Heat Pump in Cold Climate?

Page 2 of 2  


OK, that part I agree with. A 1500 watt electric heater would give you 5100 BTU.
 >The numbers for the heat pump came from the manufacturer's sheet

The numbers for what and from where? There are multiple units listed with multiple specs for each. It would be helpful if you could specify what table entry you are using and for which model. Let's look at the specs for the MSZ-GE09NA which are on page 12 of the brochure:
http://www.mitsubishicomfort.com/media/359053/m-series%20brochure%203_11-r_pages.pdf
At 17F it states:
Rated Capacity: 6600BTU Rated Total Input: 700W
A 700W resistance heater would generate 700 x 3.41 = 2387 BTU The heat pump is generating 6600 BTU Meaning the heat pump is generating 2.7 times more heat at 17F outside temp than you would get with a resistance heater using the same amount of electricity.

From the same specs, it gives the capacity at 47F as 10,900 BTU. The capacity at 17F is 6,600 which means you're still getting 60% of the heat that you get at 47F.
Now the part that I don't understand is the graph earlier in the brochure that shows capacity staying constant all the way down to 10F. I think we agree that sounds like marketing BS of some kind, given that it does not have resistive heating.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sep 18, 11:14 am, " snipped-for-privacy@att.bizzzzzzzzzzzz"

There we have it folks. The usual KRW tactic. Try to now change the discussion into something else. Art stated:
" But, it shows that you are almost getting the same amount of heat as you would if it were a resistive heater. "
There was no qualification of temperature. Now, having been wrong, just as I predicted, you try to weasel away by now adding "at some low temperatures" into it.

Perhaps you should look at the data sheet for the Mitsubishi units under discussion instead of embarrasing yourself further. Per the analysis I showed in my last reply to Art, at 17F, the MSZ-GE09NA is producing 2.7 times the heat that you would get from a resistance heater. That's pretty impressive performance in cold temps.
And it sure doesn't jive with:
"" But, it shows that you are almost getting the same amount of heat as you would if it were a resistive heater. "

YOU are the one that agreed with the analysis that the heat pump only generates about as much heat as an equivalent resistance heater. YOU were agreeing that it only moves the same amount of heat as it uses. Now of course, you're trying to weasle away, by adding "at some low temps" At 17F it's still generating 2.7 times the heat you'd get from a resistance heater. Even at 5F it's still generating far more heat than a resistance heater.
And as predicted, instead of being a man and admitting your error, you've quickly resorted to name calling.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 18 Sep 2012 12:28:01 -0700 (PDT), " snipped-for-privacy@optonline.net"

Wong, liar. The discussion *was* about operation and efficiencies at lower temperatures.

...at low temperatures.

You really are an idiot. That's what the discussion was about. What a stupid liar.
<nothing else worth reading>
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sep 18, 3:47 pm, " snipped-for-privacy@att.bizzzzzzzzzzzz"

Show me where Art gave a temp that his statment applied to. Typically YOU would be the one to jump all over something like that, because it's open ended, generally not true, and meaningless without specifying what temps you are talking about.
He now says it was at 17F that his analysis was done. Well, per the Mitstubishi data sheet, which you obviously have not even bothered to read, page 12, at 17F you get 2.7 times the heat output that you would with a resistance heater. That is not about the same amount of heat as a resistance heater, it's 2.7 times greater. Art made a mistake. YOU agreed with the analysis which is TOTALLY WRONG and instead of admit it, as usual, you start the name calling. Try reading the datasheet instead of embarrassing yourself.

YOU agreed with a faulty analysis that didn't even mention what temperature it applied to. Now in my world when someone says:
> >" But, it shows that you are almost getting the same amount

It's a very broad indictment of heat pumps. And what that faulty analysis was based on, I still don't know because Art didn't say what numbers he was using. You obviously have not done any analysis. I did. And per the Mistubishi data sheet specs, at 17F your're getting 2.7 times the heat out of their heat pump unit than you do with a resistance heater. Now for most people, 17F is a pretty cold climate. And per the Mitusbishi brochure, it's still nowhere near a resistance heater all the way down to 5F.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/15/2012 7:25 AM, Norminn wrote:

Where is here?
More to the point than having once seen it, what are the averages? Certainly a modern properly sized air-exchange HP will handle into the lower 30's w/ no problems. The one thing is that they will tend to have longer recovery time as the exit air temp's will not approach those of conventional furnace (or even a geothermal unit).
They certainly have improved even air-exchange but in very cold climates either they use geothermal (ground loop/well/deep reservoir all possibilities) or have a conventional backup.
We replaced an early air-exchange in E TN w/ geothermal and it was night/day...this is almost 20 yr ago now and the original HP wasn't but a cheap contractor-supplied unit in the late 70s when even the good weren't doing all that well, anyway. But, TVA power was cheap then so the resistance heaters weren't a big deal--probably 70% of heating in the area was electric at the time. By the early 90s the HP was on last legs and power rates were much higher and NG wasn't yet available so went w/ the higher installation cost of digging the trench and never regretted it while were still there. AFAIK the system is still functional w/ no problems--saw the new owner just a couple of years ago and he's also quite pleased.
It has a thermistor in-line w/ the aux heat that keeps them from being able to come on above about 18-20F so the 'Emer Heat' logic doesn't try to kick on if, for example, the house has been turned down and then come home and reset to normal so the dT is large and it thinks it can't catch up. Newer t-'stats may also have better logic to know the difference between chronic failure to keep up and change in demand.
A side benefit of the geothermal was essentially free hot water in summer using reject heat from the cooling cycle...replacing electric water heater inputs is _a_good_thing_ (tm) in most places given rates...
--
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Norminn wrote:

Ground source heat pumps work fine in colder climates.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.