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I could see how it blowing in conditioned air could be problematic, but…maybe it wouldn’t be?

The electrician wants to put the heat pump in the corner I want to put my main bench, I don’t know if I need to argue that or not…

I wouldn't want it blowing directly on me but I suppose you could always put a deflector on it.

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Steve Smith
"Music is what feelings sound like"

I think it could be nice--having a bit of cool air coming down when I'm wanting to get all sweaty doing some of the heavier physical activities in the shop and all. And like Steve said, a deflector could always be added for when direct air isn't what you want.

Dave

Is the heat pump just for the shop? What might be more improtant is where the return is. With a quality filter, it could help keep you shop air clean. If you’re sharing it with the rest of the house, designing so that your dust stays in the shop would be important.

It is for the RH area of the shop only. I guess I didn’t state it in the question, but my main concern is the RH issues it may cause.

Will it be blowing correct RH air onto the bench area, or will it be blowing air made up to modify the overall shop RH? So possibly blowing air that is either too low or too high right into the bench area. I don’t really know the in and outs of how they operate, I’ve never had one…

I have one about 6' behind my bench blowing across the room but not at me. They are amazing this is my first experience with one we now have them in our shop.

It doesn't bother me a bit and is fast to heat or cool and amazingly quiet too.

If it’s cooling, the direct output should be very dry. That could cause you some stability issues with any plates you are working on in the outflow. If it’s heating, the output should be what ever the relative humidity is in your shop recalculated to the output temperature. It also could be dry until the air settles back to your shop temp. Good question.

I’ve seen folks wreck a guitar in a heatwave because the AC in their home ran continuously and dried out the air.

Hesh, do you notice any effect on the RH in the immediate locale?

I think generally that it will be used by and large mostly for heat during the winter. Seems to stay relatively cool during the summer…

If you live in a climate with moderately cold winters, most heat pumps have an auxiliary heating coil (electric resistance heat) for when the temperature is so cold that it is cheaper to make heat electrically than to extract it from the air. Unless you have a humidifier hooked into the system it makes a super dry heat. The humidity might be in the teens or single digits coming out of the ductwork. It might be a problem.

Sounds like it would be smarter to locate it somewhere else, even if it’s less convenient for the installer…

More information about this thing is needed to provide a meaningful answer. Is it an outlet for a ducted system (with or without a fan) or is it an air handler for a ductless system (also called ductless split or ductless mini-split? If it will have a big duct going into it, it is the former. If it has relatively small diameter tubes usually in something like 4" plastic channel coming into it and needs a drain, it is the latter.

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R.M. Mottola
LiutaioMottola.com

Author of the books Building the Steel String Acoustic Guitar and Mottola's Cyclopedic Dictionary of Lutherie Terms.

Thank you. The answer is that I don’t know yet…

Yes but not as much as we would have liked. As you may recall we have a new shop as of last spring and we are not in the woods just outside of Ann Arbor.

We had hoped that the heat pump would lower the RH more than it did we only saw maybe 3 - 5% RH reduction. So sadly we had to get a dehumidifier and hate the loud thing often turning it off when we are present.

OK. If this installation including both the inside air handler and the outside unit are just for the shop then this is undoubtedly a ductless split system. The air handlers in such systems take the air from the room, heat or cool it, and dump it back into the room. So when heating they do not affect humidity. Although note that temperature increase in general lowers relative humidity, regardless of heat source. In such systems the temperature differential is not that high, so local temperature and humidity effects where the thing is blowing are minimal. Personally I would not want an air handler over my bench unless the ceilings were particularly high. Unless manually controlled, when these things heat they tend to keep the louvers pointed down, which might direct the airflow directly into your face. But even a few feet away and with fan speed high, the breeze is pretty gentle. If you currently need to humidify in the winter you can expect to keep having to do this.

Ductless split air handlers do dehumidify when cooling, but they don't do such a great job. This is again because of their inherently low temperature differential. They do have a mode called "dry", which is essentially maximum cooling and lowest fan speed. Another way you can improve de-humidification is to run a small heater at the same time. But realistically if you generally have to dehumidify in the summer you may still need to do that even after this is installed.

BTW these units have ~2 square ft of dust filter and they are recirculating room air. This may be a consideration for placement if the environment is at all dusty.

_________________
R.M. Mottola
LiutaioMottola.com

Author of the books Building the Steel String Acoustic Guitar and Mottola's Cyclopedic Dictionary of Lutherie Terms.

That is somewhat disappointing, I was sort of told by the electrician that the heat pump could be an all in one system, but, the discussion was quite brief…

I have no data as to year round temp and RH fluctuations, which now seems like an oversight as that data probably could have been collected. Anyway, ceilings are 12’ and the space in question is a 25x15’ section of a 1200ft2 shed that will be very well insulated and vapor barriered and hung with 5/8 drywall. My hope is that temp and RH will be fairly easy to control. If I have to buy a dehumidifier I will, the noise doesn’t bother me as I use a lot of power tools in my work and the 5hp dust extractor will be in the RH room with 2 MERV 16 canisters and the ceiling will hold a set of 24/7 HEPA blowers so hopefully the minimal air filter on the mini split won’t be a problem….