Intertherm furnace heat pump combo had a small fire in the control wiring when a contactor for one of the heating elements burnt. I am an electrician by trade and have replaced all the wiring but half the shematic was burt and I now have 3 wires from the transformer that I can not tell what they go to. I need the drawing and hopefully help on landing these 3 wires from the transformer. M# E2EB-0151

I'm not sure if I understand the question regarding a heat pump being used on top of a regular furnace? Is it a gas or electric furnace?

If you have a gas furnace with a heat pump installed on top of it, I would personally replace the system, but this is not often possible due to replacement costs, so then I would reconfigure how the system works and the first thing I would do is to eliminate the electric heating portion of the unit and allow the less expensive to run furnace to be the aux heat for when the heat pump is no longer producing enough heat or has reached the temp where the heat pump is no longer efficient.

You should be able to go to a place that sells heat pump thermostats and they will come with multiple schematics for the different configurations you might run into, and that may be enough to answer your questions. You may have to buy the stat, copy the schematics and then return the stat or possibly find a schematic elsewhere.

To help you more, I would need more info on just exactly what components you have in your system, such as the furnace type.

Often times if you understand how a heat pump works, you can figure out how and why it is wired, since you are an electrician.

Heat pumps are not my choice of systems simply because of the drafty conditions you get when in heating mode, using the AC system running in reverse when only a small amount of heat is needed to keep the house warm.

Geothermal is cost effective, but it is the only reason people should use a heat pump. Since you say you have a furnace, you might want to just use it for your heating needs and wire the heatpump to just take care of your cooling needs.

The heat pump works by removing heat from outside and transferring it into the home. When it hits the setpoint that this portion of the system is no longer efficient, then it will switch to aux or supplimental heat, which in most cases is electric strip heat, and most of the strip heaters are engaged in steps as it gets colder outside and the outdoor stats call for more strip heaters to be used to maintain indoor temps.

So in light heating needs, the heatpump will run by itself, and aux heat will come on as it is needed and at a setpoint, an outdoor stat will kick out the heatpump portion of the system, which also includes a defrost cycle that further complicates the heatpump portion of the heating system.

If you would read up on how the heatpump works, you will understand when and what components are to be energized, and that should help you complete your wiring without the aid of the schematic.

You should be able to find general heatpump schematics online, and may even be able to find the exact ones you need from intertherm, duotherm, or coleman, by going to their web pages, as they are all the same unit, and made by the same company.

You might also be able to go to a trailer sales place and ask them to see a similar unit and copy the schematics. The furnace will just be considered aux heat, and you should keep the furnace wiring separate from the heat pump portion of your system, just to keep it less confusing. Aux or auxiliary heat is used to help the heat pump warm the house and it will also kick in whenever the heat pump kicks out due to a malfunction.

I know I rambled on here, as I just typed this as I thought about it. I am still confused about the furnace part of it, as that is not common, although I have seen it used. If I had more information, I may be able to help you more.

Dan

Couple of manuals and diagrams I found at :

Manufactured Housing


http://www.nordyne.com/Literature/359a.pdf

http://www.nordyne.com/Literature/7103180.pdf

If no luck, try contacting Nordyne at :

NORDYNE Contacts

I will copy this at HVAC forum for those resident experts to help.

TK your right on the money. The links posted have the diagram he is looking for.