Can't tell from information you have posted.

Likely though based on age, you have thermostat that operates boiler only and then a separate thermostat for each HP system. If that's the case , then yes you could have both systems working at same time unless there are lockouts based on outdoor temperature.

I will point out though that 30+ yr od heat pumps are ancient, not efficient, and should be replaced especially since the idea is to save against the more expensive fuel oil used for boiler.

It really appears you don't know exactly what you have. My recommendation is to get an HVAC pro to make a service call to tell you what you have and how the controls operate each system.

IMO

"in the winter he puts it in "emergency mode"

This sounds like the heat pumps are operating in emergency mode all winter. You should ask the seller what the annual cost is to heat the house.

This post was edited by mike_home on Tue, Jun 11, 13 at 8:18

Thanks, but what does operating in emergency mode do? How does that change the performance of the system? What I don't want to do is follow the instructions of the previous owner(s) if its not how the system should operate.

I apologize I don't have more info as I don't really have access to the house yet.

If these really are HPs, then placing these systems in emergency mode means you are operating on straight electric resistance heat. The absolute worst advice you could get.

As said in my last post, you need to find out exactly what you have and the controls used to operate all these systems.

IMO

Heat pumps operate like an AC condenser in reverse. They extract the heat from the air outside to heat the house. As the outdoor temperature drops, there is less available heat. A some point the heat pump can't provide enough heat to maintain the indoor temperature. The air handler will usually have auxiliary heat strips to provide the additional heat. This is known as resistance heat which is more expensive than heating with fuel oil in most parts of the country. Emergency heat mode means the electric heat strips are energized without running the heat pump.

Once you take ownership of the house, hire an HVAC contractor who is qualified to inspect your boiler and heat pumps. You may be using the two most expensive methods to heat a house.

So i had an HVAC guy take a look and here is how it explained it to me... please let me know if this makes sense:

The thermostats are so old, there was no system in place to tell the system "hey its below 35 degrees, use oil for heat".. so putting the system in emergency mode is what tells the boiler to generate the heat. He said the current owner isn't using the system correctly, as it sounds like he just puts it on emergency and uses oil heat all winter. For example this past winter was rather mild except for the two storms.. the heat pump should have been used for most of the winter saving oil cost.

Does all of that make sense?

Obviously I'd like to update the thermostats and I probably need some sort of ourdoor sensor. I've seen that honeywell sells a good system with outdoor sensor, is this the best way to go? Is there a recommended model so I can upgrade and use the system as I should?

Thanks guys, this is all a learning experience for me!

It makes some sense, but how do the two thermostats control the boiler?

Have you confirmed the heat pumps produce heat?

I'm not 100% sure, I'm assuming the first floor is the "master" which tells the 2nd floor thermostat as to which heat source to use. Then there is clearly a thermostat wire to the boiler from the first floor thermostat..

Does that make sense?

You need to start a HP replacement program.

And I agree with Mike. Two HP thermostats can not control the boiler.

To be clear, the boiler serves the same living area as the two HP systems?

IMO

I agree with the HP replacement, not sure what program you are referring to besides me forking out a ton of money... are there any energy credits or programs out there to assist?

Yes the HP's control the entire house, there are 2 zones and I imagine 1 heat pump for each floor. The entire house also has baseboard heat controlled by the boiler.

Does that answer everything?

Thanks again!!

Highly doubt your thermostats are wired in a master/slave mode. I don't know of any thermostats that support this.

There are some small federal tax credits. The heat pump need to be a specific performance target.

Your plan should be as to what you are going to do so you can implement it this fall before the next heating season.

What they may have done is to 'connect' one of the thermostats to the boiler under the assumption that both of the HP systems had the same performance characteristics. Then when one of them went into 'auxiliary' mode (same as emergency), it activated the boiler to heat the whole house since the other unit would be struggling to heat at this point.

running Emergency all the time in winter was just using oil and was wasteful, but the previous owner might have been more comfortable this way.

So, you plan on keeping the oil burner as back up heat?