Mitsubishi ductless heating/cooling unit

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nominalBob
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Re: Mitsubishi ductless heating/cooling unit

Post by nominalBob » Fri Oct 07, 2016 1:33 pm

Ninegrams wrote:... You could actually take a thermometer and measure output temp at the discharge as I suggested previously or go on debating about who's understanding is correct, or just contact Mitsubishi and explain your situation. ...
Temperature is not enough. You also need the air volume rate being delivered at that temperature in order to calculate BTUH.

michaeljc70
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Re: Mitsubishi ductless heating/cooling unit

Post by michaeljc70 » Fri Oct 07, 2016 6:48 pm

In traveling quite a bit in South America and Europe, these are extremely common. Particularly in older homes/condo buildings in climates where it doesn't get real cold (because most of these units also provide heat). They have always performed well. I like that you can set them via remote control. Obviously, if you have a lot of rooms, it is not real practical to cool them all with this type of unit. I also haven't seen (but haven't particularly looked) if you can program these on some sort of a schedule like you can a typical AC/heating unit.

Ninegrams
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Re: Mitsubishi ductless heating/cooling unit

Post by Ninegrams » Fri Oct 07, 2016 10:55 pm

nominalBob wrote:
Ninegrams wrote:... You could actually take a thermometer and measure output temp at the discharge as I suggested previously or go on debating about who's understanding is correct, or just contact Mitsubishi and explain your situation. ...
Temperature is not enough. You also need the air volume rate being delivered at that temperature in order to calculate BTUH.

I don't see where that would be necessary. If you have temp within specs and a properly working fan you'll get 'close enough' to your rated BTUH, no calculation necessary. Now if you have good temp and suspect a slow running fan then you troubleshoot further. Again, to repeat, if I wanted to be sure I'd call in a certified tech.

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segfault
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Re: Mitsubishi ductless heating/cooling unit

Post by segfault » Sat Oct 08, 2016 9:39 pm

OP, what is the issue with the temperature in your basement? I live in a relatively moderate climate, and during the winter, the HVAC leaks enough that it warms the basement quite a bit. Light use of space heaters will keep the basement rooms warm. The basement never gets hot in the summer.

mortfree
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Re: Mitsubishi ductless heating/cooling unit

Post by mortfree » Sun Oct 09, 2016 4:35 pm

segfault wrote:OP, what is the issue with the temperature in your basement? I live in a relatively moderate climate, and during the winter, the HVAC leaks enough that it warms the basement quite a bit. Light use of space heaters will keep the basement rooms warm. The basement never gets hot in the summer.
Basement is fine in summer

Winter time it gets really cold. The cold air just doesn't seem to have anywhere to go and it settles on the floor.

Have had several HVAC guys out and it seems like a mystery to them

Valuethinker
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Re: Mitsubishi ductless heating/cooling unit

Post by Valuethinker » Mon Oct 10, 2016 5:32 am

mortfree wrote:
segfault wrote:OP, what is the issue with the temperature in your basement? I live in a relatively moderate climate, and during the winter, the HVAC leaks enough that it warms the basement quite a bit. Light use of space heaters will keep the basement rooms warm. The basement never gets hot in the summer.
Basement is fine in summer

Winter time it gets really cold. The cold air just doesn't seem to have anywhere to go and it settles on the floor.

Have had several HVAC guys out and it seems like a mystery to them
Have you had it leak tested? It feels as if your HVAC might be drawing cold air into the basement?

Concrete walls just bleed heat. It may not be feasible to insulate them on the inside (and you have to be careful what happens to your dew point-- you can get condensation in the walls, ughh, but that may be your problem.

generally you want the exit points (for the ducts) close to the floor, if you can. The situation is ripe for underfloor heating, but that's a massive expense unless you are having the floor replaced for other reasons.

There is an HVAC forum people reference here, and a lot of experts on it. Worth posting there?

Ninegrams
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Re: Mitsubishi ductless heating/cooling unit

Post by Ninegrams » Mon Oct 10, 2016 3:03 pm

mortfree wrote:
segfault wrote:OP, what is the issue with the temperature in your basement? I live in a relatively moderate climate, and during the winter, the HVAC leaks enough that it warms the basement quite a bit. Light use of space heaters will keep the basement rooms warm. The basement never gets hot in the summer.
Basement is fine in summer

Winter time it gets really cold. The cold air just doesn't seem to have anywhere to go and it settles on the floor.

Have had several HVAC guys out and it seems like a mystery to them
One possiblity to consider is installing a ceiling fan(s)? If you run it in reverse it will slowly draw cold air off the floor while pushing warm air off the ceiling creating a even temperature mix in the room.

steelgtr
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Re: Mitsubishi ductless heating/cooling unit

Post by steelgtr » Wed Dec 05, 2018 11:55 am

How do you disable the condensation pump?

Carl53
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Re: Mitsubishi ductless heating/cooling unit

Post by Carl53 » Thu Dec 06, 2018 6:20 am

steelgtr wrote:
Wed Dec 05, 2018 11:55 am
How do you disable the condensation pump?
If your system was designed with one in it, it would likely be unwise to cut the electric to it.

steelgtr
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Re: Mitsubishi ductless heating/cooling unit

Post by steelgtr » Thu Dec 06, 2018 8:40 pm

Carl53 wrote:
Thu Dec 06, 2018 6:20 am
steelgtr wrote:
Wed Dec 05, 2018 11:55 am
How do you disable the condensation pump?
If your system was designed with one in it, it would likely be unwise to cut the electric to it.
Thanks, but I read it was only needed if the out door unit was higher than the indoor? Can't find any info online.

bob

Spirit Rider
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Re: Mitsubishi ductless heating/cooling unit

Post by Spirit Rider » Thu Dec 06, 2018 9:14 pm

steelgtr wrote:
Thu Dec 06, 2018 8:40 pm
Carl53 wrote:
Thu Dec 06, 2018 6:20 am
steelgtr wrote:
Wed Dec 05, 2018 11:55 am
How do you disable the condensation pump?
If your system was designed with one in it, it would likely be unwise to cut the electric to it.
Thanks, but I read it was only needed if the out door unit was higher than the indoor? Can't find any info online.
I don't know where you read that because it can be disproved by physics. So either you misunderstood or they were wrong. The condensation comes off of the evaporator coil because it is; ... well cold. This is what causes air conditioning to dehumidify.

Both the evaporator coil and air handler are in the internal ductless unit. The condensate is subject to the forces of gravity. If the coil pan is above grade and has a clear path it will drain without a condensate pump. However this is usually only practical if the internal unit is on an outside wall, like the one in my living room. If the internal unit is below grade (such as in a basement) or on an internal wall that does not provide an adequate uninterrupted downward slope, a condensate pump will be preferred/required.

The relative heights of the external and internal units only matter with regard to refrigerant lines. The manufacturer will have specifications on maximum line length and vertical differential. Any refrigerant based system will operate more efficiently closer in length and height. This is why you will sometimes see vertically elevated condensers.

steelgtr
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Re: Mitsubishi ductless heating/cooling unit

Post by steelgtr » Thu Dec 06, 2018 9:25 pm

Spirit Rider wrote:
Thu Dec 06, 2018 9:14 pm
steelgtr wrote:
Thu Dec 06, 2018 8:40 pm
Carl53 wrote:
Thu Dec 06, 2018 6:20 am
steelgtr wrote:
Wed Dec 05, 2018 11:55 am
How do you disable the condensation pump?
If your system was designed with one in it, it would likely be unwise to cut the electric to it.
Thanks, but I read it was only needed if the out door unit was higher than the indoor? Can't find any info online.
I don't know where you read that because it can be disproved by physics. So either you misunderstood or they were wrong. The condensation comes off of the evaporator coil because it is; ... well cold. This is what causes air conditioning to dehumidify.

Both the evaporator coil and air handler are in the internal ductless unit. The condensate is subject to the forces of gravity. If the coil pan is above grade and has a clear path it will drain without a condensate pump. However this is usually only practical if the internal unit is on an outside wall, like the one in my living room. If the internal unit is below grade (such as in a basement) or on an internal wall that does not provide an adequate uninterrupted downward slope, a condensate pump will be preferred/required.

The relative heights of the external and internal units only matter with regard to refrigerant lines. The manufacturer will have specifications on maximum line length and vertical differential. Any refrigerant based system will operate more efficiently closer in length and height. This is why you will sometimes see vertically elevated condensers.
Thanks, again. I looked at the service manual and don't even see an internal condensation pump. Could it be an add on? There is a pvc drain pipe at the external unit (Condensor?)

http://meus1.mylinkdrive.com/files/MSZ- ... ervice.pdf

steelgtr
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Re: Mitsubishi ductless heating/cooling unit

Post by steelgtr » Thu Dec 06, 2018 9:29 pm

Is there a even condensation pump on these?? Maybe I am hearing something else cycling on and off? Don't see anything in parts either:

http://meus1.mylinkdrive.com/files/MSZ- ... _Parts.pdf

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segfault
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Re: Mitsubishi ductless heating/cooling unit

Post by segfault » Thu Dec 06, 2018 9:46 pm

I've heard of using miniature condensation pumps in mini-splits, if the drain has to go "uphill" before going outside. If it doesn't, I think most just gravity drain.

Spirit Rider
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Re: Mitsubishi ductless heating/cooling unit

Post by Spirit Rider » Thu Dec 06, 2018 9:47 pm

steelgtr wrote:
Thu Dec 06, 2018 9:25 pm
Thanks, again. I looked at the service manual and don't even see an internal condensation pump. Could it be an add on? There is a pvc drain pipe at the external unit (Condensor?)

http://meus1.mylinkdrive.com/files/MSZ- ... ervice.pdf
Look at the 3 SPECIFICATION on Page 6, "Cond. drain connection O.D. .in 5/8" and the 4 OUTLINES AND DIMENSIONS on Page 8 middle right, diagram and table "drain hose"

The drain hose has to be hooked up somewhere. Usually, this is to just a drain line outside, optionally where needed a drain line to a condensate pump to a line outside or sometimes to a PVC pipe through a hole in the concrete floor in the basement.

You will not find a condensate pump as part of the minisplit. It is a third party product only used when needed.

jstat
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Re: Mitsubishi ductless heating/cooling unit

Post by jstat » Thu Dec 06, 2018 10:18 pm

Maybe I am hearing something else cycling on and off?
Maybe it is going into defrost mode? I have heard some strange noises when using it to heat in cold weather.

steelgtr
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Re: Mitsubishi ductless heating/cooling unit

Post by steelgtr » Fri Dec 07, 2018 12:01 am

jstat wrote:
Thu Dec 06, 2018 10:18 pm
Maybe I am hearing something else cycling on and off?
Maybe it is going into defrost mode? I have heard some strange noises when using it to heat in cold weather.
This is on Maui and I think it's AC only.

bob

Spirit Rider
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Re: Mitsubishi ductless heating/cooling unit

Post by Spirit Rider » Fri Dec 07, 2018 10:09 am

This might be what you are hearing turning on and off. A condensate pump typically contains a tank with float switch to dynamically turn on an off.

steelgtr
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Re: Mitsubishi ductless heating/cooling unit

Post by steelgtr » Fri Dec 07, 2018 12:22 pm

Spirit Rider wrote:
Fri Dec 07, 2018 10:09 am
This might be what you are hearing turning on and off. A condensate pump typically contains a tank with float switch to dynamically turn on an off.
Thanks, and to be clear, any condensate pump would be an aftermarket add on?

bob

jstat
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Re: Mitsubishi ductless heating/cooling unit

Post by jstat » Fri Dec 07, 2018 12:53 pm

Sounds like an add-on. Maybe one of this? https://www.ecomfort.com/Mitsubishi-SI3 ... 30576.html

steelgtr
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Re: Mitsubishi ductless heating/cooling unit

Post by steelgtr » Fri Dec 07, 2018 1:07 pm

jstat wrote:
Fri Dec 07, 2018 12:53 pm
Sounds like an add-on. Maybe one of this? https://www.ecomfort.com/Mitsubishi-SI3 ... 30576.html
Good catch! :

https://www.youtube.com/watch?v=cTpNHyTl6es

nordsteve
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Re: Mitsubishi ductless heating/cooling unit

Post by nordsteve » Fri Dec 07, 2018 8:33 pm

My installer used a pump from Aspen https://aspenpumps.com/

michaeljc70
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Re: Mitsubishi ductless heating/cooling unit

Post by michaeljc70 » Fri Dec 07, 2018 8:47 pm

I have never had one installed. I have rented many apartments around the world though that have had them. They are used a lot in foreign countries in old buildings without ductwork. I found them great to use. Most have remotes that let you set the temp,time, etc. I always wondered why we didn't use them more in the US. I know if you have ductwork central AC is great, but where I live a lot of the old buildings have radiators and I don't think I've ever seen these split units used.

Spirit Rider
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Re: Mitsubishi ductless heating/cooling unit

Post by Spirit Rider » Fri Dec 07, 2018 9:56 pm

Minisplits are far more common and less expensive than when I installed mine more than 20 years ago. I had no choice because I had a hydronic heating system and 100% casement windows.

However, in most houses with hydronic heating systems and single/double hung or sliding windows, window air conditioners are still far more cost-effective than minisplits.

cadillex
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Re: Mitsubishi ductless heating/cooling unit

Post by cadillex » Sat Dec 08, 2018 1:58 am

we just installed a mini split 2 summers ago in NJ. went with a daikin with cooling and heating.
reason we picked daikin was it allows for mounting of indoor unit within 2 inches of the ceiling. others specified 6-8 inches.
in our low ceiling older house that would have looked really dumb.
outside units can be mounted on concrete blocks or higher up if wanted. we went higher to be above flood levels.
we were professionally sized, and the unit is still too strong.
we can get cool very fast, but not very good at dehumidification.
these units are known for being bad at dehumidifying.
if its 95 degrees out the unit runs hard all day and the humidity is drawn down to lets say 50%.
but in the evenings without the high heat load, the units are designed to be very efficient so they spool down.
they dont run as much and as a result the temp is maintained , but the humidity goes up all night long.
by morning we are 70 degrees 82% humidty !!
if its not 95 degrees outside, lets say only 85, the problem arises in late afternoon already.
moral of the story, if i knew then what i know now, i would have UNDERsized the unit.
which would have forced it to run harder and longer, which is the only way they dehumidify effectively.
i rather it be 75deg and 45% humidity, than 65deg and 80% humidity.
we have a 18k btu unit. should have gone undersized at 12k btu.
my father is an HVAC tech. and we were convinced 18k was right size. based on our calculations and the recommendation of the installer.
next time will not make same mistake.

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