Using excessive power

GreenGiant117

So this is a multileveled question, and most likely a long one.

First off, back in July I had a heat pump system installed, there are a total of six heads on two compressors. I live in New England and was quoted and installed by a local company. The intent was to improve heating (replacing a severely undersized forced hot water baseboard system) and provide AC in the summer (windows are almost all crank out style windows so only "portable AC's would work and they are horribly space hungry, and inefficient).

Mitsubishi Heat Pumps, model numbers:
First Floor:
MXZ-3C30NAHZ2-U1 (30K BTU Outdoor unit)
MSZ-FH18NA2 (18K BTU Indoor head)
MSZ-FH12NA (12K BTU Indoor head)

Second Floor:
MXZMXZ-4C36NAHZ-U1 (36K BTU Outdoor unit)
MSZ-FH09NA (9K BTU Indoor head) x2
MSZ-FH06NA (6K BTU Indoor head) x2
PAC-MKA51BC (5 port branch box for distribution)

Initially all was fine they worked great for AC, and then fall/winter hit and they started heating. They work pretty well, though I think placement of the units could have been a little better to distribute the heat a little better. The issue is that they are using an absolute monster amount of electricity. I knew that they would use more than I had been before but I feel like they are using way too much.

Part of this may have been my fault, the installer gave me the passcode for the "Installer" settings on the Kumo Cloud app and I have wandered through the settings there. Changing what temperature to switch over to the old heating system, etc to try to improve overall performance and reduce power consumption.

Side note I feel like there should be a way to automatically run both the old and new heating system at the same time at a certain temperature band then only the old below said temperature. I feel that would be more efficient than running the new system and if nothing changes after X time run the old system.

Does anyone have any suggestions as to how I can get the most effective and most efficient heating out my system?

The main issues that I seem to be having are as follows:
First floor: the 12K unit seems to keep the room it's in about 4-7 degrees (Fahrenheit) above the set point. While the second unit seems to struggle to keep the room it's in at temperature. The room it is in has a vaulted ceiling with an opening to the second floor so I know heat is lost to the second floor most of the time. I do keep the second floor a couple degrees about the first floor to try to help with this. I also have a ceiling fan to try to keep the warm air lower.

Power consumption: this change was an attempt to save money on heating the house, in combination with Solar panels, but so far compared to last year using only oil to heat to basically the same temperature in the house, I have spent just the same overall.
I understand last year was a very mild winter for me and this year is a lot colder, but it still seems like something is wrong.

I have asked the installer company about it and they suggested playing with the "Only heat pump" settings, the "Delay" and the "Only backup" settings, as well as the ceiling fan speeds.

pecmsg

In heat and cooling there is a minimum that compressor can turn, if 1 head is not enough it will send refrigerant to the idle heads. Those room temperatures can and do go up. I only install single or duel zones and size for cooling only.

5 1/5- Tons is hugely oversized. Id like to see the manual "J" on this one!

EBEBRATT-Ed

You should have fixed the baseboard system.

Put an outdoor air lock out on it so at 25 degrees you shut down the heat pumps and start the boilers and at 35 you go back to the heat pumps. 2 outdoor sensors with a relay and a little wiring will do it

GreenGiant117

pecmsg said:

In heat and cooling there is a minimum that compressor can turn, if 1 head is not enough it will send refrigerant to the idle heads. Those room temperatures can and do go up. I only install single or duel zones and size for cooling only.

5 1/5- Tons is hugely oversized. Id like to see the manual "J" on this one!

I understand the principle, I've worked with refrigeration for the last 7 years (mainly -20C and -80C systems and only secondarily, electrical engineer by trade).
I guess I'll just have to set up a fan in the warmer closed off room to try to move more air.

As for 5.5 tons it may be a little oversized, but it is a fairly large house, 2800 sqft, vaulted ceilings in 3 rooms (going up 16 ft) large windows in most rooms, and 4 exterior doors.
Running through a quick online calculator it gave me 59,900 BTU (not sure if the space height is correct though, I went with 12 since I think the average would be about 12 ft) which is 5 tons...

EBEBRATT-Ed said:

You should have fixed the baseboard system.

Put an outdoor air lock out on it so at 25 degrees you shut down the heat pumps and start the boilers and at 35 you go back to the heat pumps. 2 outdoor sensors with a relay and a little wiring will do it

It's not that it is broken, the issue is it was severely undersized, and there is some poor insulation in some areas that can't easily be fixed. The baseboard covers the max linear distance it can (runs along ~90% of wall space) but because there is the vaulted ceiling it would run for hours on end for less than 1 degree of temperature change. It would mean ripping out all the old baseboards and installing larger ones (that wouldn't fit under some of the windows).

I have tricked the boiler into running the first floor heat at times (closed the circuit for first floor demand) and have had the idea of setting something up to do that automatically.
There are also settings in Kumo Cloud that will basically do just that, there's an "Only Backup" setting where the heat pumps won't run, only the original heat source will (I think?) so I'll try playing with that some more.

Jamie Hall

A bit of economics and physics here...

A heat pump will only save energy at outside temperatures where its COP is at least 3. Below that it uses more energy than any decent modern boiler to produce the same amount of heat.

Now there is the question as to where that energy comes from. Gas turbine power plants? Oil or natural gas steam turbine plants? Nuclear plants? Hydro, when it's not frozen up? Wind turbines, likewise? Solar, when the sun is shining and someone swept off the panels? But it's still energy. A watt is a watt; a BTU is a BTU.

Now the economics. In New England, at least, electricity rates are... high. I won't say outrageous, because they're not -- if anything, they're low, all things considered. But they are high. Therefore again, a heat pump won't save you any money when it's colder out and -- oddly, again -- the COP is below about 3. And if it's cold enough that the auxiliary heat strips kick in, they'll cost you a fortune.

pecmsg

500 Sq Ft per ton is old school! New and even renovated structures average 750-100 sq ft per ton. 
you’re issue is over sized equipment. 

GreenGiant117

Jamie Hall said:

A bit of economics and physics here...

A heat pump will only save energy at outside temperatures where its COP is at least 3. Below that it uses more energy than any decent modern boiler to produce the same amount of heat.

Now there is the question as to where that energy comes from. Gas turbine power plants? Oil or natural gas steam turbine plants? Nuclear plants? Hydro, when it's not frozen up? Wind turbines, likewise? Solar, when the sun is shining and someone swept off the panels? But it's still energy. A watt is a watt; a BTU is a BTU.

Now the economics. In New England, at least, electricity rates are... high. I won't say outrageous, because they're not -- if anything, they're low, all things considered. But they are high. Therefore again, a heat pump won't save you any money when it's colder out and -- oddly, again -- the COP is below about 3. And if it's cold enough that the auxiliary heat strips kick in, they'll cost you a fortune.

As far as I know other than one or two days/nights since having them the temperature has been above 10 degrees which should be more than high enough to not have the heaters on.
To be honest I have no idea where the power comes from but my assumption would be primarily coal gas and solar, as there arent many hydro or wind farms nearby that I know of.
I do have solar panels, but since it's winter and minimal sunlight plus snow they aren't generating much, but I also burned through the rather large excess I had built up over the summer (>1 MWh) in less than a month.

From the frequency that they run (to my observation maybe 20-30% of the time) they shouldn't cost anywhere near as much as a forced hot water system running almost 75% of the time.

pecmsg said:

500 Sq Ft per ton is old school! New and even renovated structures average 750-100 sq ft per ton. 
you’re issue is over sized equipment. 

Not an expert but wouldn't that just cause short cycling?
They run for at least 20-30 minutes at a time when running and at least 45 minutes to an hour in between, this is from memory so I'm not sure if that's 100% accurate.

pecmsg

GreenGiant117 said:

A bit of economics and physics here... A heat pump will only save energy at outside temperatures where its COP is at least 3. Below that it uses more energy than any decent modern boiler to produce the same amount of heat. Now there is the question as to where that energy comes from. Gas turbine power plants? Oil or natural gas steam turbine plants? Nuclear plants? Hydro, when it's not frozen up? Wind turbines, likewise? Solar, when the sun is shining and someone swept off the panels? But it's still energy. A watt is a watt; a BTU is a BTU. Now the economics. In New England, at least, electricity rates are... high. I won't say outrageous, because they're not -- if anything, they're low, all things considered. But they are high. Therefore again, a heat pump won't save you any money when it's colder out and -- oddly, again -- the COP is below about 3. And if it's cold enough that the auxiliary heat strips kick in, they'll cost you a fortune.

As far as I know other than one or two days/nights since having them the temperature has been above 10 degrees which should be more than high enough to not have the heaters on. To be honest I have no idea where the power comes from but my assumption would be primarily coal gas and solar, as there arent many hydro or wind farms nearby that I know of. I do have solar panels, but since it's winter and minimal sunlight plus snow they aren't generating much, but I also burned through the rather large excess I had built up over the summer (>1 MWh) in less than a month. From the frequency that they run (to my observation maybe 20-30% of the time) they shouldn't cost anywhere near as much as a forced hot water system running almost 75% of the time.

500 Sq Ft per ton is old school! New and even renovated structures average 750-100 sq ft per ton. 
you’re issue is over sized equipment. 

Not an expert but wouldn't that just cause short cycling? They run for at least 20-30 minutes at a time when running and at least 45 minutes to an hour in between, this is from memory so I'm not sure if that's 100% accurate.

That’s oversized. 

At design conditions your looking for near continuous operation 

EBEBRATT-Ed

@GreenGiant117

You have to understand it's all about building construction.

I will give you two examples.

#1 The old "Trolley Barn" in Hartford, Ct is a big brick building. They gutted the steam system and left the outside wall brick exposed and converted it to offices. They put in gas fired roof tops with ac and a vav system. Constant complaints, never worked. You can blow all the heat you want with air into the space. The air temp was 70 deg but everyone was cold because the brick walls were cold. The old steam heat use to have CI rads on the outside walls

#2 Visiting Nurses building in Worcester, Ma. They had a conference room they couldn't use in the winter, you could see your breath in there. Same thing, gas fired roof tops. Someone had added hot water coils in the duct work to get more heat. Didn't work. One wall of the room was a glass block wall. It was like touching an ice cube. No matter how much heat you blew in there it was uncomfortable.

I proposed and we installed some high output hot water baseboard along the glass block wall. The glass blocks ran floor to ceiling. We had a carpenter build a wooden box along the floor with the baseboard mounted on the front of the box and the piping inside the box to hide it. Put it on it's own zone with it's own pump. Problem solved.

Perimeter heat is the ONLY way to heat a building with cold walls (like your un insulated stucco) and the drafty construction.

Somewhere @DanHolohan talked (or maybe in one of his books) I can't remember about "cold 70 degrees)

It's a huge factor.

I would finde a way to get creative and get some high output baseboard or radiation into the space

Jamie Hall

At 10 F ;the heaters may not have been on -- but the compressor was struggling and they might as well have been on so far as electricity use was concerned.

Your electricity in New England at this time of year is almost all natural gas and oil fired steam turbines. There is a small amount of hydro from Quebec (and my goodness they do charge for it!). There used to be a fair amount of nuclear, but the only US plant still allowed to run in New England is Millstone. There is some nuclear from Quebec, as well. Grid wind and solar contributions are negligible.

And I hate to break it to you, but that 1 megawatt which you stored up over the summer is just enough to run a boiler like yours for about a day.

GreenGiant117

EBEBRATT-Ed said:

@GreenGiant117

You have to understand it's all about building construction.

I will give you two examples.

#1 The old "Trolley Barn" in Hartford, Ct is a big brick building. They gutted the steam system and left the outside wall brick exposed and converted it to offices. They put in gas fired roof tops with ac and a vav system. Constant complaints, never worked. You can blow all the heat you want with air into the space. The air temp was 70 deg but everyone was cold because the brick walls were cold. The old steam heat use to have CI rads on the outside walls

#2 Visiting Nurses building in Worcester, Ma. They had a conference room they couldn't use in the winter, you could see your breath in there. Same thing, gas fired roof tops. Someone had added hot water coils in the duct work to get more heat. Didn't work. One wall of the room was a glass block wall. It was like touching an ice cube. No matter how much heat you blew in there it was uncomfortable.

I proposed and we installed some high output hot water baseboard along the glass block wall. The glass blocks ran floor to ceiling. We had a carpenter build a wooden box along the floor with the baseboard mounted on the front of the box and the piping inside the box to hide it. Put it on it's own zone with it's own pump. Problem solved.

Perimeter heat is the ONLY way to heat a building with cold walls (like your un insulated stucco) and the drafty construction.

Somewhere @DanHolohan talked (or maybe in one of his books) I can't remember about "cold 70 degrees)

It's a huge factor.

I would finde a way to get creative and get some high output baseboard or radiation into the space

That is fair, as far as I know the building was built to MA Code (I live in MA), and has 16 on center 2x4 with fiberglass insulation in the walls. The house was built in 1985, expanded on in the 90's and additionally expanded on in the early 00's, I fixed some of the roof insulation (degraded fiberglass in attic space, and improper placement of fiberglass insulation in another attic space). That helped immensely with the original heat (forced hot water baseboard).Then through rebate and loan programs I went with the heat pumps since there was no way to condition the space in the summer so it was miserable all summer.
And in doing that I needed to convert the heat, that's the only way you get rebates/loans is through heat.

I am planning to put a wood stove in the basement to heat that space and provide some radiant style heating, but it still feels like it shouldn't use as much as a poorly sized baseboard system.
The addition of a fan in the room with the 12k has helped over the last couple hours, and recently adding a whole house humidifier helped as well.
I guess I will have to look into upgrading the baseboard loop in my house in the next couple years.

Jamie Hall said:

At 10 F ;the heaters may not have been on -- but the compressor was struggling and they might as well have been on so far as electricity use was concerned.

Your electricity in New England at this time of year is almost all natural gas and oil fired steam turbines. There is a small amount of hydro from Quebec (and my goodness they do charge for it!). There used to be a fair amount of nuclear, but the only US plant still allowed to run in New England is Millstone. There is some nuclear from Quebec, as well. Grid wind and solar contributions are negligible.

And I hate to break it to you, but that 1 megawatt which you stored up over the summer is just enough to run a boiler like yours for about a day.

Yea it is unfortunate the stigma on nuclear power, it is a fairly clean source.
I just hope that grid storage takes off in the near future, it will greatly reduce pricing and reliability, especially during high demand and spikes in demand.

As to your math on the stored power, not quite the boiler that I have running full tilt would only chew through that megawatt over almost a month, it draws about 1-1.25A continuous when running, its the oil that's costly due to powering through a whole tank in about a month (last year $2.50-3.00 per gallon, this year about $2.00-2.50)

Jamie Hall

I didn't mean that the megawatt was to run the motor on the boiler. It was to run the heat to your house -- through, for instance, your heat pump.

Grid storage will be needed for sure (though, oddly there is a huge grid storage facility in Massachusetts -- most people don't even know it's there) but what it won't do is reduce cost to the consumer or reliability. If anything, it will increase it. Also, just to further improve your day, the best estimate I have gotten for either oil or gas for next year is oil somewhere around $5 per gallon, and natural gas, if available at all, at an equivalent price per BTU.

EBEBRATT-Ed

@GreenGiant117

Years ago we bought some "Sterling Senior" which is a larger residential baseboard but we just bought the empty enclosure with the cover and end caps etc. We then bought "Spirotube" sort of a high output mesh copper tube element which would fit in the Sterling enclosure. Used it on a few jobs where we needed high output.

That was years ago there may be better options available now