The issue is with the compressor .... they have a ramp down minimum. Some of the units are 66% ... so with 36k that's about 1T .... with a 9k head it has no place to send it.
The multi heads are always bleeding to all the heads.
MRCOOL DIY Mini Split, Seriously, I Think...
- Thread starter Spdstr280Z
- Start date
The issue is with the compressor .... they have a ramp down minimum. Some of the units are 66% ... so with 36k that's about 1T .... with a 9k head it has no place to send it.
The multi heads are always bleeding to all the heads.
And an update on my warranty replacement saga for 2 year old unit...
As mentioned previously, getting into the third season of cooling with our 2-ton unit, it wasn't blowing cold, and icing up, so a tech came out and charged it, tested and found a leak where the flex line meets the rigid section at the air handler.
It took 3 weeks to get a warranty replacement from Ingrams', that being due simply to a backlog of orders shipping out. It did finally arrive, a no-charge invoice for a new air handler, and I removed the old one and installed the new one.
It worked great but not cold enough. I was pretty sure some freon leaked out between the time the tech charged it and I determined I was getting a replacement - and so I turned of the gas valves at the compressor unit. Fortunately we had a solid week-plus of cooler weather so we didn't need AC.
Saturday my tech came back out and put his fancy gauge on it that shows all the pressures and temps, and that is how he determines freon level - temp drop from liquid line to air output, etc. Anyway, it was about half down on freon so with another pound of gas or so the thing is working stellar now. Output air temp was about 68 degrees, now at 54.
The only drawback for the DIY warranty claim is troubleshooting and diagnosing the problem, and then waiting for and doing replacements. This process took us about a month. So it's no quite like calling your HVAC contractor and they show up the next day and fix your AC unit. But we're happy nonetheless, and our house is a balmy 75 degrees on a 90 degree day.
All's well that ends well, eh??
Don't want to beat a dead horse ...... weight is how you charge a mini. It's not pressure. The charge is removed and the new is weighed in -- since the expansion occurs in the outside unit the lines are in effect all vapor.
FYI, I called Ingram's and they were not able to give an estimate on backordered units. The person I spoke with gave me a best guess of 2 months.
That was all I needed, so that I could plan next steps. I certainly have 2 months+ of finishing work to keep me busy.
(Edit: I forgot to mention, their hold messages are hilarious.)
That was all I needed, so that I could plan next steps. I certainly have 2 months+ of finishing work to keep me busy.
(Edit: I forgot to mention, their hold messages are hilarious.)
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This inverter compressor does not start at max RPM and then ramp down as the system finds the set point programmed by the air handler. It starts at the lowest RPM and ramps up. If the actual room temp and the setpoint are only a few degrees apart, then the compressor will never come anywhere near full capacity. Like the modulating boiler, the inverter system senses both indoor and outdoor temperatures and applies power to the compressor accordingly, with variable speed. I use a nest thermostat to gauge RH and this system keeps the place dry. The compressor will cycle off completely once temps are reached, and cycle according to need. With only a 6K delta between the size of the 3-head compressor and this 4 head compressor, i would not expect an extreme difference with performance.
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The compressor is hampered with a minimum output .... most are 33% ... so your compressor at start up is putting out 1T of cooling. They don't start at 0%
Even at 25% -- you are doing 9k. That's more than the 6k head .. if that is the only head calling it has to shut off at set point ... and 3k is wasted.
At 1T -- both 6k heads max output .... they can't modulate.
The goal is for the units to run all the time .. the multi systems require more thinking and calculations ... you can't use the specification for the singles or think the head is going to manage the load.
The heads are stupid -- it's a fan and heat exchanger. The magic is all happening at the compressor. That's what's directing the output. The key with the multi systems is don't oversize the compressor to house load or heads -- think if them as zoning where the compressor will move temp around a building.
Even when a head is off -- there must be refrigerant flow to it .. so you want them on.
There are also tables where you can see the max output of each head .... with many of the multi units you can't get the full output.
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I must admit, you lost me. When the heads are calling for coolant, I can hear it cycling through the head unit. When not, all you hear is the fan. When none of the heads require coolant (when temperature is reached), that compressor is off and the only thing running are the air handler fans. I know a lot of people like to overthink these minisplits as some super-secret voodoo science that requires 20 years of HVAC experience and licensing, but here's the thing; it's a DIY unit. It works for me. and I can tell you (first hand, because I installed the fu**ing thing), it efficiently keeps RH at a minimum and the house cool.
Could it be more efficient? don't know and don't really care TBH
Could it be more efficient? don't know and don't really care TBH
When looking for mini's the lack of reviews was a no no for Mr. Cool, this was over 2 years ago. Next negative was the 25' lineset looped behind the unit, ah no thanks. Maybe out behind the barn, but not on the side of the house. Now they have shorter lineset that could be installed in a serpentine fashion behind the unit.
I monitor the forums for mini problems for my own education and there are surprisingly few of them. The bulk of which are refrigerant loss do to improper flaring, which Mr C eliminates.
I monitor the forums for mini problems for my own education and there are surprisingly few of them. The bulk of which are refrigerant loss do to improper flaring, which Mr C eliminates.
It's a question of how much refrigerant is going to each head. If only one head is calling .... what is your compressor to do? If it must make 1T of cooling (1/3 of 3T ... you have a 36k BTU unit) -- it's got to sent it out. The 6k unit is never able to modulate ... I have no idea what the head produces under max w/ low fan. The problems show up in moderate temps when the heads can't put out 1500BTU for a moderate load.
Since the multi units always have to be producing something to each head they work great when doing a whole house or a big chunk of a house where you are maintaining some conditioning ...
It's a matter of doing each room/ area -- looking at the head range outputs and then looking at the overall area or house load. The compressor gets matched to this load w/o oversizing as they can ramp above the stated output. I have a three head unit in a big extended cape -- two of the heads are set to maintain 80 degrees much of the time for large bedrooms in the older part of the house and the final unit does a large room with a lot of glass. in the new. This way the load is being used .... A multi is not the best when heads are off and the compressors minimum is not effectively being used
Obviously -- there is no way to capture the lost 6K .... you would almost be wise to install another head.
The connections are the number one problem ... Second is leaking heads - and that is often from installs.
For the price point. The Mr Cools are a great way to go for lots of handy people. Now with the new Gen 3 and ability to pick line sets it's even better. Simple install situation like a garage ... it's a perfect fit. In a cold climate you can self install a modulating cabinet heater and now you have the best of everything for $3500.
For a house there may be other considerations ....
My Old Tools
Well-known member
How you like?? You got the 3-ton, right?
My Old Tools
Well-known member
3 ton. It cooled the shop down pretty quick. Nothing particularly difficult about the install. The 36k head is a handful to climb a ladder and hang by yourself. We'll see how it does when it hits 100 again. It pulled several gallons of moisture out pretty quick.
Awesome. 
Yeah, the 3-ton compressor unit is the same as the 2-ton, but the air handler is 49" long vs 42", which is the same as the 18K. The 1-ton is 31" - much easier to handle.
I had quite a time getting ten feet up a ladder with it, while feeding the lineset through the hole in the wall, and then getting it hung on the bracket. I sweat like a pig.
Compressor units - 1 ton vs 2 ton:
Yeah, the 3-ton compressor unit is the same as the 2-ton, but the air handler is 49" long vs 42", which is the same as the 18K. The 1-ton is 31" - much easier to handle.
I had quite a time getting ten feet up a ladder with it, while feeding the lineset through the hole in the wall, and then getting it hung on the bracket. I sweat like a pig.
Compressor units - 1 ton vs 2 ton:
tailshaft56
Well-known member
The window units I have looked at use resistance coils for heat. works like a standard electric heater.
tailshaft56
Well-known member
I am sure they could have taken more than 1 card to split the charge up.
MrCool is a heatpump - runs in reverse for heat. Works pretty well too, but you get condensate on the outside unit then.
In cold weather you need them up on some form of leg -- pan heater
I just got my 3rd gen 18k DIY installed this week. At coldest setting on Turbo it's reading 6 amps using my clamp meter. Not sure if I'm doing it wrong? That's half what I was expecting.
I have it set at 86 and it's keeping the garage there without seemingly working very hard. lt's drawing about 3.3 amps during the day on the few times I've checked it and it hit 116 out today.
To measure I'm checking each of the hot legs to the compressor and using the higher value. They're only about 100ma diff between them.
juddspaintballs
Well-known member
I didn't take any pictures, but I installed my DIY 12k today. It was really simple. I have line enough that it goes to the opposite end of the outdoor unit then loops back and makes the connection on the right side. Seems about perfect.
I have the MrCool brand cover kit. It covers 12'. I need to cover about 16'. I literally need just one more 4' straight section to finish the exterior installation. Anyone have a 4' section of the MrCool lineset covers that they'd like to sell me?
I have the MrCool brand cover kit. It covers 12'. I need to cover about 16'. I literally need just one more 4' straight section to finish the exterior installation. Anyone have a 4' section of the MrCool lineset covers that they'd like to sell me?
I really enjoyed the AC at first. I refered a friend to one and helped him install it and he loves his. But then I had problems with the scheduling and they took several calls in to get anyone to respond. Finially got the scheduling and they then told me that if I wanted to use scheduling I could not use the remote,but had to use my phone. I do not carry my phone all the time and if in the garage it would be nice to just pick up the remote and lower the temp.
Next problem was about a week after getting the scheduling up and renning I started to recieve E1 error. Again it took several phone calls and no response I then emailed them and we went back and fourth during the troubleshooting process but I never recieved the next step to do. I emailed them a couple of times and did not get any reply. The first email was sent June 26. A month without AC in AZ is horrible. I can not use my garage because of the excessive heat Today is 107 and the garage is showing 110.
I regret buying any product that the company does not stand behind their product.
Next problem was about a week after getting the scheduling up and renning I started to recieve E1 error. Again it took several phone calls and no response I then emailed them and we went back and fourth during the troubleshooting process but I never recieved the next step to do. I emailed them a couple of times and did not get any reply. The first email was sent June 26. A month without AC in AZ is horrible. I can not use my garage because of the excessive heat Today is 107 and the garage is showing 110.
I regret buying any product that the company does not stand behind their product.
juddspaintballs
Well-known member
SALIV8
Well-known member
Looks great!!
JackOfDiamonds
Well-known member
I've heard conflicting reports...my biggest problem with the Mr. Cool is still the fixed length of lines. Can you buy these things with different lengths of pre-charged lines yet? If I am stuck with 25 feet of pre-charged line, It's still no good. I only need about 10-15 feet of line, and if I have to hire a HVAC company to shorten the lines it defeats the purpose.
My Old Tools
Well-known member
I understand they have 16' lines as a separate item. Call and ask. Or just move the outside unit down a ways like I did and use up the extra length.
Okay, so I decided to explore a little more into the flexible lineset on the DIY MrCool, since I now have a new air handler, replaced under warranty.
In disassembling it, I found it to be very easy to take apart, and that overall the design and engineering is very good. They really are pretty simple once you see inside them.
Here's how the lineset is attached to the coil - yes, it's all one piece. My assumption is that the flex part of the line is welded on after the air handler assembly is built. Even the hard part of the line near the coil, would be very hard to kink when handling it for installation. The piping is corrugated and it's very strong - I folded it over several times and it took a concerted effort to actually get it to kink. Both lines had anti-kink coils installed on them before assembly - they're what look like black covers:
The plastic housing has three screws in the front, two under tab covers in the lower lip, and one on the front behind the flip-up door. From there, just a couple of screws the the covers come off and the whole control board just slides right out. There's a terminal block that connects the controller wires to the board, and a couple of screws and the motor housing and door actuator motor just pop out. Same for the fan cage, it just slips right out with the end bearing set. Super easy.
I decided to hang onto the electronics and the motors as spares. Kept the front door and the blower cage - can sell those as spares. In particular, the front door is flawless - they are easily damaged in shipping, so surely someone along the way is going to need/want a replacement door.
The cooling coil is a very simple affair, and nicely made. I suppose it's possible one could get a leak somewhere in this assembly. It's really durable though.
Hopefully this answers some questions on how these things are put together, and confidence to tackle the job of disassembling one for repairs if necessary. Replacing any of the components is actually pretty easy, board, the motors, etc.
And let me know if you need some parts for a 2-ton DIY.
In disassembling it, I found it to be very easy to take apart, and that overall the design and engineering is very good. They really are pretty simple once you see inside them.
Here's how the lineset is attached to the coil - yes, it's all one piece. My assumption is that the flex part of the line is welded on after the air handler assembly is built. Even the hard part of the line near the coil, would be very hard to kink when handling it for installation. The piping is corrugated and it's very strong - I folded it over several times and it took a concerted effort to actually get it to kink. Both lines had anti-kink coils installed on them before assembly - they're what look like black covers:
The plastic housing has three screws in the front, two under tab covers in the lower lip, and one on the front behind the flip-up door. From there, just a couple of screws the the covers come off and the whole control board just slides right out. There's a terminal block that connects the controller wires to the board, and a couple of screws and the motor housing and door actuator motor just pop out. Same for the fan cage, it just slips right out with the end bearing set. Super easy.
I decided to hang onto the electronics and the motors as spares. Kept the front door and the blower cage - can sell those as spares. In particular, the front door is flawless - they are easily damaged in shipping, so surely someone along the way is going to need/want a replacement door.
The cooling coil is a very simple affair, and nicely made. I suppose it's possible one could get a leak somewhere in this assembly. It's really durable though.
Hopefully this answers some questions on how these things are put together, and confidence to tackle the job of disassembling one for repairs if necessary. Replacing any of the components is actually pretty easy, board, the motors, etc.
And let me know if you need some parts for a 2-ton DIY.
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So where was your leak?
The units come with the first flex ..... it's attached to the heat exchanger prior to assembly.
The DIY are post factory products -- they have the line set and any other provision for line movement (flex) installed after the unit is constructed.
The corrugated extension allows for kink free adjustment -- but it's still firm enough to damage the exchanger if you don't support properly.
Normally -- the stub piping would all be open and visible. With the attached line set being covered most don't understand you have to be careful ... just moving the line set transfers back to the heat exchanger
The units come with the first flex ..... it's attached to the heat exchanger prior to assembly.
The DIY are post factory products -- they have the line set and any other provision for line movement (flex) installed after the unit is constructed.
The corrugated extension allows for kink free adjustment -- but it's still firm enough to damage the exchanger if you don't support properly.
Normally -- the stub piping would all be open and visible. With the attached line set being covered most don't understand you have to be careful ... just moving the line set transfers back to the heat exchanger
In my case, the leak in the lineset was right at the junction of the flex part to the fixed part, liquid line. Or assumed to be. A tech used an audible sensor, and that's where it beeped.
It may be 'post factory', or 'post production', but definitely done at the factory. Ingrams isn't welding linesets to the air handlers and repacking them. These units are factory-sealed cartons.
It may be 'post factory', or 'post production', but definitely done at the factory. Ingrams isn't welding linesets to the air handlers and repacking them. These units are factory-sealed cartons.
As I said back way back in the thread. The point where the line comes to the heat exchanger is a failure point. My guess is moving the line around w/o proper support for that spot cause the pipe to fail after many heat/cool cycles
With a typical head unit the line ends after that flex. That's the point where you connect the regular line-set to the head unit using a flare fitting. When you do a typical head -- it gets installed and then the line is attached. Or when doing a new install -- the head is mounted on a section of drywall and all the lines are positioned -- the the the head unit is removed w/o attaching the line set until the drywall is finished. Head unit placed and lines connected.
The long line attached causes problems when installing -- it's heavy and difficult to maneuver and twisting and pulling occurs.
What I am say about post production -- the heads are all done the same as they are manufactured. They take manufactured heads and add the line sets ... some companies add another flex in the line to help take some of the shock from moving the attached line.
It like in the car business -- some specialized vehicles are post production modifies. Done in a factory ... just not when first produced.
The new Gen 3 with the separate line-set elements this problem .... my guess is they had quite a few of these leak.
With a typical head unit the line ends after that flex. That's the point where you connect the regular line-set to the head unit using a flare fitting. When you do a typical head -- it gets installed and then the line is attached. Or when doing a new install -- the head is mounted on a section of drywall and all the lines are positioned -- the the the head unit is removed w/o attaching the line set until the drywall is finished. Head unit placed and lines connected.
The long line attached causes problems when installing -- it's heavy and difficult to maneuver and twisting and pulling occurs.
What I am say about post production -- the heads are all done the same as they are manufactured. They take manufactured heads and add the line sets ... some companies add another flex in the line to help take some of the shock from moving the attached line.
It like in the car business -- some specialized vehicles are post production modifies. Done in a factory ... just not when first produced.
The new Gen 3 with the separate line-set elements this problem .... my guess is they had quite a few of these leak.
ncfireman1918
Well-known member
Ross,
I have the same type red iron building, and am considering a Mr Cool for it. I have OSB walls on the lower section, and was thinking that I’d mount it on the OSB. Your install has me thinking that mounting higher might be a better plan. How did you end up mounting yours to the column? Did you just do some sort of plate to mount the bracket to, or did you fab up some sort of bracket for the bracket? Just curious as I haven’t seen any other installs done the way you did it. Thanks!
Chris
My Old Tools
Well-known member
Dirt simple, I found a piece of scrap 3/4" plywood in the shop about the size of the metal backing plate. I mounted it to the I-beam with 1/4" bolts. Screwed the plate to the plywood and called it good. The inside unit isn't very heavy, but its bulky and hard to climb a ladder with. I wanted it high enough to use the wall girt as a trough to carry the line set.
I gotta say, not withstanding all of the nay-say, watch-out-for-this-and-that, DIY is DANGEROUS F.U.D. put out by yeldogt, having a multi-zone mr. cool (three heads and a 36k condenser) has proven to be AWESOME, at leat for me. Nothing against you, yeldogt, I appreciate the warnings, but for 1/5+ the cost of an HVAC quote in my area, it's all good. All good, indeed (magically controlled with my cell phone. Aaaahhhh comfort)
Since there's no 'like button'...
Wife is bugging me for a two-head for the back bedrooms to complete the house. Since we're empty-nesters in a four bedroom house, and we really only need AC for a few weeks a year (more now it seems) I drag my feet.
We've had record heat for a couple of weeks - 110-112 last weekend, it was hotter than hades. With the 15' ceilings it's only good for about a 30* drop, so it was a little warm late-afternoon. We would have had to move out of the house otherwise. LOL At least our master suite stays nice and cool.
Since there's no 'like button'...
Wife is bugging me for a two-head for the back bedrooms to complete the house. Since we're empty-nesters in a four bedroom house, and we really only need AC for a few weeks a year (more now it seems) I drag my feet.
We've had record heat for a couple of weeks - 110-112 last weekend, it was hotter than hades. With the 15' ceilings it's only good for about a 30* drop, so it was a little warm late-afternoon. We would have had to move out of the house otherwise. LOL At least our master suite stays nice and cool.
For 1 or 2 rooms I have been watching the inverter window units coming on the market. Of course could make an opening and not use a window. Less cost and work than a mini.
Window units just won't work in this application - I would have to cut a hole in the wall as both rooms have sliding doors rather than windows. And they would intrude on the walk space on the patio where these rooms abut to. Otherwise we would have installed them years ago - I think even the plain-jane cheapo window units work great - not like a portable unit where it exhaust so much inside air to the outside. I just don't see the value in the latter at all, and really think they should be taken off the market.
So mine has been running happily for a couple months till today. it's just dead. Won't come on, no lights, fan or error codes. Thought it was the condensate pump cutting power to it but verified the tank was empty and clean.
The 1 and 2 terminals both show 120v to ground so the pump is not interrupting power to the unit. It just won't come on. Any ideas? I have not called yet. Just noticed it a couple hrs ago.
3rdgendslmech
Well-known member
Check the batteries in your remote?
ItsJustJoe
Member
Finally got mine installed, and I'm very happy!
With the orientation of my garage, panel box, window, stud orientation, and wall thickness, the head location inside isn't aesthetically perfect, but it's functionally awesome. I sanded, cleaned, and painted my line set cover kit, so it is less of an eyesore to the neighbors. The extra line coiled up against the house is however an eyesore, so I am going to make a little fence the height of the condenser to help hide it from the front/street. Only been running for the weekend, and the temperature was perfect in my garage without the unit - but in the test runs it blew really cold and hot, and the app works surprising well - better than the remote.
https://photos.app.goo.gl/N7QC2yy2b6rYEMUf6
With the orientation of my garage, panel box, window, stud orientation, and wall thickness, the head location inside isn't aesthetically perfect, but it's functionally awesome. I sanded, cleaned, and painted my line set cover kit, so it is less of an eyesore to the neighbors. The extra line coiled up against the house is however an eyesore, so I am going to make a little fence the height of the condenser to help hide it from the front/street. Only been running for the weekend, and the temperature was perfect in my garage without the unit - but in the test runs it blew really cold and hot, and the app works surprising well - better than the remote.
https://photos.app.goo.gl/N7QC2yy2b6rYEMUf6