Electric Furnace- Weird sequencer behavor

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Old 03-01-14, 09:12 AM
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Electric Furnace- Weird sequencer behavor

I am trying to figure out why all the sequencers are not coming on when aux heat is called for.. W1 and W2 are tied together, and when Heat is called for I was only seeing 1 heating element turning on, during the extreme cold of late that was actually not enough to keep up, and my house temp dropped even after hours of heating. (Shown in pic 5)

this week I started to look at it again and realized that with the cover off (pic1) all three heating elements come on (instantly at that). but with the cover re-installed (pic2) they will shutoff for a moment, then (pic3) one element will come back on. If i take the cover off again (pic4) all 3 come back on again. [i think that is the correct picture order]

Do sequencers depend on ambient air temperature? to the extent that they would self control staging if a temp delta is not achieved? this seems like it would be counter-intuitive sincethey can be independently controlled via the w1 and w2 wires.

i have checked for any wires that could be loose, or pinched by the cover and found nothing.

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Old 03-01-14, 09:24 AM
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You could be tripping a limit.
Are you using restrictive 3m filters?

Post the model number of your Lennox air handler.

What is the display that you are holding?
Does it have a clamp that actually measures current or is it displaying what the stat thinks is working?

What is the air temperature on each side of the air handler with theses different readings?
 
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Old 03-01-14, 11:19 AM
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That meter is a wireless display of actual power usage of the house, measured at the incoming lines via two clamps.

Lennox Air handler model #: CBX26UH-030-230-1

The air filter is a pretty generic looking (American Air Brand) that we changed just late fall.. i cant find the exact date just now.

I don't have the capability to measure air temp before and after the handler.. what would you recommend for this?
 
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Old 03-01-14, 11:36 AM
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A ten dollar digital meat thermometer can be used to measure the temperature entering and leaving the air handler. The supply air should be measured around a corner from the heat strip to avoid measuring the radiant heat from the heat strips.
 
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Old 03-01-14, 12:10 PM
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Intake temperatures;

Panel off: 62deg (ambient air temp of basment)
Panel on: 66deg (temp taken through air-filter slot)

Output temperatures (taken at a vent in the basement <5ft of duct work from elements)

Panel off: 87deg (3 elements working)
Panel on: 79-81deg (1 element working)
 
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Old 03-01-14, 01:11 PM
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cfm = kw/(1.08*delta tee)


We need KW and a delta tee.
Looks like that 1.083 is the fan and should be subtracted from the kw for calculating.
It may be able to help determine an airflow issue.
The panels need to be installed for testing.


http://www.innovation-group.com.ua/d...b26uh_0612.pdf
I don't see 18kw listed in the manual.
 

Last edited by Houston204; 03-01-14 at 01:37 PM.
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Old 03-01-14, 01:39 PM
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The furnace is the 15kw model, 3x5kw strips.

18kw is my whole house usage, the clamps are installed ahead of 200A main breaker.
 
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Old 03-01-14, 02:13 PM
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Hey houston, 21* delta T with 15 Kw? Maybe airflow problem...
 
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Old 03-01-14, 03:26 PM
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air flow problem has been confirmed.

with the service panel closed again, I removed the air filter 2secs later all 3 stages were on, full 15kw.

so now i guess i am looking for suggestions of preferred filters? the generic pleated filter currently here is the last of what came with the house so I am up for whatever is best.
 
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Old 03-01-14, 04:18 PM
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Is the coil in the air handler clean?

If the coil is clean and you have a basic pleated filter, not a restrictive 3m filter, adding a filter grill might be something to look into.

A manometer reading 6 inches before and another 18 inches after the air handler would show if both side are restricted.

.25 inches water column is a great reading on each side.
 
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Old 03-01-14, 07:07 PM
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I was looking into buying this gauge General Aire G99 Media Air Cleaner Filter Gauge: Amazon.com: Industrial & Scientific

I will try to look at the coils tomorrow, but since the system is only 14mos old, I have to hope it isnt too terrible yet.
 
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Old 03-01-14, 07:46 PM
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