small water chiller & diversity factor

[r.bartlett]

Chaps

we're looking at swapping out an old 10kw water chiller . Client suggests it's been wrong since installed and was told it was 'way oversized'. Our investigations suggest it's sized for the fan coils but not the 16a fuse rating.!

anyhoo there are 3 fan coils,

bedroom 1= 2kw
lounge =5kw
second bed 3.5kw

The chiller size would have been spec'ed by the architect or builder as a 100% matched load/demand .

BUT we size ac over here for expected load and on such a multi 10kw DX use a 7kw outdoor (2 x bedrooms OR lounge running). Never have a problem.

would the panel suggest or fit a downsize to 7kw chiller would be acceptable. Remember this isn't an office all on/off type environment so load differs according to time. Client said he never uses bed 2 in any case but I'm not counting on that . He doesn't rent so there isn't the usual holiday makers abuse happening either.

we can only fit a new outdoor chiller as the building is impossible to retro a complete new multi so that's a non starter.

[Brian_UK]

I've forgotten where you are based now but would an air to water heat pump be of any use or is there no need for winter heating?

Sorry, in answer to your question I would go for the 7kW.

[chemi-cool]

Chillers hardly run on full capacity.
Capacity is based on certain in and out temp so when the water temp is higher then in and out temp, capacity rises and vise verse.
A 7 KW will have no problem controlling the temp in the rooms.

[frank]

Easy way to tell if the unit is oversized, but only if it is in working condition.

Wait for a hot day (max load), run the unit, fan coils on full cooling, and then measure the water temp difference (flow and return). Q = m c (t1-t2). If you have less than 6K diff then the unit is over sized.

With a 10kW chiller, I would assume around 0.39 l/s flow rate.

[hookster]

I would retain the 10Kw chiller as this is then capable of doing the full duty required from end of June to October.
Have a look at the piping flow & return, I would guess chiller problems were due to insufficient flow.
Select your new chiller with integrated tank and pump, readily available in 10Kw size. This will then have some thermal buffer inbuilt.

On your flow and return to chiller put in a bypass loop and use this to maintain chiller rated flow.

[r.bartlett]

I've forgotten where you are based now but would an air to water heat pump be of any use or is there no need for winter heating?

Sorry, in answer to your question I would go for the 7kW.
Tenerife, Little need for heating although we have had an unusually cold winter

[r.bartlett]

I would retain the 10Kw chiller as this is then capable of doing the full duty required from end of June to October.
Have a look at the piping flow & return, I would guess chiller problems were due to insufficient flow.
Select your new chiller with integrated tank and pump, readily available in 10Kw size. This will then have some thermal buffer inbuilt.

On your flow and return to chiller put in a bypass loop and use this to maintain chiller rated flow.


as I say problems were fuse rating not chiller rating or flow.

[r.bartlett]

Easy way to tell if the unit is oversized, but only if it is in working condition.

Wait for a hot day (max load), run the unit, fan coils on full cooling, and then measure the water temp difference (flow and return). Q = m c (t1-t2). If you have less than 6K diff then the unit is over sized.

With a 10kW chiller, I would assume around 0.39 l/s flow rate.

non operating hence the need to change. :-)

[r.bartlett]

15117this is the unit in question.