ERV croaked – Part 1

We have two energy recovery ventilators (ERVs), both of them the RecoupAerator by UltimateAir. One services the garden apartment, and a second ventilates the 1st floor. Both ERVs have served us well and we have enjoyed their performance. That enjoyment shifted onto shaky ground late last fall.

Next to the heating and hot water system, I would count the ERV as one of the most important mechanical systems in the building. And as with heat or hot water, you find yourself in a pickle should the system croak. And unfortunately the ERVs croaked on us this winter.

It started back in early October 2013 when the ERV suddenly started running non stop on full blast. That was unusual as the ERV speed and runtime are controlled by the bathroom timer switch or master control switch.

ventilation-16 ventilation-17

The only way to stop the ERV was to turn off the power switch on the unit. Shortly thereafter the blower motors stopped running altogether, even if we powered the ERV back up.


I had some trouble with the troubleshooting, which didn’t help. I talked with the tech support at UltimateAir and we concluded that something was wrong with the blower motor circuit boards. Because the ERV was still under warranty, I disconnected it from the duct work and shipped it to UltimateAir for servicing. A week and a half later I had it back in the basement, reconnected to the ductwork, and – it started running again non stop at full speed, no matter what the wall control settings.

At this point we knew it wasn’t blower motor circuit board that was causing the problem. Tech support at UltimateAir pointed me to the wall controls. I disconnected one after the other until I could isolate the problem to the bathroom timer switch. I replaced it with a digital timer switch, et voilà, we again had a functioning ventilation system.


Now, what do you do when you have an almost air tight home with a non-functioning ventilation system?

You turn to the old fashioned ways and open windows.

All this could not have happened at a more inopportune time. We were just at the beginning of the heating season. Opening windows to ventilate meant that we lost a lot of thermal energy that was still stored in the unit. Because of that, we turned our heat on a full month earlier compared to previous years.

That, in a way, is a testament to the effectiveness in heat recovery the ERV provides – when it is running.

Related posts:

ERV – keeping the heat

1st floor ventilation details

1st floor ventilation planning

ERV recap

Installing the ERV

Picking an ERV

Vetting ventilation

Blower door test – after insulation

About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

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