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Does anyone have experience with Spacepak Hydronic HVAC?

jberks | Posted in Mechanicals on

Zone 6 – Toronto,

My Manual J is as follows (although it needs to be updated):
Basement – 5900 BTU Cooling, 8000 BTU Heating
First Floor – 5900 BTU Cooling, 3200 BTU Heating
Second Floor – 4300 BTU Cooling, 2700 BTU Heating
Third Floor – 6300 BTU Cooling, 3800 BTU Heating
21.3 MBH Total Cooling
17.7 MBH Total Heating

I am planning to do a ducted minisplit system in my current build. 4 outdoor units, 4 mini ducted units (one on each floor for zoning). However, I am worried that I won’t be able to get adequate ductwork through the ceilings to get an effective system. (ductwork must be hidden, I can’t have bulkheads)

However, my HVAC guy is starting to push me towards Spacepak, so I took a look and called the company. essentially the proposed is the Solstice Air-to-water heat pump, and 4 Aircell high velocity units instead.

I’m not familiar with Air-to-water systems, nor have I worked with Spacepak before. I like the idea of going high velocity and 2″ flex ducts, as I will be able to run it through walls and LVL’s and hide the ductwork much easier. Also, The aircells static pressure is 1.2″water, vs fujitsu’s or mitsubishis miniducts are closer to 0.3.

However, spacepaks website and marketing materials are uninfomative and not the best looking. Not sure how these systems work or what the potential issues are.

Does anyone have any experience with them? or have any recommendations?



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  1. Jon_R | | #1

    Take a look at the Solstice Extreme. With a hydronic heat pump, I'd probably run water to each room with either a fan coil or radiant flooring in each - no air ducts.

    There is also Chiltrix.

  2. GBA Editor
    Martin Holladay | | #2

    I have no experience with SpacePak equipment. But after some research, I wrote an article describing the company's heat pumps. Here is a link to the article: Air-to-Water Heat Pumps.

  3. SwitchgrassFarmer | | #3

    I have a Unico high velocity air-conditioning system; it's essentially the same topology as SpacePak. It's fed by chilled water from my ground source heat pump (geothermal). Works well, no complaints.

    The design of the duct main, location of terminals (registers), etc was pretty exacting. There were multiple engineers involved. Fortunately part of our contractor's practice is commercial HVAC engineering, so this just posed an interesting new challenge to them.

    We did actually put terminals in the ground floor of the home. At the time I thought it was kind of overkill, but the thought was that since most of this area was living space, some discharge there would help with dehumidification. (It's also a walkout "basement", so there is some solar load.) It was indeed borne out that the air flow in that ground floor was worthwhile, although we did throttle it back somewhat with a balancing damper.

  4. jberks | | #4

    Thanks all,

    More looking at issues like how it operates, did it fail on you, did you get condensation issues, what kind of thermostat are you using to it, is it noisy or looks like shit etc.

    @Martin, I emailed Chiltrix based on your article. Thank you, I got a phone call today from them. I just went over some concerns of mine. But its hard to get real world advice from someone who's trying to sell you their product.

    However, he mentioned a few things like how they'll sell directly to me and how install is easy enough that most builders install it themselves rather than getting a specific hydronics contractor. He also mentioned was they don't have a small unit like spacepak's Aircell but said that I could use the aircells for the fan/coils and it shouldn't be an issue. It sounds like the Chilltrix chiller is significantly cheaper than Spacepaks.

    Here's the interesting part, he was boasting that the chiltrix is by far the most energy efficient. He sent me this article:

    Interestingly, when I compare their posted data respectively the chiltrix unit more than doubles the cooling COP compared to the Spacepak:

    Chiltrix CX34 cooling avg assumed COP: 6.75
    Chilltrix CX34 heating avg assumed COP: 3.92

    Spacepak SCM-036 cooling avg COP: 2.7
    Spacepak SCM-036 heating avg COP: 2.65


  5. walta100 | | #5

    I think you need to look at the basement’s manual J numbers again. My guess is, a full basement will have almost no cooling load and your basement heat load is nearly as much as the rest of the home combined.

    Most HVAC contractors do not want to install minisplit systems. Often they will do their best to talk you out of one and if that fails will quote you an I do not want this job price. Try to find a different contractor that has installed more than a few minisplits.


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