Air exchange in new homes

Steve Ebels

Trying to find out how many of you are recommending that your customers have these installed. Mold due to excessive moisture/poor ventilation, is becoming more prevalent and therfore more of a problem. Many of the new homes I've been in have ecxess moisture even in the dead of winter when the A/C isn't on to aleviate the problem. The only answer to this problem is an HRV as far as I can see.

So, Do you

A. Never recommend this piece of equipment

B. Sometimes recommend this piece of equipment

C. Always recommend this piece of equipment.

Steve Ebels

HRV'S, ERV'S and the like....

How many of you guys address the issue of air turnover or air exchange in new construction? This is for the forced air as well as the hydronically inclined out there.

I feel myself that heating (any form) and fresh air supply to a new home are two different issues. Do any of you feel the same way? Maybe a little easier to integrate into a duct system but still needs another piece of equipment to address the issur properly.

What are your opinions?

BillW@honeywell

Ventilation

Hi, Steve! Two issues here...when the heating equipment is installed, provision for adequate combustion air must be made, most commonly by direct venting today. ER/HR ventilators typically aren't used for that, but for air exchanges for the people in the occupied spaces, or as part of a radon mitigation program. You can install an ER/HR ventilator without using a forced air system, but you must do so with care. It is much easier to do in new construction. Install intakes in laundry rooms, baths and kitchens, nursery or eldercare rooms. Fresh air outlets can be located high up on walls, so that they don't discharge directly on people...remember ER/HR ventilators are only from 65-85% efficient, and extreme cold weather or hot weather may cause discomfort, if the discharge blows directly on someone. An electric or hydronic reheat can solve this issue, however. The type of unit you use varies by geography, with HR units preferred for most of Canada and the US, with ER units preferred in the deep South, and the Desert Southwest, for moisture control reasons. At most, ER/HR units provide 200 cfm at high speed, and about 70 cfm at low speed. They can be controlled by a PC8900, a time switch or dehumidistat, and usually run 24/7 on low speed with the high speed option coming on when more ventilation is required. HR units must be mounted in a temperature controlled space, and provided with a drain.

This was a long way around to explain that yes, ER/HR units CAN stand alone, and should be part of our offerings to the homeowner. Good indoor air quality is our concern, too!

Steve Eayrs

HRV's are used extensively.........

up in Alaska. The ER's do create a negative air problems, and cold air as mentioned above. ONe reason they are so popular is the energy rating programs, ( to help lower your loan interest), recognize these units in their ratings.

The HRV's work great, and you can instantly tell the difference, between a house with one and one without. I wouldn't do a house without one. We use Venmar/Vanee and the controls can get as fancy as you want. The basic unit has a builtin de-humidistat, and high/low settings.

Most places we do are boiler/radiant floor heat systems, and I'm not sure what special care Bill is talking about, when not doing forced air systems. I would say that they need to be ducted correctly regardless of the heat system, and can be used with any type of heat system, BUT need to be balanced. Venmar has builtin balancing stations, where you can plug your guages in. You could do all the ducting right, and still have a neg. air pressure, and pull drafts in under doors, windows, etc., if not balanced properly.


Sealed combustion heating units will work better w/ a poorly installed HRV, but do not eliminate the other problems created by this HRV. Most systems we do are oil fired and not direct vent, or sealed combustion, and we have no problems.

Steve

john wood

ALWAYS

I always reccommend HRV's in every home. Usually priced them into a package with the radiant and a/c. Turns out to be a sales tool as the homeowner sees that you are covering all the bases compared with the flybynites and other lowballers. Anything you do to differentiate yourself from the "competition" is a definate advantage.

Bill NTSG

Steve E.

I almost never see it. Less than 2% of the new homes and some are very high end. Ask any mother and some one in the family has asthma or allergies. Why not put in a HRV ? I ask, "too much money" . You need money for the SUV's and the Lexus. Light fixtures and Granite counter tops come first, no money left for HVAC. So it's scorched air, the cheapest money can buy. Then they spend $2500 and up a month for the next 30 yrs on the mortgage to live in a terribley[sp] uncomfortable home. Until it becomes a law that is enforced the builders or G.C.'s are not going to push for it. Just what I see in my part of the world. P.S. I would always reccomend it.

Terry

Code Here

Mechanical 0.5 air change required by law in Canada, so It's not an option.

When you guys are using Radiant combined with fancoil heat. Do you use the fancoil for makeup (mix return & fresh) ? or add an additional HRV? (I have only been quoting the HRV's when there IS NO other mechanical form of ventilation)

"Everythings better wet!"
Terry~Frontier Supply

Frontier Plbg & Heating Supply

Alberta Hydronics Council

Paul Pollets

Always

We always mention it and price it as an alternate.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Kevin_10

I am a homeowner and had a HRV unit installed by my heating contractor last summer. I now realize that my unit was his first and he did not do a good job on my radiant flooring system. Not many air exchange units are installed in my area. How can I find out if he installed it correctly? He used 6 inch flex duct for a 1825 sq. ft. house. Should it be hard pipe? Thanks for your help.

Steve Eayrs

I would say that around 80%

of the new houses around here have HRV's. I am also sure that that number would drop a lot, if it wasn't for the loan programs that can sometimes drop your loan interest by at least 1 percent. BUT as long as the houses here have to pass the blower door tests, they are so tight that ventilation is not really an option but needed. Mold is a real issue, and can turn a nice house into something you can't live in.
Between higher efficient system, tighter house, and ventilation, your interest rate can drop by as much as 2 percent. Add this to first time buyer advantages, VA loans, etc. and around here your interest can get down around 4.5%.
Has a lot to do with us having no problem selling these things. I go out of my way to explain why these are needed, and would say that once they understand why they will go with this before the nicer counter tops........That is if I can get past the general contractors, some of who think their job is to keep the customers from spending money that they already stated they want to spend.
Steve

Mark Hunt

Air exchanges

Where to start?!?!

We are performing blower door testing on any new home we work in. HRV's are almost ALWAYS offered to the customer but sometimes the "customer" is the builder.

I have been testing old and new homes alike for 3 years as part of the New York Energy Star program and the results so far were surprising to say the least.

Of the homes that I have performed blower door testing on, I have only found a few that were tight enough to require mechanical ventilation.

Even very new homes are testing out with high amounts of leakage, far beyond MVG standards.

In this area, many builders do not require sealing of penetrations in wall and joist cavities, these are the pathways for STACK EFFECT. Recently, New York adopted the IBC, so forced air distribution systems must be sealed and supposedly NO wall or joist cavity is to be used for return air.(I have spoken to other heating contractors on this and it seems that the wall/joist cavity rule may or may not be enforced depending on locale.)

My advice to builders and homeowners alike is this, prepare at least for the possibility that mechanical ventilation will be required and rough the ducts in for HRV.(Most central air distribution systems do not incorporate return/exhaust ducting in bathrooms and kitchens and these are the sources for most of the moisture produced in a home. We recommend a seperate duct system for HRV)

Mold issues will soon make Asbestos look like a walk in the park. If you type mold into "Google search" you will be AMAZED at how many lawyers are lining up to "help mold victims get their just rewards".

Sooooo....in answer to the question, we always discuss HRV and always recommend ducting at least be installed in the event it is needed.

Mark H

John_21

FLEX DUCT

It most likley should have been done in gal. pipe, less friction loss. John

Kevin_10

What is a electronic or hydronic reheat?

Steve Ebels

It's

Either a single or series of electric resistance type elements, in the case of electronic re-heat. Or in the hydronic case it's a hot water coil. Both are installed in the duct to temper/warm the incoming air.

I'm looking at a print right now for a 12,500 sq ft restruant. Code for the maximum occupancy is a smidge over 3,000 cfm of fresh incoming air!! This would be a good example of the need for re-heat don't you think?

Steve Eayrs

The only flex duct we use is between the hrv unit

and both outside hoods. 6" 30ga galv duct is most common elsewhere. Did he run exhaust from the kitchen, all bathrooms, and laundry room? Did he duct outside intake air to all the rest of the rooms in the house? Did he seal all joints? If not then he didn't do it right.
Steve

BillW@honeywell

ER/HR

The mold issue is too complex to say what effect any one component of an HVAC system will have on it; for example, mold resulting from plumbing leaks or roof leaks. ER units recover both sensible & latent heat, and tend to balance humidity. HR units recover sensible heat only, and tend to remove humidity from a space. In new construction, off-gassing of organic vapors from carpet, glues, paint and a tremendous amount of water from sheetrock, lumber and wallpaper is a serious matter. HR units are the most effective in dealing with this "new house smell" issue.

ER/HR ventilatiors dilute and exhaust gases, vapors and odors, and bring in an equal amount of fresh outside air, while recovering up to 85% of the heating/cooling energy. They have no effect on particulate problems like dust, spores or bacteria. Advanced media filters, electronic air cleaners, ultraviolet germ-killing lights and humidification are all part of the indoor air quality package.

A minumum IAQ package should include an advanced media air filter, with the option to upgrade to an electronic air cleaner, ultraviolet light above the cooling coil, with the option of an additional light in the return air duct, and a humidifier of whatever type is appropriate; usually steam for hydronic/radiant homes. ER/HR should also be included. I am making an assumption here, but our research shows that 87% of prospective home buyers want air conditioning, so ductwork will probably be installed. I prefer to see these systems set up with metal ductwork, and care should be taken to put the outdoor air intake and exhaust at least 6 feet apart, and keep the intake & exhaust above the snow line and away from dryer vents, furnace/boiler exhaust, pet areas, automobile parking and garbage cans, since odors from these sources can be pulled into the house. HR units need a drain, and must be in a conditioned space.

Sorry about the long winded reply, but this is a very complex issue, and a good opportunity for any wethead who wants to think outside the proverbial "box"!

T.J.

That's overkill.

Fresh air to every room in the house seems like over kill to me. Fresh air to the kitchen area downstairs and any common area upstairs should be sufficient. This is assuming you don't already have an exisiting duct system for central AC.

Mason

flex duct

We use a small section of flex duct in the indoor sections as well to stop any noise transfer.
Mason

Steve Ebels

Kevin

The type of piping has some effect on the units performance but there are other issues that would have a greater impact. For example........ Is the unit sized right for the house CFM wise? Are the intake/exhaust openings correctly placed, both interior and exterior. (see Bill's post)


BTW We always use at least 15 ft. of insulated flexible duct on the outdoor intake side. This is to prevent any problems with condensation on the exterior of the duct from incoming cold air.

Kevin_10

Steve,

Where do you live? Very few people install air exchangers in the part of upstate NY that I live in. How do I find qualified and knowledgeable installers. I don't want to make the same mistake twice.

Mark Hunt

Where

in New York are you sir?

I am in the Saratoga region. If I can't take care of it personally, I'll find someone for you.

www.comforthometech.com

Mark H

Steve Eayrs

Tim, About HRV overkill.........

If you were to look up what is needed for a whole house ventilation system,in our area, and as tight as the houses are, (slaming a door shut affects your ear drum) you need to duct every room in the house.

(Average walls R25, average ceiling R60, (w/ some higher) only gasketed electrical boxes in outside walls,ceiling, and a case or two of special chaulk to seal the overlapping vapor barriers, with NO holes in it. Some of our windows have almost as much insulating value as walls down south! Seen winters where at zero deg. F. outside, it took (2) days before the home owner noticed they were out of oil, and the house temp dropped less than 10 deg.! They thought they only had a dhw problem!)
If you don't do this stuff you will not pass the State energy ratings needed for the loan programs. Alaska's standards are real similar to what is required in a lot of Canada.

Also one of the main reasons for ventilating these tight houses is to take out excess humidity, so the exhaust to outside is taken from the kitchen, bathrooms, and laundry rooms, (high moisture producing areas). You do not pump fresh air into these rooms. All the rest of the rooms in the house, (lvrm, bdrms, etc)get the fresh air ducted to them. The end result is about every room has either an exhaust or fresh air supply to it, and you are exchanging air in the whole house, not just a couple rooms. Usually end up 100-200cfm or so, depending on the size of the unit, which is determined by the size of the house.

Keep in mind that I believe there are only a few AC systems in town, almost all on just commercial buildings. You get too warm.....you just open the windows, or go out fishing and enjoy it. (Too warm around here is actually about just right)
Call it overkill if you want, but you would do it too, if it reduced your house loan by 2%. And it would be worth it regardless. I would say that a nicer 2500-4000 sq.ft. house, with HRV/ radiant/good boilers & dhw/ outdoor reset/ injection pump, (all nice stuff), is still between $70-120/month, year around average, for all the heat and dhw you need. (or to equate that to your local values, thats about 700-1100 gals. fuel oil a year. ( a lot depends on who lives there)
I cannot understand why houses are not insulated better down south, just when considering AC needs alone. Of course then you have to ventilate better too. Even without considering heating needs, some HO's spend close to this just for AC! Maybe I should call this .....underkill?

I would guess that the addition in initial construction cost, wrapped into the house loan, is less total output per month, than the option of increases in the utility bills plus the smaller bank loan. This may even still be true, if you didn't get the reduction in the loan interest.

So thats the long winded reason for the way we do things here.

Steve

Kevin_10

Mark

I live in Watertown. Thanks

John_21

live


steve lives in Homer, Alaska whitch is 90 miles south of me in Kenai, Alaska. The construstion is of much more energy design. Pays off in long run. John

Steve Eayrs

Thanks for answering for me John......

I didn't see the question, since I was actually doing a little work instead of the net. :-0

john wood

Flex ok if....

Flex is ok to use as long as the installer used the specs for the HRV as to available static and allowed for the increased static loss of the flex. If he did not, then you will not have the air flow the unit is designed to do and that you paid for. The biggest problem I see is that not too many installers balance the inlet and outlet flow. This causes excessive pressure gradiant from indoors to out. This can exacerbate the infiltration of unconditioned air. Can also cause backdrafting on "B" vented appliances. Not so much a problem with sealed combustion equipment, which is another very good reason to use sealed combustion.

As to where to introduce the fresh air? I personally install them in the Bedroom closets. Fresh smelling and a slightly cooler closet does not seem to bother anyone.

Efficiencies on HRV's can go into the mid 90's with a two core unit. See www.lifebreath.com for some examples.

Terry Larsell

Intake & Exhaust

In WA the code requires air change, but they really have trouble convincing people why it's needed or where they can get the equipment to do it.

The Vanmar unit I just ordered has a common intake and exhaust, how's that for seperation. It also had one controller and for all I could find out that is all they allow.
I like to put a booster button in every bath so I sent the unit back in exchange for broan ERV I have installed in the past, 20 min boosters are available for this unit and I can add as many as I like. I'm still waiting to here on what they dig me for restocking even though both units come from the same place.

The more I look the less I find, no brand had any good piping diagrams and good luck on finding out what kind of controllers they offer. The local supply house say " ERV whats that some kind of fancy fart fan"

Manufacturers and Dealers, Educate us and we will buy it!!

Terry

Troy_3

HRVs

We recommend and qoute them on every job. About 80% of our jobs get them. We qoute hi-velocity A/C also but only about 60% will do the hi-velocity. I'm amazed how few heating contractors qoute HRVs. And when they do it's a tiny 60cfm joke. I say joke because most of the houses we qoute are 3500sq. ft. and up. We just qouted against an 80 cfm unit proposed for a 6500 sq. ft.house. We used 2- 250 cfm units.

T.J.

Steve,
Lets assume you have a 4 bedroom house rougly 2500-3000 sq.ft and your HRV is 200cfm. How do you effectivly and precisely deliverand or exhaust an average of 25cfm to rooms? I work in the commercial HVAC side of the business and have never seen a diffuser/grille or any airflow measuring instrument that can be confidently used at such low airflows.

That's why i feel supplying and exhausting air in just 2-3 rooms at an average air flow of 75-100 cfm is more cost effective and more precise compared to whats mentioned above. I may be wrong, but 200 cfm of fresh air is still 200 cfm of fresh air ...

Steve Ebels

If you're talking to me (SE)

I live in Northern Lower Michigan. A little far from you. Give Mark Hunt a call. He's honest and knows his stuff. If he says it'll work, it will and if he says it won't, you can bet on that too.

BillW@honeywell

Info on HR/ERV's

Hi, Terry! Check out http://hbctechlit.honeywell.com and type in HR 150 or 200 and/or ER 150 or 200. That will get you a tech sheet that gives you sizing and duct hookup info. In general, we recommed that the fresh air be ducted into the return, and the exhaust intakes located in the laundy room, kitchen, baths and nursery/eldercare rooms. For homeowner info, go to www.honeywell.com/yourhome. If your wholesaler is less than enthusiastic, try dealing with either a Honeywell PerfectClimate distributor or Honeywell Enviracare Elite distributor. I'll get you the names of some in your area if you tell me where you are located. For FREE sales literature on these products, FAX an order for form number 50-8170 to 1 800 356 0149, please put your shipping address on the order. There is NO CHARGE for this consumer literature.

BillW@honeywell

Info on HR/ERV's

Check out http://hbctechlit.honeywell.com and type in HR 150 or 200 and/or ER 150 or 200. That will get you a tech sheet that gives you sizing and duct hookup info. In general, we recommed that the fresh air be ducted into the return, and the exhaust intakes located in the laundy room, kitchen, baths and nursery/eldercare rooms. For homeowner info, go to www.honeywell.com/yourhome. If your wholesaler is less than enthusiastic, try dealing with either a Honeywell PerfectClimate distributor or Honeywell Enviracare Elite distributor. I'll get you the names of some in your area if you tell me where you are located. For FREE sales literature on these products, FAX an order for form number 50-8170 to 1 800 356 0149, please put your shipping address on the order. There is NO CHARGE for this consumer literature.