Question about Heat pump, is it useful in cold winter


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Old 12-06-07, 06:55 PM
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Question about Heat pump, is it useful in cold winter

Hi
I have a heat pump which is outside the house, it works as AC and heater.
Is this heat pump useful in cold winter where temperature drops below 30
Can it warm the house, i have about 1300 sq foot single floor house.
the issue i am seeing is, it takes about 1 hour to increase 1 degree F in the house when the temperature outside is about 25 or 30 F,
Is this normal for a heat pump, or am i missing some thing.
I have air handler in attic and heat pump outside the house.
Do i need some thing more for cold winter days.

Ash
 
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Old 12-06-07, 07:36 PM
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Heat pump are best to set it and forget it.

I am guessing you have electric for back up heat?

I've seen heat pump run as low as teen's for temps.

What do you have for t-stat? A good t-stat will cycle aux heat every now and then to help keep up with temp, and do expect it to run a long time.
 
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Old 12-06-07, 07:50 PM
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Hi
I am not sure if i have electric for backup, how can i find it out.
Also if i run the heat pump for 24 hours, what is the Kwatt usage for it?
I have a programmable t-stat where i setup morning, evening temperature etc.

The heat pump really struggles to get about 64-65 on cold days like when the temperature about 20-25
 
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Old 12-06-07, 07:54 PM
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Most heat pump will have electric for back up, or some will have gas furnace.


On your current t-stat, si there a switch that says like "Emrg Heat"?

If it does, switch it over and see what the air temp is like in the vent.
 
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Old 12-07-07, 06:38 AM
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Hi
In the t-stat i have heat and emrg heat, so what is the difference between them?
I dont have gas at all in my house, every thing is electric,
how can i check if there is a backup heating system,

i do not have heating furnance in the basement,
just one heat pump out side and air handler in attic
Does the heat pump have build backup system in it?

I just tried the emer heat button, and all i got was very cold air coming into the house from the vents, does that mean i dont have a backup heating system ?
I have foot board heaters in each room, but i dont like it much as i have to go in each room to control the temperature., and the temperature is also very in accurate


Thanks for the help
Ashish
 
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Old 12-07-07, 06:41 AM
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kulkarni_ash

There are many factors to consider about the effectiveness of heat pump winter heating.

1.the insulation properties of your home including type of windows
2.your location and climate for the winter
3.age of heat pump-today's models are vastly improved from those of 10 yrs or older
4.your family's comfort level
5.is HP sized correctly including aux strip heat
6.when was system last serviced and refr charge checked-very important in delivering cool AC and hot/warm heat

it use to be that HPs were normally used in mild climates like the South but improvements have expanded the service area of HPs especially for dual fuel applications with heat pump paired with fossil fuel backup like nat gas or oil.

And of course there is the operational cost to consider-reasonable electric rates can make HPs a great choice.

I do not recommend more than a 3-4 degree setback for HPs and less for older models unless strip heat is locked out above your balance point. Just defeats your purpose.

IMO
 
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Old 12-07-07, 08:44 AM
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I just tried the emer heat button, and all i got was very cold air coming into the house from the vents, does that mean i dont have a backup heating system ?
I have foot board heaters in each room, but i dont like it much as i have to go in each room to control the temperature., and the temperature is also very in accurate
Lets check that back up heat here first. Do you have any??? Does it work???? You have to have it for when the unit goes into defrost.
What do you have then ??? Base board for heat in the homeand a AC for cool???
We try and tell people to set the tstat and let it alone with the heatpump. Also when it get down to Around +20o to +15o cost is about the same so just go over to EME for when its that temp out.
 
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Old 12-07-07, 10:32 AM
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if the air is coming out cold, can be a couple of things..

Either the wires are not hooked up right, or you don't have back up heat.

What is the make and Model of your air handler/furnace?

Take a photo if you can with the covers off.
 
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Old 12-08-07, 06:38 PM
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Hi
Finally i was able to get the model numbers of Heat pump and Air handlers.

Heat pump
Ducane - Model HP10B30
The compressor is from
Copleand - Model CR30KF

Air Handler
ADP - Mode BCRMB 1230S002
I did not find any information about them online any where.

Does anyone have any idea about these,
I will take pics and post them tomorrow

Ash
 
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Old 12-08-07, 09:33 PM
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I think we are back to what runs and what dont. That helps more than just the ###. Is the big copper line hot when it is all running??????
 
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Old 12-09-07, 05:40 AM
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This may be helpful....or not. See what size the wire is leading to the air handler. If it is gray and as about an inch in diameter, you probably have backup. If it is only about 1/2" in diameter, you probably don't. One other observation, you said you have baseboard electric heaters in each room. That would be a reason for an installer NOT to install backup in the heat pump. He could have saved a few hundred dolalrs on the install if he excluded the backup heat and let the baseboards kick in. I would not want it that way if it was my house, but I have seen it done just that way right here in PA.

Ken
 
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Old 12-09-07, 02:38 PM
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First your question about the heatpump it self.
You have a 2 1/2 ton unit. That's 30,000 Btu/hr, or 30 Mbh.

Now, rule of thumb is 600 sqft per ton of a/c. Using that, your place is just over 2 tons (24 Mbh), hopefully someone did a load calc and decided to go 2 1/2 tons.

Heatpump capacity versus outside temp.

I'm looking at a York chart for heating performance, but I think you'll get the idea. If it's 70 degrees in the house and 57 degrees outside the system has 33MBH capacity. Plenty of heat to warm the house.

Now, still with 70 degrees in the house here's where your capacity goes down.
Outdoor temp / capacity:
47 / 29
37 / 25
27 / 19
17 / 16

In a nutshell you have a 2 1/2 ton heatpump at 70 degrees inside and 57 outside. At 70 inside and 37 outside you have a 2 ton heatpump. At 70 inside and 17 outside you have a little more than a 1 ton heatpump.

So the colder it is outside the harder it is for the heatpump to heat the house.

Many thermostats (tstats) will bring on electric heat to help the heatpump reach the set temperature. Since you have a programmable tstat it should bring the electric heat on if the heatpump can't keep up.

But you said you turned on emergency heat and got cold air from the vents. You have an electric heat problem.

Look at the breaker for your indoor unit. If it's a 60 amp breaker you have at least 10 KW electric heat. 40 or 50 amps you may have 5 KW or 7.5 KW electric heat, anything less like 20 you may not have back up heat.

So where to go from here?

First, you need a tech to check the refrigerant charge in the heatpump.

Second, you need a tech to find out why the electric isn't working.
 
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Old 12-10-07, 08:10 AM
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Hi
Thanks for the detail information,
So basically the heat pump itself should have a back up heat component, i called ADP the company with the air handler, and there is no auxiliary heat in this air handler

How do i check if the heat pump has auxiliary heat,
or may be there is no auxiliary heat and so when it gets cold outside i will have to use the foot board and when it gets warm like about 40 use the heat pump.
Can i take a look into the heat pump and find out if there is any auxiliary heat pump in it.

Ash
 
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Old 12-10-07, 08:55 AM
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As I said before, someone who was trying to keep the cost to a minimum would not have added backup heat. You already have electric baseboard and the efficiency of operating that is the same as the backup heat would have been. That's where the similarities end. You have no good way of staging the secondary heat source so when the heat pump is not effective, you now have to turn up multiple thermostats to make up the difference. That is not practical or comfortable. There is no backup heat on the outrdoor unit as you mentioned. If it was me, I owuld call a different company and ask for a price to add electric backup heat to the air handler. It would require another electric circuit from the main panel and the correct amount of heat for the brand of air handler you have. Not a real big deal. The benefit is that you will be able to set ONE thermostat and maintain accurate comfort level in the whole house. Just turn off the baseboard electric heaters at that time.

Ken
 
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Old 12-10-07, 12:14 PM
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Hi
Thanks for the reply, i will look into if i can add backup heat on the Air Handler,
so basically if the outside temperature is around 40 or above i use the heat pump or else i will use the baseboard till i get the backup heat installed

Ash
 
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Old 12-10-07, 12:25 PM
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You can run that heat pump on down to like around 32o out side . After that you need the back up heat if the unit goes into defrost. Im lost as to why or how you went this way. A heat pump has like a COP. So say down to about 30o out side you get 3 time more heat off it for say $ 1 as you get fron the baseboard heaters. As it get colder outside that goes down so some say down to about 15o you get about the same heat for that $1
 
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Old 12-11-07, 11:14 AM
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Hi
I rented this house, and had no idea about the heating system as i rented it in summer
I do not have a backup heating system with heat pump.

So it will be more efficient to run heat pump + air handler when the temperature out side is above 32 F

And it will be more efficient to use the foot board when the temperature goes below 32 F outside.

I have 3 bedrooms and living room and kitchen and when i have to turn on the footboard i will turn it on only in living room, kitchen and one bedroom, and other rooms are not used.

Is this correct or am i still not getting the point.

How can i find the Kilowatt/ hour heatpump + airhandler and footboard heaters.
That way i can get an idea of how much my electric bill will be

Ashish
 
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Old 12-12-07, 04:24 AM
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ashish

I would install a heat strip module in your air handler.
Size depends on your location and load calculation for heat loss. For overall comfort, I believe this would be less expensive to operate than straight baseboard heat.

I am puzzled why there is no heat strip in your air handler. It is relatively inexpensive to install.

Do you mind saying area of country you live?

IMO
 

Last edited by TigerDunes; 12-12-07 at 05:48 AM.
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Old 12-12-07, 04:59 AM
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Actually the only reason to install the backup heat in the air handler would be for convenience of operation. The cost to operate electric heaters of any kind are equal. But you could keep different rooms at different temperatures using the individual thermostats. In addition, unless your air handler and all ducts are located inside the building envelope or are 100% leak free, you will have losses associated with the heat pump system that you will not have with the baseboard. The difference may be small but the baseboard could easily cost less to operate.

Ken
 
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Old 12-12-07, 07:28 AM
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Hi
I live in NJ-PA border, i rented this house in summer and so did not check the heating arrangement.
So basically i have heat pump, air handler, baseboard and fire place(which i use some times in evening, not very often).

I have the heat pump outside the house and air handler in attic of the house, all the ducts are inside the attic as this house is only one floor.

There are 3 bedrooms and we use 2 bedroom. other bedroom is storage room for us.



So i have to see what is the cost of putting strip module in air handler and if i get any savings by using it instead of baseboard heaters in each room, the only thing i see for now is I have the heat pump of having to use one T-stat instead of different in each room,

So i was trying to calculate how much it will cost to run 4 baseboards (2 in bedroom + 1 in living room + 1 in kitchen)
versus one strip module for whole house.

Any suggestions.
 
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Old 12-12-07, 11:15 AM
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ashish

Find out the total KW number for the four baseboard strip heat units.

Then have someone run a heat loss load calculation for you. The difference between the heat loss and the BTUs produced from the heat pump will determine the size of the strip heat module (aux heat) required for your air handler. Keep in mind your heat pump even at 20 degrees produces some heat-just not enough BTUs to maintain your home's comfort level without the aux heat.

Not an easy task but I definitely would get a strip heat module installed in air handler ASAP and run baseboard as little as possible.

IMO
 
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Old 12-12-07, 12:37 PM
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Hi
Does anyone have any idea what may be the cost involved for adding this strip heat module into air handler,
How do i find out the right guy to get the work done,
I will look into yellow pages to get quotes from different people
 
 

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