in order to pin point as exactly as possible the cause of his sensitivity.
you related...."He recently had a HRV fresh air system put in after the problem arose (so it's not the root cause). "
This is clearly one possible solution, but if the underlying cause is from an outside source (say perhaps from a neighbour just started spraying laquer and venting it outside!), it wouldn't make a difference with an outside pollutant, and any money spent tearing out work in the basement may well thereby be wasted. As well, if the offending substance was part of that work, removing it is possibly gonna release more of the offensive dust/gasses whatever into the air.
Does he have a central vac, are the filters clean? and is it exhausting outside? If it ain't exhausting outside all the really fine dust may just be re-circulated in the basement.
Got Carpet in the house. Most interviews I'm heard from allergists have said that rule#1 is to remove all carpeting, and then they go on to say that this is typically the last thing to be done.
He ain't gonna know what the cause is until the cause is clearly identified. It could be inside, or outside.
To me, a finishing/cabinet butcher kinda guy, I see what kinda drywall sanding dust gets left in the cracks, and just left there, by floor layers, homeowners, other trades. Heck, in our house, which we bought "used" when I first used my compressor to blow the dust out, there was drywall dust coming out from behind the mouldings 8 years after it was built. It might be as simple as just doing a hell of a good vacuuming job (as well as the duct cleaning.....)
Every spring when the wind is right, Cowtown opens all the windows, takes the compressor and "dusts" the house. You'd be suprised with the amount of dust and debris that can come out of a book-case, heck, even outa yer computer monitor. The fine dust exits the house with the wind, and the dust heavy enuf to settle out gets vacuumed up. Works for me, but my wife just laughs.
You was asking....Any device for this exist that has precision required? ( to measure pressure differential.....
Barometers. But the second the furnace kicks in, it's all for naught.
I ain't no expert in this area by any stretch of the imagination, so these is just my observations and experiences.
Hope I added some knowledge.
How do others handle these types of situation?
Eric
How do others handle these types of situation?
If you mean potential clients with a problem you aren't fully qualified to deal with...
A furniture-maker, I had a commissioned bed to build. Chemically sensitive client. She slept with several different wood samples under her pillow. Then glues. Then the killer... finishes. No way was she going for nitrocellulose lacquer, delivered a week/month/whatever after spraying.
Anyhow, after going the distance successfully with her (the finish, Livos, really didn't do justice to the work) we got involved with the rest of her house. I understood the rudiments of air systems from building my place. I've got allergies such that we once packed up and left Va, thinking I couldn't do woodworking here. While travelling, learned what to do to make a less-than-friendly climate work for me. It's all about clean air.
Given the dearth of competent consultants here, I encourage anybody interested in solving an air problem to give it a try. Your warnings about over-promising results are clearly proper. I wouldn't do that either. I only suggest an avenue of approach and invite the HO in on the decision process.
I once knew a woman (here) who could remember breathing freely exactly once in her life. It was in San Francisco, 25 yrs before. Astounded me that she didn't make the call to "pack it up and ship it out". Far as I know, she still doesn't live there.
Breathing's a pretty basic need.
PAHS Designer/Builder- Bury it!
Simple question here compared to the OP's, but while you guys are on the topic, thought I would ask. In a conventional house with a forced air funace, would it be beneficial to place filters at the return air grills in addition to the one that is installed at the furnace. An HVAC installer recommended against that, saying it would reduce return air draw causing an imbalance. Does this sound reasonable and would there be a way to compensate this imbalance. My thoughts were to keep the new duct work as clean as possible.
Depends on the total square inchs. If there are enough cold air returns (roughly square inches equal to maybe 3 times the size of the main filter), the flow rate through any one return is quite low, and the filter won't build up much back pressure. In fact, the filters would tend to balance the draw through the various returns, helping to eliminate stale air spots in the house.How much good the filters themselves would do is hard to say. PITA to clean/replace them all, certainly.
If ignorance is bliss why aren't more people
happy?
I've seen filters installed at the return register, in addition to one at the air handler. My mother's house is set up that way. Unfortunately I can't answer your question. Hers are the crappy woven type.
All the HVAC guys I've ever spoken with are suspicious of filters. Mention pleated filters, like I use, and they start foaming at the mouth about reduced air flow. There's gotta be a valid point there somewhere.
What I'd probably do is put in a filter and see if it reduced air flow to a problematic point. When I was discussing my air system with somebody who presumably knew considerably more than I did, he assurred me that a pleated filter would prevent my air system from working. So, rather than give up real filtration, I installed one with a huge area. Hasn't been a problem. I filter my air on the way in, partly to keep the ducts cleaner. Only makes sense.
Funny story: I traded a driveway grading for 4 defunct (formerly) active solar systems in some townhomes. Collectors were long gone but in addition to a lifetime supply of pumps and valves, I went after the radiator that put heated antifreeze in the return air stream.
The radiator air passages were packed with crud. Looking around, I noticed that the filter was installed downstream from the radiator. Oops. Checked the other systems, all the same. Seems I'd solved a 12 yr standing question there: why the elec bills were astronomic (both heat and ac) and why the filters never, ever, needed changing. You might think that one of the various HVAC guys working there would have noticed something.
Yup, "professional" installation. The radiators did a pretty good job of filtering. Better and better as they got filled up. PAHS Designer/Builder- Bury it!
"All the HVAC guys I've ever spoken with are suspicious of filters. Mention pleated filters, like I use, and they start foaming at the mouth about reduced air flow. There's gotta be a valid point there somewhere."
When you reduce the air volume in a system by installing "better" or more filters (this is more resistance), you reduce the heating/cooling air flows to individual room since the pressures throughout the system have changed.
In the worst heating cases, the air flows get so low that heat is not taken away from the heat exhanger/plenum area fast enough. The unit shuts down on "high safety"- the heat sensor that shuts most furnaces off when heating air gets to 200 deg F in the heat exchanger/plenum. The same can occur in A/C systems as low air flows will causes system refrigerant pressures to rise and the unit shuts down.
In my area, I find that at the housing level, HVAC is probably the poorest trained subtrade. Just finished a 1 year warranty inspection on a million $$+ home. The $65,000 of HVAC systems are causing the most complaints: Ductless split A/C doesn't work, the outdoor condensor is about to fall off its stand, two rooms are crosswired, leakage in condensate drains, the main ground source HP assisted heating system shuts down 2-4 times per month, the HRV which was labled as balanced at 270 CFM on high speed when installed only moved 132 CFM when I tested it, and on and on.
the HRV which was labled as balanced at 270 CFM on high speed when installed only moved 132 CFM when I tested it
Which is more than I've done with my system.
IIRC, you pooh-poohed my use of .5 ACH. No idea what I actually get, but the air's great. If I'm over-ventilating, the heat penalty is very easy to live with. Our house (passively) never gets cold (or hot)- ever. The pleated filters give me allergy relief. Wouldn't live in this climate otherwise.
A friend is just experiencing completion of his extravaganza here. Had a heck of a time finding an HVAC guy who had even an inkling of the concept. Generally no V, just HAC. I guess he was better off querying me on the subject, even if it made it very difficult to find the sub. I'll be very curious to learn how the house actually works. Doesn't look good to me, but I'm not expert.PAHS Designer/Builder- Bury it!
Tom:
"IIRC, you pooh-poohed my use of .5 ACH."
No, not doing that at all. No intent to comment on ACH's. Just saying what I found (misrepresentation/fraud by a contractor) in a very expensive house)
But I will now make some comments on the .5 ACH rate that will apply to most other folks:
You live in a temperate to warm/hot climate so over ventilating won't cost you much. And if I remember from the last time I was online for a while before Xmas, don't you live in an earth-sheltered house.....a double + for low HVAC costs.
But if people in extremes of heating and cooling climes and living above ground ventilated at .5 ACH, their ventilating costs could be substantial. In the cold areas during the coldest part of the winter, they'd be croaking and wanting to add a humidifier to the HVAC system. This is the initial rate chosen for Canada's R2000 system in 1982/3 when Iwas an inspector, researcher and trouble shooter for the program. We had people having nosebleeds, hard wood floors shrinking and static shocks from door handles, etc.
When looking at it from another perspective, really shows that the program really erred way on the side of safety!!! A large house (2,500-3,000 Sq Ft + basement) with only 4 inhabitants at .5 ACH would be ventilated at 60-75 CFM per person. From the ASHRAE 62 air quality manual, good ventilation for clean buildings such as schools/office buildings, the prescribed rate is 15-20 CFM while occupied. ASHRAE got in trouble in the first energy crunch when they tried to reduce this to 5 CFM for energy savings. That didn't work very well and we're back to the old standard for schools, etc.
The big surprise that I brought to the engineer at R2000 head office was that the ASHRAE rate for control of cigarette smoke in bars and smoking lounges was 60 CFM /person while occupied. We had people in clean houses that didn't smoke, were out of the house most of the day and led clean life styles that were ventilated more than smoking lounges had to be.... and 24/7!!! Where was the common sense???
I had put 3 "too small" HRV's in R2000 houses in 1989 that led to a lot of wrangling to the point of being threatened by one homeowner of taking me to court. That's why I had to show the unrealty of the specified CFM's to head office. The 3 houses eventually got "special" certification as R2000 houses and now the "too small" HRV's would be oversized for today's program- the required rate has been reduced 3x since my encounters.
Edited 4/26/2006 11:08 pm ET by experienced