How would you cool this space?

[paul_h]

3 rd floor office in a multi level building, so ceiling is concrete slab
They have an underceiling hitachi PR5HMK that is 30 years old. It's blows into a plaster board bulkhead that feeds into two registers.
The a/c still works as good as it could, they just think the thermostat is just a little iffy.

I would install a new thermostat, (quoted them on that years ago), but probably a waste of money as they need something better.
Maybe the t/stat wouldn't be a waste of time as they could use the same t/stat if they bought an australian made ducted system and mounted where the under ceiling unit is now if this a/c eventually dies in a few years, (they come without t/stat and use the same type as I'd try installing anyway).

Room is 6m x 8m. Existing condenser unit it one level up, on the roof.

office.png

Assuming they don't want to replace the unit, what could I say to them?

[RSTC]

if they don't want to invest in a new thermostat then what's the chance in them investing in anything else?

Ask them what do they intend investing in the system before going any further. Without knowing that you are working in a vacuum and may end up costing yourself alot of time and effort for very little return

They may wish to keep the system which is fair enough: (if it ain't broke, etc) but after 30 years it's doesn't owe them anything.

Point out that the current system is costing them $xxx per year and not preforming (eg if it's $2000 pa, so for 15 year life span that $30K) and a new system will be preforming properly and have a higher COP so will save them $y dollars per year (eg $500 pa is €7500 over the life of the machine)

BTW how is the return air getting back to the machine?

[al]

Would they go with a ducted unit, would the PR5 be about 12KW? If so an inverter 10kw would suffice, strength test the pipe work and go for replace technology to reuse pipe work?

But as RTSC says, see is there a budget!!

al

[paul_h]

BTW how is the return air getting back to the machine?

Though the door to the store room which is left open

[Magoo]

Hi Paul.
if they won't spend money on a new stat, what do they expect. But if ceiling is concrete exposed slab use that as a heat sink and purge outside air overnight. The concrete slab becomes a great source of cooling during the day

[SeanB]

Also check if you can get the roof painted silver, so that there is less heat load thorough the slab. That will make the room more comfortable, as the radiated heat from the slab in the afternoon will be less. This cost will be probably repaid in a year from reduced cooling costs.