CALIFORNIA ENERGY COMMISSION - Heat Pumps Are the Wave of the Future.

[winnie]

One issue with multi zone minisplits is modulation range.

The outdoor unit can only modulate yo perhaps 20% of its total capacity. If you only want to run one indoor unit, and loads are miderate, then the outdoor unit might not be able to modulate down sufficiently.

Another issue is that even the smallest available heads are too large for a small room. This is where the mini ducted systems are very nice tools.

Jon

 

[wwhitney]

But if one "zone" requires cooling and one requires heating, they cannot both be serviced by the same outdoor unit.

True with the simplest systems typically seen in the residential market. But I believe there are systems that can do that. May require a "3 pipe" configuration.

Cheers, Wayne

 

[electrofelon]

True with the simplest systems typically seen in the residential market. But I believe there are systems that can do that. May require a "3 pipe" configuration.

Cheers, Wayne

There are more advanced systems call VRF (variable refrigerant flow) where remote units can do combinations of heating and cooling. I hear it is quite a Cadillac expensive system though. VRFs have been initially speced on a few jobs I did, but they always got nixed due to cost.

 

[drcampbell]

... Duct systems waste energy with leaks to the attic, and under the house. ...

That's an argument for better attic thermal design, not an argument for heat pumps.

... However, propane and NG are quite high at the moment.

My latest electric bill was 25¢/kW·hour.

Just read something the other day that said by 2040 energy will be half what it is now due to green initiatives starting to bear return on investment. ...

I read something the other day saying that by 1980, nuclear power would be too cheap to meter.

It won't matter to the customers of for-profit investor-owned utilities. No matter how cheap their cost, the IOUs will continue charging whatever price they can get away with. Only by nationalizing these inherent monopolies will consumers ever see any reduction in price or improvement in reliability.

Wyandotte, Michigan, for example, has a Municipal Services division which does precisely that.

Welcome to Wyandotte Municipal Services

Wyandotte Municipal Services is a not-for-profit service provider located in Wyandotte, Michigan. The services that WMS provides are electric, cable telecommunications, and water supply and treatment to the City of Wyandotte. WMS was created by local residents more than 100 years ago. The City...

www.wyan.org

... I still don't like how much the HVAC companies charge to extract and refill refrigerant. ... That costs $1000 around here. I could buy a cylinder of refrigerant for less than 1/4 of what they charge for it, but most places won't sell it to you without an EPA license. I suppose I could probably take some stupid test to get the license, but it should not be this difficult and expensive.

Don'cha just love the "free" market?

EPA certification is not stupid, prohibitively difficult, or prohibitively expensive.
But it's not always adequate. I once had a large-chain auto parts store refuse to sell me refrigerant because my certificate doesn't say "Automotive".

 

[drcampbell]

On reliability, the second graph at the reference below says that in 2021, [California] was no less reliable than average for the US. ...

That's not a particularly high bar to clear.

 

[AC\DC]

That's an argument for better attic thermal design, not an argument for heat pumps.


My latest electric bill was 25¢/kW·hour.


I read something the other day saying that by 1980, nuclear power would be too cheap to meter.

It won't matter to the customers of for-profit investor-owned utilities. No matter how cheap their cost, the IOUs will continue charging whatever price they can get away with. Only by nationalizing these inherent monopolies will consumers ever see any reduction in price or improvement in reliability.

Wyandotte, Michigan, for example, has a Municipal Services division which does precisely that.

Welcome to Wyandotte Municipal Services

Wyandotte Municipal Services is a not-for-profit service provider located in Wyandotte, Michigan. The services that WMS provides are electric, cable telecommunications, and water supply and treatment to the City of Wyandotte. WMS was created by local residents more than 100 years ago. The City...

www.wyan.org

Don'cha just love the "free" market?

EPA certification is not stupid, prohibitively difficult, or prohibitively expensive.
But it's not always adequate. I once had a large-chain auto parts store refuse to sell me refrigerant because my certificate doesn't say "Automotive".

View attachment 2567947

That’s not free market, when the government dictates that you need a license to buy that equipment. So don’t bash the free market, if you don’t like it go to China, we’re they have even more controls, remember there are model according to some brain dead leaders.
Easy to criticize when you don’t have to live without it.

 

[mtnelect]

The big game changer is the use of "Ductless" Mini Splits:
1) No ducts
2) Compressor technology - Inverters
3) Not having to heat & cool the whole house, only the room your occupying
4) The ability to heat down to 32% without emergency heat
5) Zone systems are not allowed in California, also they require ducting with returns in each zone. When more than one zone closes down the coil will "Ice Up" for lack of air flow.

Forgot to add why CEC does not allow Zone systems. Around 1975 the manufacturer's & CSLB started getting complaints from homeowners on problems with their Zone systems not working as advertised. Here are some of major flaws in the system were discovered:

1) The HVAC contractors were not designing the ductwork with returns in each zone, which reduces return airflow when more than two zones are closed.
2) The manufactures solution was to require a "Bypass Damper" to be installed in the return system. This was a major concern with the CEC in that it required the already condition air to have a second pass through HVAC system. This became a major waste of energy.

 

[Frank DuVal]

That is true ... But consider the "Defrost" time. You might want to prepare for cooler air, for about 5 minutes. A small inconvenience for a larger electrical bill.

??? Defrost cycles when it is not heating, i.e. at the end of the call for heat cycle. And what larger electric bill?

You guys really don't see heat pumps in action?

1) The HVAC contractors were not designing the ductwork with returns in each zone,

Typical, the authorities ruin it for everyone because of a few stupid contractors who cannot design a proper system.

 

[winnie]

On my Fujitsu mini-split heat pump system, the unit modulates its output to maintain room temperature. Ideally this means that the 'call for heat' is continuous, although in practice on mild days the system has to cycle on and off.

During heating I can watch frost build up on the outdoor unit.

Periodically the system turns the indoor airflow way down and goes through a defrost cycle. I can hear refrigerant boiling in the indoor unit and see the frost melting on the outdoor unit. The airflow is so low (or off) that I don't notice much in the way of cold air being blown into the room, but clearly heat is being taking from the indoor side to melt the frost on the outdoor unit.

Also: I love most aspects of my mini-split heat pumps, but the system was designed for summer cooling and shoulder season heating. For the coldest days I still have oil fired steam heat in my house. I don't know how much I'd like the system if I was depending upon it for year round heating.

-Jon

 

[wwhitney]

Also: I love most aspects of my mini-split heat pumps, but the system was designed for summer cooling and shoulder season heating. For the coldest days I still have oil fired steam heat in my house. I don't know how much I'd like the system if I was depending upon it for year round heating.

Isn't that just a design issue? If you had adequate capacity for winter heating, what issue would there be that you don't see now?

Cheers, Wayne

 

[mtnelect]

??? Defrost cycles when it is not heating, i.e. at the end of the call for heat cycle. And what larger electric bill?

You guys really don't see heat pumps in action?




Typical, the authorities ruin it for everyone because of a few stupid contractors who cannot design a proper system.

Sorry for not having a more detailed answer. When you see the term "Defrost Cycle" it only means one thing. The system is in the heat mode and the outside unit is starting to produce ice on the coils, at that point the unit automatically turns off the condenser fan motor and runs the compressor in the cool mode for about 5 minutes to melt the ice off the coils, that is when the inside unit will be blowing cool air. Then returns automatically to the heat mode to continue heating the structure.

 

[drcampbell]

... I love most aspects of my mini-split heat pumps, but the system was designed for summer cooling and shoulder season heating. For the coldest days I still have oil fired steam heat in my house. I don't know how much I'd like the system if I was depending upon it for year round heating.

Isn't that just a design issue? If you had adequate capacity for winter heating, what issue would there be that you don't see now?

In cold climates such as Massachusetts, the peak winter heating load is ~triple the peak summer cooling load.

In the past, the practice has been to size the heat pump to match the summer cooling load and use another source of heat during the winter because oversizing the cooling resulted in poor performance -- short cycling and poor humidity removal.
(presumably, that is no longer the case with VFDs and continuous capacity control, but the actual technology manufacturers implement tends to be decades behind what's available)

There's also a tradeoff between efficiency and comfort. The highest efficiency from a refrigeration machine is achieved with the smallest indoor/outdoor temperature difference. Some high-efficiency air conditioners do a poor job of humidity removal because their discharge air is warmer, and some high-efficiency heatpumps are uncomfortable because they deliver "cold-air heat" -- air that's warm enough to heat the house, but is uncomfortable because it's below body temperature and has a cooling effect.

 

[mtnelect]

Also, when in the Defrost mode, you will sometimes see steam coming off the coils.

 

[mtnelect]

In cold climates such as Massachusetts, the peak winter heating load is ~triple the peak summer cooling load.

In the past, the practice has been to size the heat pump to match the summer cooling load and use another source of heat during the winter because oversizing the cooling resulted in poor performance -- short cycling and poor humidity removal.
(presumably, that is no longer the case with VFDs and continuous capacity control, but the actual technology manufacturers implement tends to be decades behind what's available)

There's also a tradeoff between efficiency and comfort. The highest efficiency from a refrigeration machine is achieved with the smallest indoor/outdoor temperature difference. Some high-efficiency air conditioners do a poor job of humidity removal because their discharge air is warmer, and some high-efficiency heatpumps are uncomfortable because they deliver "cold-air heat" -- air that's warm enough to heat the house, but is uncomfortable because it's below body temperature and has a cooling effect.

I agree with your statements. When selling "Ductless" I always tell the customer that the heat is "Gentle Heat" not like gas heating.

 

[winnie]

One specific design issue of these specific units is that the indoor temperature sensor is built into the indoor unit.

This means that the system has to circulate air when the call for heat has been satisfied (at least that is my understanding for why it was designed to do so), and so the system will produce a cool breeze between heating periods when heating requirements are low.

Regarding the low temperature function, I should be clearer: I do not have personal experience with the system on the coldest days. I did not mean to imply that I wouldn't like the system on the coldest days. I did _try_ one of my units on a really cold day last year. It seemed to sound like it was struggling, but it did make heat.

Jon

 

[GoldDigger]

There are more advanced systems call VRF (variable refrigerant flow) where remote units can do combinations of heating and cooling. I hear it is quite a Cadillac expensive system though. VRFs have been initially speced on a few jobs I did, but they always got nixed due to cost.

Definitely more complex flow. Since the outdoor coil must choose between sinking heat or sourcing heat, the only way to get cooling in one location and heating in another is to satisfy the smaller demand by pumping heat between two zones rather than between each zone and the outside.
IMHO too complex for the typical HVAC tech to troubleshoot. (requires more than two pressure gauges)

 

[mtnelect]

One specific design issue of these specific units is that the indoor temperature sensor is built into the indoor unit.

This means that the system has to circulate air when the call for heat has been satisfied (at least that is my understanding for why it was designed to do so), and so the system will produce a cool breeze between heating periods when heating requirements are low.

Regarding the low temperature function, I should be clearer: I do not have personal experience with the system on the coldest days. I did not mean to imply that I wouldn't like the system on the coldest days. I did _try_ one of my units on a really cold day last year. It seemed to sound like it was struggling, but it did make heat.

Jon

The Daikin system that I install, have one weak point. Their use of flaring connections that leak refrigerant that I have observed on the units that I have installed. I now use a sealing disk on every connection.

Like breaks on a car, they wear very slowly until you have to replace them. Same on all HVAC units, they must be checked yearly.

 

[drcampbell]

Definitely more complex flow. Since the outdoor coil must choose between sinking heat or sourcing heat, the only way to get cooling in one location and heating in another is to satisfy the smaller demand by pumping heat between two zones rather than between each zone and the outside. ...

The greater complexity can be justified in larger buildings by the greater energy efficiency. Pumping heat from one zone to another at nearly the same temperature will be a lot more energy efficient than sourcing/sinking heat from outdoors.

In the distant past, (before the first OPEC oil embargo of 1973, give or take) there were some ridiculous energy wasters implemented, such as using 4ºC chilled water to cool air to 8ºC for humidity control, then reheating it with a steam coil (or sometimes an electric-resistance heating element!) to 15ºC for comfort.

... IMHO too complex for the typical HVAC tech to troubleshoot. (requires more than two pressure gauges)

I may be a dreamer, but I foresee the day when the software in the built-in microcomputer that makes it run also provides onboard diagnostics that point directly to the fault(s).

It would also be nice if typical HVAC techs actually learned thermodynamics, fluid mechanics, heat transfer and control theory.

 

[winnie]

The Daikin system that I install, have one weak point. Their use of flaring connections that leak refrigerant that I have observed on the units that I have installed. I now use a sealing disk on every connection.

Like breaks on a car, they wear very slowly until you have to replace them. Same on all HVAC units, they must be checked yearly.

Most of the systems have the same flare connections.

I am a DIYer in the field. I did get my EPA-608, and have the proper tools. I used the flare-tite seals, and pressure tested everything. So far no failures after 1 year in service for 5 units.

-Jon

 

[Birken Vogt]

I may be a dreamer, but I foresee the day when the software in the built-in microcomputer that makes it run also provides onboard diagnostics that point directly to the fault(s).

In cars and equipment, most of the time, the cause of the fault is something to be troubleshot itself, and not actually pointing to the genuine fault.