What's the latest on air to water heat pumps in the US market?

AdamInEvergreen

So at the moment the American market for Air-to-Water heat pumps is pretty weak, which makes this post more theoretical than practical but hey...

I was reading Idronics 27 on Air to Water Heat Pump Systems https://www.caleffi.com/sites/default/files/file/idronics_27_na.pdf and I like the concept of adding a heat pump / boiler/ buffer tank illustrated in figures 7-14 and 7-15.



This system seems like it is definitely missing out on DHW heating (or at least pre-heating) though, especially as that adds the potential for year round energy savings. Not sure if they exist but an indoor unit on a split system that had both a DHW storage tank and inlets/outlets for integration into an existing hydronic system would be cool. I suppose you may also be able to accomplish it by running the heat pump heated water through coils on an indirect water heater (main volume of the indirect heater is the buffer tank for hydronic system) then using some diverter valves that change the flow to domestic water when appropriate. Two other options that may be feasible would be the "tank-in-tank" Caleffi mentioned (does this even exist as a product for purchase?) or perhaps a heat exchanger set up.

Or perhaps what I am suggesting is simply too complicated to be reliable and instead one should just focus on the concept of getting a heat pump as the only heating source (plus maybe a DHW booster if needed), dropping the gas boiler as an auxiliary heat source. Which bring me back to the headline - what is the latest on air to water heat pumps in the US market?

EBEBRATT-Ed

I have seen condensing units outside for air-water heat pumps use to heat swimming pool water. Same thing if you can get them with low ambient controls.

Raypak & Hayward make them

GW

Gonna be forever before this takes off in the USA. Water temp issues galore 

Ceacel

Spacepak has the Solstice A2W, a couple different configurations. A couple are packaged OD units so will need methanol, one is a split where the indoor refer to water HE looks like a tankless water heater. 

Hot_water_fan

The trouble is that the market for boilers is extremely small in the US, so it’s a niche within a niche. 

hot_rod

Might be a lot bigger then some imagine, certainly not to be ignored

https://www.gminsights.com/industry-analysis/north-america-air-to-water-heat-pump-market

AdamInEvergreen

Daikin, LH, Carrier and I'm sure others all have entire lines of A2W heat pumps for the European market. I was just poking around on the Daikin UK site and apparently they have some that do both A2W heat pumps and Propane.  I need to figure out how to sneak one over.  

https://www.daikin.eu/en_us/product-group/hybrid-heat-pump.html

Larry Weingarten

Hi, Nyle is one to have a look at: https://www.nyle.com/water-heating-systems/

Yours, Larry

GW

Spacepak—-one year warranty (we are not a Spacepak factory trained installer) on coils

they will have to work on that if they have any hope in real market share 

10 years is the standard 

JakeCK

GW said:

Spacepak—-one year warranty (we are not a Spacepak factory trained installer) on coils

they will have to work on that if they have any hope in real market share 

10 years is the standard 

One year? Are you ****ing kidding me? I had a browser tab open of their site. Not any more. That does not inspire much confidence in their product.

JakeCK

AdamInEvergreen said:

So at the moment the American market for Air-to-Water heat pumps is pretty weak, which makes this post more theoretical than practical but hey... I was reading Idronics 27 on Air to Water Heat Pump Systems https://www.caleffi.com/sites/default/files/file/idronics_27_na.pdf and I like the concept of adding a heat pump / boiler/ buffer tank illustrated in figures 7-14 and 7-15. This system seems like it is definitely missing out on DHW heating (or at least pre-heating) though, especially as that adds the potential for year round energy savings. Not sure if they exist but an indoor unit on a split system that had both a DHW storage tank and inlets/outlets for integration into an existing hydronic system would be cool. I suppose you may also be able to accomplish it by running the heat pump heated water through coils on an indirect water heater (main volume of the indirect heater is the buffer tank for hydronic system) then using some diverter valves that change the flow to domestic water when appropriate. Two other options that may be feasible would be the "tank-in-tank" Caleffi mentioned (does this even exist as a product for purchase?) or perhaps a heat exchanger set up. Or perhaps what I am suggesting is simply too complicated to be reliable and instead one should just focus on the concept of getting a heat pump as the only heating source (plus maybe a DHW booster if needed), dropping the gas boiler as an auxiliary heat source. Which bring me back to the headline - what is the latest on air to water heat pumps in the US market?

Thermo 2000 has their reverse indirect tanks and an electric boiler/buffer tank combo unit that also has an indirect dhw coil in it. I wonder how well those would work?

Wellness

I agree with @Hot_Water_Fan; and from the material I could see in the link cited by @hot_rod, I don't get the math making the case for air to water heat pumps. More than half of the U.S. population lives in the south and southwest, where boilers are rare. Like I said, I can't see the numbers in the report (at least for free :-) But even with the nationwide push to green energy, an air to water heat pump setup would seem to be only suitable for low temp infloor radiant heat, no? Cast Iron and copper radiators are non-starters because of their higher temp demands.

AdamInEvergreen

JakeCK said:

Thermo 2000 has their reverse indirect tanks and an electric boiler/buffer tank combo unit that also has an indirect dhw coil in it. I wonder how well those would work?

Cool, that is a nice product! Cheaper than I thought it would be as well. Idronics shows Reverse Indirect Tanks as one of the options they draw out. I kind of want to put one of these on my current boiler! Seems like you could get it set up with a big delta T and have your system spend a lot of time in the condensing zone.

AdamInEvergreen

Daikin has exactly what I am proposing, built as a single unit...one version you can integrate with an existing boiler and one has its own boiler...BUT the only place I can find it is on their European site!

https://www.daikin.eu/en_us/product-group/hybrid-heat-pump.html




It only weighs 45 kg...I could sneak that back on a plane.

Jamie Hall

Wellness said:

I agree with @Hot_Water_Fan; and from the material I could see in the link cited by @hot_rod, I don't get the math making the case for air to water heat pumps. More than half of the U.S. population lives in the south and southwest, where boilers are rare. Like I said, I can't see the numbers in the report (at least for free :-) But even with the nationwide push to green energy, an air to water heat pump setup would seem to be only suitable for low temp infloor radiant heat, no? Cast Iron and copper radiators are non-starters because of their higher temp demands.

Exactly the problem. Never mind steam... there is a very large amount of built infrastructure, particularly in the more northern part of the US and Canada, which had central heating with relatively high temperature systems, all installed prior to or shortly after World War II. Thiis is not as much of a problem in Europe, as many -- if not most -- houses were either built without any central heat at all but added much later, or built later on in the mid 50s and later, and when it was done it was often done with much lower temperature radiation. In that setting, air to water heat pumps can be an excellent approach for "greening" home heating.

AdamInEvergreen

@Wellness and @Jamie Hall I get what you guys are saying. Personally I have a hunch that a lot of the convectors are newer because they've been replaced since the original install. Europeans tend to live longer in one spot, have much smaller homes and probably pay notably higher amounts per BTU of energy, which all leads to being more open to "replace all the radiators on the house" type projects. Net effect is the same as what you suggested about the starting point.

Daikin does have heat pump systems that are designed for "high temperature" which is about 140F most of the time with a max of 160F. But I think the efficiency drops off notably there, as would be expected.

JakeCK

Weren't most of those high temperature heating systems designed to heat a house with no insulation and open bedroom windows on a January night? 

If so many of those systems should be able to adequately heat these old houses at much lower supply temperatures.

lkstdl

Nordic's design is a split system with the compressor inside the house -- the outdoor unit is essentially just a fan & coil. Because of that, the indoor unit can have a built-in desuperheater to provide year-round DHW.

https://www.nordicghp.com/product/nordic-products/air-source-heat-pump/air-to-water/

Lots of great information and drawings in the PDF manual.

I am very curious to try one of these.

Luke

Jamie Hall

JakeCK said:

Weren't most of those high temperature heating systems designed to heat a house with no insulation and open bedroom windows on a January night? 

If so many of those systems should be able to adequately heat these old houses at much lower supply temperatures.

A remarkably common myth. Don't count on it. "No insulation", for instance, in a house built around 1900, actually equates to somewhere around R 5 and verry low infiltration. Not modern, to be sure, but not none, either, by a long shot. And no, folks did not sleep with their windows open in January, at least not out in the country. What city folks did I have no idea....

TAG

I went looking earlier in the year. There was also an article in one of the larger periodicals with an air to water unit integrated into whole house solution. Unfortunately you can't buy that unit and the cost of the basic air to water system was in the 40k range as best as I could tell.

The spacpack system is extremely expensive and where is the benefit in a full house ?

I first took deep dive a couple years ago when planning my current project. With only Propane available and 60-80K well cost for Geo I was thinking one of the air to water HP's would be a decent fit for my all floor radiant house. Earlier this year it was for the outbuilding /studio .. again floor radiant (only need about 20k) and in this case maybe the Spacepak with some type of buffer tank for the floor with two mini-split type heads would work. My builder could not get any understanding of how it would do the floor ...

It seems that there are three main layouts ... package unit, split and a hybrid that keeps the compressor inside like a Geo system. All have lots of proprietary components .. scary

JakeCK

I have to respectfully disagree. Even assuming a very generous r5, insulating an old house can nearly double the r value. And what about the attic? r3, 4? Now lets add 16" of blown cellulose, it will be pushing almost r50. What about air sealing around chases, plumbing, and electrical penetrations. New storm windows? Just playing with slantfins heat loss shows how much a difference improving the envelope will make. So much so that the recommendation is to always start there before replacing heating equipment right? Other wise it will be oversized again.

And I obviously never lived when TB was a death sentence and a serious concern but I've always read it was believed that the fresh air improved sufferers breathing so windows being open was a common occurrence and was accounted for. I've also seen more than one old advertisement from the turn of the 20th showing a radiator under an open window and the talk of fresh air.

Hot_water_fan

Cast Iron and copper radiators are non-starters because of their higher temp demands.

You can get around this - you use R410A for the first lift, then R134a to take it up to 160.

Jamie Hall

Can't really disagree with you, @JakeCK . There is, however, a return on investment to be considered. Also, for some types of construction adding insulation isn't really all that hard -- and so I'd recommend it. For some types (all three of the places I care for!) it's very difficult and astonishingly expensive. New, quality storm windows are always a good investment (replacement windows almost never are), however, as is simply attending to the carpentry around windows and doors.

Fresh air certainly improved the quality of life for TB sufferers -- though it was still a death sentence -- and for a while around 1918 the scientific consensus was that having the windows open would keep you from getting the 'flu (and probably was somewhat beneficial)(the subject of fresh air is one which hasn't died -- if your structure has less than two air changes per hour, you will have air quality problems. I have some really funny stories from the Carter energy crunch of the '70s). But at least in the snowy regions of the country folks were no more likely to leave their windows open than they are now. Well, perhaps not that much more likely anyway!

I've sometimes thought that the biggest difference, however, was that 100 or more years ago people were far more tolerant of uneven heat than they are now. The kitchen and the parlor might well have been kept at around 70 -- or even warmer. The bedrooms? Try 45 to 50. And of course the "bathroom" would be at whatever the outside air temperature was...

hot_rod

There will always be a % of folks that just don't want to embrace new technology , ever, or until it has a 20 year track record

The panel radiators are a nice combination with air to water HPs, can certainly keep the HP in a good COP range if radiant floors are not an option. Radiant walls and ceilings also.
Panel rads are the easiest retro fit in most homes and all sorts of sizes, shapes and control option.

Coils to go in duct work can be upsized for most any SWT operation.

There are plenty of HVAC techs that understand refrigeration to work on and install, so the learning curve should not be steep.

The Altherma was released in the US way to early and did not perform well in cold climates and was pulled back. Dakin has some catching up to do as far as contractor confidence in their residential offerings
For the very small % of the year that you are at or below design conditions in cold climates, resistance heat or some fossil fuel backup would be the options. The hybrid gas/ HP option is the route I would take. Chose the fuel that makes the best $$ and have some redundancy should one system go down.

The NorAire is an interesting product, condenser coil and strip element in one cabinet, combine it with any outdoor unit you like or are comfortable with.
We have a rep that sells these with the Bosch inverter heat pump, but any brand could be used.

JakeCK

Oh you are most certainly right about ROI. Ask me about the closed cell foam estimate I got a few months ago. My eyes were watering. But dense packing the walls is usually a reasonable cost and will also help with comfort in addition to energy savings.
With historic homes there maybe no sensible solution other than to pay the price for fuel which is why I do not agree with outright bans on energy and fuel sources. But for most houses there are practical and economical ways to insulate these homes and convert the heating systems. It is just a matter of education and some subsidizing by the government. My house right now with its lack luster insulation is already running at a pretty low swt. It is border line condensing. I have the CPH set to 1 on my thermostat so it runs long enough to get hot, sacrificing comfort for the sake of the boiler. I'm actually surprised it is in such good shape after 35+ years. And I'm planning to have the walls insulated sometime this winter or spring. I may very well be forced to redo the near boiler plumbing so it has a bypass and thermostatic 3-way before next winter.
Also I like the bedrooms cooler. I could tolerate 50 ok. But 60-65 would be perfect for me. Not so much for the wife.

SweatHog

There is probably no bigger energy-efficient building fan than me: I put solar panels on my house after the state passed a small tax break earlier this year, I foamed the basement walls and put r-12 under the slab when we built the house 20+ years ago. I should have installed radiant heating in my floors during our house renovation but decided to keep the copper baseboard since the old, on-grade part of the house already had that. Although I've been looking into retrofitting a heat pump to my indirect heater so there's no boiler feeding heat into the house during the summer and to reduce electric consumption, I can't imagine it would be cost effective to replace my boiler space heating setup with an air to water heat pump plus supplemental electric or gas heating.

GW

HR yes that's the beauty of a (still) free country, we can all choose how much risk we want to roll with in a new - emerging technology. Some stuff will flop, look at Acadia heat pumps. I think there's a happy medium.

lkstdl

SweatHog, if you've got an existing boiler, there'd be no need to replace it. Over the course of the whole season, the heat pump would cover e.g. 75-95% of the load (depending on how you sized it) and your current boiler would cover the peaks.

lkstdl

Hot Rod, the NorAire is an interesting way to approach it. There seems to be an economy of scale to mainstream heat pump units that the ATW units don't have yet, and this could be a clever way around the issue.

ThermAtlantic's DX2W follows a similar approach.

Anyone have first hand experience with this style?

hot_rod

Air to air heat pumps have been around 30 years or more, really the main difference is the water and HX swap between W2AHP and A-AHP

SweatHog

@lkstdl, OK. Sorry didn't look closely at the OP last diagram for mod/con in the 1st post.

motoguy128

To me it seems like all amigos are trying ot make this too complicated.

You take a off the shelf split system heat pump, then size a coaxial coil that you mount indoors. Also removes the need for freeze protection. Add basic trim (aquastat, relief, expansion tank, buffer tank, system pump. Put all the info or parts in a nice looking little box

Jamie Hall

I don't think folks are making it more complicated. The plain problem is this: so far as I know, no one makes an air to water or steam heat pump which will provide 180 degree water never mind steam, when it's 10 below out. When that happens, maybe a lot of folks will be able to use the technology.

pecmsg

can 180* water be achieved yes! Just like a cascade system can achieve -100F. 

Can a homeowner afford it and get a return on investment. Doubt it. 

lkstdl

@motoguy128 That's essentially what the NorAire and ThermAtlantic products do, except without all trim. I like your approach of including all that though. Certain components could be oversized to account for the variation between different installs in terms of total system volume, heat load of smallest zone, required head & flow rate, etc., but there's little downside to using a slightly larger expansion tank & buffer tank, and ECM pumps have decent part-load efficiency. Good integrated controls could alert the installer to potential problems and offer solutions: "system overpressure detected: install an external expansion".

I do wonder if the standard split system outdoor units are tuned for the return temperatures they'd get from an air handler rather than a hydronic heat exchange. Even with a well-designed low-temp system, return water temperature would be in the 80F-120F range, versus 65F air temperature. Would the outdoor unit therefore need a comparatively larger coil surface area to get the same efficiency?

megharrington

JakeCK said:

GW said:

Spacepak—-one year warranty (we are not a Spacepak factory trained installer) on coils

they will have to work on that if they have any hope in real market share 

10 years is the standard 

One year? Are you ****ing kidding me? I had a browser tab open of their site. Not any more. That does not inspire much confidence in their product.


@GW @JakeCK Oh no this is not true at all!

SpacePak's warranty policy for all of the inverter air-to-water heat pumps is:
-CERTIFIED contractors get a 10-year compressor warranty and 5-year parts warranty
-NON-CERTIFIED contractors get a 5-year compressor warranty and 2-year parts warranty

And to become certified all you have to do is attend one of the live webinar trainings. We apologize this information is not currently presented better on the webite, but a total make over to our heat pump content is on the way!!

GW

Ok then I was lied to, which is even worse. The rep called me directly 

megharrington

@GW It sounds like there was miscommunication about which SpacePak product was being referred to.. based on what you said they were referring to the warranty on SpacePak small duct high velocity air handlers.. which for SpacePak SDHV, hydronic fan coils and associated equipment is:
-NON-CERTIFIED contractors receive a one (1) year parts warranty
-CERTIFIED contractors receive a five (5) year parts warranty

For reference:
-https://www.literature.mestek.com/dms/Bulletins/SpacePak/SpacePak%20Warranty%20Bulletin%20(21.3)%20(2).pdf
-https://www.literature.mestek.com/dms/SpacePak/LW-SP-0321.pdf

hot_rod

this A2W ducts air in and out

hot_rod

The vapor injection is a technology used in cold climate units.
A chart showing the heat emitter types that match best.
Several manufacturers offering force convectors, Jaga and now Runtal
A simulator that NY state is building

megharrington

@GW Just noticed you are located in Northampton, MA. Did you know we're neighbors? If you ever want to swing by our Mestek/SpacePak headquarters in Westfield and check out our air-to-water units and training facility, just let us know!