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-   -   Getting a House..heatpump or no? (http://www.diychatroom.com/f17/getting-house-heatpump-no-5027/)

DavidsCPU 11-26-2006 11:58 AM

Getting a House..heatpump or no?
 
I'm getting a double wide house and it comes with a electric furnace and i can get a 3 ton heat pump with it installed for $2,700.

I hear good and bad things about them are they worth getting?

The thing i dont understand is that when we looked at the house the furance said heating and air conditioning on it...........it was made by vexar. I thought a furance was heat only.

house is 2000 squara feet.

mdshunk 11-26-2006 12:20 PM

There's nothing bad about a heat pump, and I would definately get one. Above about 35* outdoor temperature, you will be saving money on heating versus the straight electric furnace. Below about 35*, your heat pump basically reverts to an electric furnace. They have been installed for a good 30 years or so, and there's no speical hocus-pocus about them. They are a well established technology.

acefurnacefixer 11-26-2006 06:45 PM

It all depends on the cost of your electricity. Were I live we pay the highest electrical rates in the country, so a heat pump would be foolish VS. nat.gas, or even propane.

DavidsCPU 11-26-2006 07:00 PM

thanks for the input

In some ways i don't think i need a heat pump the house comes with a furance but that leaves us with no A/C.

I mean if the furance and heat pump are both electric why do i need 2 heat sources?

Does the heat pump use that much less electricity when compared to a furance?

I need air conditioning more than heat...how good of a job does a heat pump do at coolong off a house?

btw.. why does the furance say heating and air conditioning?

Thanks

mdshunk 11-26-2006 07:07 PM

Quote:

Originally Posted by DavidsCPU (Post 24884)
I need air conditioning more than heat...how good of a job does a heat pump do at coolong off a house?

A heat pump is functionally IDENTICAL to a normal air conditioning condensing unit EXCEPT FOR the fact that it has a reversing valve to work in reverse (ie, dump the heat indoors) in the heating season.

#CARRIERMAN 11-26-2006 08:05 PM

Hi DavidsCPU

I would like to put my two cents worth in. I am an advocate for heat pumps, the modern heat pumps have been a major leap forward in technology. The reason for using a heat pump over straight electric heat is efficency. Electric heat strips are 100 percent efficient. Meaning that for every killowatt of electricity introduced you get 100% of it back out in heat. Now lets take a look at the bottom side of a heat pump. At minimum the heat pump is going to be 200% efficient, the same rules apply as before. Where people get bent over the perverbial barrel is they do not educate to these wonderfull pieces of equipment. When you go heat pump shopping you know on the A/C side it has to meet the 13 SEER rating or it can not be sold in the residential market. But keep in mind this is only the A/C side. Now we get into the heat side of the heat pump. The way the heat side is rated is in COP otherwise know as coefficency of performance. I would not reccomend purchasing a heat pump with less than a 7 COP. This means that at design temperature this heat pump is 700% efficient. Pretty impresive isn't it. Now we get to what mdshunk was talking about. As the ambient air temperature falls the amount of heat in the air also falls with it. The COP of the heat pump goes down accordingly. Now lets get into some other facts, we wont go much into this because it is one heck of a formula. The short version is that you can extract heat out of the air clear down to -461 degrees farenheight, yes that is a negative sign in front of that temperature. This is what is called absolute zero. This is where efficency comes in, even though there is heat at that temperature it would take more energy for less heat generated and is not cost effective. I have a dual fuel system on my house, that is a 90 plus furnace with a R410A heat pump. I do my changeover at 20 degrees farenheight. At this point my heat pump has a cop of 3 and is not viable to operate due to comfort and cost of heat production. However in your case, unless we got down to -461 you will always be money ahead to run the heat pump. Hope this help to educate you and make your decision a little easier.

Good luck
Rusty

acefurnacefixer 11-26-2006 10:29 PM

Quote:

Originally Posted by #CARRIERMAN (Post 24892)
Hi DavidsCPU

I would like to put my two cents worth in. I am an advocate for heat pumps, the modern heat pumps have been a major leap forward in technology. The reason for using a heat pump over straight electric heat is efficency. Electric heat strips are 100 percent efficient. Meaning that for every killowatt of electricity introduced you get 100% of it back out in heat. Now lets take a look at the bottom side of a heat pump. At minimum the heat pump is going to be 200% efficient, the same rules apply as before. Where people get bent over the perverbial barrel is they do not educate to these wonderfull pieces of equipment. When you go heat pump shopping you know on the A/C side it has to meet the 13 SEER rating or it can not be sold in the residential market. But keep in mind this is only the A/C side. Now we get into the heat side of the heat pump. The way the heat side is rated is in COP otherwise know as coefficency of performance. I would not reccomend purchasing a heat pump with less than a 7 COP. This means that at design temperature this heat pump is 700% efficient. Pretty impresive isn't it. Now we get to what mdshunk was talking about. As the ambient air temperature falls the amount of heat in the air also falls with it. The COP of the heat pump goes down accordingly. Now lets get into some other facts, we wont go much into this because it is one heck of a formula. The short version is that you can extract heat out of the air clear down to -461 degrees farenheight, yes that is a negative sign in front of that temperature. This is what is called absolute zero. This is where efficency comes in, even though there is heat at that temperature it would take more energy for less heat generated and is not cost effective. I have a dual fuel system on my house, that is a 90 plus furnace with a R410A heat pump. I do my changeover at 20 degrees farenheight. At this point my heat pump has a cop of 3 and is not viable to operate due to comfort and cost of heat production. However in your case, unless we got down to -461 you will always be money ahead to run the heat pump. Hope this help to educate you and make your decision a little easier.

Good luck
Rusty

Rusty,

Thats all very true and very good sales talk. But it still boils down to what do you pay for gas VS. electricity. In most cases NORTH of the mason dixie line a HP is a waste of money. BUT again it depends on what do you pay for your electric VS. gas.

mdshunk 11-26-2006 10:32 PM

Quote:

Originally Posted by acefurnacefixer (Post 24905)
But it still boils down to what do you pay for gas VS. electricity. In most cases NORTH of the mason dixie line a HP is a waste of money. BUT again it depends on what do you pay for your electric VS. gas.

You're missing the boat, ace...

The original poster has a choice between a straight electric furnace or an electric furnace with a heat pump. He's buying a modular home, and those are the choices offered him. Given that choice, I would absolutely add the heat pump for an extra 2700 bucks. If he had a gas heat option, he should do that and forego the heat pump option and do straight ac, depending on how far north he is. Given his choices though, I believe he got solid advice.

acefurnacefixer 11-26-2006 10:39 PM

Quote:

Originally Posted by mdshunk (Post 24906)
You're missing the boat, ace...

The original poster has a choice between a straight electric furnace or an electric furnace with a heat pump. He's buying a modular home, and those are the choices offered him. Given that choice, I would absolutely add the heat pump for an extra 2700 bucks. If he had a gas heat option, he should do that and forego the heat pump option and do straight ac, depending on how far north he is. Given his choices though, I believe he got solid advice.

Yep and i am very sorry....my bad and i apoligize!

DavidsCPU 11-27-2006 07:08 AM

I live in northern VA guys.

It don't get cold here much anymore it will be in the 60s again today but it is 30 outside now.

walt1122 02-07-2010 11:22 PM

I don't know about a 7 COP from a Heat Pump (air-to-air heat exchanger) especially a $3,700 dollar one but any time you use it you will at least break even over using straight electric or pay less. I have geothermal (run water thru pipes buried 5 feed down where the temperature of the earth stays about 45-55F year round. I take heat from the earth in the winter and put it back while airconditioning in the summer). Even with this system I only get a COP of 3.6 at peak efficiency in winter. You could do something similar with the Heat Pump. Take whatever heat there is outside in the winter and yes there is tons and tons of heat in cold air just like #CARRIERMAN says. Just make sure the system is a good quality and properly designed for the home you are considering. remember the air conditioning is simply a way of taking the hot from the air and dumping it where you don't want it so a Heat Pump does a fine job at this and can be cheaper than window units and a whole lot quiter. One issue if you go for heat pump it must NEVER make too much cold in summer cause you sized it for winter heat. Rule of thumb if AC produces more than 1.5 times the BTU's needed you will have very cold wet damp air and be very uncomfortable (shoot for no more than 1.25. Should not be a problem in VA. but up in the North it is very important. The air conditioning need time to run to remove the moisture from the air dehumidify. A price of $3,700 means it better be a pretty good unit. If you are getting the duct work for the straight electric heat then the 3.7K is just for the unit. Or are the just giving you electric radiator strips in each room? Make sure you know what you are getting for your money. Need them to supply a schedule J (heating/cooling calculations) and SEER, EER COP data on the system they want to sell you. Come back here and somebody can probably help you understand what you are getting.

Goold luck

Walt


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