Wife recently got a job working at home in our basement.  She now spends
95% of her life in the house.  I am thinking of adding a retrofit ERV to
our Natural gas central air HVAC system.  I figure if she is going to spend
this much of her time inside I should be concerned about the air quality.   Moisture is not really a problem.  When the temp drops in 20s my humidity drops in the 30s.  Only when the temp drops near zero do I get a significant amount of moisture on the windows.
My questions are as follows. 

How much will it cost to run?  I live in the Midwest and spend about $750
in natural gas to heat the house in Winter and about $350 to cool the house
in the Summer.  How much would I expect those bills to rise running an ERV?
My house is about 2750 Sq feet.

Also I have a radon level of about 2.0.  I already have a passive sub slab
suction system installed.  Would an ERV lower that level significantly?  I
could get a fan installed and activate it, but concerned with it creating a
negative pressure in house and causing other problems.  Mitigators do not
even hide the fact that they remove air out of the house.  Am I crazy for
worrying about this?

Thirdly, can anybody recommend a good ERV?  Does Carrier have a good
product?  That is what my furnace is.

An ERV will probably cost about the same to run as a fan. Probably under .50 cents/day. I have always used aprilaire LINK and have had good luck. You will want to check with each mfgr on specs. I believe most ERV's will transfer most of the temp difference between incoming and outgoing (about 80%). If it is 70 inside and 0 out side, the actual incoming air from the ERV will be somwhere around 58-60 degrees. I'm sure the energy transfer (temp and moisture) will depend on several factors.

Good Luck

I'm not sure there is all that much difference among the various units on the market. What I found is that it appears most of them are rebranded units from only about 2 or 3 manufacturers.

The one unit I found that does seem to be different is the Ultimateair unit from ultimateair.com. The only real difference with it that I can see, and want, is a controller option that will allow the unit to run as a whole house ventilator without energy exhange in the summer when the outdoor temperature is cool, like at night. That will cut down on AC use, but of course works only if outdoor temps are cooler than the desired indoor temp. Not sure how much of the summer that is the case in the midwest. Been a long time since I lived in Illinois.

UltimateAir® RecoupAerator® is probably the most efficient and cost effective. It's made by Sterling under this brand. Good experience with it and know other builders who feel the same. Not alway easy to get your hands on them due to production issues so get them while you can.

I have looked at Ultimate Air. However, I can not find anyone in my area that installs them. Also, they have two separate motors. One in the intake line and one in the exhaust. If one of the motors went bad and the other kept working, you would have a very bad situation of severly pressuring or depressurizing your house.

Anybody have any experience with the Trane Fresh Effects ventilator?
http://www.trane.com/Residential/Products/AirCleaners/FreshEffects.aspx

It is the Renewaire ventilator just repacked by trane. I have many trane installers in my area.
Do ventilators do good job of reducing radon levels when run normally?

I've got a Venmar catalog. Their better units also have two motors. Actually, I think that is an advantage. With separate motors it's easy for the ventilator to increase the supply air to compensate for air being exhausted by bathroom fans and kitchen range fans. I'd be surprised if one of them conked out you would have a "severe" pressure situation to contend with.

Find a cooperative HVAC man who is willing to order one for you and put it in. It can't be rocket science to install an UltimateAire if he's installed any ERVs. If he's a progressive dealer he'll be glad to broaden his experience. You can order directly also, but an HVAC dealer will get a wholesale price.


Based on the scarcity of info on the Trane web site I think it's safe to assume their unit is a rebranded unit.  Whose, I can't tell because there isn't enough tech info available to match it up with any other system. It looks like it's a step child system in the Trane lineup.

I went to hvi.org and compared specs. It is a renewair rebranded.

On the Ultimate Air. If one of the motors quit how would you not have a severe pressure situtation? You would either have 100-200 CFM entering or leaving your house constantly depending upon which motor gave out. Also if you wanted to increase supply air to makeup for bath room exhaust how would you know how much to increase supply by?

I guess we need to define severe. I'm guessing you have a lower threshold than I do.

You wouldn't have 100-200 cfm moving if one of the fans dies. That's because of the pressure/volume curve of every fan. If the exhaust fan dies the fresh air fan would raise the pressure only to the point where air would escape fast enough to keep the pressure from rising further. There is also a maximum pressure the fan will put out at which point the air flow is zero. All air exits from the house would have to be shut, which will never happen. The most you would probably notice is you might have to pull on an outside door a little bit harder to open it.

Actually, a slight positive pressure in the house is good. That helps to keep dust and pollutants from entering through window and door cracks, etc.

The UlitmateAir ERV has an option for a pressure sensor on it that measures house pressure. When it detects a drop because a bathroom or range vent fan is running, it increases the fresh air fan speed automatically.

You can download the installation and operating manual from UltimateAir.

Where do you install the pressure sensor? From my understanding the second floor and basement ussually operate at a slight negative pressure and the middle floor (1st floor) is ussually nuetral.

was doin some snoopin in my utility room, opend up my venmar AVS 1.5 solo, noticed the heat exchanger core was made of polypropolene, wouldnt you get better effiency with a aluminium or copper core? most plastics make good insulators. i'll measure its heat recovery performance one of these days.

Here's the pertinent section from the installation manual for the PressureGuard option. I found the manual at BlueRidge by Googling UltimateAir PressureGuard manual in case you want to check it for yourself. Considering how well connected a basement and second floor are to the  first floor I don't how you'd have them at different pressures without having tight doors and strong fans moving air in or out of the 3 spaces.

Installation
The Pressure Control Option comes with three additional componanents. Two small pressure
taps (static pickup tubes), and the pressure transducer. The pressure transducer must be
mounted in a conditioned space, in the most convenient location for wiring the transducer to
the RecoupAerator, and to connect the transducer to the two pressure taps (see the layout
diagram). It can be screwed to a wall, floor joist, or any other indoor stationary location.
The indoor pressure tap should be mounted to an interior wall, which could be considered the
central most open point in the residence. The outdoor pressure tap should be located on an
exterior wall, which is exposed to the outdoor environment. A garage, crawl space, or attic
space may be a good location for this pressure tap, if either of these spaces are not considered
part of your conditioned envelope and are vented to the outside. Avoid mounting the outdoor
pressure tap in a windy location. You will need to run ¼” tubing (flexible or non-flexible),
from the “hi” port on the transducer, to the indoor pressure tap, and from the “lo” port on the
transducer to the outdoor pressure tap.
Deciding on the Pressure Selection
While wiring to the 3-motor controller at the RecoupAerator, you should now make a
decision about what pressure differential you want the RecoupAerator to control* to. The
main objective (most simply described) is to keep humidity from entering the wall cavities,
which will lead to mold problems. In most installations, you will want to select a ‘balanced’
or zero pressure differential because high humidity levels will oscillate from inside to outside
during the year for a given climate. If your climate has higher outdoor humidity than indoor
humidity all year around, then you should select the 1 or 2.5 Pascal positive pressure
selection. The final position, or the ‘off’, disables the pressure control feature, and allows
the unit to operate as a balanced airflow ventilation system. Make your jumper selection
according to these parameters and the diagram in this manual.
*The ability of the unit to maintain (control) pressure differential is directly dependant on the overall amount of negative/positive pressure
it must overcome.

I'm building a new Energy star home in NH and have been looking at the UltimateAir RecoupAerator and the RenewAire EV130. The RecoupAerator seems more sophisticated but it comes in only one size, more than I need. The MSRP is $1899 and I would need a defrost unit for $320 since it gets below 10 degrees here. The RenewAire EV130 MSRP is $900 - $1000 and doesn't require a defrost unit. The RecoupAerator does a better job at transferring heat, but I was told by them that it is designed to run continuously, which seems strange to me. Most of them don't. The RenewAire guy told me for the size of my house, the EV130 should be on about 60% of the time. So it seems like I would actually be using less electricity with the RenewAire. Electricity is expensive here. I was also told the RecoupAerator is loud. Has anyone evaluated these two models that could provide some input? The difference in cost is substantial. Thanks.

@ hedgehog

plastic is a good insulator--ie non-conductive.  Plastic is not a good thermo-insulator.  Also hrv pass the heat from air2air.  Minimize the seperation, and maximize contact surface for maximum heat transfer.  polpypro is an exceptionally strong material, meaning the thickness of the membrane can be minimized to allow for better heat transfer.  Polypro is the material utilized by most hrv's

Davet;

I have a renewaire EV130 in my own home, I can't hear it running.very quiet