Need Ideas for Equipment Enclosure (With Heat Pump Inside)

[Stoopalini]

During the construction of our pool, I had two footers poured around the equipment, in anticipation of building a shed enclosure around it. The equipment is placed against a wall of our house, so the idea was to build 2 walls in an 'L' shape, and leave the 4th side open. The outside of the walls would be limestone blocks like our house, and the inside would be peg board .... Then put a roof on it as well, with either a gap around the top of the walls, or venting through the roof itself. This would allow good air flow, but still protect the equipment from the sun and rain; as well as provide a nice place to store pool cleaning equipment, pool toys, and other random things for the pool area.

Here's a look at the space:





The right side would remain open, and faces north.

I've since ordered an AquaCal SQ150VS heat pump, and was planning to place it on the pad, to the left of the pump. But I realize I need to account for adequate air flow when building out the enclosure. There's enough space to accommodate the clearances of the heat pump, but am worried that the discharge air would remain in the vicinity of the heat pump; causing it to pull in exhausted air, which is a really bad thing for heat pumps.



I phoned AquaCal, and they said they don't recommend enclosures, but if one is used, there must be a fan which can move 3500 CFM of air. They sent me a document describing how they recommend doing it:





Their suggestions are for completely enclosed spaces though, while mine would have one side wide open. So I don't think I need anything to promote outside air coming in, but am concerned I may need something to exhaust the discharge air out of the space.

So in thinking through this, I'd debating on a few options, and would really appreicate some other eyes and thoughts on this:

1. Enclosing it the way I originally planned, and install a 30" louvered exhaust fan on the left wall, close to the heat pump location
   • Something like this Fanpac S30 unit
   • I could wire it up so it only turns on when the heat pump is running
   • It moves 5895 CFM, and only produces 57dB (about the same as the heat pump). But I could install a speed controller, and slow it down to the 3500 CFM target to lower the sound level if needed (the window in the picture is our master bedroom)
2. Enclosing it with the L shaped wall, but make the roof with some sort of louver design so it's vented, but still blocks the sun and rain from entering
   • I'm not sure how I would do this, but it's an idea
   • Am concerned when the heat pump runs in heating mode, the cooler discharged air would not vent up, and may still be pulled back into the heat pump
3. Installing the heat pump outside of the enclosure, on the left side, right in front of that window
   • I'm not keen on this, as the window is our master bedroom
   • But also, one main point of the enclosure is to hide the equipment from view. As it stands, the equipment is viewable from the front and side streets of our house.
4. Just do what I originally planned, and see how it goes
   • Then if there are any problems, make adjustments at that time
   • Although having to cut a 30" square hole into the limestone blocks would be quite the pain to do after it's built

I also thought about ditching the limestone block walls, and just doing some sort of wooden slat fencing, alternating the slats on each side, to allow venting. Although this would look pretty out of place for my property and the area we live.

Definitely open to ideas though, and appreciate any input/assistance brainstorming solutions here.

 

[ajw22]

I think your problem is more the roof on the enclosure then the sides. Natural airflow comes from the lifting and falling of air. Any enclosure with a roof even if one side is open will reduce the efficiency of the HP.

If you put a roof and 3 walls over the HP then you need to give alternative ventilation.

I think it will be difficult for you to determine if your HP is operating at sub-optimal efficiency in an enclosure.

 

[Stoopalini]

Agreed, I definitely need to design adequate ventilation if the heat pump will go inside the enclosure.

I could extend the roof over the existing house roof, leaving a 12-24" open space between the two. Not attached to the house roof, but cantilevered over it just a bit. I plan to run a gutter across the existing house roof as well, so it would stop rain coming down the house roof from dumping into the enclosure. This design would prevent rain from coming in, but would leave 13ft x 2ft opening at the top for air to circulate. It wouldn't have to overhang the house roof by much. Just enough to prevent rain from falling in ... And with the pitch of the enclosure roof, would naturally vent hot air as it rises.

Although I do feel the issue will be with the cold air being exhausted from the heat pump, not hot air (unless I'm running it in cooling mode during the heat of the summer of course).

Maybe a roof design like that, in addition to an exhaust fan in the wall (as outlined by AquaCal's document), would be enough to allow the heat pump to operate optimally.

Their documentation has ΔT specs, and recommends installing ports for temp probes on the inlet and outlet of the heater's plumbing. If I did this, I could evaluate the efficiency of the heater in the space. According to their specs, the optimal ΔT for the SQ150VS is 3*F - 7*F.




I am also going to install a bypass in the plumbing, with a three way valve at the inlet side of the crossover, and a check valve at the heater's outlet. This way I can bypass the heater if it ever needs servicing. Or if we have another winter like this year, I can winterize it.

The check valve I purchased is also a flow gauge though. So I will be able to monitor the GPM through the heater, and then if I have the temp probes as well, verify the ΔT. In the crossover pipe itself, I'm going to place a Delcheck 5# check valve, as suggested by AquaCal. So during normal operation, the 3-way valve will be set with all ports open, and at lower GPM rates of my VS circulation pump, all flow will go through the heater since the 5# check valve will be closed. But if the pump goes to higher speeds where GPM exceeds 70 (which is the limit of the heater), the excess will go through the bypass.

 

[JohnT]

You might be able to space the blocks so there are openings in the walls if that look is acceptable.

 

[Stoopalini]

You might be able to space the blocks so there are openings in the walls if that look is acceptable.

That's another idea we were kicking around too. It would be acceptable from an aesthetics point of view. But I was concerned about rain making it through the holes and rotting out the pegboard on the inside. I wonder if doing staggered blocks on just the left wall would be enough, and then only doing the peg board along the 13ft wall?

I'm typically someone who thinks very long term (I'm a system architect by trade), and don't mind extra investment up front for long term benefit. So I'm kind of leaning toward the vented roof idea along with duct venting of the heat pump if needed. Like this AquaCal diagram:



I would have to remove the rain guard off the top of the heat pump, but that seems to be a valid approach (based on the 2nd bullet in their diagram).

So I could build the structure with the overhanging roof, but not do the limestone facing on it just yet. Then run the heatpump without the duct and fan, and see how it performs. If it's struggling, it'll be easy enough to install the 30" fan into the structure's frame, since the limestone won't be in place yet.

Here's a crude drawing of what I mean by "overhanging roof". So the right side would be completely open, and the roof would have a 2ft x 13ft long gap at the top; while still providing rain and sun protection.

 

[csconner]

My HP/chiller is under roof (see pic). I ended up building a sliding barn door on the back side of that opening. I originally planned to enclose more of the pad, at least barn doors on the long side.

after using both HP and chiller last summer, I’ve determined any further walls would seriously restrict effectiveness of the unit. When it’s heating it puts out cold, cold air, lowers the air temp under the roof area 8-12 degrees. When it’s cooling it easily exceeds 100 degrees

im contemplating putting a oscillating fan higher up on the wall to push out the cold/hot air from under the roof.

PS - dimensions under the roof are 12’x20’, roof is 14’ high

I’d be very careful enclosing / restricting airflow.

just my $.02

 

[panic_button]

Instead of cutting you plumbing to add a temp gauge, why not use the solar sensor port and add a sensor after the heater. I have an EasyTouch and instead of sensor hanging doing noting it is attached to my plumbing after the heater. I can view the exit water temp on my house remote panel. You can find them on Amazon for less than $20.

 

[Stoopalini]

My HP/chiller is under roof (see pic). I ended up building a sliding barn door on the back side of that opening. I originally planned to enclose more of the pad, at least barn doors on the long side.

after using both HP and chiller last summer, I’ve determined any further walls would seriously restrict effectiveness of the unit. When it’s heating it puts out cold, cold air, lowers the air temp under the roof area 8-12 degrees. When it’s cooling it easily exceeds 100 degrees

im contemplating putting a oscillating fan higher up on the wall to push out the cold/hot air from under the roof.

PS - dimensions under the roof are 12’x20’, roof is 14’ high

I’d be very careful enclosing / restricting airflow.

just my $.02
View attachment 319384

Good info, thanks. When I build the enclosure, I’m planning to put a 30” elbow duct on top of the unit and vent it through the wall. AquaCal engineering said this should be fine, even without an extra fan in the duct ... so long as it’s only a few feet in length.

 

[Stoopalini]

Instead of cutting you plumbing to add a temp gauge, why not use the solar sensor port and add a sensor after the heater. I have an EasyTouch and instead of sensor hanging doing noting it is attached to my plumbing after the heater. I can view the exit water temp on my house remote panel. You can find them on Amazon for less than $20.

Thanks. I wanted the inlet and outlet temps to be available with the same probes though, since were only talking about a few degrees here.

I ended up using the pentair thermometers, and here’s the final result.