Heat Pump

[Michael Thomas]

I've never seen an air-source heat-pump here in Chicago, just ground-source systems.

However, this afternoon I ran into the arrangement below -and I've not sure exactly what I'm seeing:

Exterior unit was built by York, the capacity plate was weathered and completely illegible.

At the interior there was a conventional GFAF.

The coil above it is listed for cooling use only.

On the wall next to the furnace was a controller marked: "Accessory For Heat Pump", connected to the furnace as shown (brown wire to left in 6th picture).

In the blower compartment, connected to the blower, there was a relay, as shown.

What am I looking at here?

Thanks as always.

[James Duffin]

It would help to know what wires were on the thermostat if you have that info available.

[Michael Thomas]

Sorry, in retrospect I realized that the T-Stat is likely an important piece of the puzzle, but as best I remember it it was a conventional programmable heating/cooling unit, I did not notice an "emergency heat setting".

(Part of the problem is that I have never seen an air-source heat pump here - the climate is too cold - so I have no experience with operating or inspecting them other that what I have encountered in casual reading).

[mitch buchanan]

Michael,

One easy way to identify an air source heat pump is to look for the reversing valve inside the condenser next to the compressor. Sorry I don't have a picture, but it's a small "box" in-line with the vapor and suction lines. I'm sure others have a better explaination, but when I can't tell from looking at the thermostat, I look for the reversing valve. Hope this helps!

[James Duffin]

The best I can tell that box on the wall is the dual-fuel kit for a heat pump. Here is a link to a similar item:

http://www.hamiltonhomeproducts.com/resource-files/manuals/accessories/WWF-601_Fossil-Fue-Kit.pdf

[Michael Thomas]

One easy way to identify an air source heat pump is to look for the reversing valve inside the condenser next to the compressor. Sorry I don't have a picture, but it's a small "box" in-line with the vapor and suction lines. I'm sure others have a better explaination, but when I can't tell from looking at the thermostat, I look for the reversing valve. Hope this helps!

Hum... there was THIS, but at the expansion coil.

[Nick Ostrowski]

An air source heat pump in Chicago doesn't sound like the best heating option for a house.

[Michael Thomas]

An air source heat pump in Chicago doesn't sound like the best heating option for a house.

As I said, if there is a air-source heat pump as a component of this system, it will be a first for me.

[James Duffin]

From what you described it sounds like a dual fuel heat pump system with a gas furnace as the backup heat rather than electric heat strips. How hot was the air leaving the registers in heat pump mode (if it wasn't too cold for the heat pump to be running).

[Vern Heiler]

Michael, you have pic's of data plates that state: "80,000 btu natural gas", and another that states: "cooling air conditioner".

What makes you think it is a heat pump?

[Michael Thomas]

Michael, you have pic's of data plates that state: "80,000 btu natural gas", and another that states: "cooling air conditioner".

What makes you think it is a heat pump?

The presence of the heat pump controller in the 5th picture, and its connection to the furnace.

[Vern Heiler]

The presence of the heat pump controller in the 5th picture, and its connection to the furnace.

Remnants of an old and long gone system!

The indoor coil of a heat pump has to be able to handle the condensing pressures. The label states for cooling only! Can't be used as a heat pump indoor coil.

[Michael Thomas]

Remnants of an old and long gone system!

The indoor coil of a heat pump has to be able to handle the condensing pressures. The label states for cooling only! Can't be used as a heat pump indoor coil.

Vern,

The controller is connected to the existing furnace, which appears to be original to the townhome.

Confusing, I know....

[Vern Heiler]

I can't explane the controller, or what ever it is, as I have never seen one like it. But I can tell you that the coil that is marked "cooling only" can't be used as a heat pump. You also have to have a transfer valve at the outdoor unit.

[Jim Luttrall]

I'm with Vern on this, even if it was an exterior heat pump, looks like they replaced it with a cooling coil to keep the a/c functioning. Need to know if the outdoor unit was in fact a heat pump still from either the data plate or look for the reversing valve. If I saw no method of operating the heat pump then I would just punt it to and a/c tech mentioning "mismatched parts and pieces from incompatible systems" and let them figure it out. Obviously it was too cold to test the A/C so your kind of at a loss anyway.

[Michael Thomas]

Thanks for the comments.

[James Duffin]

As I said, if there is a air-source heat pump as a component of this system, it will be a first for me.

I don't know how cold it gets and stays in your area but there are heat pumps that are efficient down to -13 degrees. I use my conventional heat pump down to 20 degrees and it is more efficient than my gas backup furnace.

[Vern Heiler]

Michael, I just looked at the link James posted regarding the "heat pump add-on". That is the old technology. New thermostats are available that take the place of the extra panel and wiring, making dual fuel systems much more affordable.

You may have more dual fuel systems than you know! Sometimes it is hard to tell during an inspection. The thermostats do not look any different than single fuel thermostats. Here are a few things I look for: (1) the word "Heat Pump" on the outdoor unit, that one is a give-me, (2) three service test points instead of two at the outdoor unit, (3) reversing valve viewed at the outdoor unit, sometimes hard to see, Trane hides them behind the cover. (4) thermostat set for heat, and the furnace does not ignite, check to see if the outdoor unit started instead.

If you find that a system is a "dual fuel system" you should advise the customer to verify the thermostat is configured correctly. If it is not setup for duel fuel heat pump, the compressor can run at the same time as the furnace. Not good for the heat pump. If the manual is available I tell them they can check the settings, but suggest having a qualified HVAC contractor do it during the next maintenance.

[David Bell]

Furnace , coil and humidifier look new. My guess is they tried to save some bucks by re-using the heat pump as a straight cooling condenser. The hawkeye in the blower compartment is most likely for the humidifier so it will only operate if the blower is going. The remaining accessory box may still be used to operate the heat pump/condenser as it may have a cool active reversing valve that needs to be powered for cooling.

[Markus Keller]

I don't think that's a heat pump system. I think the controller was put in for some reason and is confusing the appearance. Based on what I'm seeing and the label plates looks like standard heat/ac. The controller may have been put in to run the blower motor for air circulation during moderate weather.

[Rod Butler]

I don't know how cold it gets and stays in your area but there are heat pumps that are efficient down to -13 degrees. I use my conventional heat pump down to 20 degrees and it is more efficient than my gas backup furnace.

Heat pump more efficient than gas furnace? Of course, but it isn't less costly to operate than a gas furnace. At least in my neck of the woods.

[Dan Hagman]

Looks to me that they installed a furnace and a-coil and used the old heat pump as a condenser. You have a gas furnace with DX cooling! pic 7 is a current sensing relay for the humidifier, and pic 6 is a transformer/fan relay. Also note in pic #2 The furnace and water heater vent connectors are installed wrong, they are to go into the side of a B-Vent "T" and not up into the bottom of the B-Vent. FYI

[Vern Heiler]

Also note in pic #2 The furnace and water heater vent connectors are installed wrong, they are to go into the side of a B-Vent "T" and not up into the bottom of the B-Vent. FYI

Dan, can you expand on this? All of the diagrams I have found in the 1993 NC Gas Code (I know its old!), show the first appliance into the bottom, with the rest of the connections into the side of a "T". I couldn't find anything that prohibited the use of a "Y" though.

[James Duffin]

Heat pump more efficient than gas furnace? Of course, but it isn't less costly to operate than a gas furnace. At least in my neck of the woods.

It is if you gas is propane. The cost per BTU using the heat pump is about 1/3 the cost of propane. What is the cost of gas and electricity in your area?

[James Duffin]

Looks to me that they installed a furnace and a-coil and used the old heat pump as a condenser. You have a gas furnace with DX cooling! pic 7 is a current sensing relay for the humidifier, and pic 6 is a transformer/fan relay. Also note in pic #2 The furnace and water heater vent connectors are installed wrong, they are to go into the side of a B-Vent "T" and not up into the bottom of the B-Vent. FYI

Since we are guessing...I guess they put a heat pump coil in an old coil box.

[Dan Hagman]

Dan, can you expand on this? All of the diagrams I have found in the 1993 NC Gas Code (I know its old!), show the first appliance into the bottom, with the rest of the connections into the side of a "T". I couldn't find anything that prohibited the use of a "Y" though.

Vern, I hear what you are saying! I see the same thing also, but, I have replaced too many rusted out vent connectors on water heaters and inducer motors on 80% efficent furnaces that were installed into the bottom of the B-Vent. What happens alot, is the furnaces are replaced with a 90% + and the water heater vent connector is left in the bottom of an oversized B-Vent. On a 2-story house the water heater flu gas does not stay hot enough all the way to the top and condensation forms on the inside of the B-Vent and runs down and into the single wall vent connector and rusts it out and then you have a possible CO leak. If the vent connector goes into the side of the B-Vent there is no way the condensation will rust out the single wall vent connector or the inducer motor on the furnace. The condensation goes to the bottom of the "T" cap and evaporates. A properly sized B-Vent will not have this problem. The local inspectors would alway require this installation to be done. I can't find it either in the UMC or the National Fuel Gas Code or the IRC but think of it as good,better, best. I "RECOMMEND" this as an installation method, I don't say it's wrong to the customer because I can't find it in the IRC. I hope this helps with my logic. I think local jurisdiction adopted this method around here.

[H.G. Watson, Sr.]

MT,

Its a york systems add-on "control" board & pwr supply interface which can house a "York Guard" demand defrost unit rather than relying on "timed defrost".

I'm guessing (or maybe you said it already) that the coil and furnace are in a full basement and the folks get a frigid basement and are warm upstairs and like to run the AC all the time, and keep the upstairs really cold, not just in worst of summer but all "season" and even when its "too cold outside" they don't cut it off or open the windows and the york controler will prevent freeze ups on the coil inside when they're running their AC even when its below 60 outside and their still feeling "warm" and humid upstairs. Dark roof? poorly insulated? heat sinks/brick? two story or split level?

See the wiring diagram and jumper instructions for interfacing "control unit" with gas fired FA and near bottom page 2 right column in the first pdf. I think the diagrams & references to IV is what you might find present.

Second pdf is order sheet for a split HP similar vintage/era note bottom right column of first page ordering list of field installed accessories.

You might try googling "york guard" and see what you find.

HTH.