Q674L 1272 to Robertshaw 9520

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Old 11-08-14, 07:23 AM
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Q674L 1272 to Robertshaw 9520

Hi,
I've found several threads on this base and some even going to Robertshaw but would like to get the mappings since none of them are perfectly matched to mine.

I wanting to go from Q674L 1272 to Robertshaw 9520 (old to slightly less old)

Handler - Wire - Q674L 1272

Y - Yellow - Y
O - Orange - O
X - Black - X
R - Red - R
G - Green - G
B - Tan - B
60 - White - W


The 9520 has

1st block

C
L
R

2nd block

Y2
Y1
E
G
W2
O
B

The setup is a heat pump with aux heat strips.
Not sure if this is the right number or not but handler shows g/hc018sa

Thanks
 
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Old 11-08-14, 01:20 PM
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The 9520

1st block

C = tan
L = not used
R = red

2nd block

Y2 = not used
Y1 = yellow
E = black
G = green
W2 = white
O = orange
B = not used
 
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Old 11-09-14, 06:52 AM
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Thanks a lot! It's all working great except emergency. I switch the tstat to emergency and the air feels cold where I expected it to smell/feel like aux does. Is that not how it should be?
 
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Old 11-09-14, 08:58 AM
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I'd place a jumper wire between W2 and E if you get no heat after giving the stat an emergency heat demand and waiting a few minutes for the sequencer to engage the heat strips.
 
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Old 11-10-14, 05:51 AM
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Would there be any potential side effects (wear and tear, efficiency/utility cost) with that or is that essentially the same thing that emergency should be doing anyways?
 
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Old 11-10-14, 04:59 PM
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It depends on the way the heat strips are wired and the heat strip size and the air handler size.

If you have a 10 KW heat strip all 10 should be energized for emergency heat. For that setup I would jumper Aux to E and tape off the old E wire.

If you have 20 KW, which is usually four elements, then you may have a bad sequencer, or fuse link for the 10 KW energized by the E terminal.

If you have a 15 KW heat strip, you may have 10 KW wired to Aux and only 5 KW wired to the E terminal. This would not produce much heat in emergency heat mode with an air handler much larger than 2 tons.

5 KW pulls around 20 amps, so 20 KW can be expensive to run. If you have an intermittent problem with a heat sequencer you could end up running 20 kW intermittently if you jumpered Aux to E and didn't tape off the old E wire.

If you post some pictures of the heat strip tag, the model number of the air handler, and wiring connections we can offer more accurate assistance.
 
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Old 11-10-14, 08:12 PM
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Here are some photos that will hopefully help.
Thinking about it today though, it may all be moot -
This heat pump handles what used to be a garage converted to living space and a room above that. So it doesn't have a whole lot of square feet to condition.
Considering that, I guess Emergency heat in this situation isn't a big deal as there would never be an emergency situation where I would have to have those two rooms heated. So that being said, I'll go ahead and post the photos as I appreciate your insight but feel free to put answering this one to the bottom of your undoubtedly long list.

Since it's 10, looks like I can just bridge Em to Aux and tape E as you suggested.

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Old 11-10-14, 08:36 PM
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I would jumper Aux to E and tape off the old E wire.
 
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