Heat Pump

[93legendti]

We have a furnace venting issue re: our addition, so I am looking at a heat pump to replace our ac and 80% eff. furnace. (So as to keep it cycling content for my friend Blue Jays, I want to heat my winter workout room more efficiently. :) )

If I understood my h/c guy, the local rates are $.12 a unit (kw?) for a furnace and $.02 a unit for a heat pump. We would install a 90% eff. furnace as back up on the coldest days of this new mini ice age.

Anyone have one? Climb probably does. :) I am curious as to real world experiences.

Thanks.

[Louis]

Are you talking Ground Source heat pump, or "air source"?

Up where you are the "air source" would be little help in the winter. It's just too cold. I switch from heat pump to "toaster element" electric heat if the outside temp goes below 30*F. If it's sunny and above that furnace hardly runs anyway. As a result, for heating my heat pump only works over a narrow range to temps. I could almost live without it.

On the other hand, ground source is great (don't have one myself) since the temp once you get below xx inches is constant. Works great for A/C and for heating.

I would try to find a way to fix the venting problems.

Louis

[Dekonick]

heat pumps work best in moderate to warm climates. I have a gas furnace as my emergency heat, with a heat pump for the remainder of the time. It seems to be the best bang for your buck - if gas is cheap, change the temp that the gas kicks on, if electric is the better bargain, then do the opposite. Whatever you do get a programmable thermostat.

[RPS]

If I understood my h/c guy, the local rates are $.12 a unit (kw?) for a furnace and $.02 a unit for a heat pump. We would install a 90% eff. furnace as back up on the coldest days of this new mini ice age.I'd question the cost and get clarification on the details if you are likely to go in that direction.

A cost of $0.12 could be for kilowatt-hour (cost to run one kilowatt for one hour) which would apply to electric heat, but for the cost of a heat pump (which runs on electricity) to be $0.02 suggest a coefficient of performance that is higher than I'd expect you would see in Michigan (on an average basis).

[93legendti]

I'd question the cost and get clarification on the details if you are likely to go in that direction.

A cost of $0.12 could be for kilowatt-hour (cost to run one kilowatt for one hour) which would apply to electric heat, but for the cost of a heat pump (which runs on electricity) to be $0.02 suggest a coefficient of performance that is higher than I'd expect you would see in Michigan (on an average basis).
I did question the cost. Michigan is trying to encourage peope to go to heat pumps.

Louis:

I think it is air. The venting issue will cost $2,000 to extend our chimmey above the addition's roof. The furnaces we have now are 12 years old and 80% eff. The furnaces could last another 3 - 10 years and then they would be replaced with 90% eff. furnaces, which do not need venting.

My h/c guy, who I trust, showed me his bills comparing the difference before and after he installed a heat pump in his house. He says the heat pump works on the ~20 degree and above days. His summer a/c bills are $20 a month for a 5,000 sq foot home.

[Tobias]

I did question the cost. Michigan is trying to encourage peope to go to heat pumps.How? How are they reducing the cost for you in order to encourage?

For the operating cost to be reduced from 12 to the equivalent of 2 cents per kw-hr says the heat pump can pump about six times more heat than it uses. I expect that's what RPS was questioning indirectly.

Last time I looked at the specifications of a heat pump they didn't pump that much heat for the amount of energy used. It's easy to look up. I'd start there even if the state of Michigan is giving you financial incentives to buy.

[Pete Serotta]

YOU will be very cold in Michigan with an air heat pump. I have one of the latest here in RALEIGH and the few days that it gets to single digit, it is working VERY hard and once in a while I need to turn the heat strips(electric strips on) to supplement, That really burns thru electricity.

I am far from an expert but I would definitely not entertain an air heat pump in the north. Please keep in mind that I am currently using the newer type and while they are better than the prior generation, they have no place in a far north climate (if you like to be toasty)

[93legendti]

From DTE Energy's website:

"Detroit Edison offers a special electric rate for geothermal heating and cooling. The D1.7 Space Heating rate offers customers a 50 percent savings over the standard D1 residential rate.

Home With Geothermal Gas Propane System
1,800 sq. ft. $525 $2,450 $3,500
2,400 sq. ft. $650 $2,950 $4,400
3,000 sq. ft. $800 $3,600 $5,300
4,000 sq. ft. $1,050 $4,600 $7,000

* Based on 90% efficient gas furnace, gas water heater, and electric central air conditioning
**Based on 90% efficient propane furnace, propane water heater, and electric central air conditioning
Costs listed are typical; your actual costs may vary."

http://my.dteenergy.com/home/savings/geothermal.html

The question may not be "how", it may by "why".

Anyway, I am curious if anyone has had bad experiences with a heat pump.

[93legendti]

YOU will be very cold in Michigan with an air heat pump. I have one of the latest here in RALEIGH and the few days that it gets to single digit, it is working VERY hard and once in a while I need to turn the heat strips(electric strips on) to supplement, That really burns thru electricity.

I am far from an expert but I would definitely not entertain an air heat pump in the north. Please keep in mind that I am currently using the newer type and while they are better than the prior generation, they have no place in a far north climate (if you like to be toasty)

Do you have a furnace as well?

[Louis]

I think it is air. The venting issue will cost $2,000 to extend our chimmey above the addition's roof. The furnaces we have now are 12 years old and 80% eff. The furnaces could last another 3 - 10 years and then they would be replaced with 90% eff. furnaces, which do not need venting.

My h/c guy, who I trust, showed me his bills comparing the difference before and after he installed a heat pump in his house. He says the heat pump works on the ~20 degree and above days. His summer a/c bills are $20 a month for a 5,000 sq foot home.

If his heating is all electric also ask what the electric bills are in the winter.

Down to 20* you can be sure that the heat pump will be running nearly 100% of the time and the air coming out will not be very warm.

I agree that they are most likely proposing air. Ground source requires either lots of trenching or a very deep hole. You can do the NPV calculations to compare costs now vs costs later, but IMO $2000 to have air that feels warm would be worth it.

If you're really want to consider the heat pump I suggest you go to a friend's house who has one to check it out.

Good luck.

[Pete Serotta]

Louis is correct - the air is warn - not hot!. As to cost, in the middle of the winter I run about 225/month (two months). the units at current rate will pay for themselves in less than three years based on the efficiency as compared to units that were 10 years old.

I live in a water shed area, there is no gas availability for me and oil heat was not an option here, 20 years ago. House is 3200 sq feet..

the pump does not run 100% of the time for the house is well insulated. If I had a choice at the time, heat pumps would have been the last choice. When I lived in NJ, I had gas/steam and it was nice and warm and efficient.

Life is a series of trade offs and I would not change the location of where my house is in RALEIGH to have been able to get gas heat.

[NHAero]

Check:
gotohallowell.com
www.nyletherm.com/spaceheating.htm
Mitsubishi Hyperheat

All have completely changed the way we think about air source heat pumps in cold climates. Recently some engineering colleagues of mine, who installed two 4 ton Daikin minisplit heat pumps in the NH office, were surprised to come in one -13F morning and find them cranking away and the office fully heated. No electric back-up heat BTW.

[93legendti]

Louis is correct - the air is warn - not hot!. As to cost, in the middle of the winter I run about 225/month (two months). the units at current rate will pay for themselves in less than three years based on the efficiency as compared to units that were 10 years old.

I live in a water shed area, there is no gas availability for me and oil heat was not an option here, 20 years ago. House is 3200 sq feet..

the pump does not run 100% of the time for the house is well insulated. If I had a choice at the time, heat pumps would have been the last choice. When I lived in NJ, I had gas/steam and it was nice and warm and efficient.

Life is a series of trade offs and I would not change the location of where my house is in RALEIGH to have been able to get gas heat.
So, no furnace?

[Pete Serotta]

So, no furnace?


no furnace....Heat and air are in the same unit and use same air flows in house... Most homes are done that way in the south.

[rwsaunders]

I wouldn't recommend an air source HP in Michigan. A ground source HP has a high initial cost and will require deep wells or trenches for the piping.

How long do you plan on keeping your home?

[93legendti]

no furnace....Heat and air are in the same unit and use same air flows in house... Most homes are done that way in the south.
See, my guy is talking about both. His furnace automatically kicks on for coldest days. I've seen his bills and he has young kids like me.

[93legendti]

I wouldn't recommend an air source HP in Michigan. A ground source HP has a high initial cost and will require deep wells or trenches for the piping.

How long do you plan on keeping your home?
At least 20 years.

[Pete Serotta]

See, my guy is talking about both. His furnace automatically kicks on for coldest days. I've seen his bills and he has young kids like me.

then you have the best of both worlds........

[93legendti]

then you have the best of both worlds........
That's the point! I have 2 furnaces now anyway (one for each floor, the hosue was built that way in '68), so it's either I buy two 90% efficiency furnaces and two a/c's, or 1 furnace and 1 heat pump.

[hochstes73]

You need to check the information in your link. The reduced energy rate is for homes with in ground geothermal heat pumps, not air source heat pumps.

See http://my.dteenergy.com/otherInformation/geothermalRate.html

"To qualify for rate code 036, with a D 1.7 meter, homes or businesses must have either:

Geothermal ground source heat pumps
Split systems with a natural gas, propane or an oil booster, if the heat pump is designed to operate at least 80 percent of the time
Air source heat pumps qualify for rate code 090, with a D1.1 meter. This is the same rate as the interruptible air conditioning rate. Detroit Edison does not interrupt during the heating season of October through April."


That being said, I'd love to have a in-ground geothermal heating/cooling system (currently have oil here in the northeast), but installation is pretty pricey and I'm not certain I'll be in living in my home long enough to make it worth my while. It would be nice to get off the oil heat so I don't have to ride the oil pricing roller coaster.

[Z3c]

I spent a few years in the HVAC business; I strongly do not recommend a heat pump where you are. I am in KC and the local utilities have really worked this issue. The punchine is that you are trading gas usage for electric usage. In the summer here, everyone uses tons of electricity for ac; in order to meet that demand, the elec. utilities must invest in a lot of capacity. In the winter, that capacity goes untapped. So, someone had the great idea of introducing heat pumps here. Punchline is that your gas bill will drop and your electric bill will rise. Gas is more efficient for heating and you have serious/long winters. From a cooling/ac standpoint, they are no more efficient than the same seer rated ac condensor; you will have the same ac bills either way. A heat pump is nothing more than an ac condensor with the additon of a reversing valve that lets it bring heat into the coil; it is not some great device that is better.

I just read your last post; you cannot replace two systems with 1.5 systems. A heat pump is not a complete system. A heat pump still requires something to move the air, typically an air handler which is a furnace like device with no burners. A heat pump cannot operate by itself. It really sounds like someone is not telling you the whole story. Please understand that in KC, the utilities pay serious commissions to people who sell HP's.. Beware please.

Trust me on this; feel free to pm if you want..


Scott

[Lifelover]

See, my guy is talking about both. His furnace automatically kicks on for coldest days. I've seen his bills and he has young kids like me.


His electric bill is so low in the winter because the heat pump is not doing any of the heating, the furnace is.

[93legendti]

http://www.costhelper.com/cost/home-garden/heat-pump.html


Typical costs:
Expect to pay around $1,500 -$4,500 to add an air source ("air-to-air") electric heat pump in an average home (3 ton capacity). Self-contained through-the-wall or window units in single rooms don't require ductwork; the more common split-systems (with both indoor and outdoor equipment) require the same ductwork as central air conditioning. Air-source heat pumps work best in climates where temperatures rarely drop below freezing. Higher-end models have options such as a two-stage compressor for more power when additional heat is needed or including a hot water heater as part of the system.
For about $2,100 -$5,500, a dual-fuel air-source system combines an electric heat pump with a gas or propane furnace and existing ductwork. Ideal for regions with extremely cold winters, a dual-fuel system uses the best fuel source depending on outside temperatures.

[RPS]

Check:
gotohallowell.com
www.nyletherm.com/spaceheating.htm
Mitsubishi Hyperheat

All have completely changed the way we think about air source heat pumps in cold climates. Recently some engineering colleagues of mine, who installed two 4 ton Daikin minisplit heat pumps in the NH office, were surprised to come in one -13F morning and find them cranking away and the office fully heated. No electric back-up heat BTW."Leave Fossil Fuels in the Dust"

Where does the incremental electricity come from? I'd love to see a total system energy impact, not just at the end user.

[RPS]

A heat pump cannot operate by itself.In the south the term heat pump is used for a reversible central air conditioner that can cool the outdoors, thereby heats the inside. ;)

They look just like a normal central air conditioning system. I don't understand what you mean by not being able to operate by itself. :confused:

[Z3c]

In the south the term heat pump is used for a reversible central air conditioner that can cool the outdoors, thereby heats the inside. ;)

They look just like a normal central air conditioning system. I don't understand what you mean by not being able to operate by itself. :confused:

Exactly; the unit cannot operate by itself, it still requires an indoor component that moves the air within the structure. Just as an air conditioner does. The furnace blower is what moves the air during heating and cooling modes. An ac condensor cannot provide cool air by itself either; it simply condenses gas(freon) and sends that gas indoors to the coil which it cools.
The coil, positioned above the blower is in the air flow path above the burners of the furnace.

[Pete Serotta]

:)Z3c is correct...There is an outside component with coolant and an inside component.


Exactly; the unit cannot operate by itself, it still requires an indoor component that moves the air within the structure. Just as an air conditioner does. The furnace blower is what moves the air during heating and cooling modes. An ac condensor cannot provide cool air by itself either; it simply condenses gas(freon) and sends that gas indoors to the coil which it cools.
The coil, positioned above the blower is in the air flow path above the burners of the furnace.

[alancw3]

YOU will be very cold in Michigan with an air heat pump. I have one of the latest here in RALEIGH and the few days that it gets to single digit, it is working VERY hard and once in a while I need to turn the heat strips(electric strips on) to supplement, That really burns thru electricity.

I am far from an expert but I would definitely not entertain an air heat pump in the north. Please keep in mind that I am currently using the newer type and while they are better than the prior generation, they have no place in a far north climate (if you like to be toasty)

my townhouse up in leesburg, va has what they call a hybrid system. heat pump for the top floor (bedrooms) and gas furnace for the main and lower floors. i absolutely hate the heat pump and curse the day i bought a house with one. they tend to work well when the outside temp is 40-55 but are inefficent below. i have had two hvac men out to look at it and both have told me that when temp goes below 35 to turn on the auxiliary electric heat grid. what happens is that the heat pump blows out cool air if the electric grid is not on. it heats with much cooler air than that coming out of the gas furnace. if i remember correctly the heat pump puts out air at 75-80 degrees versus a gas furnace at 100-110 degrees. consequently the heat pump runs forever to try to heat. trust me DON'T GET A HEAT PUMP IN MICHIGAN!!!!

[Louis]

Bottom line for me - If I lived in Michigan there is no way I would want an air-exchange heat pump. Ground source HP or propane / gas furnace would be the way to go. Especially if it's an older house that is presumably not insulated to the max. (Attic, wall, windows, doors, etc.)

Louis

[Blue Jays]

Sounds like it's going to be a comfortable, cozy, and pleasant winter workout room!
An incrementally lower temperature in that section of the home might go unnoticed. I've just begun researching this same topic for the same application, too. :beer:

[RPS]

:)Z3c is correct...There is an outside component with coolant and an inside component.Do you mean a “split” system? Technically a heat pump can be a window unit also (although I guess anyone could argue the part inside the window is inside and the rest outside).

A heat pump basically pumps heat. An air conditioner is a heat pump set up to pump heat from your house to the outdoors, which makes your house cooler. We just don’t call it a “heat pump” but the basic operation is the same. And in both cases a refrigerant is required to pass through heat exchangers at both the inside and outside. Normally we call these heat exchangers a condenser and an evaporator; depending on whether the refrigerant is condensing or evaporating.

In a central split system (with inside and outside major components) the heat-pumping cycle is modified to reverse the direction heat is pumped to make what we normally call an air conditioner into a heat pump. I'm not sure what is actually being questioned. :confused:

[Tobias]

Heat pumps require more power to operate when the temperature difference is higher. Because of this design characteristic it’s more advantageous to discharge air into the house at a relatively low temperature compared to a traditional furnace.

For instance, if the desired home temperature is 70 F, it is more efficient to discharge air into the house at 80 F than at 100 F. The same amount of total heating can be accomplished by moving more air, but it won’t feel as “warm” if one placed their hand in front of a vent.

It may not be a sign the heat pump is not working right or lacks capacity. It may be that way to save electricity (i.e. – operating costs).

[Pete Serotta]

Yep :D

Do you mean a “split” system? Technically a heat pump can be a window unit also (although I guess anyone could argue the part inside the window is inside and the rest outside).

A heat pump basically pumps heat. An air conditioner is a heat pump set up to pump heat from your house to the outdoors, which makes your house cooler. We just don’t call it a “heat pump” but the basic operation is the same. And in both cases a refrigerant is required to pass through heat exchangers at both the inside and outside. Normally we call these heat exchangers a condenser and an evaporator; depending on whether the refrigerant is condensing or evaporating.

In a central split system (with inside and outside major components) the heat-pumping cycle is modified to reverse the direction heat is pumped to make what we normally call an air conditioner into a heat pump. I'm not sure what is actually being questioned. :confused:

[jbrainin]

The last apartment I lived in (1100 sq.ft) had heat pumps and the cost of heating was at least $200/month--more than 15 years ago. As far as I know, a heat pump is almost certainly the most expensive, least efficient way to heat one can find. (Other than burning junk mail, etc. in the middle of a room.)

[rwsaunders]

Here's what your front yard will look like if you decide to utilize a ground source system with deep wells. In this case, we drilled 10, 200' deep wells for an 8,000 sf home.

This client had no access to natural gas and neither oil nor propane were preferred. We did use a heat exchanger to heat the pool with the waste heat when in the AC mode. After 6 years the system runs very well, but we also supplemented the heating side with radiant heat in several areas of the home, and insulated the walls and attic with a very dense insulation product.

[Louis]

This client had no access to natural gas and neither oil nor propane were preferred.

Did they say why they didn't want to go with propane or oil? Environmental reasons?

[rwsaunders]

Did they say why they didn't want to go with propane or oil? Environmental reasons?

Pricing volatility primarily, as neither fuel source is really common in western PA. Natural gas is king around here, but the site was remote and did not have gas service available.

[93legendti]

Here's what your front yard will look like if you decide to utilize a ground source system with deep wells. In this case, we drilled 10, 200' deep wells for an 8,000 sf home.

This client had no access to natural gas and neither oil nor propane were preferred. We did use a heat exchanger to heat the pool with the waste heat when in the AC mode. After 6 years the system runs very well, but we also supplemented the heating side with radiant heat in several areas of the home, and insulated the walls and attic with a very dense insulation product.
We now have r40 (iirc) insulation in both the new and old parts of the attic (it's a 2nd story addition). The old attic only had r19.

[RPS]

Did they say why they didn't want to go with propane or oil? Environmental reasons?If by environmental you mean trying to reduce carbon footprint (since natural gas burns so clean), I’m not sure it makes much difference as long as incremental electricity doesn’t come from nuclear or renewable.

As an example, I use natural gas to heat, and if I converted to a heat pump, much of the added electrical load would also come from natural gas. If we consider that on a good day the power plant may run in the range of 40 percent efficiency, the heat pump would have to have an “efficiency” of something near 250 percent in order to break even. To ballpark these numbers I assumed the inefficiency of my heater is approximately offset by the inefficiency of the power grid.

In the Houston area where winter temperatures are relatively mild a high-efficiency heat pump “may” save a little energy, but the savings wouldn’t be enough to pay for the equipment. Tax payers would have to give me a huge incentive, or I’d have to be charged much higher price for natural gas than what the power company pays. In either case I wouldn’t actually reduce the amount of energy used by much if at all.

[Louis]

If by environmental you mean trying to reduce carbon footprint (since natural gas burns so clean), I’m not sure it makes much difference as long as incremental electricity doesn’t come from nuclear or renewable.

I think it would make a difference. Ground source heat pumps us much less energy, whether they are heating or cooling. Very high up-front costs, but much lower operating costs.

[alancw3]

Pricing volatility primarily, as neither fuel source is really common in western PA. Natural gas is king around here, but the site was remote and did not have gas service available.

question? on a ground source heat pump, like the one you've shown here, what is the air temperature coming out of the vents on a typical 20 degree day? is it still in the 75-80 degree range? also when you installed the radiant heat in the floors did you use fossil fuel (oil/propane) for that or someting else?

[Louis]

Adam, what was your final decision? (If you've made it yet.)

Louis

[93legendti]

Adam, what was your final decision? (If you've made it yet.)

Louis
Not yet. I misunderstood: two 90% furnaces would be cheaper than the heat pump and a 94% eff. furnace- the system my h/c guy has in his house.The price for two, 90% furnaces is $5,000 installed- really hard to beat. I have inquired about one 94% eff. furnaces to replace the two 80% eff. furnaces and I am waiting to hear back.

My thought is to go with one 94% eff. furnace to replace the 80%'s. I already have a 90% eff. furnace up stairs for ~1300 q. feet and the 94% would handle ~2500 sq ft. The existing 90% eff. furnace is from a previous addition - our duct work could not extend and we needed a new furnace for it.

So the dollars may not justify the heat pump.

[Louis]

Assuming you know (or can guesstimate) what the utility costs will be for the various options it really helps to have different NPV calculation in a spreadsheet so you can compare the benefits of spending money now to save it later. (MS Excel has an NPV function and can help you with that.)

Good Luck
Louis