Mitsubishi Components in Air-to-Water Heat Pump
rhl_
| Posted in General Questions on
Has anyone considered building an air to water heat pump with Mitsubishi components? For example just buy an outdoor unit and hook it up to a buffer tank and a heat exchanger. Can the indoor units use water as a transfer medium ?
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pretty sure that is exactly what the Chiltrix by hotspot energy is.
One would think that air to water heat pump manufacturers would make a simple "hydronic head" and sell it in the US at a reasonable cost. Apparently not.
My understanding is that the heads used in heating/cooling mini-splits don't include the metering valve (it's outside) - so there isn't much going on in the interior unit.
Make that "air to air heat pump manufacturers". Lots of those - the missing part is a "to water" indoor head that would work with their compressor.
I have a Chiltrix on my house (Montana) assisting with radiant heating. It is tied to a buffer tank. In this climate I do not expect it to meet 100% of the heat load. But it's performance appears to match the manufacturer's performance specs. Trying to get good handle on it's operation, control, and performance before I install over a dozen of them on a commercial application that will involve pre-heating domestic hot water for an apartment complex (and off-setting their electrical usage with solar PV).
Sanden CO2 mini split air to water heat pump is the ticket.https://www.sandenwaterheater.com/ is by far the best solution. COP up to 5. Look up the University of Washington test results.
Or read the story in Green Building Advisor:
https://www.greenbuildingadvisor.com/question/sanden-water-heater-split-co2-heat-pump
The SanCO2 has two major drawbacks compared to an air-air heat pump. One, it can only do heating and not cooling. Two, the price is high for what it can do.
Ryan,
I guess you can take something like a ducted head pull the coil out of it and replace it with a high pressure plate heat exchanger and pump. You would have to move a couple of sensors to get it to go. My guess you would have to leave the blower motors connected but can take the wheel off it to reduce power.
The issues I can see is that refrigerant leaving the outdoor unit is not that hot, at best you would get lukewarm water out of the plate HX. This would probably be hot enough to run slab based floor heat, but nowhere near hot enough for an air handler.
Would be an interesting experiment to try.
Mitsubishi, makes hydronic indoor heads for their commercial city multi line. You can find them on mylinkdrive. I think they are limited to fairly low water temperatures (45C rings a bell).
The 3 ton PWFY-P36NMU-E-BU has an internal R134A refrigerant "booster" heat pump capable of delivering 160F/71C water output when tied to the appropriate primary compressor, starting at 6 tons in the City Multi line...
They have used that module in some smaller experimental VRF multi-split compressors for doing potable domestic hot water in both heating and cooling mode (using the recovered heat from cooling for higher hot water efficiency) with, but no commercial products seem imminent. The high-temp hydronic "booster" units can't be used for radiant cooling the way their simpler hydronic modules can.
https://aceee.org/sites/default/files/pdf/conferences/hwf/2015/4D-Doppel.pdf
http://meus1.mylinkdrive.com/files/PWFY-P36NMU-E-BU_Submittal.pdf
Any idea if they're ever planning on releasing one of those units that is compatible with the single phase S series hyper heating ODUs?
LG has a line up that works with their Multi V S single phase VRF units that works nicely for residential, but I prefer Mitsubishi equipment for a variety of reasons.
With the chiltrix I chose to run freeze protected glycol through outdoor unit and to a submerged heat exchanger in buffer tank instead of using a flat plate heat exchanger and second (potable) pump. The Chiltrix also is compatible with their air handlers (indoor hydronic heads) much like a typical minisplit except they are hydronic (not refrigerant) lines.
I have been interested in the Sanden but one issue I recall is that you need to buy the tank with the outdoor unit. The tank does not have a heat exchanger and seemed over-priced for what it does. Any first hand experience with the Sanden in cold climates would be welcome as the use of CO2 as refrigerant makes goods sense.
By the way sorry to somewhat hijack the the topic...really need to start a new post on updates on people's experience with A2W heat pumps like the Chiltrix, Nordic, Sanden etc as more of these are getting installed.
I'd be interested in the Sanden as well, if they would sell the outdoor unit separately, for a reasonable price.
I purchased the Sanden outdoor unit only because I already had a 115 gal stainless steel tank for DHW. However Sanden is rightly concerned about the design of a system that will use third-party tanks since the ODU performance could be affected by location of supply/return ports, stratification in tank and possibility of sending back mixed/pre-heated water to the ODU. I suggest contacting John Miles @ Sanden with a description/drawing of your proposed system so they can advise accordingly.
I very recently became aware of LG's new Multi V-S (light commercial & residential) fully VRF heat recovery systems, that are compatible with both a low-temp and high temp Hydro Kit each of which comes in two capacities. The low temp version are good for 14kw or 28 kw of output, the high temp versions 14kw or 22kw of output.
These are fully VRF systems with heat recovery, not like the typical residential multi-split. These systems are capable of simultaneously running have some zones heating, others cooling, and rely on branch boxes for up to something like a dozen micro-zones if desired. For domestic hot water the heat would have to be stored in a "reverse indirect" tank such as a TurboMax or Ergo-max the hydro kit is not suitable for potable water on it's own.
The Multi V-S systems come as small as 2 tons, as big as 5 tons, and can manage cassette/kit capacity up to 130% of the compressor's nominal capacity.
https://lghvac.com/Commercial/product-type?productTypeId=a2x44000003XR0O&iscommercial=true&class=Outdoor%20Units
https://www.lg.com/global/business/air-solution/vrf/hot-water-solution-hydro-kit
The extended capacity tables only go down to -4F/-20C, and there doesn't appear to be pan heaters for managing defrost ice build up, but both the capacity and efficiency aren't bad at -5C. Without the automatic defrost ice management during extended very-cold weather use it's probably hot a great choice for zones 6 and higher, but should be fine for most of zone 5 and lower.
No idea what they cost (can't be as cheap as a 4-8 zone multi-split), but it looks like a pretty good solution for low temp hydronic heating with air-coil cooling as well as hot water, with total capacities adequate for most US homes. This could be the rising wave of the air source heat pump future beyond mere mini-splits. I would hope the big Japanese vendors would be coming out with smaller versions of their full on VRF stuff sometime soon too, along with cold climate versions.
I'll be digging into the documents on this series a bit more as time allows.
This was recently featured in a This Old House episode on a Net Zero house. The HVAC stuff (what little there is) starts at around the 14:10 mark on this video:
https://www.pbs.org/video/net-zero-comes-together-the-jamestown-net-zero-house-o8rv5v/
Well that LG unit is awesome! That was EXACTLY what I was looking for a year ago. Oh well, so far the Condensing propane boiler is keeping our floors nice and warm and shower water hot. I'd love to see fujitsu and Mits bring something like this to market and train their support network to properly install/service. Would be a gamechanger.
>" I'd love to see fujitsu and Mits bring something like this to market and train their support network to properly install/service. Would be a gamechanger."
No kidding!
Mitsubishi and Daikin have that type of technology in their commercial heat pump lineups, but they are for much MUCH larger loads than a typical house. The 2-5 ton LG VRF systems are sized in sweet spot of US home's loads.
I'll be looking more closely at the LGs for a project coming up in 6-9 months on a house in eastern MA currently heated with a kludged together hot air wood furnace + oil burner backup system with an oil fired Everhot for hot water. I had been thinking two mini-ducted Fujitsus with a 80 gallon heat pump water heater to fill the spa tub would work (and it would) but a 3-4 ton Multi V S and a Turbomax might be a better solution. There is a lot of weatherization work that needs to go in before even running the Manual-J, but the homeowner (who acquired the house only 10 days ago) wants to get rid of the fossil burners and build out enough PV to offset the bulk of the energy use.
Any update to this Dana? We are looking very closely at this LG Multi VS system for a NYC based townhouse renovation. The brief is to run the hydronic heating for a Warmboard-S infloor heating system, run an indirect hot water tank for DHW and then power 2.5 tons of cooling in the summer via 3 high static ducted heads and get some heat recovery to help with the DHW production. It looks possible and we have had some preliminary talks with the local LG rep here in NYC who has been helpful but seems to want to oversize the system (3 Multi VS condensors and 3 hydrokits, instead of one 5 ton Heat recover unit)but it would be great to see if you/anyone in the GBA community had done this. edit: I should add that there is an existing 6KW PV array recently installed
Dana,
LG has another line of heat pumps, the Multi F that can come with the LGRED Heat Technology. LGRED allows those units to go down to -13 F (lgredheat.com).
Carl
"Air-to-water heat pump..." is the primary topic of this thread. I know LG has cold climate heat pumps, but the LGRED series are fairly conventional minisplits/ multi-splits- and don't do hot water or heat recovery the way the full-on VRF Multi V and Multi V S can . Cold climate heat pumps w/ hydronic output doesn't seem to appear on their menu (yet).
(I really hate surfing LG's website, BTW. Digging out the tech docs or model numbers is a PITA. Igo neun ke dong. There are worse, I suppose)
Dana, looks like this packaged solution is only compatible with the 3 phase LG VRF systems.
Dana,
I looked through the submittals and engineering docs, but could not find much with regards to the modulation capabilities when setup as a multi-zone system. What I could find relative to modulation is below, but I am not sure how to interpret this. Do you think these will actually modulate below the rated capacity of the indoor units?
the frequency inverter is
designed by LG and is capable
of providing a modulation range
for 2 ton units from 20 Hz to 75
Hz (cooling and heating), for 3
to 4.4 tons from 20 Hz to 90 Hz
(cooling) and 20 Hz to 100 Hz
(heating), and for 5 ton from 20
to 125 Hz modulating in incre-
ments of 1.0 Hz.
Full VRF systems often micro-step the refrigerant flows to the individual heads through separate smartly controlled refrigerant valves the distribution boxes in smaller increments that the compressor step size, splitting the compressor step sizes between multiple zones.
But even if limited to the compressor speed increments you're looking at ~1% steps which is less than 600 BTU/hr per step even for the 5 tonner, which is fine even for a 1/2 ton head.
I'm not familiar enough with how these systems are controlled to tell you for sure what the modulation range is, but it may be wider under some operating conditions than a single-zone mini-split. There is always going to be the limiting factor of the minimum speed of the compressor though, which may under low load conditions cycle on/off the compressor if serving just one 1/2 ton head.
Richard talks about the heat pump in a previous show, (https://www.thisoldhouse.com/watch/rogers-nod-to-sod-jamestown-net-zero-house) S40E11 (around 7:25). He calls the heat pump, a heat recovery unit, and the fact that the unit uses three lines between the heat recovery unit and the heads. He does NOT talk about the DHW on that show. The VRF technology and three line heat pumps was all news for me, not that I follow the HVAC stuff that closely. From what I understand, LG has both a heat recovery unit (5 ton only) and 2 to 5 ton heat pumps in the Multi V S line. From looking at the specs, it looks like the heat pumps are two line units, and the 5 ton heat recovery unit is the only three line unit. The TOH show notes point to the LG HVAC website (lghvac.com), but I wasn't able to find any information about how the system integrated with the DHW system. I see from Dana links, that the lg.com/global/business/air-solution link does.
From what I heard from the show, and a quick look at the documents online, I looks to me as the system that can heat and cool at the same time and support HDW is only the three line system, which LG calls the Heat Recovery unit. I think the 5 ton Heat Recovery unit is really for light commercial, but can also be used in larger residential (but maybe overkill for most EE house). It sure looks like it's the first step toward the heating/cooling/DHW solution that we want. From my reading of VRF, when in cooling mode, it should be able to transfer the heat directly to the DHW, basically getting free DHW heating during the summer.
Carl
A little birdie says Mitsu may have something headed to the US market soon.
Define "soon".
That bit of experimental work with residential scale hydronic output VRF using a PWFY
hydro unit from their Multi-City line and an MXZ compressor was five years ago, with no updates since. Don't hold start holding your breath just yet...
https://aceee.org/sites/default/files/pdf/conferences/hwf/2015/4D-Doppel.pdf
That is discouraging Dana. Particularly given how widespread air to water heat pump systems appear to be in the EU. Lots of candy in those aisles...
https://termo-plus.com/wp-content/uploads/2019/02/air-source-heat-pumps-brochure.pdf
Has anyone seen an update on these products? I too had an industry person tell me one of the big manufacturers was coming to market in NA this year. We are dying in this heat wave waiting for a proper air to water heat pump. So frustrating that they are everywhere on the planet except here.
I'm not aware of anything improper about Chiltrix or Arctic models. But agreed, they aren't big manufacturers (although the apparently the components come from big names ).
The ability to use water buffer tanks is a big advantage of hydronic - no concerns about compressor over sizing, even in the smallest bedroom. It allows various options for time shifting load into periods of better efficiency or price. Avoiding refrigerant work is another plus.
It's not clear to me why non-hydronic multi-split heat pumps don't use a large refrigerant buffer tank (aka receiver). About $120 worth of R410A should absorb perhaps 15 min of 1/3 compressor output, making the smallest bedroom loads possible without compressor short cycling. Of course it would also require "micro-heads" capable of very low outputs.
Stash Energy's M1 pairs an air-to-air heat pump with up to 14 kWh of thermal storage.
From their product page ( https://stash.energy/products/ ) :
----------------
"The energy storage material used in the Stash M1 can store up to 48,000 BTU per cycle, which has an electrical equivalent of 7kWh per cycle.
The Stash M1 cycles twice a day, for a total storage capacity of 94,000 BTU or 14kWh.
---------------------
14kwh is 47,768 BTU, or about half the stated 94,000 BTU of storage, which implies a COP of about 2, or an HSPF of about 7, which is below the legal minimum 8.0 HSPF efficiency of a space heating heat pump in the US.
While it might be able to save money in strongly tiered time of use rate structures, it's not even close to beating a mini-split on efficiency.
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Is LG the best option for a whole home system in the Pacific Northwest?
I've got a personal residence 2400ft 4b/3ba we're about to build in Bend, OR
Will have a 10kwh PV system on the roof and I'd prefer to leverage the VRF instead of the gas boiler Warmboard is suggesting I use for the radiant floor.
>"Is LG the best option for a whole home system in the Pacific Northwest?"
Somehow I missed this post when it first went up.
With that sort of system it's important to get it figured out well in advance before you build or design yourself into a corner, but a 4 or 5 ton Multi V S is probably plenty for a reasonably deisigned better than code-min house in Bend.
There is at least one "sorta-local" design contractor that can probably design an LG Multi V s for that house in Bend:
Contact Gayle Borst of Borst Engineering down in Rogue River:
https://www.borstengineeringconstruction.com/
(541) 826-7222
Fantastic, thanks Dana!
Just listened to your podcast conversation around sizing these systems. Great stuff appreciate you sharing. :)
That wasn't MY podcast, but could you provide a link to it?
https://www.greenbuildingadvisor.com/article/multi-zone-heat-pump-issue
In 2013 I purchased 2 Fujitsu AOU9RLSH2 high efficiency heat heat pumps which I converted to heat the water for my radiant floor heating. I accomplished this using 2 flat plate heat exchangers (5 KW) that I purchased on Alibaba. The heat exchangers has approximately the same refrigerant volume as the Fujitsu indoor unit so there was no need to add refrigerant.
The biggest obstacle was to design an electronic control system to control the heat pumps. I used parts of the indoor unit PCB in addition to my own design.
Following a month of conversion I fired up the system (2 heat pumps in parallel) with electric support for outdoor temperatures below -15C. The system has worked flawlessly to date. The heat pumps also assists in heating my domestic water as well as providing air conditioning by cooling the floors along with a dehumidifier.
I built an energy efficient house i 2012 with approximately 28000 Btu heat loss. The house is approximately 2200 sqft on slab. I live in eastern Canada (near Ottawa) an we have temperatures down to -30C. I am achieving an COP of approximately 2.6 with supplementary heat being typically 9-10% of total. I have reduced the the price of electricity to approximately $0.058 per kWh from the present price of $0.15 per kWh.
If you decide to convert the Mitsubishi air to air heat pump to air to water make sure you can obtain all schematics and documentation. It is an advantage if you have a technical background to embark on the project.
Have fun !!
Einar.
I'd love to hear more about the details. You should start a new thread just to talk about this build.
Einar, do you have any photos of your conversation?
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We are in the middle of new construction and installing radiant floor heating and cooling. We have no intention of installing any kind of air handler. Curious as to whether this LG Multi V work with this application if the hydro kit is added?
If you are building to current codes you will almost certainly have to have supplemental ventilation. You don't say where you are but in most of the US you'll also need dehumidification along with cooling. So you will need some sort of air handling.
We are in the midwest but we have already determined how to handle the humidity without supplemental ventilation. Dehumidification can be handled by sensors that monitor radiant fluid temps, controlling the dew point We have done our research 110% but have not been able to decide on a heat pump. Purchasing stateside is a must and that is proving a little difficult.
If your plan is to limit cooling when the indoor dew point is higher than the coolant temperature, that doesn't dehumidify anything, that's just a recipe for being hot and sticky. Unless you live someplace where dew points never get above 50 or so you need some sort of mechanical dehumidification.
>" Curious as to whether this LG Multi V work with this application if the hydro kit is added?"
Yes, assuming you've done the math on water temp and heat load correctly and there's a reasonable amount of margin.
>"We are in the midwest but we have already determined how to handle the humidity without supplemental ventilation. "
Radiant cooling in most of the midwestern US isn't going to cut it. When the INDOOR dew points are north of 70F (which they will be at least some of the time if there isn't active dehumidifiction) it's almost impossible to provide sufficient cooling with a radiant system. The cooling surfaces would have to stay above the dew point by at least a few degrees to limit rapid mold growth.
Ventilation isn't going to keep indoor dew points low enough either, since most midwestern locations see peaks where the OUTDOOR dew points are well north of 70F, even if you DID have active ventilation. At current IRC code minimum air tightness, the IRC also calls for active ventilation, so one way or the other an UN-ventilated new house would violate the code. (Whether local code enforcement would make that an issue is TBD.)
You would have to talk to somebody knowledgeable about these systems, these are not the simplest systems to get right.
The 2 ton Multi VS with a low temp hydro kit should cover a reasonable sized building, these are speced down to -10F which should cover most zones. Depending on your building load and the amount of piping for your floors, you might need a buffer tank. Their spec sheet is pretty sparse on minimum capacity but it seems to have a 10x modulation range, which should work even with a low load building.
I would plan on hooking in at least one ceiling/wall mount unit sized for the latent load of the house in case you do need humidity control. This is easy to do now and much harder down the road.
John Straube did a "roll your own" air-to-water heat pump at his own house (Waterloo, Ontario, CZ 6) back circa 2010. See slides 45-48 in this presentation. I don't know what the outcome was, and whether or not it's still being used.
https://www.buildingscience.com/sites/default/files/2010-02-10-WWJD.pdf
His heat exchanger is just an unpressurized 55 gallon drum with coils of 3/8 tubing that have refrigerant running through them. Three 50' coils, it's unclear whether they are in series or parallel. Then another coil to provide domestic hot water, 50-60 feet of 1/2 tubing. Water for hydronic heating comes directly from the tank.
He makes the coils by winding tubing around a drum.
He makes it sound so easy I'm tempted to go out and get one of the precharged DIY minisplits and build my own.
I agree, i found a nice used Mitsubishi 28k btu for $1500.
I'm thinking a flat plate heat transfer glued to the Mitsubishi heat transfer plate. But i have no idea if that would work.
I saw the coils in the pdf doc, on page 12, is there no heat transfer plate? It's just a copper loop on the end? It's pretty cool idea for a buffer tank. I agree, it does seem simple, but how do turn it on without a indoor unit to relay the temp control? So many questions! :)
He says he has a thermostat on the tank that controls the heat pump. It just maintains tank temperature. I suspect a room thermostat controls a circulator for heating.
I ended up ordering one of these, hopping it will work out. https://m.alibaba.com/product/60828434476/Nulite-High-COP-ErP-A+++-R32.html?__sceneInfo=%7B%22cacheTime%22%3A%221800000%22%2C%22type%22%3A%22appDetailShare%22%7D
How did it go? Did you set up the system yourself?
So funny you posted about it, it took 4 months to get and I have been traveling all summer and fall so been ignoring it. But was ordering some plumbing adapters just tonight. I started a write up which I wanted to post once its done but since your interested here it is so far https://docs.google.com/document/d/1j52mUnGxyDJ3ylnDulkma6kWd4w-0y1N__YDlJhMeSI/edit?usp=sharing Most of the hard prep is done, PEX, buffer tank, holes in the house etc. Should be up and running in Feb sometime.
I'd love to hear more about the whole process, from buying on Alibaba to the installation. Since this thread is four years old would you mind starting a fresh thread?
Thanks.
Great idea, will do as I get a further along with the install.