heat pumps

[yeldogt]

I replaced both of my straight ducted AC HVAC systems last year with a Carrier variable speed ducted HP and a Mitsubishi VS ductless hyper heat unit w/ three heads. It's a strange old house with some of the house heated with hot water.

So ... it was 15 last night and currently 20. Both of the HP's are working beautifully --- house was set for 72. I'm impressed with the temp of the Carrier's outlet air.

One of the Mitsubishi units was placed in a room not often used -- so I had it at 67 ... just to test ..... I pushed it up to 74 this morning. Quickly pumping out lots of heat.

These new heat pumps really work ... and boy are they quiet.

 

[GirchyGirchy]

Emergency heat didn't come on? That's impressive.

Do you have any electric bills showing heavy use of the new HPs? Were they NG furnaces before?

 

[toplessHO]

my Bard water source unit really shines on heat mode,over 60K btu

air temp difference is over 35* inlet vs outlet.

 

[theoldwizard1]

Thanks for the report ! Please put your location in your profile so we know where you are at.

I'll bet those 3 rooms handled by the mini-split have never been so warm in the middle of winter !

 

[xravenx]

Emergency heat didn't come on? That's impressive.

Do you have any electric bills showing heavy use of the new HPs? Were they NG furnaces before?

They don't have emergency heat

 

[yeldogt]

Emergency heat didn't come on? That's impressive.

Do you have any electric bills showing heavy use of the new HPs? Were they NG furnaces before?

No emergency heat -- none have resistance coils.

A friend of mine has one of the original single head Mitsubishi hyper heat units from a couple of years ago. Mine is the new multi head hyper heat system that they introduced last summer.

The carrier unit tracks energy usage -- it's very cool. It said $4 -- for yesterday. Thats is doing almost 1/2 the house. It's a fraction of the old resistance heat.

 

[bandit067]

Replaced a strip heat unit several years ago with a Trane package unit......has worked wonderful for 14 years now. Put in new Carrier package unit in my coming up retirement home, and it has performed terribly. Both are heat pumps and I was the thinking this newer Carrier unit {2013} would be even better that the Trane......ha ha. Maybe I got a lemon....but never plan on another Carrier......glad yours is working good for ya. Now that I am paying for the service calls....it may be replaced sooner than I planned....

 

[yeldogt]

Replaced a strip heat unit several years ago with a Trane package unit......has worked wonderful for 14 years now. Put in new Carrier package unit in my coming up retirement home, and it has performed terribly. Both are heat pumps and I was the thinking this newer Carrier unit {2013} would be even better that the Trane......ha ha. Maybe I got a lemon....but never plan on another Carrier......glad yours is working good for ya. Now that I am paying for the service calls....it may be replaced sooner than I planned....

Don't think they have VS in a packaged unit -- this is a split system.

 

[manwithtools]

I'm confused, are you saying your conventional split system heat pump was working in 15 -20 degree weather without supplementary heating? The air coming from it was warm? I've not seen an example of that type of system that works much below 35 or so with an ability to provide much heat from air to air exchange. Physics don't support it.

Can you please update your profile with your location?

 

[d3ad1ysp0rk]

I'm confused, are you saying you conventional split system heat pump was working in 15 -20 degree weather without supplementary heating? The air coming from it was warm? I've not seen an example of that type of system that works much below 35 or so with an ability to provide much heat from air to air exchange. Physics don't support it.

Can you please update your profile with your location?

http://www.fujitsugeneral.com/wallmountedRLS2.htm

I might be misunderstanding, but my father in law installs mini splits and has one in his home that we just experienced working well around ~20 degrees the other day (Maine).

Heating capacity at low outdoor temperatures was improved by adopting a large heat exchanger and a high capacity compressor. Rated heating capacity is maintained up to 20°F. This new model can operate down to -5°F.

 

[yeldogt]

I'm confused, are you saying you conventional split system heat pump was working in 15 -20 degree weather without supplementary heating? The air coming from it was warm? I've not seen an example of that type of system that works much below 35 or so with an ability to provide much heat from air to air exchange. Physics don't support it.

Can you please update your profile with your location?

This is my house in NJ. Carrier split system with variable speed compressor and fans. The Mitsubishi is also VS. They don't need back up resistance heat. The Carrier unit will provide full capacity down to about 10 and the Mitsubishi is bellow 0.


Both unit ramp up and down depending on the current inside and outside temps .. what the current setting are ... it's very cool. The Carrier unit will tell me what it's doing -- they are both connected to the internet with remote control.

 

[manwithtools]

I was aware of mini-splits working in those temps but had not heard of conventional split systems achieving the same. That's very interesting, I'm assuming that operating at full capacity down to 10 degrees F is more economical than others that switch to resistive backup elements below 30 degrees or so.

 

[yeldogt]

I was aware of mini-splits working in those temps but had not heard of conventional split systems achieving the same. That's very interesting, I'm assuming that operating at full capacity down to 10 degrees F is more economical than others that switch to resistive backup elements below 30 degrees or so.

I don't have the information in front of me -- my memory is about 2.5x over resistance. It's over 4 above freezing.

So ... even when it's very cold .. factoring in some loss I'm still at 2x the resistance heat. The house is much more comfortable now -- the unit matches the heat loss of the house -- so it's never off.

 

[crabjoe]

I'm confused, are you saying your conventional split system heat pump was working in 15 -20 degree weather without supplementary heating? The air coming from it was warm? I've not seen an example of that type of system that works much below 35 or so with an ability to provide much heat from air to air exchange. Physics don't support it.

Can you please update your profile with your location?

There are heat pumps now that work down to -10F.

I just did this to show you how much heat my Heat pump is putting out when the outside temp is 33F. As you can see the backup heat is NOT on.

The top shows current conditions, before the test was started.. 33F outside. Inside is 69F and it's set to 69F. The bottom is the installer Test screen with the heat pump running for 5 mins on the noise.

BTW I think my Rheem Heat Pump is rated at 2.4 COP at 17 Deg F.

 

[manwithtools]

Well that figures, three years after I replaced the last of my heat pumps they have models that work to temps as low as we would ever see here in middle TN. I guess when I get to the next house I'll be looking into these new units. This makes it even harder to justify geothermal, with those numbers the payback becomes even longer. Maybe this will drive geothermal cost down some.

 

[yeldogt]

Well that figures, three years after I replaced the last of my heat pumps they have models that work to temps as low as we would ever see here in middle TN. I guess when I get to the next house I'll be looking into these new units. This makes it even harder to justify geothermal, with those numbers the payback becomes even longer. Maybe this will drive geothermal cost down some.

I am building a new house -- and you are on point with the geothermal. With natural gas available -- that is currently cheaper. I don't have NG at my new location -- so it's electric or propane. The new HP's get very close to geothermal ... I'm under 50 degrees with geothermal .. with the new oversized high pressure air to air -- they get close enough. 50k buys a lot of electricity.

 

[crabjoe]

Going to bed now, so I wanted to show you another test shot.. I let it run longer than 5 mins but it was because I had to step away.

Outside temp is 27 Deg F.

BTW, my heat pump isn't a high Seer or anything fancy. It's a 3.5 ton Rheem RP14 (14 Seer), which is their "new" Classic series ... It's just a single stage HP with demand defrost matched to a Rheem 3.4-4 ton evap coil.

 

[machsnell]

So I am confused (easily) seer rating doesn't have anything to do with how low a heat pump can produce heat which it counterintuitive to me because that seems like it would increase efficiency DRAMATICALLY.

For hvac guys - are these heat pumps readily available? Just coming out now using inverter technology of mini splits?

I was set on a 20 or so seer mini but heard jonjon1 talk about how bad mini splits are and he would never install one etc so it had me on the fence again ....now this.

If I can get an efficient conventional heat pump that makes heat in the teens I would go back to that route.

Any advice out there?

Sent from my SM-G900V using Tapatalk

 

[crabjoe]

If you're looking for heat vs AC, look at the HSPF rating. That's the rating for heating efficiency. I think my Rheem RP14 is rated at 8.5 HSPF. Inverter tech isn't new, it's been around for a long time. It's just new to us. It's like the mini split, in other countries mini splits have been around a long long time, but they're only now getting popular here. I don't know why, but it seems other counties get new tech much sooner than us.

Oh one other thing, make sure to look at COP numbers for any heat pump. They'll have it rated at 47 and 17 degs F.

 

[Gila Monster]

I guess I don't understand "how" newer heat pumps are able to do this. When you look at a heat pump, the basics are still all there, basically a compressor, condensor and evaporator.

What new technology has allowed them to move "heat" from the air where they weren't able to before?

I can understand how they are more efficient with things like slowing down the speed, but is that why it can now "move" heat at such low temperatures?

 

[crabjoe]

I guess I don't understand "how" newer heat pumps are able to do this. When you look at a heat pump, the basics are still all there, basically a compressor, condensor and evaporator.

What new technology has allowed them to move "heat" from the air where they weren't able to before?

I can understand how they are more efficient with things like slowing down the speed, but is that why it can now "move" heat at such low temperatures?

I think it's a combination of a lot of things like the size of the coils, using TXV instead of Pistons and a host of other things I have no idea about. It could be the pressures too.

When I replaced my AC with a heat pump, I replaced the indoor coil to match. Both my old coil and new are rated for 3.5 -4 TON, but the new coil is gigantic I can't remember, but either the SH or SC recommendation was at the high end of what I'd thought should have been normal.

Personally, I don't care how they do it as long as it's affordable, reliable, and does what they advertise. I guess you can say it's like being a driver of a car. Most have no idea how a car works, but they know how to use one.

 

[dsimatt]

I was just talking to a friend about these last night as his house is a older modular one with electric heat and his heating bill are crazy in the winter so he has looked at installing a pellet stove but those are expensive to. These heat pumps would work great for him as he could heat his living room warmer than the rest of the house and save a lot of money that way and be more comfortable.

My house is hot water heat and it ***** because right now i'm heat 75% of the house I very rarely use to the same temp as the rest of the house i'm in just to be comfortable. The biggest plus I see with the heat pump is putting one in my living room I could keep that area comfortable while the rest of the house can be cooler which will work better when going to bed as I like it colder in there.