Dehumidification Settings and Wiring with the Ecobee thermostat

HVAC School - For Techs, By Techs

Bryan Orr

Training, Careers, Airconditioning, Self-improvement, Hvac, Business, Education, Refrigeration, Heating, Ac, Apprenticeship

4.8 • 985 Ratings

🗓️ 8 January 2018

⏱️ 35 minutes

🔗️ Recording | iTunes | RSS

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Summary

Bryan talks with Jesse and Nathan about setting up dehumidification for residential equipment in general. They also discuss some of the required and recommended settings on an Ecobee thermostat.

On typical single-stage residential equipment, dehumidification works based on CFM per ton. We control humidity by dropping the CFM across the indoor coil and extending runtime. However, as you cool the air, you reduce its ability to hold moisture. So, you increase relative humidity through cooling.

When we have achieved the desired humidity but not the desired temperature, the thermostat reduces the fan speed. Thermostats should vary the fan speed based on the call for cooling and the humidity in the air. Some systems have a dehumidification terminal; when there is a call on that terminal, the fan speed gets maxed out.

Some older thermostats would display relative humidity but did not have a dehumidification terminal; these systems would merely overcool instead of removing the humidity. These systems would be very prone to freezing. Nowadays, freezing still occurs on occasion, but our newer thermostats can control their CFM per ton much better to prevent freezing.

Ecobee thermostats work to integrate many different accessories. So, Ecobee thermostats try to solve every problem on a system, even on systems with supplementary humidifiers or dehumidifiers. These thermostats don't have a dehumidification terminal, but they have ACC- and ACC+ terminals for accessories, including dehumidifiers. Many technicians become confused when they think that the fan is a core element of dehumidification. Instead, the ACC terminals should be set as single-transformer, and you can choose the dehumidification option (which should NOT have the fan on). When wiring the Ecobee for dehumidification, connect the DH terminal to ACC+, remove the jumpers, set up the single-power source, do NOT dehumidify with a fan, and set "Dehumidifier Active" to "Open."

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Transcript

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0:00.0	This episode of the HVAC School Podcast is made possible because of generous support
0:10.0	from our sponsors Rector Seal, Carrier, and Mitsubishi Comfort.
0:15.0	So as service technicians, I mean that's the bulk of you listening are service technicians.
0:20.0	You may not be a service technician, but most of the people listening are generally
0:24.0	service technicians.
0:25.3	We want our customers to value what we do for more than just the price.
0:29.9	It's tough when a customer looks up online and sees how much a part costs and they want to
0:34.7	hold us to that part when really it's not the part, it's everything that goes to back it up,
0:38.7	it's the warranty, it's the service, it's the quality of the installation right but often we as technicians can do the same
0:46.6	thing to manufacturers we can look at price we can compare just price and we can say
0:51.0	well this is you know this is better than that when you know the reason
0:54.6	why I deal Mitsubian carrier and I have ever since I started my business it's not just
0:59.1	because they sponsor this podcast in fact I would probably say it's more likely that they sponsor this
1:03.4	podcast because I've used them for so many years and I beg them until they decided
1:08.4	to decide to sponsor the podcast.
1:10.8	Mitsubishi and Carrier both backed their product really well.
1:14.0	And so say what you will, you know, everybody has complaints about different pieces of equipment
1:18.0	from time to time and everybody's got their opinion, right?
1:20.2	It's like Ford and Chevy, you know, you're either a Ford guy or a Chevy guy, and there's probably a lot of you out there who aren't carrier people and I understand that, but I can tell you that carrier has always treated me really well and the same is true of Mitsubishi on the on the duckless side.
1:32.8	So we've dealt Mitsubishi for years.
1:35.0	We're a Mitsubishi diamond contractor, a diamond contractor elite,
1:39.1	which is their top tier.
	...

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