Installing a Heat Pump in an Enclosed Room - Ventilation Requirements?

[hvac d]

I'm looking at installing a Daiken RXS15DVJU heat pump matched with a Daiken FTXS15DVJU wall mount to cool a homeowners small addition to their home. The homeowner would like to install the heat pump in a small (5'X5'X8') room. I see no problem with this so long as the room is ventilated well enough that it maintain as close to ambient temperature as possible. Any guidelines for how many CFM (or air changes per hour) I would need to accomplish this? The unit will output approximately 15,000btu.

Thanks for any help in advance.

[Zeiss Nut]

I don't even want to comment on this :rolleyes::rolleyes:

You want / can install a ventilation for a heat pump/condenser inside a room but don't / can't mount the condenser outside ! ROTFL .

Dont want to be harsh put please post the pictures of install in WOS

[hvac d]

I don't even want to comment on this :rolleyes::rolleyes:

You want / can install a ventilation for a heat pump/condenser inside a room but don't / can't mount the condenser outside ! ROTFL .

Dont want to be harsh put please post the pictures of install in WOS

Is it really that hard/difficult to believe/understand that a homeowner wouldn't/doesn't want to see/view a condensing unit/heat pump outside, but can/does want to see/view a couple louvers/grilles?:rolleyes:

Thanks for the helpful/productive response/reply.:rolleyes:

[docholiday]

so they want a dehumidifier? Do they realize that the condenser rejects more heat than the evaporator will absorb? You'd be better off not installing anything and just putting a dehumidifier in there considering your warranty is uselsss.

[hvac d]

so they want a dehumidifier? Do they realize that the condenser rejects more heat than the evaporator will absorb? You'd be better off not installing anything and just putting a dehumidifier in there considering your warranty is uselsss.

No, they want cooling. I think you missed the point...unless the heat pump was in the SAME ROOM as the evaporator, I think that the fact that the heat pump rejects more heat than the evaporator absorbs (i.e., the fact that the system is not 100% efficient) is a moot issue. They want to take heat FROM the office, and dump it outside. However, they don't want to look at the unit (the heat pump) that is dumping the heat, so they would like to conseal it in a room. To make sure the system functions, it is my job to determine how much mechanical assistance is required to bring the heat dumped into the room, outside. Is this really a wild concept?:confused:

[beenthere]

You'll need more then just louvered grilles.
You'll need to either use a fan, or turbines to make sure you have your 2000CFM for the condenser.

[hvac d]

You'll need more then just louvered grilles.
You'll need to either use a fan, or turbines to make sure you have your 2000CFM for the condenser.

I realize this. Hence why I said I'm trying to determine how many "CFM" or "Air Changes per Hour" I will need to provide via "mechanical assistance". I only mentioned louvers when describing what the homeowners will see on the exterior of the building.

[beenthere]

Did you inform him, that if there is no interlock between the exhaust fan and condenser, he'll lose the compressor, and that its not covered under warranty in that case.

[hvac d]

Did you inform him, that if there is no interlock between the exhaust fan and condenser, he'll lose the compressor, and that its not covered under warranty in that case.

Yes, I explained that there would have to be an exhaust fan that would be wired to operate whenever the compressor was running - he was fine with that. I'm currently playing phone-tag w/ an engineer at Daiken regarding their specific recommendations for air changes, and warranty issues. From what I've been told so far, there is no problem doing this "so long as the unit sees temperature that are approximately equal to ambient".

[beenthere]

Has to be wired that if the fan fails the condenser doesn't run.

[hvac d]

Has to be wired that if the fan fails the condenser doesn't run.

Similar to a combustion air setup on a boiler - gotcha.

[gplant]

I'm looking at installing a Daiken RXS15DVJU heat pump matched with a Daiken FTXS15DVJU wall mount to cool a homeowners small addition to their home. The homeowner would like to install the heat pump in a small (5'X5'X8') room. I see no problem with this so long as the room is ventilated well enough that it maintain as close to ambient temperature as possible. Any guidelines for how many CFM (or air changes per hour) I would need to accomplish this? The unit will output approximately 15,000btu.

Thanks for any help in advance.

The solution is really quite simple.

Find out the rate of CFM moved by the heat pump’s outdoor unit fan. Match or exceed that # with your ventilation.

Do take into account a few things:

1) You must provide an equal quantity of air infiltration into the room. Just one vent will result in a vacuum, and all kinds of trouble.

2) The air flow must pass sufficiently across the outdoor unit. Just putting two vents in the window at the other end of the room will do little to help.

3) Any failure on the part of the ventilation system will result in a failure of the heat pump.

4) Failing to set the outdoor unit in a location approved by the manufacturer will almost certainly void any warranty. Outdoor units are called “outdoor units” for a reason.

Hope it goes well. Be ready for call-backs.

Glenn

[beenthere]

[QUOTE=gplant;1857936]The solution is really quite simple.

Find out the rate of CFM moved by the heat pump’s outdoor unit fan. Match or exceed that # with your ventilation.

Do take into account a few things:

1) You must provide an equal quantity of air infiltration into the room. Just one vent will result in a vacuum, and all kinds of trouble.


Need to move more air then the condenser.
you have to move enough air through the room to keep the room temp down also.

[wogpa67]

put a ptac in or use a through the wall condensor very simple

[hvaclover]

Be intersting to see if exfiltration becomes an issue if the structure is attached to the home.

2000cfm is equal to a five ton airflow.

[cmajerus]

is this room existing or something to be built? If it is not built yet, why not use a lattice type wall so it is hidden and still open to ambient. It will probably work great for heat pump operation inside like that, but to add an exhaust fan that runs on straight AC current to a inverter type minisplit makes the inverters electrical savings kinda null.

[beenthere]

Be intersting to see if exfiltration becomes an issue if the structure is attached to the home.

2000cfm is equal to a five ton airflow.
That would be air flow for teh evap. The condenser uses more air flow. It also has to eject the heat of the compressor.
Now with this being in a shed, he has to move enough outdoor unconditioned air to cool the shed also.

[hvaclover]

That would be air flow for teh evap. The condenser uses more air flow. It also has to eject the heat of the compressor.
Now with this being in a shed, he has to move enough outdoor unconditioned air to cool the shed also.

OP stated a room 5x5x8. Sounds to me like it is attached to the home.

Let him clearify if otherwise.

[beenthere]

Post number 5 makes it pretty clear.

However, they don't want to look at the unit (the heat pump) that is dumping the heat, so they would like to conseal it in a room.

[hvaclover]

Reread it. Still mentions the room. What I said.

[beenthere]

Yes, it mentions an office that they want to cool, and a room to conceal the condenser because they don't want ot see it.

From post #3
Is it really that hard/difficult to believe/understand that a homeowner wouldn't/doesn't want to see/view a condensing unit/heat pump outside, but can/does want to see/view a couple louvers/grilles?

[hvaclover]

Yes, it mentions an office that they want to cool, and a room to conceal the condenser because they don't want ot see it.

From post #3
Is it really that hard/difficult to believe/understand that a homeowner wouldn't/doesn't want to see/view a condensing unit/heat pump outside, but can/does want to see/view a couple louvers/grilles?

You are repeating what I posted.

[beenthere]

He's not air conditioning the room. he's cooling the office.

[hvaclover]

He's not air conditioning the room. he's cooling the office.

Why are you changing the subject?

[acmanhoney]

just do thru the wall style instead of rigging and hoping

[souper phly]

If your going to void the warranty anyway, why not remove the cfm, attach a duct to the top of the condenser and use a centrifugal type blower to exaust the air directly outdoors. Then add makeup air grills low on the wall for fresh air.

[hvac d]

The "room" the heat pump is going to be installed in is a sealed 5'X5'X8' room within the Garage below the office. The room will be ventilated via a Greenheck CSP-A1750 pulling air into the room via a 30"X30" louver (this fan will also blow air directly into the Daiken heat pump). Another 30"X30" louver will be installed to allow the air to escape the space.

I already priced this and sent it off the the homeowner. One price to install the heat pump outside - another to do the aforementioned interior setup. The homeowner can decide if the additional cost is worth not seeing the heat pump or not.

This was all approved by Daiken - warranty will still be good. Thanks for the help guys.:)

[hvaclover]

The "room" the heat pump is going to be installed in is a sealed 5'X5'X8' room within the Garage below the office. The room will be ventilated via a Greenheck CSP-A1750 pulling air into the room via a 30"X30" louver (this fan will also blow air directly into the Daiken heat pump). Another 30"X30" louver will be installed to allow the air to escape the space.

I already priced this and sent it off the the homeowner. One price to install the heat pump outside - another to do the aforementioned interior setup. The homeowner can decide if the additional cost is worth not seeing the heat pump or not.

This was all approved by Daiken - warranty will still be good. Thanks for the help guys.:)

That's works for me. We used to set up super market racks in mechanical rooms with monsterous prop fan blades and louvers and it was satfactory for
for tons of air-cooled low and med temp condensers.

[cmajerus]

The "room" the heat pump is going to be installed in is a sealed 5'X5'X8' room within the Garage below the office. The room will be ventilated via a Greenheck CSP-A1750 pulling air into the room via a 30"X30" louver (this fan will also blow air directly into the Daiken heat pump). Another 30"X30" louver will be installed to allow the air to escape the space.

I already priced this and sent it off the the homeowner. One price to install the heat pump outside - another to do the aforementioned interior setup. The homeowner can decide if the additional cost is worth not seeing the heat pump or not.

This was all approved by Daiken - warranty will still be good. Thanks for the help guys.:)

that will work, wonder if it would be better to suck in through the louver and just exhaust with the fan though?

We cool the local cable tv substation with all the recievers in it in the winter with a 12x12 intake louver and 12x12 prop fan. Saves running the 10 tons of cooling any time its below 30 degrees.

[hvac d]

that will work, wonder if it would be better to suck in through the louver and just exhaust with the fan though?


I don't think so. Having the fan blow ambient air directly at the heat pump will ensure that the heat pump will always have the coolest air possible. Remember, I technically don't care about the temperature of the room - I care about the temperature of the air directly around the heat pump.

[beenthere]

Is this mini, one of the inverter ones. If so, blowing the air directly at it, could be detrimental, when it wants less air flow.

Drawing the air through the room, would allow the mini to use the air flow it needs.

[hvac d]

Is this mini, one of the inverter ones. If so, blowing the air directly at it, could be detrimental, when it wants less air flow.

Drawing the air through the room, would allow the mini to use the air flow it needs.

Yes, it's an inverter unit. When the unit is in cooling mode, when could it possibly want less airflow (this is not a "true" office space - only a "home office", i.e., it will not be run when ambient temperatures are below 60 degrees)? I understand that at some given times it will need less, but how could more airflow than it "needs" actually be detrimental?:confused:

[beenthere]

You might think it won't be used when it 60 out. But many home offices that have seperate units from the rest of the house are used at 60.

Inverter units slow down as the load drops. In order to keep the head up. If air is being forced through it, the head will drop, shutting it off on on LP. Then the guy won't have A/C.

[paul42]

The simple answer to that is to add a thermostat to the blower and shut it off anytime the temperature drops below whatever temperature makes sense.