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Need some help with non-heating mitsubishi mini-split

Hello everyone - thanks in advance for your time.
We just had a mini-split system installed - outdoor unit MXZ-3C30NA2-U1 30k BTU UNIT with 3 indoor units installed connected to the one outdoor unit models are MSZFH12NA (x2 of these) and one MSZFH09NA. So two 12000 BTU units and one 9000 BTU unit connected to that outdoor unit. We were told prior to installation that this model was rated to negative temperatures, which we rarely get where we live in Idaho. However since installation it has been around 20-30 degrees during the day and getting into single digits at night and the house is FREEZING. Okay, maybe not freezing but sitting in my living room where there is a 12000 BTU unit is is 59 degrees with another electric heater going!

This is not what we were sold and we thought our house would be comfortable. So here is my question - is our outdoor unit being over taxed with the 3 heads? Is there another reason that this could be happening? A service tech is coming out today but short of draining the lines and recharging the system correctly I am not sure what else we can do. I don't know how much line they used on install but I do know they did not add any extra refrigerant other than what is covered up to 25 ft or something. I will find out more from the tech, but is this model rated at negative temps? And is the capacity on it too high for it to work properly? All I've found online says it is rated to 17 degrees outdoor temp.

Please help! Thank you!!!
Amber
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Comments

  • BPHBPH Member Posts: 39
    How many sq/ft are you trying to condition? Line set lengths/amount of refrigerant are critical for proper operation.
  • asanford10asanford10 Member Posts: 15
    The house is 1550 sq ft. There is a 12000 btu in the living room (a 13 ft x 27 ft room) which was supposed to heat living room, kitchen and hallway, a 12000 btu which heats 3 front rooms two typical 12 x 12 bedrooms and a larger 14 x 14 (roughly) room and then the 9000 is in our master bedroom. And honestly, the 9000 in our master bedroom doesn't work that well.
    These things turn off before they reach set temp (which is set to 88 right now just to keep the place at 57-66 degrees max) with two other heaters running in 10 degree weather.

    I will have to ask line set lengths when they come here today. Is the length determined by adding up the line sets routed to all 3 indoor heads or separately? Could you explain that to me so when he comes today I can ask correctly? Thank you. I know for a fact that over 25 ft had to be used to the one in the living room because the outdoor unit is on the opposite side of the house and routed up the side of the house, through the attic, and over to the living room. So either way, I feel like they should have added more refrigerant on that fact alone from what I've read.
  • Jamie HallJamie Hall Member Posts: 6,865
    I have to ask -- was a heat loss done on the house? And how does that compare with the rated output?
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • asanford10asanford10 Member Posts: 15

    I have to ask -- was a heat loss done on the house? And how does that compare with the rated output?

    I don't think so. What I've read of a heat loss is measuring windows and doors, right? He did not do this. I assumed we would be good with this guy but I guess I should have done more research. The company is a diamond preferred dealer of these things, so you would think they knew what they were doing...
  • BPHBPH Member Posts: 39
    1550 sq/ft seems to be quite a load for a 21/2 ton outdoor unit Jamie is right only way to know is a heat loss calc. Anything over max lineset length requires a critical charge done by adding fractions of ounces to the system. The max lineset length is individual not cumulative so if max length is 25' each indoor units lineset can't be over 25' without adding refrigerant
  • BPHBPH Member Posts: 39
    Also keep in mind elevation plays a role in performance of airflow output. For instance where I live (5000' above sea level) I have to account for an 18% decrease in equipment output.
  • asanford10asanford10 Member Posts: 15
    BPH said:

    Also keep in mind elevation plays a role in performance of airflow output. For instance where I live (5000' above sea level) I have to account for an 18% decrease in equipment output.

    I live at approx 2444 feet above so would that be a 9% or so decrease?
    Man, I don't think this guy calculated any of this stuff!
  • JUGHNEJUGHNE Member Posts: 3,478
    Did you try to turn off 2 of the inside units and see if the third unit will heat its area better?

    Can't imagine any heat pump installed in your or my (NE) climate without some back up heat.
  • asanford10asanford10 Member Posts: 15
    Yeah, I've tried that. It seems to put out heat a little hotter same as turning the fan speed down would, but majority of the house won't get warm. I'm trying to find the capacity we are running at the current temp. My friend (HVAC guy) just told me we are screwed basically and below 20 degrees running at 50% capacity and below 10 running at 15% capacity. I can't find that in writing anywhere though and they didn't leave us the manual for the outdoor unit.

    The tech called me this morning and told me at 5 degrees these units should be heating the house comfortably and he thinks there is a leak. Been waiting for a service tech all morning. The lead tech is getting annoyed with me for researching this stuff because he says he knows what he is talking about. They offer a money back guarantee 365 days and he said they have never had to use it - but I'm pretty sure we will be returning these units and going for a furnace.
  • asanford10asanford10 Member Posts: 15
    Found the max heating capacity chart. At the current temp we are operating at 80% capacity and when it gets down to 5 degrees looking at like 55%. Awesome. Got bamboozled.
  • SWEISWEI Member Posts: 7,356
    edited December 2016
    One other point: Residential multi-split heat pumps lose far more of their heating capacity at low ambients when compared with single split models.
  • asanford10asanford10 Member Posts: 15
    SWEI said:

    One other point: Residential multi-split heat pumps lose far more of their heating capacity at low ambients when compared with single split models.

    Do you know if the heating charts in manuals are done with single units or mulitsplits? It doesn't specify.
  • SWEISWEI Member Posts: 7,356
    edited December 2016
    There are separate charts for each type and model. By single split I mean units which support only one indoor unit. A multi-split outdoor unit paired with only one indoor unit would short-cycle like crazy.

    Last time I researched this, the Mitsubishi and Fujitsu single splits had much better low temperature heating outputs than either Daikin or LG. Heating output on the 9k, 12k, and 18k Fujitsu single splits is roughly the same (they all use the same outdoor coil, which makes the small ones really shine in low ambients.)
  • bulldoglaxbulldoglax Member Posts: 26
    Lg daiken Fujitsu and Mitsubishi all heat to negative 13 and most pull full capacity at sea level at zero degrees. This would be for a single head unit or one to one however you want to say it.

    How are you controlling the units are they set up with the redlink thermostats or are you using the wall mount handhelds. Only reason I ask is because I wanted to see if you set the set point to the max temp usually around 84-86 degrees.
  • GWGW Member Posts: 2,602
    Amber, there is a mass of confusion. 17 degree rating is AHRI rating at 17 degrees. All heat pumps have a '17 degre' rating.

    Your unit is not the Hyper Heat model, you need a different outdoor unit if you want the more-robust heating output. It will have HZ typed after the NA.

    25 feet max? Someone is confused. The label on the outdoor unit shows you the maximum total footage of pipe run before additional refrigerant is needed. We installed the NAHZ, and it can handle 96' (if my memory serves me)

    If you have a leak in your system, the performance will drop like a rock.

    Either you misunderstood or the installer must have been very misinformed. Normally speaking you can expect good comfort with ac, but heating??? No, unless your home is very small and very tight/well insulated, you can't expect this system to heat your home.

    If your contractor is reputable, ask for the Hyper Heat. If you bought from some schmoe, then it's a hard lesson.

    I'm sorry you're having heating issues.

    Gary
    Gary Wilson

    Wilson Services, Inc

    Northampton, MA
  • asanford10asanford10 Member Posts: 15

    Lg daiken Fujitsu and Mitsubishi all heat to negative 13 and most pull full capacity at sea level at zero degrees. This would be for a single head unit or one to one however you want to say it.



    How are you controlling the units are they set up with the redlink thermostats or are you using the wall mount handhelds. Only reason I ask is because I wanted to see if you set the set point to the max temp usually around 84-86 degrees.

    Apparently the unit we have is not a hyper heat unit so it is only good to about 5 degrees and even that capacity is really low. This guy is telling me that capacity just means that the lower the heat capacity the longer the units will run without cycling off, but I thought heat capacity is the level or quality of heat you are getting out of the machine. I don't know. We have 3:1 head to outdoor unit ratio so I am assuming that lowers capacity by itself anyway. The guy told us specs from the hyper heat unit on our first meeting and then gave us this other model on install and now he is changing his tune that at 5 or 10 degrees we will need resistance heating. We thought below 0 we would need resistance heat. And our resistance heat doesn't seem to be helping at all anyway.
    We use the wall mount handhelds and they are all set to 84-88 degrees just to keep them on as much as possible. I mean, I am in my house and I can't feel my fingers. It has been 60 degrees or lower in here all day and I have a 4 year old kid. Needless to say, I'm pretty unhappy about this entire experience.
  • asanford10asanford10 Member Posts: 15
    GW said:

    Amber, there is a mass of confusion. 17 degree rating is AHRI rating at 17 degrees. All heat pumps have a '17 degre' rating.



    Your unit is not the Hyper Heat model, you need a different outdoor unit if you want the more-robust heating output. It will have HZ typed after the NA.



    25 feet max? Someone is confused. The label on the outdoor unit shows you the maximum total footage of pipe run before additional refrigerant is needed. We installed the NAHZ, and it can handle 96' (if my memory serves me)



    If you have a leak in your system, the performance will drop like a rock.



    Either you misunderstood or the installer must have been very misinformed. Normally speaking you can expect good comfort with ac, but heating??? No, unless your home is very small and very tight/well insulated, you can't expect this system to heat your home.



    If your contractor is reputable, ask for the Hyper Heat. If you bought from some schmoe, then it's a hard lesson.



    I'm sorry you're having heating issues.



    Gary

    Looks like it is time for a furnace. We bought from a reputable contractor luckily and we can get our money back for everything (minus the damage and holes in our walls and ceilings) but our home is neither small or well insulated, so I think we are going to have to get a ducted system.
  • GWGW Member Posts: 2,602
    Amber, each set of pipes is called a line set. If the units are all 20 feet of linear piping length, that would be 60 total feet. Yes there are two pipes per line set, that is irrelevant. Ok sure---my example has 120 feet of tubing, but the total line sets are 60. Don't double the numbers.

    Look at the label on the outdoor unit it will say how many feet it's rated for. If you exceed that you need more juice
    Gary Wilson

    Wilson Services, Inc

    Northampton, MA
  • JUGHNEJUGHNE Member Posts: 3,478
    What did you have in this house for a heating system before this?
  • BobCBobC Member Posts: 4,515
    I have a similar 12k single head unit just south of Boston that does my first floor. I find it works efficiently down to the high 20's, it will work below that but when it gets colder I need more BTU's to heat the space so I use the steam system when it gets colder.

    I bought the unit to handle the shoulder seasons and have been using it most days this winter after the steam system brings the house up from a 3 degree setback.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • asanford10asanford10 Member Posts: 15
    JUGHNE said:

    What did you have in this house for a heating system before this?

    Wood stove was our only source of heat for the last 4 years
  • SWEISWEI Member Posts: 7,356

    This guy is telling me that capacity just means that the lower the heat capacity the longer the units will run without cycling off, but I thought heat capacity is the level or quality of heat you are getting out of the machine. I don't know.

    Heating capacity refers to the quantity of heat the system is capable of extracting from the outdoor air and delivering to the indoor air. If the system was undersized, then (at some point) as the outdoor air temp drops, the system will fail to keep up and the house will get cold.

    I would look into swapping the outdoor unit for a HyperHeat model, assuming the indoor units are up to the task.
  • GWGW Member Posts: 2,602
    Shell need a larger wire and breaker
    Gary Wilson

    Wilson Services, Inc

    Northampton, MA
  • bulldoglaxbulldoglax Member Posts: 26
    you have probably spent a lot of money at this point for a system you are not pleased with but I would see if you could strategically place one single additional unit to compensate for difference in heat loss. You could even send me the building information I will do a heatloss in rightsoft for you and make up the difference.

    Heat pumps are a great solution if sized correctly but unfortunately the last few year it's all about marketing and getting an upper edge in terms of specs. Most equipment is the same packaged different and then sent off to ahri for ratings. Some companies will take their 15k head rate it as 12 and say it gets better ratings than he company that has a true 12k unit.

    Let me know if you want a heatloss done.
  • asanford10asanford10 Member Posts: 15
    I want to thank everyone for their input so far, this has all been really helpful. We are going to look into the hyperheat model because that is what we thought we were going to get originally. They came out yesterday and found a large leak in the system right at the connection to the outdoor unit - he fixed this and refilled refrigerant and the house immediately started heating up the house. This morning the house was at a good temperature without using any other heaters overnight. So far, I'm happy with the performance. We will be in the negatives for a couple nights and that will really test them though we will use resistance heating as well. We are going to get a quote for a furnace system and decide in about two weeks if we will switch over and get these ripped out. My husband wants one heat source I think instead of worrying about needing a backup.
    The company I am getting a quote from will perform a heat loss calculation for the furnace so I will see what they come up with so you don't have to worry about that extra work. Thank you though bulldoglax!
    Happy New Year everyone!
  • pecmsgpecmsg Member Posts: 172
    Any heat pump should have a back up source of heat.

    When this company first installed this system how was there a leak. A pressure test to 600-psig and a vacuum to less then 1000 microns would have shown the problem right away!

    When they repaired this leak did they weigh the old charge, pressure test and pull a vacuum to less then 1000 microns? Weigh in a new virgin charge according to the name plate + or - the extra line length?

    You've purchased a great system but i get the feeling the installing contractor cut corners.

    Contact another Diamond dealer and have the complete install checked.

    Keep the Mitsubishi and get a back up source. The mini are the most efficient heat source when installed properly!
  • GWGW Member Posts: 2,602
    Depending on energy costs you must mean<<<<
    Gary Wilson

    Wilson Services, Inc

    Northampton, MA
  • GWGW Member Posts: 2,602
    Wow my whole schpeal got dropped again, how frustrating.

    I suspect the installer may be willing to give you the Hyper vs. ripping out the entire system.
    Gary Wilson

    Wilson Services, Inc

    Northampton, MA
  • njtommynjtommy Member Posts: 1,072
    Leaks at flare joints are very common on these units unfortunately not too many guys use the correct flaring tool or even tighten them down correctly. As @pecmsg said the leak should of been found with a correct pressure test and evacuation process of the refrigeration circuit. I have pressure tested units up to 400psig and found nothing. Once I get to the 600psig range that's when you'll find your leaks. Once again tho this is not uncommon do to lack of training and understanding the equipment being installed.

    I would wait and see if the unit can handle the house with the proper charge in it.
  • pecmsgpecmsg Member Posts: 172
    GW said:

    Depending on energy costs you must mean<<<<

    energy costs and balance point..........

    Yes
  • JackJack Member Posts: 946
    Your tech suggested a leak. If he is correct, the repair is made and the unit is recharged it may do what you were originally told it would do. My units are several years old at this point, but when I selected my Fujitsu's I bought a dual unit for the bedrooms and a single much higher efficiency single unit for the main living area. With the exception of the added electrical circuit, it netted out cost wise about the same as buying a triple, which is what you have. I would not be quick to throw out the mini-split once they are right. Let the repair be done, see how they perform and demand an extension of the "satisfaction guarantee." Please report back.
  • asanford10asanford10 Member Posts: 15
    GW said:

    Wow my whole schpeal got dropped again, how frustrating.



    I suspect the installer may be willing to give you the Hyper vs. ripping out the entire system.

    Not sure what the first sentence means, but they aren't willing. The unit shut off last night when we hit 0 degrees and I had no idea it would do that. We were told lower efficiency not a no heat output at all. I told them I want them gone. They want to charge me 1400 more (as a "deal") for the hyper heat unit because I am livid with this company. I told them no way. This guy never told us the unit would shut down completely between 0 to 5 degrees but I confirmed it with mitsubishi this morning. We have wall heaters but they aren't strong enough to heat the entire house without some other heat coming in. My entire house except for the bedroom and workout room where there are other heaters was iced over last night. Still is. We have better wall heaters on the way, but we are just over it.
    After they were fixed they worked great, but what is the point in a heating system that doesn't have you covered when you are at your most vulnerable. And he acted like he knew that they would shut off but didn't tell us that...? Idk at this point. I feel like I've been lied to. Our quote had "hyper heat" right on the indoor units and we assumed that with the indoor being HH and him giving us specs into the negatives that we were getting the hyper heating unit outdoors. Well, that is not the case. I take some of the blame here too - we should have researched it more honestly, but you expect someone that does this for a living to know what they are doing and tell you everything.
  • asanford10asanford10 Member Posts: 15
    Here is a question though - SEER - can someone explain this. Is it pointless to have higher SEER units indoors if your machine outdoors can't provide the right heat? I mean a HH outdoor unit with lower SEER indoor units would have been better than the set up we have now - correct?
  • JUGHNEJUGHNE Member Posts: 3,478
    I just have a gut feeling that the HH unit won't cut it either.
    If this unit delivered the full 30,000 BTUH even at 0 degrees ambient (which it won't), I doubt if it would heat your house on a day like today.
    I have installed maybe a couple dozen mini HP of various brands and have always had enough back up heat to handle the house in the event of break down. It was usually electric BB heaters and in one case of a farm house they have kept the wood stove for days as this.
    They are great economical heat source and the AC is what is usually prime factor in the customer purchase in my area of NE. But heating just has it's limitations for any air source heat pump.
  • BobCBobC Member Posts: 4,515
    i have never thought they could be use as a primary source of heat in the colder parts of the US. I have found they do a great job from the high 20's on up and can save a lot of fuel on moderately cold days.

    When it gets colder my steam system picks up the slack with no problem.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • GWGW Member Posts: 2,602
    Amber, I typed a couple of paragraphs but when I hit Post Comment the text was almost all gone.

    Anyway, your Mitsubishi dealer is nuts!

    There is no such thing as an indoor Hyper Heat unit, the Hyper Heat defines the outdoor system.

    If you have single zone FH series hyper heat systems you need the FH indoor units, no matter what. If you have a multi zone you can use the FH or the GL series wall units. The efficiency doesn't change.

    The outdoor system has the ratings, the indoor units just need to be a "matched" unit.

    Have some other company cone put in the correct system

    Gary
    Gary Wilson

    Wilson Services, Inc

    Northampton, MA
  • njtommynjtommy Member Posts: 1,072
    edited January 7
    Hyper heat units use what they call flash injection into the compressors. flash injection is the refrigerant coming back from the indoor head and they send it into the compressor through another valve. This does two things keeps the compressor from over heating and it keeps the suction pressure higher. If you can keep the suction pressure normal you can maintain you efficiency and your btus.

    I'm use to seening liquid injection on Trane and York frequency driven screw chillers. Same theory to drive efficiency and less strain on the compressor.
  • BPHBPH Member Posts: 39
    I dig the consensus that mini splits shouldn't be used as primary heat however I disagree to an extent: install at 7500' elevation last reading on a 2 ton unit installed in a 709 sq/ft unit @ 18* odt saw putting out 118* with a retun air temp of 61*. I love wet heat but you can't argue with the numbers. Calm down it's ok
  • asanford10asanford10 Member Posts: 15
    Well, I told him I want them removed and he got very rude with me through text message. So I think I made the right choice. We are going with a gas furnace because if winters like we are having this year become the norm, we want something reliable at all temperatures -15 the other night and -9 last night. Nothing but infrared heaters and a couple space heaters to get us through. We are living in our bedroom, haha. And with a 4 year old that is not easy.
  • GWGW Member Posts: 2,602
    I'm in disbelief the guy sold this as a stand alone system, shameful.

    What about a couple of gas wall heaters, direct vent? You're at these crazy cold conditions such few days in a year i presume

    I have no idea what your setup is, if it's Ducting friendly then just do that. Having holes in the house isn't good though
    Gary Wilson

    Wilson Services, Inc

    Northampton, MA
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