twinning dual heatpumps one hot water coil


Old 12-16-18, 07:30 AM
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twinning dual heatpumps one hot water coil

i have a unique setup i need a little help with.

we currently have two heat pumps. each are 3 ton.
it was installed in the house about 25 years ago.
back when honeywell had the eim were seperate e terminals and aux terminals.

we swaped the two heatpumps out this year back in march and upgraded to the honeywell prestige iaq 2.0. which gave us a new eim with all the w/w2 wires were intergrated into one terminal now.

currently they have been running great. one heat pump is stage one. the second is stage 2 y and y2. with w1 being the hotwater pump/relay coil.

the problem now is in the winter when the units go into defrost i have two W wires coming from each outdoor unit trying to power the hotwater coil relay and its blowing the transformer fuse in the air handler.
what is the correct way to do this without blowing fuses?

ive debated on just leaving the stage 2 unit W wire unwired since the 1st stage will be running when the 2nd is.

btw the setup is a common duct system. both outdoor units does run at the same time.
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Old 12-16-18, 09:58 AM
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Each incoming W wire would need its own relay.
All the switching contacts of the relays would be wired together in parallel.

You need 24vAC coils with a single pole normally open switch. There are many for sale. Some are double pole. Any relay can be wired to work.

Here's one example.... Relay
Old 12-16-18, 07:00 PM
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Ill attach a pic of what is here now and the drawing.
Old 12-18-18, 09:17 AM
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use a 75 watt transformer. this is a must with twined units.
Old 12-24-18, 04:37 PM
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awesome! so just remove the 2nd transformer in the other air handler and replace the number one unit with a bigger transformer that will supply both AH.

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