Grunaire Mini-split

I've ordered a mini-split which I'm going to install myself. I will have someone show up with the vacuum and gauges for the final test but other than that I'm doing all the grunt work.

Couple questions:

#1. Has anyone put a outdoor condenser into a crawlspace? I understand the condensation issue off the heat exchanger and my crawlspace is completely encapsulated with 24mil plastic up to the sill plate. I have drainage and a sump pump so the condensate will drain right into the sump basin.

The reason I'm looking at this route is because the crawl maintains a temp that is a good 10-15 deg. F warmer than the outside air during heating season. The temp is largely controlled by the ground temp. I have good temp & RH readings from the crawlspace for the last year and I know that the heat pump will drop the temps a couple degrees but overall.... I should maintain much more efficient operation.

#2. If anyone has the process for the final checkout on the Grunaire units I'd be appreciate the help. I want to make sure the guy I hire does it right.

Model # GSI121HX Indoor Unit
GSU121HX Outdoor Unit

Quote:

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Originally Posted by kevperro

I've ordered a mini-split which I'm going to install myself. I will have someone show up with the vacuum and gauges for the final test but other than that I'm doing all the grunt work.

Couple questions:

#1. Has anyone put a outdoor condenser into a crawlspace? I understand the condensation issue off the heat exchanger and my crawlspace is completely encapsulated with 24mil plastic up to the sill plate. I have drainage and a sump pump so the condensate will drain right into the sump basin.

The reason I'm looking at this route is because the crawl maintains a temp that is a good 10-15 deg. F warmer than the outside air during heating season. The temp is largely controlled by the ground temp. I have good temp & RH readings from the crawlspace for the last year and I know that the heat pump will drop the temps a couple degrees but overall.... I should maintain much more efficient operation.

#2. If anyone has the process for the final checkout on the Grunaire units I'd be appreciate the help. I want to make sure the guy I hire does it right.

Model # GSI121HX Indoor Unit
GSU121HX Outdoor Unit

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Do you propose also to use this for cooling in the summer, if so re-think the location of the Out door unit.
For the heating mode it might be advantageous but it will have an adverse effect when in the cooling mode.

I think what you are planning (fitting your own equipment) would be illeagal in Europe with out the correct ticket, but i don't know what the laws are where you live.

I can see that the crawl space area now has a pretty constant temperature but, once you try putting in or taking out x amount of btu's an hour things may well change. a friend was telling me of a system he worked on that used a moat around a house as a source of heating and cooling for a heatpump, in the winter the moat was soon cooled down and the heatpump became inoperable for about 4 months when it was needed most.
You may be better siting the unit in a situation the manufactures invisaged when they designed the unit.

There may be 3-5 days per year where we actually would use an AC. It is primarily for heating but I guess I don't understand why it wouldn't be advantageous for cooling too? Not that it matters.... there is only a couple days a year where we would actually run in cooling mode.

Quote:

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Originally Posted by monkey spanners

I think what you are planning (fitting your own equipment) would be illeagal in Europe with out the correct ticket, but i don't know what the laws are where you live.

I can see that the crawl space area now has a pretty constant temperature but, once you try putting in or taking out x amount of btu's an hour things may well change. a friend was telling me of a system he worked on that used a moat around a house as a source of heating and cooling for a heatpump, in the winter the moat was soon cooled down and the heatpump became inoperable for about 4 months when it was needed most.
You may be better siting the unit in a situation the manufactures invisaged when they designed the unit.

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Sure... I would agree but I can calculate the number of BTUs per hour that the ground is capable of contributing and I have active venting for the crawlspace that I can control with fans and a micro-controller. I can literally re-write the code and change the outside air contribution. Right now it is designed to minimize inside air RH. It also won't circulate outside air into the crawl if the outdoor temp drops below 40 deg. F.

I'm in the USA and we like to be slightly illegal. Otherwise you never never have any fun.

If you are confident that the unit will be able to get enough or get rid of enough heat, depending on mode of operation to work then the only thing i would say is try and find a tech who will comission it for you there before you site it, just incase the don't like the idea and won't touch it. ( i am basing this on an American fridge forum i have visited, and the attitudes displayed there to diy installs)

Good luck with your install.

Jon :)

Quote:

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Originally Posted by monkey spanners

If you are confident that the unit will be able to get enough or get rid of enough heat, depending on mode of operation to work then the only thing i would say is try and find a tech who will comission it for you there before you site it, just incase the don't like the idea and won't touch it. ( i am basing this on an American fridge forum i have visited, and the attitudes displayed there to diy installs)

Good luck with your install.

Jon :)

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I would imagine the heat exchange between ground and air is just a matter of getting enough surface area into the act. Ground to air heat exchangers are used for passive cooling/heating of air and looking at a quick Google search... most of them are using 100-500ft sections of buried pipe. While I could rent a small excavator and bury some PVC I'm not going that far with the idea. It quickly doubles the project cost to bury 100ft of PVC.

Our temps are mild year around so even if I have to pull outside air our average winter temp is 35-38 deg. F. If I pull that in from the outside the only concern is getting condensation of pipes and other surfaces. If that occurred... I'd be moving the outside unit outside and you guys could tell me "I told you so".

I'm thinking of just buying my own equipment and doing it myself. If a local guy won't touch it I'll do it myself.

I came across a potential problem for your setup some years ago.

The link below shows the thread and there is a photo which might be of interest.

http://www.refrigeration-engineer.co...ead.php?t=4229

Quick calc of these heat exchangers..... if they use 12" pipe 200ft long that is roughly 89,000 in^3. My crawlspace has 144,000 in^3 on the floor and the walls are probably another 37,000 in^3. You wouldn't get near as good of heat transfer as you would in a pipe with airflow through it because areas of the crawl space would be stagnant..... but the greater area would help. Average ground temp in heating season should be around 50 deg F. Average outside air temp is in the 37-38 deg. F range. So.... it should at least add some warming contribution with a corresponding greater heat loss through the floor.

[quote=Brian_UK;194272]I came across a potential problem for your setup some years ago.

The link below shows the thread and there is a photo which might be of interest.


Yea.... that would definitely be a problem. Our climate is extremely mild year around but I imagine if you had enough capacity.... you could easily get temps in the crawl below freezing. I think you would have to design it so that you exit that cooled air out. In our climate you could never get the ground cold enough to do that but you could freeze pipes so it is a legit concern.

I could monitor crawl temps with a sensor and have a fan kick-on to ventilate the crawl once it reached a given temp. I could also stop the heat pump if it reached a critical value. That is obviously counter productive but it would be a fail-safe mechanism.

The unit is only a 1 ton unit and with our mild temps.... I think it will never occur but it is worth planning around.