Author Topic: Evap Coil Placement on Electric furnace  (Read 6030 times)

Offline scarey8

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Evap Coil Placement on Electric furnace
« on: July 04, 2012, 06:33:20 AM »
Situation:

Customer of mine has a downflow electric furnace installation and heat pump by another company.  Furnace is installed ontop of a cased A coil, they have said they have had numerous service issues with this unit.  They are looking for recourse against the installing contractor, as the system has been installed incorrectly by most standards. (R22 lineset reused and not flushed while paired with an R410A system) as well as the electric heat elements are installed upstream of the heat pump coil preheating the evaporator air on temperature.  It was always my understanding the this was a no no, as it screws up "heat pressure" in the heating cycle.  looks like a very poor install of a furnace and heat pump that someone had in the warehouse and needed to get rid of rather than installing a proper downflow unit with a built in coil.  Trying to find some sort of literature to supply the customer with respect to this coil install issue.  any takers

Offline scarey8

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Re: Evap Coil Placement on Electric furnace
« Reply #1 on: July 04, 2012, 07:23:32 PM »
It is a luxaire heatpump and MC cased coil, the furnace is a broan I believe.  I've haven't been able to find much on the install of it with respect to literature, there is a picture deplicting the proper installation with evaporator coil upstream of elements but it is listed with the heading "typical installations"  I'm looking for a shall or a must clause of some type.  temporarly I've set the system up thru programming on the vision pro 8000 as fossil fuel system to prevent the two systems from running at the sametime.  I will post the exact model and serial numbers tomorrow, thanks for your help thus far

Offline scarey8

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Re: Evap Coil Placement on Electric furnace
« Reply #2 on: July 05, 2012, 06:16:03 AM »
Model of outdoor unit is LHJD2454151A  Serial W089611492
Indoor Unit  MC3583XH1H  Serial Number W009718104

http://www.upgnet.com/PdfFileRedirect/331473-YSD-A-0507.pdf

Page 4

This is the best I can find this far

Offline Admin

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Re: Evap Coil Placement on Electric furnace
« Reply #3 on: July 07, 2012, 04:00:15 PM »
It looks like they installed the coil incorrectly on the supply side.

What kind of problems are you having with the unit?

I've been fooled by electric elements before.  They were being energized during a call for cooling and killing my temperature drop.  It ended up being a faulty sequencer.  Now I use my clamp on to make sure no elements are running while cooling.

Offline scarey8

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Re: Evap Coil Placement on Electric furnace
« Reply #4 on: July 08, 2012, 08:36:50 AM »
Was a no cooling call, unit was low on refrigerant.  service valves leaking as well as unit installed in a  closet with one return air at 6x14 in size.  sealed the service valves and cut in two 8 x 30 returns to allow more air to the unit.  recharged the unit with the factory charge and still required more as I could not build any subcooling, both metering devices are txv.  factory charge was 8 lbs and after hitting the unit with 11 lbs and still no subcooling i knew something was up.  superheat was always in check and have a clean condenser with good air flow.  to troubleshoot i switched it to heating mode and watched the unit jump to 800 head, indoor tx will no throttle refrigerant or allow reversed flow.  so poor customer is on the hook for a pair of tx valves as well as flush of the line set and more refrigerant as well as a system that will never have the ability to work properly

Offline WXNEUMANN7

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Re: Evap Coil Placement on Electric furnace
« Reply #5 on: December 21, 2018, 01:29:40 PM »
Most mobile home electric furnaces have evap coils on the return side of the furnace, which I think sounds backwards to have a part that has condensation above an electrically charged open wires.
Not sure what the main reason for this?

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Re: Evap Coil Placement on Electric furnace
« Reply #6 on: December 21, 2018, 01:43:56 PM »
It sounds like you have a downflow furnace with the coil above the elements on the return side.  You make a good point.  I had assumed a coil was installed on the return side of a standard upflow electric furnace incase the drain line plugged up and water started pouring out of the coil drain pan onto the electric elements.  But with a downflow furnace the coil would be above the elements and could leak onto the elements as well.  You figure they would move the coil to the supply side on an downflow furnace.

I attached a picture from an ICP electric furnace manual.