Novel application for a Daikin FTXS 25 R410A split system

[hunter gatherer]

Hi All,

New to the forum, having lurked for a while...

I've got a client who has installed a Daikin FTXS 25 R410A split system in a insulated vegetable storage room on their market garden / roadside store. It's a smallish store, around 6x6x3m, and has 100mm of polystyrene insulation in the walls. It has a vapour resisting coating (bathroom paint!) on the inner surface.

The unit was installed by someone who failed to appreciate the target temperature was lower than the min setpoint of the unit (18 deg C). It seems that the off coil temperature the unit can achieve is around 7 deg C, so theoretically, it should be possible to get down to maybe 8 deg C, although possibly not if it's being accessed regularly. I've said I'll have a think about whether it can be used or not, and I've come up with some questions I'd like to get an opinion on from the community here.

So, my questions are:

Could the thermostat be adjusted to give a lower room setpoint? If so, what level of knowledge would be required to make the adjustment?
If the above is not possible, could the thermostat be fooled into thinking it's warmer than it is, and forced to overshoot to get down below 10 deg C in the room? Would a small resistive heater (torch bulb perhaps) connected to a room thermostat that turns on at around 10 deg C and cuts out at 8 deg C do the job? I think you could install it so as to give a false reading on the indoor unit's sensor.
I've read that for cold stores, acidity in the air from ripening of produce can cause premature coil failure. The unit in question has a copper coil. Does anyone have an opinion as to whether in-situ application of PU or Silane anti-corrosion treatments are required / possible for this unit type?
What about condensation removal? Should there be additional ventilation to the space. I think a domestic HRV type unit might be applicable.
What are people's experience with the plastic door curtains. Any good ideas on how to increase their effectiveness?


I'm sure the above would void the warranty on the unit, but as it's installed, I said I'd see if there was a way to make use of it...

Hope this makes sense, and this is the correct place to post it.

Go easy on me, I'm a first timer!

Cheers :D

[mad fridgie]

No warranty!
But the out door unit inside the room, but the indoor unit outside the room, set the the controller to heat pump cycle. Fit thermostat control to main incoming power and set control to auto reset.
And it looks way to small to do the job
Advice Rip it out and do the job correctly

[paul_h]

Who is making fridges on r410a?
Split systems aren't designed to get that cold. In fact, split system's only designed as comfort coolers for people set to over 20C and that's it! Even below 20C they run like crap (possible icing up, heaps of mold and mildew growth)
That system capacity is only suited to high temps for the room size anyway.

edit: Split systems used to have a full 5 yr warranty here, but because of stuff like this, many manufacturers have reduced it to a 1-2yr for commercial usage, ie many using it for server or comms rooms, or cooling products and chemicals to 18C.
Screws up businesses using them for the intended purpose and not abusing them for a non intended use. I wish splits were harder to get and install, for this reason and the DIY-ers and cowboy installers.
If you want a coolroom, get a refrig unit. It's not like drop in refrig cassette or slide in units aren't available. The prevalence of splits with the ignorance of end users or cowboys is a problem. They want to go to a retailer and buy a split, then get some cowboy to install it, rather than speak to a fridgy first for solutions.

[monkey spanners]

Its unlikely to work in a satisfactory manor and experience with this type of customer, the ones dumb enough to have agreed the original install is that you will be the biggest sh!t on the planet for trying to get it to.

Get the system sized by the wholesaler to see what duty it should have for the room and product loading, then compare this to what the existing system is capable of.

Fins too close, no defrosts, not designed to go that low, not enough air throw, air filter will block up very frequently, :eek::confused:

Don't touch anything without money up front.

The fact that the previous company were idiots isn't your problem, if they want their product cool then they need to pay up or pack up.

Also have a listen here,

http://www.youtube.com/watch?v=fjFzUVCQ1vM&feature=related

MS :)

[r.bartlett]

No warranty!
But the out door unit inside the room, but the indoor unit outside the room, set the the controller to heat pump cycle. Fit thermostat control to main incoming power and set control to auto reset.
And it looks way to small to do the job
Advice Rip it out and do the job correctly

Sounds good until a hot summer and then the thing won't run on heat..

[al]

there was a thread some time ago on an american company utilising splits for fruit and veg/potato storage, consists of a thermostat mounted to control the unit to room temps of about 6 to 8, they've been doing it for a number of years, was looking at it myself for beer rooms....

alec

[climarm]

there is a little trick .... strech your ears .....
you could try this but i am not sure if it is going to work ,, but it worths to be tested ....
1-turn the power off and unplug the power cable ... (safety first)
2-open the indoor unit and find in the indoor pipes the thermistor
3- cut the thermistor's wire and tranfer the thermistor with a new longer wire at a corner of the room .
(so it can take measurements from another spot in the room)
this could drop the temperature enough , but i am not sure if it works , because the thermistors work with Ω and as much longer the cable is , so much bigger the Ω rate is......
quick and cheap solutions from greece .

[r.bartlett]

6424

Here's a cheap split we modified back last year for a house cool room. The temps is set at 10c and it works fine.
Remove any controls from the unit. Wire a simple fridge control panel with the indoor fan on hi at all times. Wire the outdoor unit through the controller. This was as we'd just got it running. his handy man was going to box in the pipes etc..

Make sure there are plenty of defrost cycles and you're good to go


We used a std R407c system., Avoid inverters and fancy controls as they will inhibit the operation and it's unlikely to ever work

[r.bartlett]

there is a little trick .... strech your ears .....
you could try this but i am not sure if it is going to work ,, but it worths to be tested ....
1-turn the power off and unplug the power cable ... (safety first)
2-open the indoor unit and find in the indoor pipes the thermistor
3- cut the thermistor's wire and tranfer the thermistor with a new longer wire at a corner of the room .
(so it can take measurements from another spot in the room)
this could drop the temperature enough , but i am not sure if it works , because the thermistors work with Ω and as much longer the cable is , so much bigger the Ω rate is......
quick and cheap solutions from greece .


Not a solution in any way shape or form..!
The std controller is 18 c for cooling. he want's the room at 8 c. Which little corner of the room is going to make 10 c difference. Then you have icing problems etc etc

[paul_h]

I've seen the condition of units used at 18 or 16C, full of mold in the coil and on and around the fan resulting in poor airflow. Would be even worse if no one cleaned the filters.
I'm surprised you'd do such an install, using a split a/c for a 10C room.
Though would be a money spinner for all the maintenance it needs I guess...

[r.bartlett]

I've seen the condition of units used at 18 or 16C, full of mold in the coil and on and around the fan resulting in poor airflow. Would be even worse if no one cleaned the filters.
I'm surprised you'd do such an install, using a split a/c for a 10C room.
Though would be a money spinner for all the maintenance it needs I guess...

Nope sorry no maintenance costs as he's never had an issue with it. I did the same years ago to an old Fujitsu window rattler -and apart from it being slightly too small duty wise (it struggled in summer) in the 3 years it was there we never had a moments problem with that one either..

[hunter gatherer]

Wow! Thanks for all the useful information guys.

@mad fridgie - I agree it seems small. I've yet to get round to a heat loss estimate for a summer time peak of 30 deg C - it doesn't get much hotter than that this far South.

@paul_h - What drop-in / slide-in refrig units have you got good experience with for this application?

@al - couldn't find that thread. Any idea where it might be?

@climarm - As r.bartlett says, pretty sure that wouldn't work, as I want lower than the 18 deg C set point, across the space.

@r.bartlett - That's something like the sort of suggestion that I'd hoped for when posting. Some great pointers! Can you suggest a schematic for the control panel? Did you use a proprietary system? I'd want to include a strategy that says 'turn it off and open the doors when external temps are lower than the set point'.

@paul_h - do you have specific experience of maintaining these units. How easy would it be to introduce a regime for the owners to pull off the fascia and brush the coil regularly to help reduce maintenance intervals. They are quite a proactive lot!

@r.bartlett - was there much moisture in the space originally?

I've also been considering management strategies / fabric modifications that would improve the viability such as air drying produce before introducing it to the space, the HRV unit I mentioned originally, and also increasing the thermal mass externally to reduce diurnal variation with say a 50mm slab above and to the sides, and an insulated slide door for when the room is not being accessed.

Thanks again for the responses. What a great community!

[al]

This is the thread, company is www.storeitcold.com

http://www.refrigeration-engineer.com/forums/showthread.php?28407-Turn-your-window-shaker-into-a-walk-in-cooler&highlight=window%20unit

Alec

[hunter gatherer]

BUMP! Any more answers to my follow-up questions guys? Cheers al for your response...


Wow! Thanks for all the useful information guys.

@mad fridgie - I agree it seems small. I've yet to get round to a heat loss estimate for a summer time peak of 30 deg C - it doesn't get much hotter than that this far South.

@paul_h - What drop-in / slide-in refrig units have you got good experience with for this application?

@al - couldn't find that thread. Any idea where it might be?

@climarm - As r.bartlett says, pretty sure that wouldn't work, as I want lower than the 18 deg C set point, across the space.

@r.bartlett - That's something like the sort of suggestion that I'd hoped for when posting. Some great pointers! Can you suggest a schematic for the control panel? Did you use a proprietary system? I'd want to include a strategy that says 'turn it off and open the doors when external temps are lower than the set point'.

@paul_h - do you have specific experience of maintaining these units. How easy would it be to introduce a regime for the owners to pull off the fascia and brush the coil regularly to help reduce maintenance intervals. They are quite a proactive lot!

@r.bartlett - was there much moisture in the space originally?

I've also been considering management strategies / fabric modifications that would improve the viability such as air drying produce before introducing it to the space, the HRV unit I mentioned originally, and also increasing the thermal mass externally to reduce diurnal variation with say a 50mm slab above and to the sides, and an insulated slide door for when the room is not being accessed.

Thanks again for the responses. What a great community!