Heat pump for split system

[Richard Roshak]

House today has a 4 year old York heat pump as part of a gas forced air slip system. Never seen this before. Would the reversing valve need to be removed, what other modifications were required or is this wrong altogether.

[Bruce King]

House today has a 4 year old York heat pump as part of a gas forced air slip system. Never seen this before. Would the reversing valve need to be removed, what other modifications were required or is this wrong altogether.

It may be ok, depends on the t-stat type, control wiring methods etc.

Some t-stats have complicated options for 2 stages and/or dual fuel.

Did it have an e-heat or emerg heat mode on the t-stat?
Did the compressor and the gas burners both run in regular heat mode?

[Garry Sorrells]

Richard,
Why would you think that there is something wrong?
You have a Heat Pump that has a gas furnace instead of elect back-up.strip?

[Scott Patterson]

I have a split-system, dual fuel heat pump in my home. Common in my neck of the woods.

[Garry Blankenship]

It sounds like all is as it should be. The gas, ( or electric ), furnace should rarely operate. The heat pump should satisfy both the heating and cooling needs at least 90% of the time, ( in a perfect world all the time ). Heat pumps are more efficient, economically speaking, and the less the furnace portion runs the lower the utility bills. Depending on the efficiency of the heat pump, somewhere around 35o or lower, heat pumps are unable to git-r-done so the furnace kicks in.

So I have a question for the mech. heads. I believe a "split" system is a furnace and an A/C only unit, ( no heat pump ). Is that correct ?

[Rick Cantrell]

Garry
"Split " system refers to having the condenser/compressor separate from the evaporator.
Example is compressor is outside and evap is in the attic.

[Garry Blankenship]

Thanks Rick ! I was a bit reluctant to expose my ignorance there. I'll be your friend and I have no interest in bloodying your nose, so I'm feelin pretty large about my wisdom status.

[ted kidd]

Op went away, so we're left to guess what real or perceived problem his hybrid has.

As inspector, what reporting requirements might he have that cause him to be asking about reversing valves, and why on earth would he be thinking about removing one from a nearly new unit?

Even if it made sense, wouldn't recommendations about modifications such as this be going beyond the scope of "inspection"?

[Garry Sorrells]

ted,
OP was just not fluent with HVAC. Richard having only seen split AC using the Furnace as the air handler and Heat Pumps with their dedicated Air Handler. He thought that it had to be one way or the other no mixing or matching. It is just a mater of a lack of experience/knowledge in HVAC. Wait till he sees a boiler hooked up to a Heat pump with an Air Handler or a split AC with an Air Handler.

[Rick Tackett]

Dual Fuel... I have my home system set up like that. When it gets too cold for the heat pump to make us comfortable, we like gas heat better than electric resistance. It usually has an upgraded thermostat for dual fuel, but it works basically the same. Heat pump provides the heat under normal mode, auxiillary or e-heat is gas rather than resistance.

[Rod Butler]

I agree with most of what's been said here.

Exception; Saying a heat pump is more efficient "economically" must be a geographic thing. In Utah the natural gas prices are so low that the added cost of a heat pump over a standard furnace condensing unit just doesn't make sense.

Operating costs and installation costs are less using a natural gas fired furnace when compared to a heat pump system.

[ted kidd]

I have a tendency to distrust broad, authoratative sounding but completely unsubstantiated knee jerk rules of thumb. You may know what you are talking about, but nothing in that post has anything to suggest you do or don't.

What does super cheap even mean? And is electricity "super expensive"? Is air conditioning typically not installed in your climate? Have you ever tracked results of your projections to verify your claims of what is or isn't cost effective?

I can't quantify "super cheap" or "added cost", or comment on whether operating or installation are cheaper without understanding circumstances. That means case by case, not generalities. But in my neck of the woods, where ac quite often would be installed with a furnace, and natural gas is $1/therm and elec $.11 /kwh, heat pumps make a huge amount of sense. In fact, have never sold straight a/c, only heat pumps or hybrids.

[Jerry Peck]

Operating costs and installation costs are less using a natural gas fired furnace when compared to a heat pump system.

Not when a split system central a/c is installed to start with - there is not a lot of difference in cost between a 'straight cool' a/c system and a 'heat pump' a/c system as related to the installation of an additional piece of equipment.

Which is not the same as trying to compare a fuel fired furnace with an evaporator coil/condenser unit stuck on it as the fuel fired furnace is already being purchased.

Not sure if I worded that where you could follow it.

Here is another way to consider it:
- If your area is mostly cooling season with some heating, then a a/c with heat pump is practical.
- If your area is mostly cooling season with little or no heating (such as, say, from Ft. Pierce/Stuart on the east coast of Florida across to Sarasota/Port Charlotte on the west coast of Florida and south), then straight cool with electric strip heating is practical.
- If your area is mostly heating with some cooling, then you probably would use a heat source of your choice for your area and add on an evaporator/condenser unit for the a/c.
- If your area uses igloos for housing, then you likely do not need any cooling at all. :)

[Garry Blankenship]

I agree with most of what's been said here.

Operating costs and installation costs are less using a natural gas fired furnace when compared to a heat pump system.

It may indeed be geographical, but in the Pacific Northwest a heat pump can heat with less cost than any fossil fuel source, ( until it gets really cold ). If your statement is correct for your area, there is no need / reason to have a heat pump at all. Your hood should be fossil fuel furnaces and an A/C unit, if anybody wants cooling. If the gas heat costs less than the electricity for the heat pump heat, no need for a heat pump. If there are heat pumps in your area, I believe your gas is cheaper premise is incorrect.

[Garry Sorrells]

Here is a little fuel for the efficiency discussion.

Many older homes built with no AC have had AC installed onto an existing furnace (old) or have at some time had the furnace replaced and AC added at that time. Which can work fine if done correctly.

The issue comes when an AC split system is replaced with a Heat Pump. Many time the Heat Pump is just installed without taking into account the old duct work designed only for a furnace and heating. Leaving the Heat Hump to struggle (not perform) due to incorrect duct sizes.

The local electric company in the 80's made a big push for people to get off gas and oil and move to electric, which they made at the time and had surplus capacity. Many homes built before 1965 did not have AC installed originally.

Do you, when looking at the HVAC system, make an effort to determine if the exiting system is adequate for design and function? Especially if the gas FHA furnace has a Heat Pump with it?

[Rod Butler]

. .. . . . I believe your gas is cheaper premise is incorrect.


My premise is not incorrect. In Utah, natural gas is relatively cheap and much less expensive to heat with than electric strip or heat pump. Those that choose to install heat pumps in this area are doing so because they are far off the beaten track or have been misguided by an ill informed salesperson.