Viessmann A2WHP installation part 1
This is their 2 ton unit for my @700 sq ft shop. Design load around 12,000. Radiant slab is 6"oc tube for low SWT requirement. I will run the HP 115°, hopefully a 3-5°∆
I poured a concrete footing and two concrete piers with 8" Sonotube.
An aluminum frame over the piers, HP mounted on the rubber donuts supplied.
For the flexible connectors I used 1" Watts Onix hydronic tube. Insulated the tube and slid 3" pvc over it into the shop. I will get some rubber flashings for the PVC before I tighten it all up.
On to the inside assembly. I'm sizing a plate HX to go between then outdoor unit with glycol and the 20 gallon buffer tank. So just the outdoor piping will need glycol.
trainer for Caleffi NA
Living the hydronic dream
Comments
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Looks great. It appears that the unit is about twelve inches above the ground, how high does the snow get in your area? I have to assume the unit will melt away any snow that accumulates?
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Down here in the valley we don't get those big dumps anymore. 6, 8" maybe, and it melts quickly. This unit has the control onboard to bring on the boiler also.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Looking forward to your long term evaluation of this.
When you built your shop AtWHPs were not a thing. Now they are. Do you have any advice for building a shop today?
What could be done during construction to better position the building for an eventual heat pump, even if it will initially have a mod-con?
slab designed for lower temp water?
electric to run the HP?
etc
Thank you.
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Keeping an eye on this. I have several of these quoted but other than you I don't know anyone else that installed one yet.
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spot on with you observations. The tube 6” on center and 2” below the surface allow for the lowest SWT, 100- 105 on coldest day.
The shop has 1” spray foam, 6” batts in the wall, 10” batts in the ceiling.
And yes I should have run a larger service for power. I may not be able to weld and run the heat pump at the same time. 🤔
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Sean Cunningham, Resolution Energy, out in Colorado installed one recently. I’ve hit him up for installation tips. I think he posted it at the Hydronic Heating Tech room on FB, or LinkedIn maybe
It is certainly Viessmann quality as far as the build of the modules. Excellent packaging around the buffer and indirect tank. Nothing arrived damaged. The indirect has a large, 20 sq ft coil, looks like the solar tanks they offer
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Looking good!
I would take issues though with the Caleffi label being upside down on the air separator.
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good eye
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
What model is this? The smallest "Vitocal 100-AW" model?
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It is the smallest VitoCal 100-AW version, 1.5 ton cooling, 20, 500 btu/hr. on heating.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Is your design temp around 12F or so? It's interesting that the COP of the AM2V-020028 with 113F water is about 1.5 from 24F to 14F outside (the closest numbers on their plots), while for the bigger AM2V-034043 it can maintain a COP of like 2.7-2.4 over that range. At least for this model, it seems like the efficiency is way higher if you're not close to the max output of the heat pump (which is counter to the usual "Don't oversize your heatpump or it will tank the efficiency" message i see).
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I suppose you won’t be doing DHW since it’s your shop?
I’ve been waiting for these to become available in my area and will be keeping an eye out on your progress. Thanks for sharing.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
Oversizing issue is with anything to air. When these are oversized, the runtime can be very short which causes big hits in efficiency.
With air to water, you can use a buffer tank or high mass emitters and there won't be any short cycling. On the other side of the pond, there are guys running air to water with seasonal efficiency of 4 by tweaking sizing and temperatures.
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I’m interested in hearing how Entertech runs without a buffer. Ive heard claims of connecting to just a towel bar load?! Defrost pulls from the connected indirect. Unless you don’t have an indirect?
Running a resistance element to defrost seems counter productive.
Register for this seminar at the link.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0
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