Lifebreath HRV w. ECM motor noisy?

[sbe]

I've been told by an installer that he had to remove a Lifebreath 155 with the ECM motor due to excessive noise. Apparently the unit sounded like it was growling which the client found problematic due to its location behind a closet.

Lifebreath's solution was to supply a sound dampener for inside the duct. Unfortunately since the noise was coming directly from the case this wasn't helpful and the installer was forced to swap out the unit for the non-ECM motor version.

Has anyone installed either the 155 or 195 with the ECM motor and if so any comments on this?

I was all set to specify one of these into a job I'm working on but now I'm concerned it might cause problems.

[fisette]

I just replaced a Lifebreath 155 ECM (new house, 2 months old) with a Lifebreath 155 MAX (non ECM). The original unit was totally offensive. The motor sound was eccentric with a very detectable sound pattern (high-low) that was transmitted through the supply vents in every room, even on low speed. On high speed, it sound like a growling or like the motor/fan was actually tapping on a surface of the fan housing. If you stood next to the unit in the basement, you would swear the fan was hitting the housing or it had some severe vibrational problem (at high speed). It sounded broken to me. I had the Tech Rep come out and he said that the engineers at Lifebreath were aware of the issue (not problem) and could not figure out a way to stop the noise. They indicated that it had to do with the variable speed function, which is responsible for saving energy. They offered up a muffler system, which I declined because they only promised a 50% reduction in noise. The new system is whisper quiet --- just like you would expect. Lifebreath anticipates it will cost me an extra $30/year in electrical energy, but the quiet is well worth it. The control system that comes with the non EMC unit is superior in my opinion. I am left to believe the EMC on this unit is not ready for prime time.

[sbe]

They must have some sort of engineering problem since there are lots of ECM based air handlers that seem to work just fine. I can't imagine what it would be in the motor. Maybe the small fan has it so lightly loaded that for some reason the system isn't working correctly.

I see they even have a warning on the data sheet now regarding noise. Too bad because the ECM unit at low speed runs about a quarter the power of the non ECM one.

[fisette]

SBE -- looking at the tech data sheet for LifeBreath 155 MAX it says it uses 49 watts on low speed and the 155 ECM version uses 34 watts. Also it shows that the ECM version has an efficiency of 72% and the non ECM version has an efficiency of 76%. Not sure how all this stacks up, but it doesn't seem too significant.

[sbe]

It looks like Lifebreath has two sets of numbers for power consumption.

I remember a spec sheet listing 17 watts on low but I can't find it this morning and the only one I find when I go to their website is says 34 watts. But I'm not imagining the lower number because that is what is shown on the Oregon DOE website.

http://www.oregon.gov/ENERGY/CONS/RES/tax/HRVList.shtml

Ah, hah. I just called Lifebreath. Apparently the testing protocol is that "low" is at 66 cfm, which on these is speed two not speed one. At the lowest speed (about 30 cfm) the ECM unit uses 17 watts. They didn't have a number for the non ECM but the delta between that and the ECM should be greater than at speed two.

I also asked about noise. The tech the problem seemed to be most severe at high back pressures. I asked to have someone call who is familiar with the details of what is actually going on and will post if they get back to me.

[fisette]

Thanks for the update. Do you know if low speed (speed 1) on the NON ECM version is also 30cfm? I was told that it was 49 cfm, but not to rely on that number because it is all related to stack pressure. The reason I ask is because my house is pretty tight 390 CFM50, which translated into 0.05 ach nat --- and I would like to have 60 cfm air exchange continuous during the heating months. My HVAC contractor said set it on 1 and it would be fine...

[sbe]

The easiest way to tell is to look at the curves. You can find these on their website by navigating to Literature and Manuals then clicking the top link and then on 5th link from the top. Scroll down in the document to the 155 spec and you will see the curves.

Speed 1 will give you about 50 cfm at 0.1". I have no idea what your ductwork or topology is like but once you have that you can calculate your total flow.

BTW keep in mind that even at very low infiltration levels you're still getting quite a bit of air and if the house is lightly occupied you might be fine. In my case I've got a 4500 sf house with 10' ceilings which is sealed as well as yours and with the house all closed up and no HRVs installed at all the leakage is enough that we aren't seeing IAQ issues during the final stages of construction. Not surprising since at 0.05 ACH the house is almost certainly 50 cfm all on its own.