Mitsubishi system.

[ITD]

The math in some of these savings stories is giving me some issues. They are just not adding up for me, although admittedly I haven't seen many numbers.

[4Fun]

Originally Posted by ITD

The math in some of these savings stories is giving me some issues. They are just not adding up for me, although admittedly I haven't seen many numbers.

Maybe the math does not add up if you are installing these to just save oil. I wanted to install AC and these was the most efficient way to get AC in my house. The heating capability is just a bonus. The electric bill this month will help me decide when to turn the oil heat.

[ITD]

Originally Posted by 4Fun

Maybe the math does not add up if you are installing these to just save oil. I wanted to install AC and these was the most efficient way to get AC in my house. The heating capability is just a bonus. The electric bill this month will help me decide when to turn the oil heat.

And that is perfectly reasonable, glad it is working for you.

[tummyman]

I agree...my prior post was just my way of explaining my action. We also installed the Mitsubishi's for AC and the heat was an added bonus. They are fabulous for BOTH heat and AC, but there is always a price part of the equation.

[SIKSUKR]

How can a regulated electric utility increase 30% in 1 year? Am I missing something?

[Little Bear]

Originally Posted by SIKSUKR

How can a regulated electric utility increase 30% in 1 year? Am I missing something?

If the utlility to which they are referring is New Hampshire Electric Coop, then the answer is clear: They are not regulated by NH Public Utilites Commission, or anyone else for that matter. They are crooks - plain and simple.

[pcmc]

Originally Posted by Little Bear

If the utlility to which they are referring is New Hampshire Electric Coop, then the answer is clear: They are not regulated by NH Public Utilites Commission, or anyone else for that matter. They are crooks - plain and simple.

Are there other electric providers to choose from?

[ishoot308]

Here's a great cost comparison chart I found for home heating. You can enter the current cost of each fuel to get actual comparison numbers. As you can see ductless heat pumps are an incredible money saver!

http://www.efficiencymaine.com/at-ho...st-comparison/

Dan

[4Fun]

Originally Posted by ishoot308

Here's a great cost comparison chart I found for home heating. You can enter the current cost of each fuel to get actual comparison numbers. As you can see ductless heat pumps are an incredible money saver!

http://www.efficiencymaine.com/at-ho...st-comparison/

Dan

That's a good chart if the calculations are correct. Trouble is I am not sure what portion my heat is over hot water. With long showers and lots of laundry and dishwashing I am sure my boiler is running a lot anyway. I do know I burn way less in the summer though

[ITD]

So the calculation is not that easy and I'm a little skeptical of the numbers in ishoot's link. Electric rates have skyrocketed this year, especially in Mass. due directly to Gov. Patrick's clean air initiative and the resultant closing of coal plants. Add to that a shortage of natural gas when temps approach 20 degrees and electricity becomes very expensive. ( the gas plants have to switch to diesel so that pressure can be maintained for NG heating customers). Also heat pump output diminishes below 40 degrees, regardless of technology, there is just less heat available in the air.

I don't have time to calculate the numbers right now but I don't think the difference is as great as that link alludes.

[ishoot308]

Originally Posted by ITD

So the calculation is not that easy and I'm a little skeptical of the numbers in ishoot's link. Electric rates have skyrocketed this year, especially in Mass. due directly to Gov. Patrick's clean air initiative and the resultant closing of coal plants. Add to that a shortage of natural gas when temps approach 20 degrees and electricity becomes very expensive. ( the gas plants have to switch to diesel so that pressure can be maintained for NG heating customers). Also heat pump output diminishes below 40 degrees, regardless of technology, there is just less heat available in the air.

I don't have time to calculate the numbers right now but I don't think the difference is as great as that link alludes.

Your supposed to input your own values based on the current price of fuels, then hit calculate...

[ITD]

Originally Posted by ishoot308

Your supposed to input your own values based on the current price of fuels, then hit calculate...

I understand, for most of the systems listed, the efficiency is pretty constant regardless of outdoor temperatures. For a heat pump not so much. It is very difficult to find this info is the Mitsubishi web site. Most of the pertinent data is apparently in the technicians side of the website, I'm not sure I can get to that info, it certainly hasn't been easy to find. But they do put a sample table at the end of one of the brochures. I'll transcribe below.

at 32 degrees this unit produces 16,469 btus
at 14 degrees it produces 13,453 btus
at 5 degrees it produces 11,260 btus
at -4 degrees it produces 8,970 btus


This is fine if the system is designed properly, but it definitely affects the efficiency..... I would feel better about the link you provided if it disclosed how they got their numbers.

Here's where I found mine:

http://www.mitsubishipro.com/media/3...actorguide.pdf

[DickR]

Originally Posted by ITD

.... Also heat pump output diminishes below 40 degrees, regardless of technology, there is just less heat available in the air.

For a heat pump in heating mode, the term to be used is not efficiency, as for a combustion device, but "Coefficient of Performance" (COP), which is the total heat delivered divided by the heat equivalent of the electric power input (3412 BTU/hr per KW). There is a theoretical limit to COP, for infinite heat exchange surface area on both heat absorption and heat release sides of the system and for an engine operating isentropically, which is T(hot)/[T(hot)-T(cold)], for T on the absolute scale (t in F +460). Thus for any heat pump the COP must drop as the temperature difference from hot to cold increases). This comes from here: http://hyperphysics.phy-astr.gsu.edu.../heatpump.html.

It isn't as much that there is less heat in the air; one just has to move more air to grab the same amount of heat from it. It's more a matter of "how high" that heat has to be pumped, temperature-wise. It's like pumping water uphill; the higher the lift, the more power it takes to deliver a given water flow. Or, for a given pumping power (compressor input), the flow decreases as the "lift" (temperature difference) increases.

The refrigerant fluid used for absorbing heat from the outside air must evaporate at some temperature below that of the outside air, and after compression of the vapor to some high enough pressure it must condense at some temperature greater than that of the inside room air. A heat pump can be designed for almost any range of outside air temperatures by selection of the right fluid and operating pressures, and for any unit there is a lower limit below which it can't move any heat, because there is no temperature difference to drive heat into the evaporating refrigerant.

[pcmc]

Hi All,
Now that we are having a January freeze would some of the owners if these split systems chime in with some feed back if you don't mind?

Are the split systems meeting your expectations for heating?
Are they sufficient or at this time of year or merely a supplemental heating source, or are they not that useful?

I would still like to invest in one but am curious how well they really perform.

Thanks and Happy New Year!

[pjard]

I just now shut my three systems off. I just can't feel them pulling much heat tonight. However this is the first time all this winter that I have shut them off. I am extremely satisfied with work they do.

[ishoot308]

Originally Posted by pjard

I just now shut my three systems off. I just can't feel them pulling much heat tonight. However this is the first time all this winter that I have shut them off. I am extremely satisfied with work they do.

pjard;

Can I assume you you do not have the "hyper heat" units and are running the standard units??...

Thanks!

Dan

[pjard]

I must admit I'm not sure. I installed them last summer (2013). I believe they were the latest and greatest! They were still throwing heat late this afternoon but I figured with oil prices in the dirt and my garage FULL of pellets and bio bricks that I would crank up the wood stove and pellet stove tonight and give the splits a break.

[ishoot308]

Originally Posted by pjard

I must admit I'm not sure. I installed them last summer (2013). I believe they were the latest and greatest! They were still throwing heat late this afternoon but I figured with oil prices in the dirt and my garage FULL of pellets and bio bricks that I would crank up the wood stove and pellet stove tonight and give the splits a break.

The reason I ask is the hyper heat units throw plenty of heat well below zero and are 100% efficient at 5 degrees and was curious why you were turning them off.

Dan

[tummyman]

I had my units installed in Oct 2013. Ran them exclusively last winter with my oil heat system totally off. We were extremely pleased with results and saved money overall, but maybe not as much as some since my house was very efficient. That said, this winter we have done the reverse....turned off the Mitsubishi's entirely unless we go up for a few days when we can adjust the inside temp higher using the mini-splits from our laptop before we get there. With the 27% increase in electric rates and the very large drop in oil prices, we are substantially money ahead using oil this winter so far. We had zero issues with the Mitsubishi's....it was just an economic decision since the prices of oil and electricity were going in opposite directions. I suspect in future years this will not be the case, but we will revisit it each year. My Mitsubishi system is a 36K BTU system and does not have the hyper heat, as it was not available in the 36K BTU system and the wife did not want two outside units.

[DRH]

Originally Posted by pcmc

Hi All,
Now that we are having a January freeze would some of the owners if these split systems chime in with some feed back if you don't mind?

Are the split systems meeting your expectations for heating?
Are they sufficient or at this time of year or merely a supplemental heating source, or are they not that useful?

I would still like to invest in one but am curious how well they really perform.

Thanks and Happy New Year!

Even with the bitter cold we are now experiencing at the lake, our two Mitsubishi mini-split heat pump systems are working very well. We are getting plenty of heat from our two systems even when the outside temps. are in the single digits.

Mitsubishi recently issued a recall on the primary circuit boards in its 18K BTU heat pump systems. Apparently the original boards caused too-frequent defrost cycles when the outside temps. were very low. The replacement boards were installed in our 18K system yesterday and it is operating well, with far fewer defrost cycles.

We continue to be very satisfied with our two Mitsubishi heat pump systems. They are our primary heat source.

[BroadHopper]

It was to my understanding there is a program when you populate the cost of electricity and the cost of backup heat, the system will automatically shut down and turn on the boiler whatever is most economical. That was what I was told by the dealer.