Micoe Heat Pump - A Dead Loss
All I can do is warn everyone here away from Micoe heat pumps, wherever in the world you are.
I've figured out a number of problems. First, its control of the three-way valve (DHW or hydronic) is backward from others, so I had to replumb the 1" lines, swapping the roles of DHW and hydronic. This is a Euro valve so requires 230vAC, so I send it L1 and L2 to blue and brown. Black is the control, so it needs connected to its opposite (L1 or L2, depending on how the outside is wired. Bottom line: now the infernal heat pump appropriately switches the valve according to whether I select DHW or hydronic, or both.
I actually got the damned thing to heat the house for several days in hydronic mode, after purging tiny bits of air using scores of gallons of water. But the need for a shower became intense. I switched it to DHW and oh, I heard air. Purged and purged and purged, but it still faults on 'water flow' switch.
It is hyper-sensitive to air in the system and faults. It has an air purge, and I have an air purge, but they're not enough. Either the cheap-arse pump can not prime when a few bubbles, or the flow switch is badly located.
I know that some here are DIYers, but I am a developer and am the final say in tech support for all aspects of building houses with the most advanced techs -- seismic-safe, non-combustible, exceptionally energy efficient. I am ultimately responsible for everything in my business, because I do not shuck that responsibility as so many weaklings do. I have to be good, not least to keep good people and lead by expertise rather than fear.
For those who come here looking for an AWHP, I recommend Arctic Air. They are also made in Red China (yeees, it is still a Communist State) and can be had much cheaper than from Arctic, but I don't want to help the Haters.
And to Micoe: I am a developer. I am currently building out a 9 unit development of houses >$1m each. (Seattle) My own house is my test-bed. tsk tsk. Your tech support responds to me with "I see", and "millions of units work everywhere else", lol. IOW, 'too bad, so sad.' Bonus: I have developer friends. I will certainly apprise them of my findings.
Comments
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same crap you posted on H- Talk
Sorry no sympathy.
you buy chinese crap on line you get what you pay for.
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Wiring diagrams being a bit off is pretty common for these. Had to use a multimeter to figure out which way mine would drive the 3 way valve for DHW mode, I would not call that a big issue.
As for air purging, no heat source likes air in the loop and getting all the air out is never easy. A good purge setup with high flow connection to an external water source usually works. I would not blame equipment on something that is so dependent on actual install.
Post a link to the install manual of your unit, might see something there that would help you figure it out.
First install of any new technology is never easy if you have never done it before. AWHP is no different than figuring out a new modcon.
P.S. Wait till you get to trying to configure the HMI, those are extra fun.
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these engineers generally know what they’re doing. I often amaze myself, I get a glitch on a job, I call the tech person, and sure enough there’s something I missed in the finer aspects of the installation.
Everything changed, a couple decades ago an installer could open up a box and install it without reading a single word in the manual (those appliances still exist, I’m talking about the modern stuff)
installers are creatures of habit, like most people in society. You’re positive something wasn’t missed? Yes, sometimes there might be a defective part, Sensor , Control. But often times it’s the installer
Before you go ripping things out it might be good to slow down and go through the whole thing with a smart installer that’s not in a hurry. Sometimes, pushing air out of a loop isn’t a slam dunk. In any case, I hope it works out.
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Systems running chilled water, or low temperature hydronics take a bit more patience to get all the air out.
The Viessmann A2WHP includes a microbubble remover in the box. Although I used a different model to clean up the piping.
In my case this was also the highest point in the system so it vented as I filled and within an hour the fluid was 100% air free. Glycol gives up it's air slower also.
I have some glass tubing in my system to observe the air removal process. The blue colored glycol ran milky for a while before all the microbubbles were removed. Temperature increase helps air removal also.
Truth be known many of the HP systems come from the same factory and have different brand names on the box.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
good eye!
yes the parts are common to both. These are just seeds and stems I have lying around the shop that I assemble for different demos or personal use.
The polymer media inside is also the same for dirt and air.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Thanks folks.
Interesting pics hot_rod. A "microbubble remover", huh. Is that what the Calefi is? Because it's identical to mine. Never know what to do with that darned cap — leave it tight or loosen it? Isn't that the vent?
On the outside supply line of mine I have two drops, one with a female hose fitting and the other just an ell. Cutoff ball in between.
I stop then start the machine (takes a minute or so to start its pump), then connect the hose, open the ell then open the hose — this sends hose water into the house, and since I'd set the controller to DHW the T-valve routes to the buffer tank coil, out the coil, back to the heat pump, through its system then out the ell. (I never close off the discharge while the hose is on… might not be good for the machine. Might blow up the machine. I have make-up water set to 15psi)
I have noticed a foaminess often in the discharge, like microbubbles.
This isn't my first install and I'm rather careful. Know a good deal of electronics — was Depot Repair in Air Force Intel 50 years ago, lol. {snif} I charge the system with 5 gallons of 95% propylene glycol, and tint it with river dye so I can spot leaks under the carpet or elsewhere, or at least know I have a leak if it loses tint. Propylene glycol because it's food-grade and my DHW coil is single-wall.
That red knob in the machine is a bleeder from its highest point, and it always squirts out water.
Also, I don't know what to do about the pipe connections. Running them straight in could result in material fatigue if you have the holes sealed really tight, so I generally build in a zig-zag.
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Red knob looks to be the PRV for the unit. There is usually a separate air vent, normally near the top of the plate HX.
95% glycol won't fly as it is too thick. Get a mix for your local climate. You can also run water with some precautions (I'm zone 5 and that is what I run).
I'm guessing the strainer is on the intake. Depending how the interior is plumbed, that dip down will hold air and the built in pump will not be be able to purge it.
What is the rest of the piping?
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The red knob does purge from about the top of the heat exchanger. It lets out water.
Keep in mind that my system is full of water. This 95% glycol comprises about 25% of the total volume.
Yes the strainer is on the intake, and indeed air does accumulate in the house behind this in the ceiling of the basement. I've put in a purge valve for this. The circ piping is PEX-A jags up, then the rest is below the heat pump level in the basement. Hydronic in the floors is all PEX just above the level of the heat pump, and at the top of its manifold is my air purge.
I finally seem to have purged all air and the system does not fault on water flow. However when set to DHW 50*C for a while, I set it to Heat, and it has the darling attribute of starting at 77*C and faulting on overpressure, even with Heat set to 50*. I suspicion this is because it monitors DHW at the buffer tank while in that mode, and heat temp at the unit output when in Heat mode, so when in DHW the output is always scalding. When in Heat mode the temp ultimately comes down to the setpoint. It really hurts itself and costs energy when in DHW mode.
I've also noticed that it is not actually changing the voltage on "terminal 11", keeping the three-way forever on DHW. I should mention that what is -labelled- "terminal 11" on this unit is terminal 10 if you actually count the screws! What the f*ck?! So I measured the voltages on terminals 9-12 while changing the unit between heat and DHW — NONE OF THEM CHANGE IN ANY WAY in reaction to the change in mode. There is no way that this heat pump can automatically switch the three-way valve, with this firmware.
I complained to Micoe about this and asked for a firmware update, and this is when I was told that "millions of units are working fine worldwide." Bilgewater. Road apples.
So I can have heat… or I can have hot water and fault on high (refrigerant) pressure. And I have to switch them manually. What a terrible, unusable heat pump. Shame on Micoe.
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" I charge the system with 5 gallons of 95% propylene glycol, and tint it with river dye so I can spot leaks under the carpet or elsewhere, or at least know I have a leak if it loses tint."
This statement worries me. The fact that you're anticipating it losing tint makes me think you have it connected to automatic makeup water. If you're using glycol that's a really bad idea. It's much better to let it get low on fluid if there's a leak than for the glycol to get diluted.
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35- 40% glcyol covers even the coldest of climates. A refractometer, even a floating ball type from an auto parts will tell you if it is too rich. Rich glycol mixes take days to get all the micro bubbles and entrained air out, especially at cold fluid temperatures
Two things about a thick mixture it is harder to pump, and the heat transfer goes down Of course this happens when the HP needs to work it’s hardest
I threw a flat plat HX on mine, so Im dealing with about 4 gallons of glycol, instead if 30 or so to do the entire system in glycol
You should use a glycol fill tank and not a connection to the potable water
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Post a link to the manual for your unit and wiring diagram. Quick google is not turning it up and hard to troubleshoot without it. For example, my AWHP needs to be configured to drive the 3 way valve for DHW. You might have also blown the fuse for the 3 way valve drive if it was miswired.
On the return pipe to the AWHP, at the high point inside the house, you might want to put an air separator with an auto air vent. This would avoid that getting air locked if any air gets in the system.
For your plumbing side, do you have any other pumps outside the one in the unit? Any zoning?
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DCContrarian I do have makeup water. But in 8 years no leaks, so it only comes into play when purging.
hot_rod I have my glycol mix at about 25%, so there should be no problems there.
Kaos Here's the service manual:
I have the MMHP15D1 and on page 51 it says the "SV2# 3-Way Valve (to Heating)" is terminal 10 (labelleled and referred to by Micoe as "11"). Picture in the manual shows labelling correctly as per a count.
Page 56, SV1 shows how the three-way should be wired, and how Micoe told me to connect it, with them providing this screenshot. Unfortunately actual terminal 10/ labelled pin 11 is powered no matter what the mode is set to.
Here are my measurements while setting the machine to the respective modes:
Unfortunately none of the terminals show a capability of powering the three-way. Oh Neutral-9 shows a possibility, but really? When I am instructed 10 or 11? I always play strictly by the rules, but maybe I should try terminal 9?
In the basement equipment room I do have a powerful circ-pump in the return line, a Grundfos UPS15-58FC. I've never understood head pressure nor sizing of circ pumps.
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#31 on the expolded parts diagram is the auto air vent. These usually come with the cap tight, you can open it to allow air out. Make sure to close it once primed though.
My reading the 3 way valve connects to 8, a hot and one of the neturals. When 8 is energized it the valve should switch to DHW port, when de-energized, it should be to heat. There also different types of valves, which one you have as some require a power signal to both open and to close. In case the terminal block labels are off, should be to wire OUT5.
There should be a DHW tank temperature sensor connected to T16 on the motherboard.
Do a quick sketch of your pluming setup. Include all pumps, valves and any tanks/buffers.
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Try the terminals with a test light of the appropriate voltage or a wiggy. If they are solid state switches they may always have voltage or no voltage with no current but switch if they allow current to flow or not. You may need a small load to test them.
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Kaos yes the cap on the air vent is loose for now. I don't understand the rationale for tightening it?
Terminal 8/OUT5?! The valve I have is energized for DHW (the way it's plumbed, backwards from before), and when not energized it automatically drives back to the default state of heat. I believe this is done with a spring, although I've only tried it with power connected.
I do have the DHW tank thermistor in the tank. To read Heat temp it relies on heat pump supply out temp. This is what goes ballistic while on DHW. (77"C) I'm late for work now. I'll try to do a sketch tomorrow.
mattmia2 good point. Outputs may need to be loaded to get a good reading as everything is switching power supply.
Meanwhile I'll move my three-way control wire to terminal 8 as Kaos suggests.
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Terminal 8/OUT5 is unresponsive to Mode, as with most of the other terminals.
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